Title: Decomposition of 2-Pyrazolines
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 Material Information
Title: Decomposition of 2-Pyrazolines
Physical Description: x, 79 l. : illus. ; 28 cm.
Language: English
Creator: Sanderfer, Paul Otis, 1937-
Publisher: s.n.
Place of Publication: Gainesville
Publication Date: 1965
Copyright Date: 1965
 Subjects
Subject: Pyrazolines   ( lcsh )
Chemistry thesis Ph. D
Dissertations, Academic -- Chemistry -- UF
Genre: bibliography   ( marcgt )
non-fiction   ( marcgt )
 Notes
Thesis: Thesis - University of Florida.
Bibliography: Bibliography: l. 76-78.
Additional Physical Form: Also available on World Wide Web
General Note: Manuscript copy.
General Note: Vita.
 Record Information
Bibliographic ID: UF00097910
Volume ID: VID00001
Source Institution: University of Florida
Holding Location: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: alephbibnum - 000423941
oclc - 11035122
notis - ACH2346

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DECOMPOSITION OF 2-PYRAZOLINES























By
PAUL OTIS SANDERFER










A DISSERTATION PRESENTED TO THE GRADUATE COUNCIL OF
THE UNIVERSITY OF FLORIDA
IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE
DEGREE OF DOCTOR OF PHILOSOPHY











UNIVERSITY OF FLORIDA


August, 1965











ACKNOWLEDGMENTS


The author wishes to extend his thanks to his research

director, Dr. W. M. Jones, for his invaluable guidance and encourage-

ment throughout the progress of this work and the preparation of this

dissertation. He wishes also to thank the other members of his com-

mittee, Dr. G. B. Butler, Dr. W. S. Brey, Dr. J. F. Helling and Dr.

T. O. Moore, for their kind assistance.

Special thanks go to the author's wife, Miriam, for typing

this dissertation and for having the patience and understanding which

made this task so much easier.

The National Science Foundation provided a portion of the

financial assistance for this research.












TABLE OF CONTENTS


Page

ACKNOWLEDGMENTS . . . . . . . . .. . . ii

LIST OF TABLES . . . . . . . . . . viii

LIST OF FIGURES . . . . . . . . ... . .ix

Section

I. INTRODUCTION . .. . . . . . ... .. 1

II. INSTRUMENTATION AND TECHNIQUE . . . . ... 12

III. RESULTS AND DISCUSSION . . . . . . .. 17

IV. SUMMARY ........................ 44

V. EXPERIMENTAL . . . . . . . .... . .46

General procedure followed for the melt and
solution decompositions used for the
stereochemical studies . . . . ... .46

Preparation of ethyl diazoacetate . . .. 47

Preparation of 4-phenyl-3,5-dicarboethoxy-
2-pyrazoline . . . . . . . ... 49

Preparation of methyl glycinate hydrochloride 49

Preparation of methyl diazoacetate . . ... 49

Preparation of 4-phenyl-3,5-dicarbomethoxy-
2-pyrazoline . . . . . . . . 50

Preparation of 4-phenyl-3,5-dicarboisopropoxy-
2-pyrazoline . . . . . . . ... 50

Preparation of phenyldiazomethane . . ... 51











TABLE OF CONTENTS (Continued)


Section Page

V. EXPERIMENTAL (Continued)

Preparation of cis-5-phenyl-3,4-dicarbomethoxy-
2-pyrazoline . . . . . . . ... 51

Preparation of trans-5-phenyl-3,4-dicarbo-
methoxy-2-pyrazoline . . . . . ... 51

Preparation of trans-5-phenyl-3,4-dicarbo-
butoxy-2-pyrazoline . . . . . ... 52

Preparation of 4-phenyl-3-carbomethoxy-5-
carboethoxy-2-pyrazoline . . . . .. 52

Preparation of 4-phenyl-3-carboethoxy-5-
carbomethoxy-2-pyrazoline . . . ... 53

Preparation of benzophenone hydrazone . . .. .54

Preparation of diphenyldiazomethane ...... .54

Preparation of 5,5-diphenyl-3,4-dicarbomethoxy-
2-pyrazoline . . . . . . . ... 55

Preparation of 5,5-diphenyl-3-carbomethoxy-
2-pyrazoline . . . . . . . . . 55

Preparation of 4,4'-dimethylbenzophenone
hydrazone . . . . . . . ... 56

Preparation of 4,4'-dimethyldiphenyldiazomethane 57

Preparation of 5,5-(4,4'-dimethyldiphenyl)-3,4-
dicarbomethoxy-2-pyrazoline . . . . 57

Preparation of 5,5-(4,4'-dimethyldiphenyl)-3-
carbomethoxy-2-pyrazoline . . . ... 58

Preparation of 4-methylbenzophenone ...... .59

Preparation of 4-methylbenzophenone hydrazone . 59










TABLE OF CONTENTS (Continued)


Section Page

V. EXPERIMENTAL (Continued)

Preparation of phenyl-p-tolyl-diazomethane . . 60

Preparation of 5-(4-methylphenyl)-5-phenyl-
3,4-dicarbomethoxy-2-pyrazoline . . ... 61

Preparation of 5-(4-methylphenyl)-5-phenyl-
3-carbomethoxy-2-pyrazoline . . . ... 61

Preparation of 1,1-(4,4'-dichlorodiphenyl)-
2,2-dichloroethene . . . . . .... 62

Preparation of 4,4'-dichlorobenzophenone .... .62

Preparation of 4,4'-dichlorobenzophenone
hydrazone . . . . . . . .... .63

Preparation of 4,4'-dichlorodiphenyldiazomethane 64

Preparation of 5,5-(4,4'-dichlorodiphenyl)-3,4-
dicarbomethoxy-2-pyrazoline . . . ... .65

Preparation of 5,5-(4,4'-dichlorodiphenyl)-3-
carbomethoxy-2-pyrazoline . . . ... 65

Preparation of 5,5-(4,4'-dimethyldiphenyl)-3,4-
dicarbomethoxy-l-acetyl-2-pyrazoline .... .66

Preparation of 5,5-(4,4'-dimethyldiphenyl)-3-
carbomethoxy-l-acetyl-2-pyrazoline . . .. .66

Preparation of 5-phenyl-5-p-tolyl-3,4-dicarbo-
methoxy-l-acetyl-2-pyrazoline . . ... .67

Preparation of 5-phenyl-5-p-tolyl-3-carbo-
methoxy-l-acetyl-2-pyrazoline . . ... .67

Preparation of 5,5-(4,4'-dichlorodiphenyl)-3,4-
dicarbomethoxy-l-acetyl-2-pyrazoline .... .68











TABLE OF CONTENTS (Continued)


Section Page

V. EXPERIMENTAL (Continued)

Preparation of 5,5-(4,4'-dichlorodiphenyl)-3-
carbomethoxy-l-acetyl-2-pyrazoline . . .. .68

Isolation of 2,2-diphenyl-cyclopropane-
carboxylic acid . . . . . . ... 69

Isolation of 2-phenyl-2-p-tolyl-cyclopropane-
carboxylic acid . . . . . . ... 69

Isolation of 2,2-(4,4'-dimethyldiphenyl)-cyclo-
panecarboxylic acid . . . . . .. 69

Isolation of 2,2-(4,4'-dichlorodiphenyl)-cyclo-
propanecarboxylic acid . . . . ... .70

Isolation of 3,3-(4,4'-dimethyldiphenyl)-l,2-
dicarbomethoxycyclopropane . . . ... .70

Isolation of 3,3-diphenyl-l,2-dicarbomethoxy-
cyclopropane . . . . . . .... .70

Isolation of 3,3-(4,4'-dichlorodiphenyl)-l,2-
carbomethoxycyclopropane . . . . .. 71

Isolation of 3-phenyl-3-p-tolyl-l,2-dicarbomethoxy
cyclopropane . . . . . . . ... 71

Preparation of 4-phenyl-3-carboethoxy-5-carbo-
methoxy-l-acetyl-2-pyrazoline . . ... 71

Preparation of 4-phenyl-5-carboethoxy-3-carbo-
methoxy-l-acetyl-2-pyrazoline . . ... .72

Partial decomposition of 4-phenyl-3-carboethoxy-
5-carbomethoxy-2-pyrazoline . . . ... 73

Partial decomposition of 4-phenyl-5-carboethoxy-
3-carbomethoxy-2-pyrazoline . . . ... 73










TABLE OF CONTENTS (Continued)


Section Page

V. EXPERIMENTAL (Continued)

Purification of the nitrogen gas bubbled
through the hexadecane prior to a kinetic
run . . . . . . . . . ... 74

Preparation of Fieser's solution . . . ... 74

Preparation of the metal ketyl of benzophenone
and sodium . . . . . . . ... 74

Purification of hexadecane . . . . ... .75

Purification of methyl acrylate, tri-n-propyl-
amine, triethylamine, triisoamylamine and
dimethyl maleate . . . . . . ... 75

LIST OF REFERENCES . . . . . . . . ... .. .76

BIOGRAPHICAL SKETCH . . . . . . . . ... ... 79











LIST OF TABLES


Table Page

1. Percent of the Cis-Isomer (Two Ester Groups Cis)
Resulting from the Thermal Decomposition of
Selected 2-Pyrazolines in Tetraglyme and in
the Melt . . . . . . . .... . 10

2. Rates of Decomposition of 5,5-Diaryl-3,4-Dicarbo-
methoxy-2-Pyrazolines in Hexadecane ...... .23

3. Rates of Decomposition of 5,5-Diaryl-3-Carbomethoxy-
2-Pyrazolines in Hexadecane . . . . .. 24

4. Data Calculated from the Plot of kobs. Versus Base
obs.
Concentration for XI-XVIII . . . . .. 31

5. Comparison of the Observed Rate Constants between Like
Members of the Two Series of Compounds .... .34

6. Rates of Decomposition of 4-Phenyl-3-Carboethoxy-5-
Carbomethoxy-2-Pyrazoline in Hexadecane .... .41


viii











LIST OF FIGURES


Figure Page

1. Route of Addition of Diazomethane to 0(, B Unsatu-
rated Carbonyl Compounds . . . . . . 1

2. Suggested Path for the Decomposition of Three
2-Pyrazolines . . . . . . . . 4

3. Photograph of the Kinetic Reaction Vessel Showing
the Nitrogen Bubbler and the Pellet-Dropping
Assembly .. . . . . . . .... 13

4. The First-Order Plot of the Data Obtained from the
Decomposition of 1.87 x 10-3 Mole of 5,5-(4,4'-
Dimethyldiphenyl)-3-Carbomethoxy-2-Pyrazoline
in the Presence of 2.11 x 103 Mole of Tri-n-
propylamine in 50 ml. of Hexadecane at 1350 .. 19

5. The First-Order Plot of the Data Obtained from the
Decomposition of 2.59 x 10-3 Mole of 5,5-(4,4'-
Dichlorodiphenyl)-3-Carbomethoxy-2-Pyrazoline
in the Presence of 2.11 x 10-3 Mole of Tri-n-
propylamine in 50 ml. of Hexadecane at 135 . 20

6. The First-Order Plot of the Data Obtained from the
Decomposition of 2.0 x 10-3 Mole of 5,5-
Diphenyl-3,4-Dicarbomethoxy-2-Pyrazoline in
the Presence of 2.11 x 10~- Mole of Tri-n-
propylamine in 50 ml. of Hexadecane at 1350 . 21

7. The First-Order Plot of the Data Obtained from the
Decomposition of 2.19 x 10-3 Mole of 5,5-(4,
4'-Dimethyldiphenyl)-3,4-Dicarbomethoxy-2-
Pyrazoline in the Presence of 2.11 x 10-3 Mole
of Tri-n-propylamine in 50 ml. of Hexadecane
at 1350 . . . . . . . . . 22










LIST OF FIGURES (Continued)


Figure Page

8. Plots of the Observed First-Order Rate Constants
Versus Base Concentration for the 5-Phenyl-
5-(4-Methylphenyl)-3-Carbomethoxy-2-Pyra-
zoline ([) and 5,5-(4,4'-Dimethyldiphenyl)-
3-Carbomethoxy-2-Pyrazoline ( ) . . .. .26

9. Plots of the Observed First-Order Rate Constants
Versus Base Concentration for the 5,5-(4,4'-
Dichlorodiphenyl)-3,4-Dicarbomethoxy-2-Pyra-
zoline ( ) and 5,5-(Dichlorodiphenyl)-3-
Carbomethoxy-2-Pyrazoline ( 0) . . . .. .27

10. Plots of the Observed First-Order Rate Constants
Versus Base Concentration for the 5-Phenyl-5-
(4-Methylphenyl)-3,4-Dicarbomethoxy-2-Pyrazoline
( E) and 5,5-(4,4'-Dimethyldiphenyl)-3,4-
Dicarbomethoxy-2-Pyrazoline (0 ) ...... 28

11. Plots of the Observed First-Order Rate Constants
Versus Base Concentration for the 5,5-Diphenyl-
3-Carbomethoxy-2-Pyrazoline ( [) and 5,5-
Diphenyl-3,4-Dicarbomethoxy-2-Pyrazoline ( ) 29

12. Reaction Scheme Taken from an Investigation of W. M.
Jones . . . . . . . . ... .. . 35

13. An Activation Energy Diagram for the Decomposition
of 5,5-Diaryl-2-Pyrazolines (-) and 5-Carbo-
alkoxy-2-Pyrazolines (---) in Hexadecane in the
Presence of Added Base . . . . . ... 43

14. A Proposed Mechanism for the Base-Induced Thermal
Decomposition of 5,5-Diaryl-3-Carboalkoxy-2-
Pyrazolines . . . . . . . ... 45












LIST OF FIGURES


Figure Page

1. Route of Addition of Diazomethane to OC, B Unsatu-
rated Carbonyl Compounds . . . . . . 1

2. Suggested Path for the Decomposition of Three
2-Pyrazolines . . . . . . . . 4

3. Photograph of the Kinetic Reaction Vessel Showing
the Nitrogen Bubbler and the Pellet-Dropping
Assembly . . . . . . . . . . 13

4. The First-Order Plot of the Data Obtained from the
Decomposition of 1.87 x 10-3 Mole of 5,5-(4,4'-
Dimethyldiphenyl)-3-Carbomethoxy-2-Pyrazoline
in the Presence of 2.11 x 103 Mole of Tri-n-
propylamine in 50 ml. of Hexadecane at 135 .. 19

5. The First-Order Plot of the Data Obtained from the
Decomposition of 2.59 x 10-3 Mole of 5,5-(4,4'-
Dichlorodiphenyl)-3-Carbomethoxy-2-Pyrazoline
-3
in the Presence of 2.11 x 103 Mole of Tri-n-
propylamine in 50 ml. of Hexadecane at 1350 20

6. The First-Order Plot of the Data Obtained from the
Decomposition of 2.0 x 10-3 Mole of 5,5-
Diphenyl-3,4-Dicarbomethoxy-2-Pyrazoline in
the Presence of 2.11 x 10~- Mole of Tri-n-
propylamine in 50 ml. of Hexadecane at 1350 . 21

7. The First-Order Plot of the Data Obtained from the
Decomposition of 2.19 x 10-3 Mole of 5,5-(4,
4'-Dimethyldiphenyl)-3,4-Dicarbomethoxy-2-
Pyrazoline in the Presence of 2.11 x 10-3 Mole
of Tri-n-propylamine in 50 ml. of Hexadecane
at 1350 . . . . . . . . . .. .22










LIST OF FIGURES (Continued)


Figure Page

8. Plots of the Observed First-Order Rate Constants
Versus Base Concentration for the 5-Phenyl-
5-(4-Methylphenyl)-3-Carbomethoxy-2-Pyra-
zoline ([]) and 5,5-(4,4'-Dimethyldiphenyl)-
3-Carbomethoxy-2-Pyrazoline (0) . . .. .26

9. Plots of the Observed First-Order Rate Constants
Versus Base Concentration for the 5,5-(4,4'-
Dichlorodiphenyl)-3,4-Dicarbomethoxy-2-Pyra-
zoline ( ]) and 5,5-(Dichlorodiphenyl)-3-
Carbomethoxy-2-Pyrazoline (0) . . . .. .27

10. Plots of the Observed First-Order Rate Constants
Versus Base Concentration for the 5-Phenyl-5-
(4-Methylphenyl)-3,4-Dicarbomethoxy-2-Pyrazoline
( ) and 5,5-(4,4'-Dimethyldiphenyl)-3,4-
Dicarbomethoxy-2-Pyrazoline ( ) . . .. .28

11. Plots of the Observed First-Order Rate Constants
Versus Base Concentration for the 5,5-Diphenyl-
3-Carbomethoxy-2-Pyrazoline ( [) and 5,5-
Diphenyl-3,4-Dicarbomethoxy-2-Pyrazoline (0 ) 29

12. Reaction Scheme Taken from an Investigation of W. M.
Jones . . . . . . . . ... .. 35

13. An Activation Energy Diagram for the Decomposition
of 5,5-Diaryl-2-Pyrazolines (--) and 5-Carbo-
alkoxy-2-Pyrazolines (---) in Hexadecane in the
Presence of Added Base . . . . .... 43

14. A Proposed Mechanism for the Base-Induced Thermal
Decomposition of 5,5-Diaryl-3-Carboalkoxy-2-
Pyrazolines . . . . . . . .... 45











LIST OF FIGURES


Figure Page

1. Route of Addition of Diazomethane to CO, B Unsatu-
rated Carbonyl Compounds . . . . . . 1

2. Suggested Path for the Decomposition of Three
2-Pyrazolines . . . . . . . . 4

3. Photograph of the Kinetic Reaction Vessel Showing
the Nitrogen Bubbler and the Pellet-Dropping
Assembly .. . . . . . . .... 13

4. The First-Order Plot of the Data Obtained from the
Decomposition of 1.87 x 10-3 Mole of 5,5-(4,4'-
Dimethyldiphenyl)-3-Carbomethoxy-2-Pyrazoline
in the Presence of 2.11 x 103 Mole of Tri-n-
propylamine in 50 ml. of Hexadecane at 1350 .. 19

5. The First-Order Plot of the Data Obtained from the
Decomposition of 2.59 x 10-3 Mole of 5,5-(4,4'-
Dichlorodiphenyl)-3-Carbomethoxy-2-Pyrazoline
in the Presence of 2.11 x 10-3 Mole of Tri-n-
propylamine in 50 ml. of Hexadecane at 135 . 20

6. The First-Order Plot of the Data Obtained from the
Decomposition of 2.0 x 10-3 Mole of 5,5-
Diphenyl-3,4-Dicarbomethoxy-2-Pyrazoline in
the Presence of 2.11 x 10- Mole of Tri-n-
propylamine in 50 ml. of Hexadecane at 1350 . 21

7. The First-Order Plot of the Data Obtained from the
Decomposition of 2.19 x 10-3 Mole of 5,5-(4,
4'-Dimethyldiphenyl)-3,4-Dicarbomethoxy-2-
Pyrazoline in the Presence of 2.11 x 10-3 Mole
of Tri-n-propylamine in 50 ml. of Hexadecane
at 1350 . . . . . . . . . . 22










LIST OF FIGURES (Continued)


Figure Page

8. Plots of the Observed First-Order Rate Constants
Versus Base Concentration for the 5-Phenyl-
5-(4-Methylphenyl)-3-Carbomethoxy-2-Pyra-
zoline (]) and 5,5-(4,4'-Dimethyldiphenyl)-
3-Carbomethoxy-2-Pyrazoline ( ) . . .. .26

9. Plots of the Observed First-Order Rate Constants
Versus Base Concentration for the 5,5-(4,4'-
Dichlorodiphenyl)-3,4-Dicarbomethoxy-2-Pyra-
zoline ( ) and 5,5-(Dichlorodiphenyl)-3-
Carbomethoxy-2-Pyrazoline (0) . . . .. .27

10. Plots of the Observed First-Order Rate Constants
Versus Base Concentration for the 5-Phenyl-5-
(4-Methylphenyl)-3,4-Dicarbomethoxy-2-Pyrazoline
( ) and 5,5-(4,4'-Dimethyldiphenyl)-3,4-
Dicarbomethoxy-2-Pyrazoline ( ) . . .. .28

11. Plots of the Observed First-Order Rate Constants
Versus Base Concentration for the 5,5-Diphenyl-
3-Carbomethoxy-2-Pyrazoline ( 3) and 5,5-
Diphenyl-3,4-Dicarbomethoxy-2-Pyrazoline (0 ) 29

12. Reaction Scheme Taken from an Investigation of W. M.
Jones . . . . . . . . ... .. 35

13. An Activation Energy Diagram for the Decomposition
of 5,5-Diaryl-2-Pyrazolines (--) and 5-Carbo-
alkoxy-2-Pyrazolines (---) in Hexadecane in the
Presence of Added Base . . . . .... 43

14. A Proposed Mechanism for the Base-Induced Thermal
Decomposition of 5,5-Diaryl-3-Carboalkoxy-2-
Pyrazolines . . . . . . . .... .45











LIST OF FIGURES


Figure Page

1. Route of Addition of Diazomethane to 0(, B Unsatu-
rated Carbonyl Compounds . . . . . . 1

2. Suggested Path for the Decomposition of Three
2-Pyrazolines . . . . . . . . 4

3. Photograph of the Kinetic Reaction Vessel Showing
the Nitrogen Bubbler and the Pellet-Dropping
Assembly .. . . . . . . .... 13

4. The First-Order Plot of the Data Obtained from the
Decomposition of 1.87 x 10-3 Mole of 5,5-(4,4'-
Dimethyldiphenyl)-3-Carbomethoxy-2-Pyrazoline
in the Presence of 2.11 x 10- Mole of Tri-n-
propylamine in 50 ml. of Hexadecane at 1350 .. 19

5. The First-Order Plot of the Data Obtained from the
Decomposition of 2.59 x 10-3 Mole of 5,5-(4,4'-
Dichlorodiphenyl)-3-Carbomethoxy-2-Pyrazoline
in the Presence of 2.11 x 10-3 Mole of Tri-n-
propylamine in 50 ml. of Hexadecane at 1350 . 20

6. The First-Order Plot of the Data Obtained from the
Decomposition of 2.0 x 10-3 Mole of 5,5-
Diphenyl-3,4-Dicarbomethoxy-2-Pyrazoline in
the Presence of 2.11 x 10~- Mole of Tri-n-
propylamine in 50 ml. of Hexadecane at 135 . 21

7. The First-Order Plot of the Data Obtained from the
Decomposition of 2.19 x 10-3 Mole of 5,5-(4,
4'-Dimethyldiphenyl)-3,4-Dicarbomethoxy-2-
Pyrazoline in the Presence of 2.11 x 10-3 Mole
of Tri-n-propylamine in 50 ml. of Hexadecane
at 1350 . . . . . . . . . . 22










LIST OF FIGURES (Continued)


Figure Page

8. Plots of the Observed First-Order Rate Constants
Versus Base Concentration for the 5-Phenyl-
5-(4-Methylphenyl)-3-Carbomethoxy-2-Pyra-
zoline (] ) and 5,5-(4,4'-Dimethyldiphenyl)-
3-Carbomethoxy-2-Pyrazoline ( ) . . .. .26

9. Plots of the Observed First-Order Rate Constants
Versus Base Concentration for the 5,5-(4,4'-
Dichlorodiphenyl)-3,4-Dicarbomethoxy-2-Pyra-
zoline ( ) and 5,5-(Dichlorodiphenyl)-3-
Carbomethoxy-2-Pyrazoline (0) . . . . 27

10. Plots of the Observed First-Order Rate Constants
Versus Base Concentration for the 5-Phenyl-5-
(4-Methylphenyl)-3,4-Dicarbomethoxy-2-Pyrazoline
(0) and 5,5-(4,4'-Dimethyldiphenyl)-3,4-
Dicarbomethoxy-2-Pyrazoline ( ) . . .. .28

11. Plots of the Observed First-Order Rate Constants
Versus Base Concentration for the 5,5-Diphenyl-
3-Carbomethoxy-2-Pyrazoline ( ) and 5,5-
Diphenyl-3,4-Dicarbomethoxy-2-Pyrazoline (0 ) 29

12. Reaction Scheme Taken from an Investigation of W. M.
Jones . . . . . . . . ... .. 35

13. An Activation Energy Diagram for the Decomposition
of 5,5-Diaryl-2-Pyrazolines (--) and 5-Carbo-
alkoxy-2-Pyrazolines (---) in Hexadecane in the
Presence of Added Base . . . . .... 43

14. A Proposed Mechanism for the Base-Induced Thermal
Decomposition of 5,5-Diaryl-3-Carboalkoxy-2-
Pyrazolines . . . . . . . .... .45














I. INTRODUCTION


Numerous investigators have studied the condensation of

substituted diazomethanes with olefins, especially the olefins of

the o< ) unsaturated carbonyl type, under quite varied conditions

(1,2). This type reaction at low temperatures leads to the general

class of heterocyclic compounds known as pyrazolines. The route of

addition for the diazomethane to O(, ) unsaturated carbonyl compounds

is shown in Figure 1.




R CH CH CO2R'
I I
CH N





RCH = CHCO2R' + CH2N2



R CH CH CO R'

N CH
N /I 2




Fig. 1. Route of Addition of Diazomethane to o, B
Unsaturated Carbonyl Compounds (3).












There are three possible isomeric forms of these compounds

I, the l-pyrazoline; II, the 2-pyrazoline; III, the 3-pyrazoline.



(4)
(3)


(5) N (2)N N" N \
(1) H H

I II III


The subsequent discussion in this dissertation will deal exclusively

with forms I and II.

Von Auwers and Konig (4) have reported that the initial prod-

uct of the reaction is I and if one of the substituents on position 3

is hydrogen and the other a group which can conjugate with a double

bond (>C=O, Ph, -COOR, etc.) then I, either under reaction conditions

or by treatment with mineral acids, tautomerizes to the more stable

isomer II.

Perhaps the most widely studied reaction of this class of

compounds has been their thermal decomposition. Upon heating at or

above the melting point, pyrazolines decompose to produce nitrogen

gas, olefinic compounds and substituted cyclopropanes. This decom-

position has stimulated much interest (1-20).

The conversion of 1-pyrazolines to cyclopropanes and ole-

finic materials has received quite an intensive study with numerous

reports related to its stereospecificity and its proposed path of

decomposition (1,4-15).












The 2-pyrazoline structure has not received such a concen-

trated study. Jones (5,15) began such a study. The initial step

was to study the stereochemistry of the decomposition of three

2-pyrazolines IV, V and VI. The mechanism of the thermal decom-

position has long been presumed to proceed via the 1-pyrazoline

followed by loss of nitrogen (1,5,7,15).



CO2Me C02Me C02Me
MeC02C CO2Me Ph



/ P Me02C
I I I
H H H


IV V VI


Jones (15) found that IV and V gave predominately the

cyclopropane isomer in which the ester groups were trans and VI gave

predominately the cis isomer. These results were very easily ex-

plained by the presumed initial tautomerization of the 2-pyrazoline

to the thermodynamically favored 1-pyrazoline followed by a

stereospecific loss of nitrogen as proposed in Figure 2. This line

of reasoning also explained the results of von Auwers (17) who found

that the decomposition of 3,4-dicarbomethoxy-2-pyrazoline gave 33%

trans-1,2-dicarbomethoxycyclopropane and 2% of the cis isomer.

The predominance of the trans isomer over the cis in the case of

von Auwer, the stereochemistry of the decomposition of IV, V and












Ph
IV >


Me02C
C02Me

N
N


C02Me


Me02C


CO2Me


V


CO2Me


Me02C N


C02Me
C0M


Fig. 2.- Suggested Path for the Decomposition of Three
2-Pyrazolines.


VI


z













H
COOMe
MeOOC I A
NI \ COOMe +

MeOOC MeOOC COOMe
H


33% 2%



VI from Jones's work, and the report by van Alphen (18) that the

decomposition of 5,5-diphenyl-3,4-dicarbomethoxy-2-pyrazoline, VII,



CO2Me
C0O2Me
--- -CO2Me
Ph
N Ph
Ph N Ph
P Ph C02Me
H

VII trans


gave predominately the trans cyclopropane has been taken as pre-

sumptive evidence for the intermediacy of the 1-pyrazoline in these

reactions (1,15,20).

In an attempt to further elucidate the mechanism of these

conversions, Baarda (21) undertook a kinetic study of the conversion

of certain 2-pyrazolines to cyclopropanes. To briefly summarize his

results, he found 1) 5,5-diphenyl-2-pyrazolines underwent abnormally

rapid decompositions relative to the 5-carboalkoxy-2-pyrazolines; 2)

with added base, the decompositions fit the rate expression:












Rate = kI (2-Pyrazoline) + k2 (2-Pyrazoline)(Base); and 3) the

thermal decomposition of the 2-pyrazolines under study without

added base and in hydrocarbon solvents showed first-order kinetics.

From these results, he concluded that the proposed 2-pyrazoline

-- 1-pyrazoline reaction scheme was not general and he pos-

tulated various possible alternatives.

One alternative suggestion was cleavage of the carbon-

nitrogen single bond (C5-N1) to give an open intermediate which then

could proceed to products. One such scheme is shown in the following

equation.



CO2R CO2R


Ph Ph N >--- Product
N
Ph Ph *

H




This path was particularly attractive in view of the extremely rapid

decomposition rate of the 5,5-diphenyl-2-pyrazolines and the observed

first-order kinetics. If an open intermediate of this type were

involved, then substitution of phenyl groups at the 5 position would

obviously stabilize any type of intermediate that developed. Also,

the ring opening would involve only the pyrazoline and if this were

the slow step (or rapid step followed by unimolecular decomposition),

it would show first-order kinetics.












In order to test the possibility of rapid cleavage of the

C5-N1 bond, the optically active 5-phenyl-5-(P-methylphenyl)-3-

carbomethoxy-2-pyrazoline was synthesized and subjected to partial

decomposition. The unreacted starting material was recovered and

found to have lost none of its optical activity. This definitely

excluded rapid cleavage of the carbon-nitrogen single bond as

racemization of the active center would have taken place.

Slow cleavage of the carbon-nitrogen single bond was also

eliminated. It was felt that if any open intermediate could form

in the case of the l-hydrogen-2-pyrazoline, it could form much more

easily in the case of the l-acetyl-2-pyrazoline. Therefore, the

above optically active 2-pyrazoline was acylated and then subjected

to the identical decomposition conditions as used for the parent

compound. This reaction was continued over a period of time equiva-

lent to several half-lives of the unacylated compound. Under these

conditions, again, no racemization was observed. Only unreacted

starting material was isolated.

Apparently from these data, total cleavage of the C5-N1

bond was not the reaction path.

A second alternative reaction route which would explain the

lack of racemization at C5, the first-order kinetics and the abnormal

rate of decomposition of the 5,5-diphenyl-2-pyrazolines, was for-

mulated. If there were a concerted bond formation between C3 and C5

along with the cleavage of C5 and N1, then each of the above results

could be rationalized as shown in the following equation.















Rf2 R2 R2



R/ lR -,. __ Products


R1 N=N-R3
R3 R3





This possibility was tested in the following way. If the

cyclopropylazo intermediate were formed, if R1 and R2 were distin-

guishable and if the intermediate could attain equilibrium with the

starting 2-pyrazoline, then it should be possible to observe a

scrambling of the positions of R1 and R2 in the original 2-pyrazoline.

Investigating this possibility, Pyron* prepared 4-phenyl-5-(j-

methoxyphenyl)-3-carbomethoxy-2-pyrazoline and 4-(p-methoxyphenyl)-

5-phenyl-3-carbomethoxy-2-pyrazoline and acylated both compounds to

give VIII and IX. These compounds were then subjected to the same

conditions required to decompose the parent compounds. Again, no


Ph C02Me pMeO-Ph CO2Me




EMeO- Ph Ph
I |
C= 0 C=O
I I
Me Me
VIII IX










intermixing was observed (there was quantitative recovery of the

starting material), thus excluding concerted bond formation and




Ph

VIII CO2Me IX

pMeO-Ph N=N-C-Me
II
0



collapse of the pyrazoline ring system.

Having excluded the obvious possible alternatives and since

much of the published evidence (1,5,15,17,18) for the 2-pyrazoline

>- 1-pyrazoline route for the thermal decomposition in the

melt had resulted from stereochemical studies, an attempt was made

to gain more insight into the "new mechanism" by studying the

stereochemistry of the cyclopropane products formed under the same

conditions in which the "new mechanism" was thought to be operating.

A number of pyrazolines were synthesized and decomposed both in the

melt and in solution. The results, summarized in Table 1, showed

only slight differences in the stereochemistry of the products

resulting from the melt or solution decomposition. Thus, these

results suggested that the same mechanism was operating in each case

Since the melt decomposition was believed to involve 2-

pyrazoline --- 1-pyrazoline tautomerization, it was therefore

decided to very carefully re-examine Baarda's arguments to determine










TABLE 1

PERCENT OF THE CIS-ISOMER (TWO ESTER GROUPS CIS) RESULTING
FROM THE THERIAL DECOMPOSITION OF SELECTED 2-PYRAZOLINES IN
TETRAGLYME AND IN THE MELT


% Cis in Solution % Cis in Melt
2-Pyrazoline at 2300 at 2300

CO2Me
I- CO2Me


39%


48%


H Cis

CO2Me
C02Me


Ph |
H Trans

CO2Bu
P-- C02Bu
Ph 11|
N-

H Trans


25%


16%


.15%


23%





71%


C02Me


80%


Me02C


Trans


CO2Et



Trans


Et02C


80%


Ph
-_--r2 I CO2-i-Pr


i-Pr02C N
H Trans


71%


85%









11


whether they could be made consistent with the 2-pyrazoline -

1-pyrazoline scheme.

The purpose of the remainder of this dissertation is to

report the re-examination of these arguments and to show that they

are all consistent with the proposed 2-pyrazoline -- 1-pyrazoline

scheme.











II. INSTRUMENTATION AND TECHNIQUE


The decomposition of the 2-pyrazolines used in this study is

easily followed due to the fact that nitrogen gas is lost quanti-

tatively during the course of the reaction. Therefore, the progress

of the reaction was assessed by the collection of the evolved gas

over mercury in a constant temperature burette calibrated in 0.1 ml.

increments. The gas entered through a three-way stopcock at the top

of the burgtte and atmospheric pressure was obtained at each reading

by means of a leveling bulb.

The decomposition was carried out in a cylindrical vessel

19.5 cm. tall and 4 cm. in diameter fitted with 29/42 ball joints as

shown in Figure 3. A side-arm nitrogen bubbler was permanently

attached about 40 mm. from the bottom of the vessel. The tip of the

bubbler extended down inside the vessel to a point such that it would

be about half the height of a column of 50 ml. of solvent. The bub-

bler was attached to a three-way stopcock which could seal the vessel

from the atmosphere.

A nitrogen exit tube was permanently attached near the neck

of the flask and was attached to the burette by a capillary side arm,

tygon tubing, a three-way stopcock connected to a vacuum pump and

more tygon tubing.
































































Fig. 3,- Photograph of the Kinetic Reaction Vessel Showing
the Nitrogen Bubbler and the Pellet-Dropping Assembly.












At the top of the reaction vessel was attached a section of

glass which held the sample. This section was not in the bath. The

sample, a pellet for the solid samples and a glass tray for the oil

samples, was placed on a hinged glass plate which was held in place

by a glass bar with a magnet sealed in the opposite end. This section

was then sealed by a glass stopper held in place by a clamp, as were

all joints in the system.

When the sample to be decomposed was to be introduced into

the solvent, an external magnet was used to slide the glass bar back,

thus releasing the trap and allowing the sample to drop into the

solvent.

The solvent was stirred by a teflon-coated magnetic stirring

bar which was controlled, when the vessel was suspended in the con-

stant temperature bath, by a variable chuck magnetic stirring motor.

The constant temperature bath was GE SF 1017 silicone oil.

The temperature of the bath was maintained to an accuracy of 0.010

by a Sargent Model S Thermonitor.

The general procedure used in carrying out each decomposition

may be outlined as follows:

1. The reaction vessel was rinsed several times with acetone

and allowed to dry thoroughly.

2. A 50 ml. sample of hexadecane, which had been previously

distilled and stored over molecular sieves, was pipetted

into the flask.

3. The sample was placed'on its hinged trap door.










4. The whole reaction vessel was assembled and the

nitrogen bubbler and exit tube connected. The system

was now sealed from the atmosphere except for the

stopcock at the top of the burette which was still

open to the atmosphere.

5. Nitrogen gas, purified by bubbling through wash bottles

filled with Fieser's solution (see Experimental), lead

acetate, concentrated sulfuric acid, the sodium ketyl

of benzophenone in xylene, and paraffin oil, was then

allowed to bubble through the solvent and the rest of

the system thence into the air for 30-45 minutes. The

solvent was stirred continuously during this period.

6. The system was then closed and evacuated until bubbles

no longer came out of the solvent.

7. The evacuation was stopped and nitrogen gas again was

bled into the system. This procedure insured an atmos-

phere of nitrogen throughout the system.

8. The reaction vessel was then suspended in the oil bath

and the temperature allowed to become constant again.

The bubbling of nitrogen gas through the vessel was

continued for a time after the vessel had been placed

in the bath.

9. The nitrogen bubbler was sealed for the duration of the

reaction.

10. Stirring of the solvent was continuous from this point

to the end of the reaction period.











11. The system was then closed to the atmosphere.

12. The solid pellet or tray of oil, weighed to the

nearest 0.1 mg., was dropped into the hot solvent.

The time observed for the dissolving of the sample

did not exceed 30 seconds. The procedure of Over-

berger (22) was followed for solid samples in which

Vo was taken as the calculated volume of nitrogen

converted to the temperature and pressure of the

collecting burette and zero time was the time of

introduction of the sample. This procedure was

checked and found to be quite accurate.

For runs made with the oil materials, the actual observed

too volume reading was taken as V,, because the exact purity of the

oil was unknown.

The actual burette readings were taken as Vt.












III. RESULTS AND DISCUSSION


One of the strongest arguments that was presented for the

"new mechanism" was the very rapid rate of decomposition of 5,5-

diaryl-2-pyrazolines. In an attempt to elucidate the role of the

aryl groups at the 5 position of the 2-pyrazoline, two series (XI-

XIV) and (XV-XVIII) of 5,5-diaryl-2-pyrazolines were prepared. The

series differed only in the substituent at the 4 position.


CO2Me CO2Me CO2Me

Ar Ar
N N

Ar' N Ar'
1 I
H H



XI Ar=Ar'=Ph XV Ar=Ar'=Ph

XII Ar=Ph;Ar'=p-Me-Ph XVI Ar=Ph;Ar'=p-Me-Ph

XIII Ar=Ar'=p-Me-Ph XVII Ar=Ar'=--Me-Ph

XIV Ar=Ar'=.-Cl-Ph XVIII Ar=Ar'=p-Cl-Ph


The 2-pyrazolines were prepared by adding the diaryldiazo-

methanes to dimethyl maleate (XI-XIV)-and to methyl acrylate (XV-

XVIII).



*For elaboration, see the Experimental.













These compounds were subjected to kinetic decomposition in

approximately 0.01 molar hexadecane solution in the presence of

added tri-n-propylamine. The kinetics were followed by the evolution

of nitrogen gas and the rates were found to follow a first-order

kinetic plot. Some typical plots of these data are shown in Figures

4-7, The temperature was held constant at 1350 for each run in order

that there would be no ambiguity involved in drawing comparisons

between the various observed rates. The results of the decompositions

are summarized in Tables 2-3.

It will be noted that electron-donating substituents slightly

retarded the rate whereas electron-attracting substituents slightly

increased the rate. These results suggest a slow formation of the

1-pyrazoline by a process, for example, such as outlined below

where there is a rapid equilibrium setup prior to the rate-determining

step.


k k k
9 2 3
AH + B 1 A + Bi 2 A'H + B 3 Product
-1 -2



AH = 2-Pyrazoline

B = Base

A'H = 1-Pyrazoline

This process is described by the expression d(Product) = k3(A'H).
dt
If k2 is the slow step and using the "steady-state" assumption, the

total rate expression develops into equation 1, where K is the




























































I I I I I I I I I


10 20 30 40 50 60


70 80 90


Minutes


Fig. 4. The First-Order Plot of the Data Obtained from
the Decomposition of 1.87 x 10-3 Mole of 5,5-(4,4'-Dimeth ldiphenyl)-
3-Carbomethoxy-2-Pyrazoline in the Presence of 2.11 x 10" Mole of
Tri-n-propylamine in 50 ml. of Hexadecane at 1350.


1.3


1.21-


1.1



1.0


41







0
SI










>
__ _-
.U


0.7


0,6


0.5 -


0.4


0.3


0.2


0.1


0.9 -


0.8 -

































S
>5


1.8


1.7


1.6


1.5


1.4


1.3


1.2


1.1


1.0


0.9


0.8



0.7


0.6


0.5


SI I I I I I I I


Minutes


Fig. 5. The First-Order Plot of the Data Obtained from the
Decomposition of 2.59 x 10-3 Mole of 5,5-(4,4'-Dichlorodiphenyl)-
3-Carbomethoxy-2-Pyrazoline in the Presence of 2.11 x 10" Mole of.
Tri-n-propylamine in 50 ml. of Hexadecane at 1350.











1.4

1.3


1.2


1.1


1.0


0.9


0.8 -


0.7


0.6


0.5


0.4


0.3


0.2


0.1


0.0 2 4 6 8 10 12 14 16 18 20

Minutes

Fig. 6. The First-Order Plot of the Data Obtained from the
Decomposition of 2.0 x 10-3 Mole of 5,5-Diphenyl-3,4-Dicarbomethoxy-
2-Pyrazoline in the Presence of 2.11 x 10-3 Mole of Tri-n-propylamine
in 50 ml. of Hexadecane at 1350.










1.4 -


1.3 -


1.2 -


1.1


1.0


0.9


0.8


S0.7
8
S0.6


0.5


0.4


0.3 -


0.2


0.1


0.0 I I 111
2 4 6 8 10 12 14 16 18 20

Minutes

Fig. 7. The First-Order Plot of the Data Obtained from the
Decomposition of 2.19 x 10-3 Mole of 5,5-(4,4'-Dimethyldiphenyl)-3,
4-Dicarbomethoxy-2-Pyrazoline in the Presence of 2.11 x 10-3 Mole
of Tri-n-propylamine in 50 ml. of Hexadecane at 135.


























-4



U)








0
1-1


1-





C
o
,-4

X

0
C)



*C
+'




-4










r-4








I



-4
i-

oC











0


I / I I ,1

0 P O N

ci c 5


(N

-4






CO
rl



-4
0








i-













X
C












1-4

-4




















o
C











0


1-4


n
o

x


-4
o

o

+.'



















-4
CM
r-
r(



















o











cl-
1-


C L'4 CM PI P



04I I a 1 I
a I I s.


o
-4


o
C
C)





















X
+l
-4
rl









CY)

-4



-4

-4
N











0

cl-
-4


0

4J
co



r0-


.-I Gi


4 '


*r-4 a)
& ,


X E-4




















4-)
r.1
Ci
Xc











(ti
4-J
C.
Cd
tij









24

0




(" (n1 *
-4 -4 I-






S0 0 0


0 0 0 0


to ,N C N




0
0H m C O <







I 0 o o 0
>*c- 4 -4 -4 r-4


i-i- r --4-
0 C
O muo o 8 n








I






I1 -, 4 L LIi

L0 0

O









0 0
o08 X


) 0



U





I
enu










Er r

















r-I
^ 5 ^ );a r" r-"

s r,-/ y^ r^











equilibrium constant for the formation of AP. From this expression



d(Product) = k2K(AH)(B) (1)
dt



the effect of substituents upon the rate can be explained by the

manner in which the substituents change the equilibrium constant

(electron-donating substituents would decrease K whereas electron-

attracting substituents would increase K) since the effect on K

should be greater than the effect on k2.

Since the suggested rate expression included a base term, the

dependency of the decompositions on base concentration was checked.

As would be predicted for a reaction first order in a catalyst, it

was found that a plot of kobs. versus the base concentration gave a

straight line (see Figures 8-11). Surprisingly however, it was also

noted that, in most of the cases, the intercept of the line at

kobs. = 0 was not the origin (as would be predicted by equation 1).

Furthermore, it was found that the plots passed through the base

coordinate at essentially the same point which corresponded to a

base concentration of minus 0.01 molar. This behavior requires the

relationship shown in equation 2 which is most readily interpreted



kobs. = k(Base) + k' (2)
obs.


as a decomposition mechanism in competition.with the added base-

induced mechanism. The nature of this competitive mechanism was of





























25-


20-


15-


10 -


0 1 I I I
0 1 2 3 4


0 1 2 3 4


Moles of (CH3CH2CH2)3N M x 102








Fig. 8. Plots of the Observed First-Order Rate Constants
Versus Base Concentration for the 5-Phenyl-5-(4-Methylphenyl)-3-
Carbomethoxy-2-Pyrazoline (0) and 5,5-(4,4'-Dimethyldiphenyl)-3-
Carbomethoxy-2-Pyrazoline ( ).


























8 16 -


14-


6 -12 -

- 10 --
10

0 a
4 8


6 -


2 4


2 -



0o I II I
0 1 2 3 4 0 1 2 3 4


Moles of (CH3CH2CH2)3N Mx 102



Fig. 9. Plots of the Observed First-Order Rate Constants
Versus Base Concentration for the 5,5-(4,4'-Dichlorodiphenyl)-3,4-
Dicarbomethoxy-2-Pyrazoline (0) and 5,5-(Dichlorodiphenyl)-3-
Carbomethoxy-2-Pyrazoline (0).




















16


14


12


10


8


6


I I 2 3 I
0 1 2 3 4


16


14


12


S 10
x


SI I I I
0 1 2 3 4


Moles of (CH3CH2CH2)3N Mx 102







Fig. 10. Plots of the Observed First-Order Rate Constants
Versus Base Concentration for the 5-Phenyl-5-(4-Methylphenyl)-3,4-
Dicarbomethoxy-2-Pyrazoline (0) and 5,5-(4,4'-Dimethyldiphenyl)-3,
4-Dicarbomethoxy-2-Pyrazoline (0).













































I 1 I I


0 1 2


3 4


I I I I I
0 1 2 3 4


Moles of (CH3CH2CH2) NM x 102





Fig. 11. Plots of the Observed First-Order Rate Constants
Versus Base Concentration for the 5,5-Diphenyl-3-Carbomethoxy-2-
Pyrazoline (0) and 5,5-Diphenyl-3,4-Dicarbomethoxy-2-Pyrazoline
(0).












some interest, especially in view of Baarda's general "new mechanism"

conclusions. However, a close examination of the kinetic data sug-

gested that this competitive mechanism was probably no more than a

simple competitive 2-pyrazoline to 1-pyrazoline conversion probably

catalyzed by a basic surface of the reaction vessel. Thus, it was

found that the plots of kobs. versus base gave values for k' that

followed essentially the same order with changes in the pyrazoline

structure as did the values of k. (These results are summarized

in Table 4.) .In fact, the ratio of k/k' was nearly constant from

one compound to the next. This observation was certainly suggestive

of similar mechanisms in the two reactions. Since this competitive

reaction was probably no more than a surface-catalyzed reaction due,

quite possibly, to base from the previous run being adsorbed to the

surface of the reaction flask, it was not surprising that there were

slight variations in the k/k' ratio.

These observations were all consistent with the 2-pyrazoline

---: 1-pyrazoline tautomerization scheme but a problem was encoun-

tered when Baarda's results were checked. It was found that for

Baarda's work, a plot of kobs. versus the base concentration did not

give a straight line. However, his results were found to fit an

expression of the type shown in equation 3. This type of correlation



1 + k" (3)
k Base

arises directly from the following reaction scheme.if two criteria

arises directly from the following reaction scheme.if two criteria


















TABLE 4

DATA CALCULATED FROM THE PLOT OF KOBS. VERSUS

BASE CONCENTRATION FOR XI-XVIII


Base Concentration k
at kobs. = 0 k k' k'



XIV 1.0 x 10-2 1.50 x 10-1 1.50 x 10-3 100


XI 1.0 x 10-2 3.00 x 10-2 3.00 x 10-4 100


XVIII 0.9 x 10-2 3.20 x 10-2 2.88 x 104 111


XII 1.0 x 10-2 2.67 x 10-2 2.67 x 104 100


XIII 0.9 x 10-2 2.67 x 10-2 2.40 x 10-4 111

-3
XV 0 6.67 x 10-3 through zero


XVI 1.0 x 102 5.00 x 10 5.00 x 10-5 100


XVII 0.9 x 10-2 5.00 x 10-3 4.50 x 10-5 111












are met. First, a competitive reaction must not be important.


k k
2-Pyrazoline + Base 1-Pyrazoline + Base 2- Products





k k (Base)
Rate 1 2 = k (4)
(2-Pyr.) k (Base) + k obs.





k
1 1 (5)
kobs. kl(Base) klk2



Second, the reversal of 1-pyrazoline to 2-pyrazoline must be competi-

tive with loss of nitrogen. An examination of Baarda's experimental

conditions shows that both of these criteria could be fulfilled. Thus,

Baarda's studies were run with base concentrations varying from 0.1

to 0.48 molar (in contrast to 0.01 to 0.042 molar in the present

study). At these concentrations, the competitive surface reaction

would account for less than 10% (down to about 1%) of the total

reaction. Furthermore, the higher base concentrations would promote

reversal of the 1-pyrazoline to the 2-pyrazoline without appreciably

affecting the 1-pyrazoline to cyclopropane conversion.

Thus, all of these observations are quite consistent with

the 2-pyrazoline --->- 1-pyrazoline conversion. In fact, the

present study with low base concentrations points strongly toward

this proposed reaction path.












A striking comparison which appeared during the course

of this work was the observation that between corresponding members

of the two 5,5-diaryl-2-pyrazoline series under study (i.e., 5,5-

diphenyl-3,4-dicarbomethoxy-2-pyrazoline and 5,5-diphenyl-3-carbo-

methoxy-2-pyrazoline, etc.) the ratio of their respective observed

rate constants was nearly constant. For example, the observed rate

constants (these constants are for runs with 2.11 x 10-2 mole of

base added) for XI, XII, XV and XVI were 1.67, 1.51, 0.277 and

0.253 x 10 sec1 respectively. The ratios of XI to XV and XII

to XVI were 6.02 and 5.99 respectively (for comparison between the

remaining members of the two series see Table 5). The 5,5-diaryl-

3,4-dicarbomethoxy-2-pyrazoline series had the faster observed

rate constants. This can be explained easily using the proposed

reaction scheme. The 4-carbomethoxy group is an electron attractor

and in the five-membered pyrazoline ring system it increases the

initial equilibrium constant K which causes an increase in the

rate. The parallelism between the two series also suggested that

the same mechanism was being followed in each series.

These results and observations are therefore consistent

with the proposed 2-pyrazoline --- 1-pyrazoline conversion

and suggest that for the decomposition of 5,5-diaryl-2-pyrazolines

the rate-determining step is the formation of the 1-pyrazoline.

The above suggestion that formation of the 1-pyrazoline is

the slow step for the 5,5-diaryl-2-pyrazolines presented a major

problem. This problem centered around the evidence of Jones (5a)





















0
o


















0
u






















i-4
(n



































z
o
O




















O


0






co
























z
0






o







Cr





ia-4
0
Cr
oH




















:


H

1 0)
> >
I -l
v>
XU

0
S C

o


I a
I I


p. p.
I -4
pG Fr
I I











that in the melt the rate-determining step for the decomposition of

5-carboalkoxy-2-pyrazolines was the formation of the 1-pyrazoline as

shown in Figure 12. In other words, if the rate-determining steps

in each case were the same, why did the 5,5-diaryl-2-pyrazolines

undergo such an abnormally rapid decomposition relative to the

5-carboalkoxy-2-pyrazolines? Jones found that starting from either

XX or XXI as pure material and effecting partial decomposition in

the melt followed by recovery of the starting material, gave only

the pure 2-pyrazoline with which he had started. If the slow step

of the decomposition shown in Figure 12 had been the decomposition

of the 1-pyrazoline, then it would have been possible to establish

an equilibrium between the 2-pyrazoline and the 1-pyrazoline. This

possibility would have resulted in.a scrambling of the two ester

groups because in the 1-pyrazoline they would have been equivalent.

Since no scrambling of the ester groups was observed, the slow step

of the decomposition was indicated to be the formation of the

1-pyrazoline.

Ph CO2Me


Et2C ~~Ph NCO2Me h


SEtO2C *N
XX Ph CO2Et Et02C C02Me



MeO2C N

XXI H

Fig. 12. Reaction Scheme Taken from an Investigation of
W. M. Jones.











Baarda (21) in some of his investigations found that the

rate of decomposition of 5-carboalkoxy-2-pyrazolines in solution

was much less than the 5,5-diphenyl-2-pyrazolines. These results

for the 5,5-diphenyl-2-pyrazolines and the 5-carboalkoxy-2-pyrazolines

place one or more of the following requirements on the mechanism:

1) either the two phenyl groups accelerate the formation of the

1-pyrazoline, or 2) the 5-carboalkoxy group must decelerate the

rate of formation of the 1-pyrazoline, or 3) whereas the rate-

determining step for the decomposition of the 5-carboalkoxy-2-

pyrazoline in the melt is the formation of the 1-pyrazoline, the

rate-determining step in solution is the decomposition of the

1-pyrazoline.

In view of the kinetic data discussed thus far and the

pKa's of analogous carboxylic acids, the first of these three pos-

sibilities seems highly unlikely. For example, the pKa for diphenyl-

acetic acid is 3.94 whereas the pKa for malonic acid is 2.85. Since

the same factors probably operate in the 2-pyrazoline system as in

the example acids (i.e., inductive effects), then the 5-carboalkoxy

group would be expected to exert a stronger influence upon the N1

hydrogen atom than the diaryl substituents. Thus, the diaryl

substituents on C5 must exert their rate-increasing powers in some

step other than the formation of the 1-pyrazoline.

The second requirement could pertain due, possibly, to some

sort of special stabilization of the 2-pyrazoline relative to the

1-pyrazoline in the 5-carboalkoxy case caused by intramolecular

hydrogen.bonding of the ester group with the hydrogen atom attached











to the nitrogen atom. However, this possibility was made unlikely

by the observations of Pyron that the thermal decomposition of

5-phenyl-2-pyrazolines was also extremely slow. Thus, all the

previous evidence suggests that, indeed, the slow step in the case

of the 5-carboalkoxy-2-pyrazoline is the decomposition of the

1-pyrazoline, or in other words, substitution of two phenyl groups

on C5 accelerate the decomposition of the 1-pyrazoline. This latter

statement is intuitively obvious since any type of intermediate

formed by the loss of nitrogen from the 1-pyrazoline (7,14) would

be stabilized by the two aromatic rings.









Ph *
Ph Ph





An attempt to check this extremely attractive possibility

experimentally was carried out again by synthesizing both XX and

XXI and subjecting each pure compound to partial decomposition in

solution in the presence of added base. Each 2-pyrazoline was

dissolved in 50 ml. of decalin to which.0.3 ml. of triisoamylamine

had been added. This solution was heated at 1500 until 50% of the


*Unpublished observations, R. S. Pyron.












calculated volume of nitrogen had been evolved. ,Numerous attempts

were made to isolate the 2-pyrazoline from the decalin solution but

each one met with failure until finally a procedure was developed

for preparing the acetyl derivatives in decalin solution. Acetyl

chloride proved to be utterly useless for this reaction but acetic

anhydride catalyzedby a few drops of sulfuric acid and heat per-

formed the desired operation nicely.

The infrared spectrum of the pure acetyl derivatives, which

were prepared directly from the pure 2-pyrazolines, offered a very

nice diagnostic tool for identifying the two isomeric compounds.

A peak at 11.4 p for the 5-carboethoxy isomer and at 12.6 p for the

5-carbomethoxy isomer proved to be present only in the spectrum of

each compound respectively. When either of the two pure mixed-

ester 2-pyrazolines (XX or XXI) was partially decomposed, acylated,

and the resulting product isolated, the infrared spectrum of the

product indicated the presence of both acetyl derivatives by the

presence of both analytical peaks (11.4 ) and 12.6 i). Blanks showed

that no isomerization of the 2-pyrazoline occurred during the

acylation reaction. These results indicated that in solution the

5-carboalkoxy-2-pyrazoline attained an equilibrium with its 1-pyrazoline

and as a result, a mixture of isomers was isolated from the partial

decomposition experiments as shown by the following reaction scheme.

These results differed completely from the work of Jones (5a) in the

melt, and constituted evidence for the proposed change in the rate-

determining step for the 5-carboalkoxy-2-pyrazolines.










C02Et



Ph CO2Me

Partial Ph Partial
S Decomposition \ Decomposition
-\ LCO2Me XXI

N
Et02C N/


Ph CO2Me Ph C02Et

acylation of P acylation of
reaction mix- reaction
ture from N N MeO2C N-N mixture from
partial de- Et02C partial de-
composition C=0 C= composition
Me Me

This above conclusion was confirmed by a kinetic study of

the decomposition of a 5-carboalkoxy-2-pyrazoline. Using 4-phenyl-

3-carboethoxy-5-carbomethoxy-2-pyrazoline, XXI, as the sample, such

a study was undertaken. In this case, the temperature of the con-

stant temperature bath was increased from 1350 (for 5,5-diaryl-2-

pyrazolines) to 1600 in order to get a measurable rate of nitrogen

evolution. Also, tri-n-propylamine was replaced by triisoamylamine

because the 1600 bath temperature was above the boiling point of

tri-n-propylamine. All other conditions and procedures were the

same as those used in the kinetic decomposition of the 5,5-diaryl-2-

pyrazolines.

If the rate-determining step in the thermal decomposition in

solution of the 5-carboalkoxy-2-pyrazolines is actually the decom-

position of the corresponding 1-pyrazoline, then the rate of the

reaction should be independent of the concentration of added base.












The results of the base-catalyzed decomposition are summarized in

Table 6.

As can readily be seen from Table 6, the rate of nitrogen

evolution from 4-phenyl-3-carboethoxy-5-carbomethoxy-2-pyrazoline

under the above conditions is completely independent of the amount

of base added to the reaction mixture. These observations lend more

support to the proposed mechanistic path and explain the abnormally

rapid rate of the 5,5-diphenyl-2-pyrazolines.

One final question that needs to be considered is the first-

order kinetics for decomposition of 2-pyrazolines reported by Baarda.

However, in light of the previous discussion on the surface-catalyzed

reaction, this was probably simply a result of a surface-catalyzed

2-pyrazoline to 1-pyrazoline conversion. Before it was recognized

that this might be a simple surface reaction, an attempt was made to

check the generality of the first-order kinetics in the absence of

base. Several 5-phenyl and 5-carboalkoxy-2-pyrazolines were synthe-

sized and decomposed kinetically. There was no generality to the

observations of first-order kinetics in the absence of base. In fact,

the results could not be reproduced from one run to the next. In

retrospect, these anomalies probably resulted from different prepa-

rations of the reaction vessel. This Jwas not investigated further.

In conclusion, all major areas of disagreement with the

2-pyrazoline -- -pyrazoline tautomerizations which were pro-

posed by Baarda have been shown to be completely consistent with and

suggestive of such a proton transfer mechanism. The kinetics and
























































































/ / 'o
P4 o
un


rla -1
Ce d

n4 J
S0w

















41


(d

od











base dependence studies of the 5,5-diaryl-2-pyrazoline series eluci-

dated the role of the aryl groups at C5 and pinpointed the rate-

determining step for these compounds. The work with the mixed ester

3,4-dicarboalkoxy-2-pyrazolines confirmed a change in the rate-

determining step from the melt to solution decomposition. The general

reaction scheme as outlined below is the reaction path now proposed

for the base-catalyzed decomposition of 2-pyrazolines. For the 5,5-

diaryl-2-pyrazolines the formation of the 1-pyrazoline is the slow

step (or k2 is slow), whereas for the 5-carboalkoxy-2-pyrazoline the


k k
1 O 2
2-Pyrazoline + Base (2-Pyrazoline ) + H Base
k.1 k-2



1-Pyrazoline + Base

k3

Products



decomposition of the 1-pyrazoline (k3 is slow) is the rate-determining

step. An activation energy versus reaction coordinate diagram (Figure

13) summarizes these considerations.





































1-Pyrazolines \
\-- 2-Pyrazolines


Products




Reaction Coordinate











Fig. 13. An Activation Energy Diagram for the Decomposition
of 5,5-Diaryl-2-Pyrazolines (- ) and 5-Carboalkoxy-2-Pyrazolines
(-------) in Hexadecane in the Presence of Added Base.














IV. SUMMARY


A kinetic study of the base-catalyzed thermal decomposition

of 2-pyrazolines in solution was undertaken to elucidate further the

mechanism of their decomposition. The initial task was to determine

the role of aromatic substitution at C5 in the over-all mechanism

and to evaluate the work of Baarda in terms of the published mecha-

nistic suggestions. These suggestions were to the effect that the

2-pyrazoline initially tautomerizes to the 1-pyrazoline which then

loses nitrogen.

The present study did, in fact, elucidate the role of aromatic

substituents on C5. It also revealed that the base-catalyzed decom-

positions exhibit first-order kinetics. All of Baarda's evidence

suggesting that the 2-pyrazoline 1-pyrazoline tautomerization

was not operative was shown to be entirely consistent with such a

mechanism. Finally, a mechanism was proposed. This mechanism,

including conversion to cyclopropane products, is illustrated in

Figure 14.





































0
-4


s-I <


0
Iri




CN y (


-I.
P-i


II
*d









P4
k
II
*-i


z


(l's

P-I


+


I
L.






0
Ul


0
c9


0
*C

o
4)











-oI
*C

a)
ca













C)
4.1






0 o
Q I
0a




UN



P .I

SI


p 0
0












-4
co


'C4
o
'0 FH
(U 1r




















*^l
QI














V. EXPERIMENTAL


Infrared spectra were run on a Perkin-Elmer Model 137B

Infracord Spectrophotometer. Ultraviolet spectra were run on'a

Cary Model 14 Spectrophotometer. Compound.analyses were performed

by Galbraith Laboratories, Incorporated, Knoxville, Tennessee. All

melting points were taken on a Thomas-Hoover melting point apparatus

and were uncorrected. All boiling points also were uncorrected.

The vapor-phase chromatographic analyses were run on an

Aerograph Hy-Fi Model 600-B vapor-phase chromatograph using a hydrogen

flame ionization detector. The Minneapolis-Honeywell recorder was

equipped with a disc chart integrator.

Elemental analyses for the 2-pyrazolines which were oils

were taken on the respective acetyl derivatives.

General procedure followed for the melt and solution decom-

positions used for the stereochemical studies. The melt decom-

positions were run in a 13 x 120 mm. test tube which was attached to

a water-filled burette. An amount of sample was chosen so that about

50 ml. of nitrogen was evolved. The test tube was immersed in an

oil bath heated to 2300. The sample remained in the bath until gas

was no longer evolved. The resulting oil was then dissolved in ether



*The results from these decompositions are summarized in the
Introduction.











and analyzed by vapor-phase chromatography. The retention times

were compared to those of pure samples of cis and trans 3-phenyl-l,

2-dicarbomethoxy-cyclopropane which were prepared respectively by

decomposition in the melt of 4-phenyl-3,5-dicarbomethoxy-2-

pyrazoline and 5-phenyl-3,4-dicarbomethoxy-2-pyrazoline. The'ratio

of integrated intensities of the two peaks gave the percentage com-

position of each component.

For pyrazoline esters other than the dimethyl esters, the

oil resulting from the decomposition of the pyrazoline was hydrolyzed

in methanolic potassium hydroxide, acidified with hydrochloric acid

and reacted with excess diazomethane, prepared by the method of

DeBoer and Backer (23). This procedure converted all cyclopropanes

to the dimethyl esters.

The solution decompositions were run at 2300 in a 200 ml.

round-bottomed flask in which the pyrazoline sample was dissolved

in tetraglyme which had been purified by reaction with calcium

hydride followed by distillation from lithium aluminum hydride.

Work-up involved the addition of water to the tetraglyme

solution. This procedure caused the products to form an oil which

could be separated easily from the tetraglyme-water solution.

Analysis for the cyclopropane products was carried out in the

same manner as for the melt decompositions. All cyclopropane esters

were converted to the methyl esters, as described above, for

analytical purposes.

Preparation of ethyl diazoacetate. The method of Searle

(24) was followed in the preparation of the diazoacetic ester. This












compound was potentially explosive, therefore much care was used in

handling it.

A solution of 140 g. (1.0 mole) of ethyl glycinate hydro-

chloride in 250 ml. of water was mixed with 600 ml. of methylene

chloride in a two-liter three-necked round-bottom flask fitted with

a stirrer, dropping funnel, thermometer, and nitrogen inlet tube,

and cooled to -50. The flask was flushed with nitrogen and an ice-

cold solution of 83 g. (1.2 moles) of sodium nitrite in 250 ml. of

water was added with stirring. The temperature was lowered to -90

and 95 g. of 5% sulfuric acid was added from the dropping funnel

during a period of about 3 minutes. The temperature rose to a

maximum of +10 with the cooling bath at -230. The reaction termi-

nated within 10 minutes when heat was no longer evolved.

The reaction mixture was transferred to an ice-cold two-

liter separatory funnel, and the yellow-green methylene chloride

layer was run into one-liter of cold 5% aqueous sodium bicarbonate

solution. The aqueous layer was extracted once with 75 ml. of

methylene chloride. The methylene chloride and sodium bicarbonate

solutions were returned to the separatory funnel and shaken until

no trace of acid remained, as shown by indicator paper. The yellow

organic layer was separated and dried for 5-10 minutes over 15 g. of

anhydrous sodium sulfate. The dried ethyl diazoacetate solution

was filtered and the methylene chloride removed on a rotary evapo-

rator at room temperature. The yield of the yellow diazoacetic ester

was 100 g. (88%). This product was pure enough for preparative work.











Preparation of 4-phenyl-3,5-dicarboethoxy-2-pyrazoline. -

The procedure of Buchner (25) was followed with a slight modification.

Twenty-five grams (0.219 mole) of ethyl diazoacetate was mixed with

37 g. (0.21 mole) of ethyl cinnamate and a pinch of hydroquinone

added. This mixture was heated overnight on a steam bath. The

resulting orange oil was poured into a crystallizing dish and scratched

to induce crystallization. This procedure produced an oily, yellow

solid which was filtered and recrystallized from hot methanol.

Yield: 33 g. (0.114 mole; 54%) of white crystals, m.p. 75-77,

reported m.p. 790 (25). Significant absorptions in the infrared

spectrum (Nujol) were at 2.99, 5.80, 5.90, 6.42 and 6.85 1.

Preparation of methyl glycinate hydrochloride. Following

the method of Curtius and Goebel (31), 100 g. (1.33 moles) of glycine

was added to a large excess of methanol. This mixture was heated to

reflux and dry hydrogen chloride gas, made by dropping commercial

concentrated hydrochloric acid into stirred concentrated sulfuric

acid, was bubbled into the methanol. When all of the glycine had

dissolved, the reaction was complete. The hot solution was then

poured into a beaker and allowed to cool, thereby precipitating the

crude hydrochloride. This solid was filtered from the methanol

solution and recrystallized several times from methanol. The yield

was 125 g. (1.0 mole; 75%) of white needles, m.p. 175-1760, reported
0
m.p. 175 (31).

Preparation of methyl diazoacetate. .- This diazoacetic ester

was prepared in the same manner as the ethyl ester, following the

procedure of Searle (24). One hundred twenty-six grams (1 mole) of











methyl glycinate hydrochloride was diazotized with sodium nitrite

and sulfuric acid.

Following the usual work-up, 100 g. (1 mole; 100%) of the

yellow diazo compound was obtained. This liquid was stored in a

brown bottle in the refrigerator until needed. The infrared spectrum

(plates) had significant peaks at 3.28, 4.7, 5.9 and 6.95 p. The

ultraviolet spectrum gave 'max. in cyclohexane at 244 mu (( 1.06 x

104 ).

Preparation of 4-phenyl-3,5-dicarbomethoxy-2-pyrazoline. -

Following the same procedure as used in the preparation of 4-phenyl-

3,5-dicarboethoxy-2-pyrazoline, 32 g. (0.32 mole) of methyl diazo-

acetate and 51 g. (0.315 mole) of methyl cinnamate were mixed

together along with a pinch of hydroquinone. This mixture was

then heated overnight on a steam bath. The resulting oil was

worked up in the usual way. Yield: 48 g. (0.184 mole; 58%) of

white needles, m.p. 1060, reported m.p. 1070 (26). Significant

absorptions in the infrared spectrum (Nujol) were at 3.0, 5.79,

6.46 and 6.88 p.

Preparation of 4-phenyl-3,5-dicarboisopropoxy-2-pyrazoline. -

Five grams (0.021 mole) of 4-phenyl-2-pyrazoline-3,5-dicarboxylic

acid, prepared by the alkaline hydrolysis of the corresponding

dimethyl ester, was dissolved in ether and mixed with excess dimethyl-

diazomethane, prepared by the silver oxide oxidation of acetone

hydrazone (27). After all bubbling had ceased, the ether was

removed under reduced pressure. The resulting yellow oil was dis-

tilled at 600/2 mm. The infrared spectrum (plates) of the residue,











a brown oil, boiling above 600/2 mm. indicated the presence of a

2-pyrazoline ester by peaks at 2.95, 2.78, 2.83, 6.40 and 6.88 p.

Preparation of phenyldiazomethane. Phenyldiazomethane was

prepared by the method of Staudinger and Gaule (28) using red, rather

than yellow, mercuric oxide. The crude mixture was found to contain

about 30% phenyldiazomethane by titration of 2 ml. of the diazo

solution with a standard solution of maleic anhydride. This crude

solution was used without further purification since the primary

contaminant was benzaldehyde azine which would not be expected to

interfere with the desired reactions.

Preparation of cis-5-phenyl-3,4-dicarbomethoxy-2-pyrazoline. -

Following the procedure of Jones (5b), 8.2 g. (0.058 mole) of dimethyl

fumarate and a pinch of hydroquinone were dissolved in 130 ml.

(approximately 0.059 mole as standardized with maleic anhydride) of

ethereal phenyldiazomethane. The red solution was placed in the

refrigerator until the color had been discharged. During this time,

a white solid precipitated which was then filtered and recrystallized

from methanol. Yield: 5.4 g. (0.038 mole; 65%) of white needles,
O o
m.p. 132-133 reported m.p. 130-132 (5b). Significant absorptions

in the infrared spectrum (Nujol) were at 2.98, 5.80, 5.91, 6.45

and 6.90 p.

Preparation of trans-5-phenyl-3,4-dicarbomethoxy-2-pyrazoline. -

Following the same procedure used for the preparation of cis-5-

phenyl-3,4-dicarbomethoxy-2-pyrazoline, 8.2 g. (0.058 mole) of

dimethyl maleate and a pinch of hydroquinone were dissolved in 130

ml. (approximately 0.059 mole as standardized with maleic anhydride)












of ethereal phenyldiazomethane. This solution was placed in the

refrigerator until the red diazo color had disappeared. The solvent

was then removed under reduced pressure giving rise to a yellow oil

which resisted all attempts at crystallization. Significant absorp-

tions in the infrared spectrum (plates) were at 2.97, 5.70, 5.80,

6.43 and 6.97 p.

Preparation of trans-5-phenyl-3,4-dicarbobutoxy-2-

pyrazoline. Following the same procedure as used in the preparation

of cis-5-phenyl-3,4-dicarbomethoxy-2-pyrazoline, 10 g. (0.044 mole)

of di-n-butyl maleate and a pinch of hydroquinone were dissolved in

an ether solution of phenyldiazomethane of approximately equimolar

concentration. The usual work-up gave a yellow oil which resisted

all attempts at crystallization. Absorptions in the infrared

spectrum (plates) which indicated the presence of the 2-pyrazoline

were at 2.98, 5.75, 5.85, 6.43 and 6.88 u.

Preparation of 4-phenyl-3-carbomethoxy-5-carboethoxy-

2-pyrazoline. Following the procedure of Buchner and von der

Heide (30), 45 g. (0.395 mole) of ethyl diazoacetate was added to

48 g. (0.297 mole) of methyl cinnamate. To this mixture a pinch of

hydroquinone was added. The mixture was then placed on a steam bath

for 24 hours. During this period, there was some visible decomposition

of the diazo compound. At the end of the reaction time, the resulting

orange oil was poured into a beaker and washed with pentane. The



*For a discussion concerning the structures of this compound
and its isomer, see references 5a and 29.












remaining oil was dissolved in a small amount of ethyl ether and

cooled in dry ice. During cooling, a yellow oily solid formed

which was filtered and recrystallized from ethyl ether to give

41.4 g. (0.150 mole; 50%) of a white solid, m.p. 74-76 reported

m.p. 760 (30). The significant absorptions in the infrared spectrum

(potassium bromide) were at 2.99, 5.78, 5.95, 6.57, 13.3 and 14.3 p.

The ultraviolet spectrum gave Amax. in 2-propanol at 288 mp

(E 1.30 x 104).

Preparation of 4-phenyl-3-carboethoxy-5-carbomethoxy-

2-pyrazoline. Again, following the procedure of Buchner and von

der Heide (30), 50 g. (0.50 mole) of methyl diazoacetate was added

to a mixture of 81 g. (0.460 mole) of ethyl cinnamate and a pinch

of hydroquinone. This mixture was then placed on a steam bath and

heated for 28 hours. Also during this time, there was visible gas

evolution. At the end of this time, the solution was a deep orange

color. The solution was poured into a crystallizing dish while still

hot and a small amount of ether added. The oil dissolved in the

ether. The solution was stirred and at the same time the vessel was

scratched to induce crystallization. Crystallization took place

rapidly giving an oily yellow solid which was filtered and recrystal-

lized from hot methanol. This procedure yielded 83 g. (0.30 mole;
o o
65%) of white crystals, m.p. 105-107 reported m.p. 107 (30). The

significant absorptions in the infrared spectrum (potassium bromide)

were at 2.99, 5.79, 5.95, 6.53, 13.3 and 14.3 p. The ultraviolet

spectrum gave Amax. in 2-propanol at 288 my (C 1.44 x 10 ).











Preparation of benzophenone hydrazone. Following the pro-

cedure of Grasley, 400 g. (2.18 moles) of commercial benzophenone

was added to 200 g. (6.25 moles) of anhydrous hydrazine. This

mixture was then dissolved in 400 ml. of absolute ethanol and the

solution was then refluxed for 17 hours. Following the reflux period,

the solution was poured into a beaker and allowed to cool, depositing

large needle-shaped crystals. The solid was filtered from the solu-

tion and washed several times to remove the excess hydrazine. The

solid was then recrystallized repeatedly from absolute ethanol.

Yield: 420 g. of white needles, m.p. 97-99, reported m.p. 990 (32).

The significant absorptions in the infrared spectrum (potassium

bromide) were at 2.85, 2.99, 6.20, 6.31, 6.40, 6.69, 6.92, 12.82,

13.00, 14.21 and 14.39y The ultraviolet spectrum gave max. in

2-propanol at 273 mu (( 1.16 x 10 ).

Preparation of diphenyldiazomethane. Following the general

procedure .as outlined by Miller (33), 26 g. (0.132 mole) of benzophenone

hydrazone was dissolved in 400 ml. of ether. To this solution, 15 g.

anhydrous sodium sulfate and 20 ml. of ethanol saturated with potas-

sium hydroxide were added with stirring. The stirring was continued

for 3 hours during which time 70 g. (0.323 mole) of red mercuric

oxide (commercial N.F. IX) was added in small portions. There was

ample evidence of reaction, for upon addition of the mercuric oxide,

the oxide lost its red color and a deep purple solution was formed.

After the reaction period, the purple solution was filtered


*Unpublished observations, M. H. Grasley.











and the solvent removed under reduced pressure giving rise to a

purple oil which sometimes, upon standing in the refrigerator, did

form low-melting crystals. Significant absorptions in the infrared

spectrum (plates) were at 4.90, 6.29, 6.71, 6.94, 13.39 and 14.42 p.

The ultraviolet spectrum gave max. in cyclohexane at 282 mu

(( 3.78 x 104).

Preparation of 5,5-diphenyl-3,4-dicarbomethoxy-2-pyrazoline. -

Using the procedure of van Alphen (18), approximately equimolar

amounts of diphenyldiazomethane (25 g., 0.129 mole) and dimethyl

maleate (18.6 g., 0.129 mole) were dissolved in ether and allowed to

stand at room temperature until the loss of the red color was com-

plete. Upon removal of the solvent, the remaining oil completely

solidified, m.p. 120-1450 dec. This solid was recrystallized from

methanol giving 30.1 g. (70%) of white crystals, m.p. 141-1420 dec.,

reported m.p. 1420 dec. (18). The significant absorptions in the

infrared spectrum (potassium bromide) were at 2.98, 5.70, 5.88 and

6.32 p. The ultraviolet spectrum gave max. in methanol at 297 mn

(C 1.16 x 10 ).

Preparation of 5,5-diphenyl-3-carbomethoxy-2-pyrazoline. -

The general procedure followed was that of Jones, Glenn and Baarda

(34). The flask used in the reaction was soaked in a saturated

solution of trisodium phosphate for several days and then washed

with distilled water.

A mixture of 5.71 g. (0.064 mole) of cold triethylamine,

5.5 g. (0.064 mole) of cold, freshly distilled methyl acrylate and

11.3 g. (0.058 mole) of diphenyldiazomethane was added to 100 ml. of










cold technical pentane. The mixture was stirred until it was homo-

geneous and then placed in the refrigerator overnight or until the

red diazo color was discharged. Upon discharge of the red color, a

large amount of white solid precipitated. This solid was filtered

from the solution and recrystallized from methanol several times.

Yield: 13 g. (0.046 mole; 80%) of white crystals, m.p. 138-1400 dec.,

reported m.p. 138-1390 dec. (34). Significant absorptions in the

infrared spectrum (potassium bromide) were at 2.95, 5.88 and 6.38 r.

The ultraviolet spectrum gave max. in methanol at 298 mn (C 1.05 x

104).

Preparation of 4,4'-dimethylbenzophenone hydrazone. This

compound was prepared by a slight adaptation of the method used by

Baltzly, et al. (35).

Fifty grams (0.238 mole) of 4,4'-dimethylbenzophenone was

dissolved in 120 ml. of 1-butanol in a 500 ml. round-bottom flask

equipped with a reflux condenser. After all the solid ketone had

dissolved, 30 ml. (0.798 mole) of 85% hydrazine hydrate was added.

The solution turned bright yellow upon the addition of the hydrazine

hydrate. The solution was then refluxed for 18 hours. At this time,

the alcohol solution was set aside to cool overnight. During this

time, white crystals were deposited on the sides and bottom of the

flask. The mixture was filtered and the white solid recrystallized

from absolute ethanol. Recrystallization gave 40 g. (0.174 mole;

73.1%) of white crystals, m.p. 107-1080, reported m.p. 108-1100

(35). The infrared spectrum (potassium bromide) gave peaks at 2.90,

3.0, 6.2, 6.35 and 6.61 p. The ultraviolet spectrum gave > max. in

2-propanol at 264 mi (( 1.48 x 104).











Preparation of 4,4'-dimethyldiphenyldiazomethane. This

diazo compound was prepared by the method of Miller (33). Thirty

grams (0.132 mole) of 4,4'-dimethylbenzophenone hydrazone, prepared

by the method of Baltzly, et al. (35), was mixed with 20 g. of anhy-

drous sodium sulfate in a one-liter three-necked flask equipped with

a mechanical stirrer. To this mixture, 400 ml. of anhydrous ethyl

ether was added along with 17 ml. of saturated alcoholic potassium

hydroxide solution. After the hydrazone had dissolved, 70 g. (0.323

mole) of red mercuric oxide was added slowly over a period of 1 hour.

The mixture was then stirred for 5 more hours. The solution was a

very deep purple. The purple ether solution was filtered and the

spent mercuric oxide-sodium sulfate mixture was washed several times

with small portions of ethyl ether. These washings were filtered and

added to the first solution. The ether was then removed by vacuum

distillation yielding 23 g. (0.104 mole; 78.8%) of a purple solid,

m.p. 100-101 reported m.p. 1010 (36). Significant absorptions in

the infrared spectrum (potassium bromide) were at 4.91, 6.26, 6.63,

12.32 and 14.25 p. The ultraviolet spectrum gave max. in cyclo-

hexane at 286 mu (C 5.58 x 103).

Preparation of 5,5-(4,4'-dimethyldiphenyl)-3,4-dicarbomethoxy-

2-pyrazoline. In a 250 ml. Erlenmeyer flask prepared in the same

manner as for the preparation of 5,5-diphenyl-3-carbomethoxy-2-

pyrazoline, 5.6 g. (0.955 mole) of triethylamine and 8 g. (0.0555

mole) of dimethyl maleate were mixed with 100 ml. of anhydrous ether

and set in the refrigerator to cool. Upon cooling, 11 g. (0.050

mole) of 4,4'-dimethyldiphenyldiazomethane was added and the solution











returned to the refrigerator. The solution remained in the refrigera-

tor until the diazo color was discharged, whereupon the solvent was

removed under reduced pressure giving rise to a brown oil which

crystallized when dissolved in a small amount of methanol, cooled to

dry ice temperature, and the vessel scratched with a glass rod. The

resulting solid was filtered and then recrystallized from methanol,

again with cooling and scratching the vessel. Yield: 6 g. (30%) of a

white powder, m.p. 50-520 dec. This compound was not stable enough

at room temperature to obtain a good analysis. Significant absorp-

tions in the infrared spectrum (potassium bromide) were at 2.95, 5.73,

5.89, 6.40 and 12.25 p. The ultraviolet spectrum gave max. in 2-

propanol at 298 my (C 1.42 x 10 ).

Preparation of 5,5-(4,4'-dimethyldiphenyl)-3-carbomethoxy-

2-pyrazoline. In a 250 ml. Erlenmeyer flask prepared as described

in the preparation of 5,5-diphenyl-3-carbomethoxy-2-pyrazoline, 5.6 g.

(0.055 mole) of triethylamine and 4.7 g. (0.055 mole) of methyl

acrylate were mixed with 100 ml. of technical pentane and brought to

00, whereupon 11 g. (0.050 mole) of 4,4'-dimethyldiphenyldiazomethane

was added and the solution returned to the refrigerator until the red

diazo color had disappeared. Then the solvent was removed under

reduced pressure giving rise to a yellow oil which resisted all

attempts to induce crystallization. Significant absorptions in the

infrared spectrum (plates) which indicated that the 2-pyrazoline was

indeed present were at 2.95, 5.89, 6.41 and 12.25 p. The ultra-

violet spectrum gave max. in 2-propanol at 298 m~. This oil was

used in the subsequent kinetic decompositions, without further











purification. For each decomposition, the oil contained 85-95% of

the 2-pyrazoline as calculated from the observed volume of nitrogen

evolved.

Preparation of 4-methylbenzophenone. Following the procedure
*
of Hughes, Ingold and Taher (37), a mixture of 190 g. (1.36 moles)

benzoyl chloride, 145 g. (1.09 moles) of anhydrous aluminum tri-

chloride and one liter of carbon disulfide was heated on the steam

bath under reflux conditions for 2 hours and then cooled. After the

addition of 150 g. (1.63 moles) of toluene, the heating was continued

for 4 hours. The solution was then cooled and added to ice water.

The filtered carbon disulfide solution was washed with successive

amounts of dilute hydrochloric acid, water, saturated sodium bicar-

bonate solution and water. Then the solution was dried over anhydrous

sodium sulfate and distilled.

When all the carbon disulfide had been removed, the residue

was cooled and filtered. The resulting solid was recrystallized from

pentane. Yield: 147 g. (0.75 mole; 55%) of a white solid, m.p. 55-

560, reported m.p. 570 (39). Significant absorptions in the infrared

spectrum (potassium bromide) were at 6.05, 6.23, 6.91, 12.71, 13.65

and 14.34 p. The ultraviolet spectrum gave A max. in 2-propanol at

257 mu (C 1.52 x 104).

Preparation of 4-methylbenzophenone hydrazone. Utilizing

the procedure of Baltzly, et al. (35), 34 g. (0.174 mole) of 4-methyl-

benzophenone and 15 ml. of 85% hydrazine hydrate were dissolved in


*See also reference No. 38.












100 ml. of 1-butanol and refluxed for 2 days. At the end of this

time, the solution was poured into a beaker and cooled in dry ice

to precipitate the hydrazone. When the solid had precipitated, the

solution was filtered and the solid recrystallized several times

from absolute ethanol. Yield: 20 g. (0.095 mole; 55%) of white

crystals, m.p. 86-870, reported m.p. 80-810 (39). The melting

point of this material was depressed by addition of the starting

ketone. The significant absorptions in the infrared spectrum

(potassium bromide) were at 2.91, 3.01, 6.22, 6.36, 6.65, 6.97,

12.17, 13.00 and 14.40 p. The ultraviolet spectrum gave I max.

in 2-propanol at 273 nmp (C 1.30 x 10 ).

Preparation of phenyl-p-tolyl-diazomethane. Following the

outline of Baltzly, et al. (35), 8 g. (0.038 mole) of 4-methylbenzo-

phenone hydrazone was dissolved in 50 ml. of anhydrous ether. Five

grams of anhydrous sodium sulfate and 8 ml. of saturated ethanolic

potassium.hydroxide were added with stirring. The stirring was

continued as 16 g. (0.076 mole) of red mercuric oxide was added in

small portions over a period of 1 day. The solution was a deep

purple color at the end of the reaction period. The solution was

then filtered and the solvent removed under reduced pressure giving

7 g. (0.037 mole; 88%) of a purple solid, m.p. 54-550 dec., reported

53-550 dec. (40). Significant absorptions in the infrared

spectrum (potassium bromide) were at 4.89, 6.62, 12.30, 13.37 and

14.40 p. The ultraviolet spectrum gave )max. in cyclohexane at

278 ~y. ( 1.54 x 104).











Preparation of 5-(4-methylphenyl)-5-phenyl-3,4-dicarbomethoxy-

2-pyrazoline. In 220 ml. of anhydrous ether, 11.7 g. (0.0564 mole)

of phenyl-p-tolyl-diazomethane was mixed with 8.1 g. (0.0564 mole) of

dimethyl maleate, a small amount of triethylamine and a pinch of

hydroquinone. This solution was put in the refrigerator until the

diazo color had been discharged. Then the solvent was removed under

reduced pressure giving rise to a yellow oil. Significant absorp-

tions in the infrared spectrum (plates) which indicated the presence

of the 2-pyrazoline were at 2.99, 5.85, 6.39, 12.12, 12.95 and

14.42 p. The ultraviolet spectrum gave X max. in 2-propanol at

295 mnj. This oil was used in subsequent kinetic determinations with-

out further purification. For each decomposition, the oil contained

from 85-95% of the 2-pyrazoline as calculated from the observed

volume of nitrogen evolved.

Preparation of 5-(4-methylphenyl)-5-phenyl-3-carbomethoxy-

2-pyrazoline. In 150 ml. of anhydrous ether, 8 g. (0.038 mole) of

phenyl-p-tolyl-diazomethane, 3.3 g. (0.038 mole) of methyl acrylate,

2 ml. of triethylamine and a pinch of hydroquinone were mixed and

the solution set in the refrigerator until the diazo color disappeared.

Then the solvent was removed under reduced pressure yielding a yellow

oil which failed to crystallize. Significant absorptions in the

infrared spectrum (plates) which indicated the presence of the 2-

pyrazoline were at 2.96, 5.90, 6.42, 12.20, 12.92 and 14.35 p. The

ultraviolet spectrum gave max. in 2-propanol at 292 xy. This oil

was used in subsequent kinetic determinations without further puri-

fication. For each decomposition, the oil contained 85-95% of the











2-pyrazoline as calculated from the observed volume of nitrogen

evolved.

Preparation of 1,1-(4,4'-dichlorodiphenyl)-2,2-dichloro-

ethene. One mole (335 g.) of 4,4'-dichlorodiphenyltrichloro-

ethane (DDT) was mixed with 67 g. (1.3 moles) of potassium hydroxide

dissolved in absolute ethanol and refluxed for 4 hours. At the end

of this time, a yellowish solid had precipitated and the solution

was a dark brown. The solution was filtered and set aside to cool.

The residual yellow solid was washed with ethanol which removed the

color and left a white powder. This solid proved to be potassium

chloride.

The washings and the original ethanol solution were combined

and allowed to cool further, whereupon a heavy mass of crystals was

deposited in a short time. The solution was filtered and the solid

was recrystallized from ethanol. Yield: 161 g. (0.51 mole; 51%) of

yellow crystals, m.p. 87-89 reported m.p. 890 (41). Significant

absorptions in the infrared spectrum (potassium bromide) were at

6.30, 6.40, 6.71, 12.05 and 12.55 1. The ultraviolet spectrum gave

Smax. in 2-propanol at 223 my (C 2.54 x 10 ) and 247 mp

(C 2.65 x 104).

Preparation of 4,4'-dichlorobenzophenone. This ketone was

prepared by the nitric acid oxidation of l,l-(4,4'-dichlorodiphenyl)-

2,2-dichloroethene. This was the method as used by Backeberg and

Marais (42). In a typical run, 2 g. (0.0063 mole) of the olefin

was dissolved in 20 ml. of glacial acetic acid and 10 ml. of fuming

nitric acid (sp. gr. 1.51) was added. The solution was then heated











on a steam bath in the hood for 2-2.5 hours. Almost immediately

upon addition of heat to the vessel, the red-brown fumes of nitrogen

dioxide were observed and the solution itself was a reddish color.

At the end of the heating period, the red solution was poured

into water, covered and set in the refrigerator to cool. A white

powder formed upon contact with the water.

Also, one of the side products formed upon the addition to

water was a very powerful lachrymator, and care was taken to filter

the solution in the hood.

The cold water solution was filtered and the white powder

recrystallized from absolute ethanol. Yield: 1.5 g. (0.006 mole;

95%) of white flakes, m.p. 144-1460, reported m.p. 145-1460 (42).

Significant absorptions in the infrared spectrum (potassium bromide)

were at 6.08, 6.35, 6.75 and 12.02 p. The ultraviolet spectrum gave

- max. in 2-propanol at 264 my (C 2.73 x 10 ).

Preparation of 4,4'-dichlorobenzophenone hydrazone. This

compound was prepared using a slight modification of the method of

Szmant and McGinnis (43).

Twenty-one grams (0.0837 mole) of 4,4'-dichlorobenzophenone,

prepared by the nitric acid oxidation of l,l-dichloro-2,2-(4,4'-

dichlorodiphenyl)-ethene (42) was added to 25 g. (0.742 mole) of

95% anhydrous hydrazine in 250 ml. of 95% ethanol. The solution was

allowed to reflux in a one-liter round-bottom flask equipped with a

Soxhlet extractor for 2 days. The extraction thimble was filled with

20 g. of calcium oxide that had been previously heated at 1100 in an

oven for 2 days. After the reflux period, some of the solvent was











removed by applying a slight vacuum to the reaction vessel. The

solution was then poured into water and allowed to stand. A white

precipitate formed and was collected by filtration. Recrystallization

from 95% ethanol gave 17 g. (0.0642 mole; 76.7%) of white crystals,

m.p. 90-930, reported m.p. 92-930 (43). The reported color was

yellow but the melting point and infrared spectrum indicated that

this was the hydrazone. Significant absorptions in the infrared

spectrum (potassium bromide) were at 2.91, 3.01, 6.31 and 6.75 p.

The ultraviolet spectrum gave max. in 2-propanol at 273 my

(( 5.42 x 103).

Preparation of 4,4'-dichlorodiphenyldiazomethane. This

compound was prepared according to the general procedure of Miller

(33). Five grams (0.0189 mole) of 4,4'-dichlorobenzophenone hydra-

zone, prepared by the method of Szmant and McGinnis (43), was dis-

solved in 100 ml. anhydrous ethyl ether and 10 g. of anhydrous sodium

sulfate added to the solution, followed by 5 ml. of a saturated

alcoholic potassium hydroxide solution. Fifteen grams (0.0693 mole)

of red mercuric oxide was added slowly. This mixture was placed in

a 500 ml. flask equipped with a mechanical stirrer. The mixture was

then stirred for 3 days at room temperature. The ether solution was

reddish-purple. This solution was filtered and evaporated to dryness

giving a reddish-purple solid. Recrystallization from pentane gave

4 g. (0.0141 mole; 74.6%) of red needles, m.p. 68-700, reported m.p.

700 (36). Significant absorptions in the infrared spectrum (potassium

bromide) were at 4.88, 6.35, 6.73, 12.2 and 12.3 p. The ultraviolet

spectrum gave -max. in cyclohexane at 288 mi (C 1.56 x 10 ).











Preparation of 5,5-(4,4'-dichlorodiphenyl)-3,4-dicarbo-

methoxy-2-pyrazoline. In a typical run, 1 g. (0.0038 mole) of

4,4'-dichlorodiphenyldiazomethane was added to 0.55 g. (0.0038

mole) of dimethyl maleate in 20 ml. of anhydrous ether. To this

solution, 1 ml. of triethylamine and a pinch of hydroquinone were

added and the total solution placed in the refrigerator until the

red diazo color had been discharged. The solvent was then removed

under reduced pressure giving rise to a yellow oil which failed to

crystallize. Significant absorptions in the infrared spectrum (plates)

which indicated the presence of the 2-pyrazoline were at 2.98, 5.79,

5.88, 6.40 and 12.10 p. The ultraviolet spectrum gave max. in

2-propanol at 298 mp. This oil was used without further purification

in the subsequent kinetic runs. For each decomposition, the oil

contained from 85-95% of the 2-pyrazoline as calculated from the

observed volume of nitrogen evolved.

Preparation of 5,5-(4,4'-dichlorodiphenyl)-3-carbomethoxy-

2-pyrazoline. In a typical run, 1.8 g. (0.0069 mole) of 4,4'-

dichlorodiphenyldiazomethane and 0.53 g. (0.0069 mole) of methyl

acrylate were added to a cold solution of 25 ml. of anhydrous ether,

2 ml. of triethylamine and a pinch of hydroquinone. This solution

was then placed in the refrigerator until the red diazo color disap-

peared. The usual work-up gave a yellow oil which failed to crystal-

lize. Significant absorptions in the infrared spectrum (plates) which

indicated the presence of the 2-pyrazoline were at 2.97, 5.89, 6.40

and 12.09 p. The ultraviolet spectrum gave X max. in 2-propanol at

297 mp. This oil was used without further purification in the











subsequent kinetic runs. For each decomposition, the oil contained

85-95% of the 2-pyrazoline as calculated from the observed volume

of nitrogen evolved.

Preparation of 5,5-(4,4'-dimethyldiphenyl)-3,4-dicarbo-

methoxy-l-acetyl-2-pyrazoline. The solid (0.6 g., 0.0016 mole)

prepared by the reaction of 4,4'-dimethyldiphenyldiazomethane and

dimethyl maleate was dissolved in acetic anhydride and 3 drops of

concentrated sulfuric acid were added. The solution was swirled and

then heated a short time on a steam bath. The hot solution was

allowed to cool and then was poured into cold water. An oil imme-

diately separated upon contact with the water. Solid sodium bicar-

bonate was added with stirring until the bubbling ceased. The solu-

tion was washed with ether and the ether solution was dried over

anhydrous sodium sulfate. The ether was removed under reduced pres-

sure giving rise to a white solid, m.p. 143-1460, after recrystal-

lization from methanol. The significant absorptions in the infrared

spectrum (potassium bromide) were at 5.70, 5.83, 5.92 and 6.29 p with

the absence of a peak in the 2.8-3.1 p region indicating no nitrogen-

hydrogen bond. The ultraviolet spectrum gave max. in 2-propanol

at 281 mp (C 1.27 x 104).

Anal. Calcd. for C23H24N205: C, 67.23; H, 5.92; N, 6.86.

Found: C, 67.50; H, 6.01; N, 6.90.

Preparation of 5,5-(4,4'-dimethyldiphenyl)-3-carbomethoxy-

l-acetyl-2-pyrazoline. The oil from the reaction of 4,4'-dimethyl-

diphenyldiazomethane and methyl acrylate was dissolved in 5 ml. of

acetic anhydride and 3 drops of concentrated sulfuric acid were added.











The usual work-up afforded a white solid, m.p. 152-153.5 after

recrystallization from methanol. Significant absorptions in the

infrared spectrum (potassium bromide) were at 5.82, 5.91 and 6.29 p

with no peak in the 2.8-3.1 p region. The ultraviolet spectrum gave

Smax. in 2-propanol at 279 mp (C 1.25 x 10 ).

Anal. Calcd. for C21H22N203: C, 71.98; H, 6.33; N, 8.00.

Found: C, 72.01; H, 6.44; N, 8.16.

Preparation of 5-phenyl-5-p-tolyl-3,4-dicarbomethoxy-l-

acetyl-2-pyrazoline. The oil from the reaction of phenyl-j-tolyl-

diazomethane and dimethyl maleate was dissolved in 5 ml. of acetic

anhydride and 3 drops of concentrated sulfuric acid were added. The

usual work-up gave a white solid, m.p. 132-134 after recrystal-

lization from methanol. Significant absorptions in the infrared

spectrum (potassium bromide) were at 5.76, 5.81, 5.91, 6.32 and

6.88 p. The ultraviolet spectrum gave ).max. in 2-propanol at

278 mp (C 1.26 x 104).

Anal. Calcd. for C22H22N205: C, 66.99; H, 5.62; N, 7.10.

Found: C, 66.81; H, 5.60; N, 7.02.

Preparation of 5-phenyl-5-p-tolyl-3-carbomethoxy-l-acetyl-

2-pyrazoline. The oil from the reaction of 4-methylphenyl-phenyl-

diazomethane and methyl acrylate was dissolved in 5 ml. of acetic

anhydride and 3 drops of concentrated sulfuric acid were added. The

usual work-up afforded a white solid, m.p. 138-1400, reported m.p.

138-1400 (21), after recrystallization from methanol. The infrared

spectrum (potassium bromide) gave peaks at 5.80, 5.92 and 6.29 p with

no peak in the 2.8-3.1 p region. The ultraviolet spectrum gave










4
Amax. in methanol at 278 mp (C 1.34 x 10 ) (21).

Anal. Calcd. for C20H20N203: C, 71.41; H, 5.99; N, 8.33.

Found: C, 71.48; H, 5.78; N, 8.43.

Preparation of 5,5-(4,4'-dichlorodiphenyl)-3,4-dicarbo-

methoxy-l-acetyl-2-pyrazoline. The oil from the reaction of 4,4'-

dichlorodiphenyldiazomethane and dimethyl maleate was dissolved in

5 ml. of acetic anhydride and 3 drops of concentrated sulfuric acid

were added. The usual work-up gave a white solid, m.p. 174-175.50,

upon recrystallization from methanol. The infrared spectrum (potas-

sium bromide) showed peaks at 5.76, 5.81, 5.91, 6.29 and 6.70 p.

The ultraviolet spectrum gave Xmax. in 2-propanol at 266 mn

( 1.74 x 104).

Anal. Calcd. for C21H18C12N205: C, 56.14; H, 4.04i Cl, 15.78;

N, 6.24. Found: C, 56.22; H, 4.17; Cl, 15.81; N, 6.12.

Preparation of 5,5-(4,4'-dichlorodiphenyl)-3-carbomethoxy-

l-acetyl-2-pyrazoline. The oil from the reaction of 4,4'-dichloro-

diphenyldiazomethane and methyl acrylate was dissolved in 5 ml. of

acetic anhydride and 3 drops of concentrated sulfuric acid were

added. The usual work-up gave a white solid, m.p. 183-185 after

recrystallization from methanol. Significant absorptions in the

infrared spectrum (potassium bromide) were at 5.74, 5.99 and 6.29 y

with no peak in the 2.8-3.1 p region. The ultraviolet spectrum gave

Smax. in 2-propanol at 277 my (C 1.74 x 104).

Anal. Calcd. for C 9H 6C12N203: C, 58.33; H, 4.12; Cl, 18.12;

N, 7.16. Found: C, 58.53; H, 4.38.

The major portion of this sample was lost in an accident at











Galbraith Laboratories. Only enough material for the carbon and

hydrogen determinations was recovered.

Isolation of 2,2-diphenyl-cyclopropanecarboxylic acid. -

Following the procedure of Baarda (21), the residue from reduced-

pressure removal of the solvent from a spent kinetic reaction mix-

ture from the decomposition of 5,5-diphenyl-3-carbomethoxy-2-

pyrazoline was hydrolyzed with methanolic potassium hydroxide.

The usual work-up procedure gave 0.455 g. (0.00668 mole; 83%) of

a white solid, m.p. 170-1720, reported m.p. 169-1710 (44)

Isolation of 2-phenyl-2-p-tolyl-cyclopropanecarboxylic

acid. This acid was isolated in the same manner as the 2,2-

diphenyl-cyclopropanecarboxylic acid. The usual work-up gave

0.340 g. of a crude solid. Recrystallization of this solid from

ether/pentane gave 0.110 g. (0.0044 mole) of a white solid, m.p. 144-

1520, reported m.p. 145-153 (21). The wide range was due possibly

to a mixture of cis and trans isomers. The infrared spectrum (potas-

sium bromide) gave significant peaks at 3.2-3.9 (broad), 5.9, 6.68,

6.95, 13.32, 13.9 and 14.40 p. The ultraviolet spectrum gave max.

in 2-propanol at 229 mx (( 1.99 x 10 ).

Isolation of 2,2-(4,4'-dimethyldiphenyl)-cyclopropane-

carboxylic acid. This acid was isolated in the same manner as 2,2-

diphenyl-cyclopropanecarboxylic acid. The usual work-up gave 0.123 g.

(0.00463 mole) of a white solid, m.p. 153-154.50. Significant absorp-

tions in the infrared spectrum (potassium bromide) were at 3.3-4

(broad), 5.9, 6.65, 12.4 and 12.95 p. The ultraviolet spectrum gave

Amax. in 2-propanol at 228 m~ (4 1.79 x 10 ).











Anal. Calcd. for C18H1802: C, 81.17; H, 6.81. Found:

C, 81.16; H, 6.93.

Isolation of 2,2-(4,4'-dichlorodiphenyl)-cyclopropane-

carboxylic acid. This acid was isolated in the same manner as 2,2-

diphenyl-cyclopropanecarboxylic acid. The usual work-up gave 0.200 g.

(0.000652 mole) of white crystals, m.p. 171-1720, reported m.p. 170.5-

1710 (45). Significant absorptions in the infrared spectrum (potassium

bromide) were at 3.2-3.92 (broad), 5.90 and 6.69 p. The ultraviolet

spectrum gave A max. in 2-propanol at 232 rmu (( 2.22 x 10 ).

Anal. Calcd. for C 6H C1202: C, 62.56; H, 3.94; Cl, 23.09.

Found: C, 62.47; H, 4.07; Cl, 23.20.

Isolation of 3,3-(4,4'-dimethyldiphenyl)-1,2-dicarbomethoxy-

cyclopropane. The solvent from a spent reaction mixture from the

kinetic decomposition of 5,5-(4,4'-dimethyldiphenyl)-3,4-dicarbo-

methoxy-2-pyrazoline was removed under reduced pressure leaving a

solid residue. The residue was recrystallized from methanol. Yield:

0.422 g. (0.00125 mole) of white needles, m.p. 142.5-144.50. Signifi-

cant absorptions in the infrared spectrum (potassium bromide) were

at 5.76, 6.68, 6.98 and 13.77 u. 'The ultraviolet spectrum gave A
4
max. in 2-propanol at 228 mu (( 1.47 x 10 ).

Anal. Calcd. for C22H2204: C, 74.54; H, 6.55. Found:

C, 74.49; H, 6.57.

Isolation of 3,3-diphenyl-1,2-dicarbomethoxycyclopropane. -

This ester was isolated in the same manner as for 3,3-(4,4'-dimethyl-

diphenyl)-l,2-dicarbomethoxycyclopropane. Recrystallization of the

residue gave 0.376 g. (0.00121 mole; 68%) of white solid, m.p. 174-176,











reported m.p. 174-174.50 (15). A mixed melting point with an

authentic sample gave no depression of the melting point. The

infrared spectrum (potassium bromide) gave peaks at 5.77, 6.67,

6.95, 13.38 and 14.38 p.

Isolation of 3,3-(4,4'-dichlorodiphenyl)-1,2-carbomethoxy-

cyclopropane. This ester was isolated in the same manner as for

the 3,3-(4,4'-dimethyldiphenyl)-l,2-dicarbomethoxycyclopropane.

Recrystallization from methanol gave 0.480 g. (0.00126 mole) of

white crystals, m.p. 151-1530. Significant absorptions in the

infrared spectrum (potassium bromide) were at 5.76, 6.68, 6.98,

and 13.77 p. The ultraviolet spectrum gave max. in 2-propanol

at 232 mp (( 2.33 x 10 ).

Anal. Calcd. for C19H16C1204: C, 60.18; H, 4.25. Found:

C, 59.98; H, 4.05.

Isolation of 3-phenyl-3-p-tolyl-l,2-dicarbomethoxycyclo-

propane. This cyclopropane was isolated in the same manner as the

3,3-(4,4'-dimethyldiphenyl)-l,2-dicarbomethoxycyclopropane. Recrystal-

lization from methanol gave 0.347 g. (0.00107 mole) of white crystals,

m.p. 134-136. Significant absorptions in the infrared spectrum

(potassium bromide) were at 5.73, 6.68, 6.95, 13.33, 13.9 and 14.37 p.

The ultraviolet spectrum gave max. in 2-propanol at 226 nym

(C 8.27 x 103).

Anal. Calcd. for C20H2004: C, 74.06; H, 6.22. Found:

C, 73.90; H, 6.20.

Preparation of 4-phenyl-3-carboethoxy-5-carbomethoxy-l-

acetyl-2-pyrazoline. One gram (0.00362 mole) of the 4-phenyl-3-











carboethoxy-5-carbomethoxy-2-pyrazoline, prepared by the reaction

of methyl diazoacetate with ethyl cinnamate, was added to 5 ml. of

acetic anhydride to which 1 drop of concentrated sulfuric acid had

been added. This mixture was placed in a flask and heated on the

steam bath for about 10 minutes. The solution thus obtained was

cooled and poured into water. Solid sodium bicarbonate was added

in portions until all bubbling had ceased. Then the solution was

washed with ethyl ether. The ether solution was dried over anhydrous

sodium sulfate. The ether solution then was evaporated to dryness,

giving a white solid. Recrystallization of the solid from 95%

ethanol gave 0.9 g. (0.00283 mole; 78.2%) of white crystals, m.p.
o
105-108 The significant absorptions in the infrared spectrum

(potassium bromide) were at 5.7, 5.8, 5.9 and 12.6 p. The ultra-

violet spectrum gave Xmax. in 2-propanol at 276 mp (( 1.63 x 10 ).

Anal. Calcd. for C16H 8N205: C, 60.37; H, 5.70; N, 8.80.

Found: C, 60.20; H, 5.71; N, 8.90.

Preparation of 4-phenyl-5-carboethoxy-3-carbomethoxy-l-

acetyl-2-pyrazoline. This compound was prepared by the same method

used to prepare 4-phenyl-3-carboethoxy-5-carbomethoxy-l-acetyl-2-

pyrazoline. The usual work-up gave a clear oil which resisted all

attempts at crystallization. This procedure gave 0.9 g. (0.00283

mole; 78.2%) of the oil. Significant absorptions in the infrared

spectrum (plates) were at 5.7, 5.8, 5.92 and 11.4 p. The ultraviolet

spectrum gave max. in 2-propanol at 275 mp (C 1.66 x 10 ).

In comparison with the infrared spectrum of the 4-phenyl-3-

carboethoxy-5-carbomethoxy-l-acetyl-2-pyrazoline, it was found that











the spectra were quite similar except at 11.4 and 12.6 p. The

11.4 p peak was found only with the 5-carboethoxy isomer and the

12.6 p peak only with the 5-carbomethoxy isomer. The presence of

these peaks served as an analytical tool in subsequent reactions.

Anal. Calcd. for C16H18N205: C, 60.37; H, 5.70; N, 8.80.

Found: C, 60.19; H, 5.75; N, 8.79.

Partial decomposition of 4-phenyl-3-carboethoxy-5-carbo-

methoxy-2-pyrazoline. A sample of the 2-pyrazoline (0.6435 g.,

0.00233 mole) was dissolved in 50 ml. of decalin in which 0.3 ml.

of triisoamylamine had been mixed. This solution was placed in a

constant temperature oil bath at 1500 until 50% of the calculated

amount of nitrogen had been evolved. The solution was then removed

from the bath and allowed to cool, whereupon 5 ml. of acetic anhydride

and 3 drops of concentrated sulfuric acid were added. The liquids

formed a two-phase mixture which was heated overnight at 600. The

two layers were then separated and the anhydride layer worked up

in the usual manner. This work-up gave 0.3 g. (0.00094 mole; 81%)

of a yellow oil. The infrared spectrum (plates) of this material

gave peaks at 3.38, 5.78, 5.80, 5.95, 11.4 and 12.6 p. The appearance

of both peaks at 11.4 and 12.6 p indicated a mixture of the two

acetyl derivatives.

Partial decomposition of 4-phenyl-5-carboethoxy-3-carbo-

methoxy-2-pyrazoline. A sample of the 2-pyrazoline (0.6537 g.,

0.00236 mole) was dissolved in 50 ml. of decalin in which 0.3 ml.

of triisoamylamine had been mixed. This solution was placed in a

constant temperature bath at 1500 until 50% of the calculated amount











of nitrogen had been evolved. The same work-up procedure used for

the acylation of the reaction mixture from the partial decomposition

of 4-phenyl-3-carboethoxy-5-carbomethoxy-2-pyrazoline was followed

here. Yield: 0.3 g. (0.00094 mole; 80%) of a yellow oil. The

infrared spectrum (plates) gave peaks at 3.38, 5.78, 5.95, 11.4

and 12.6 p. The appearance of both peaks at 11.4 and 12.6 p

indicated a mixture of the two acetyl derivatives.

Purification of the nitrogen gas bubbled through the hexa-

decane prior to a kinetic run. A system similar to that described

by Fieser (46) was used to purify the nitrogen gas which was bubbled

through the hexadecane solvent as part of the preliminary treatment

for a kinetic run. This system consisted of a series of wash bottles

containing, respectively, Fieser's solution (47), saturated lead

acetate solution, concentrated sulfuric acid, the metal ketyl from

benzophenone and sodium in xylene and a final bottle of paraffin oil.

Preparation of Fieser's solution (47). This solution con-

tained alkaline sodium hydrosulfite with sodium anthraquinone

B-sulfonate added as a catalyst. The solution was prepared by dis-

solving 20 g. of potassium hydroxide in 100 ml. of water and adding

2 g. of sodium anthraquinone B-sulfonate and 15 g. of sodium hydro-

sulfite to the warm solution. The mixture was stirred until a clear,

blood-red solution was obtained.

Preparation of the metal ketyl of benzophenone and sodium. -

Five grams of sodium was covered with xylene and 5 g. of potassium

dropped onto the sodium. The metals were pushed together with a glass

rod until they alloyed and became a liquid. This liquid was











transferred by pipette, under a layer of solvent, to a suitable

amount of xylene in the wash bottle. Ten grams of benzophenone was

added and the bottle sealed at the top. The solution turned a very

bright blue. Prior to each use, the solution had to be shaken

vigorously.

Purification of hexadecane. Eastman practical hexadecane

was distilled under reduced pressure and stored under argon and

over Linde 3 A molecular sieves. B.p4.0 mm. 133.2-134

Purification of methyl acrylate, tri-n-propylamine, tri-

ethylamine, triisoamylamine and dimethyl maleate. Each of these

liquids was distilled at atmospheric pressure and middle cuts

taken. Methyl acrylate, b.p. 79.5-80.50, reported b.p. 80.50 (48);

tri-n-propylamine, b.p. 154-1560, reported b.p. 1560 (49);

triisoamylamine, b.p. 235-2370, reported b.p. 2370 (50); triethylamine,
O 0
b.p. 88-89 reported b.p. 89.5 (51); dimethyl maleate, b.p. 203-

2050, reported b.p. 2050 (52).














LIST OF REFERENCES


1. T. L. Jacobs in R. C. Elderfield, "Heterocyclic Compounds,"
John Wiley and Sons, Inc., New York, N. Y., Vol. 5, 1957,
Chapter 2.

2. (a) W. von E. Doering, R. G. Buttery, R. G. Laughlin and
N. Chaudhuri, J. Am. Chem. Soc., 78, 3224 (1956).

(b) W. von E. Doering and P. La Flamme, ibid., 78, 5447 (1956)

(c) H. M. Frey, ibid., 80, 5005 (1958).

3. K. von Auwers and E. Cauer, Ann., 470, 284 (1929).

4. K. von Auwers and F. Konig, ibid., 496, 27 (1932).

5. (a) W. M. Jones, J. Am. Chem. Soc., 82, 3136 (1963).

(b) W. M. Jones, ibid., 81, 5153 (1959).

(c) W. M. Jones, ibid., 80, 6678 (1958).

6. (a) W. M. Jones and W. T. Tai, J. Org. Chem., 27, 1030 (1962).

(b) W. M. Jones and W. T. Tai, ibid., 27, 1324 (1962).

7. T. V. von Auken and K. L. Rinehart, Jr., J. Am. Chem. Soc.,
84, 3736 (1962).

8. W. G. Young, L. J. Andrews, S. L. Lindenbaum and S. J. Cristol,
ibid., 66, 810 (1944).

9. A. N. Kost and V. V. Ershov, Uspekhi Khim., 27, 431 (1958).

10. S. G. Beech, J. H. Turnbull and W. Wilson, J. Chem. Soc., 4686
(1952).

11. D. E. McGreer, Ph.D. Thesis, Univ. of Illinois, 1959, p. 22.

12. W. I. Awad, S. M. Abdel, R. Omran and M. Sobhy, J. Org. Chem.,
26, 4126 (1961).











13. C. G. Overberger and J. P. Anselme, J. Am. Chem. Soc., 84,
869 (1962).

14. F. J. Impastato and H. M. Walborsky, ibid., 84, 4838 (1962).

15. W. M. Jones, ibid., 81, 3776 (1959).

16. E. Buchner and H. Dessauer, Ber., 25, 1147 (1892).

17. K. von Auwers and F. Konig, Ann., 496, 252 (1932).

18. J. van Alphen, Rec. tray. chim., 62, 210 (1943).

19. E. Buchner and H. Witter, Ann., 273, 239 (1893).

20. L. L. McCoy, J. Am. Chem. Soc., 80, 6568 (1958).

21. (a) D. G. Baarda, Master's Thesis, Univ. of Florida, 1960.

(b) D. G. Baarda, Ph.D. Thesis, Univ. of Florida, 1962.

22. C. G. Overberger, M. T. O'Shaughnessy and H. Shalit, J. Am. Chem.
Soc., 71, 2661 (1949).

23. J. DeBoer and H. J. Backer, "Organic Syntheses," John Wiley and
Sons, Inc., New York, N. Y., Vol. 36, 1956, p. 16.

24. N. E. Searle, ibid., p. 25.

25. E. Buchner, Ber., 21, 2643 (1888).

26. (a) E. Buchner and H. Dessauer, ibid., 26, 258 (1893).

(b) E. Buchner and H. Dessauer, ibid., 25, 1147 (1892).

27. H. Staudinger and A. Gaule, ibid., 49, 1897 (1916).

28. H. Staudinger and A. Gaule, ibid., 49, 1906 (1916).

29. W. S. Brey, Jr. and W. M. Jones, J. Org. Chem., 26, 1912 (1961).

30. E. Buchner and C. von der Heide, Ber., 35, 31 (1902).

31. T. Curtius and F. Goebel, J. prakt. Chem. (2), 37, 150 (1888).

32. I. Heilbron and H. M. Bunbury, "Dictionary of Organic Compounds,"
Oxford University Press, New York, N. Y., 1953, p. 256.

33. J. B. Miller, J. Org. Chem., 24, 561 (1959).

34. W. M. Jones, T. Glenn and D. G. Baarda, ibid., 28, 2887 (1963).











35. R. Baltzly, et al., J. Org. Chem., 26, 3669 (1961).

36. D. Betheil and J. D. Callister, J. Chem. Soc., 3808 (1963).

37. E. D. Hughes, C. K. Ingold and N. Taher, ibid., 949 (1940).

38. P. J. Montagne, Rec. tray. chim., 27, 357 (1908).

39. M. P. Bourcet, Bull. soc. chim. France, III, 15, 945 (1896).

40. H. Staudinger and J. Goldstein, Ber., 49, 1926 (1916).

41. S. Cohen, A. Kaluszyner and R. Mechoulam, J. Am. Chem. Soc.,
79, 5979 (1957).

42. 0. G. Backeberg and J. L. C. Marais, J. Chem. Soc., 803 (1945).

43. H. H. Szmant and C. McGinnis, J. Am. Chem. Soc., 72, 2890 (1950).

44. H. M. Walborsky and F. M. Homyak, ibid., 77, 6026 (1955).

45. M. Hamada and A. Okamoto, Botyu-Kagaku, 18, 70 (1953).

46. L. F. Fieser, "Experiments in Organic Chemistry," 3rd Ed.,
Revised, D. C. Heath and Company, Boston, Mass., 1957,
pp. 299-300.

47. L. F. Fieser, J. Am. Chem. Soc., 46, 2639 (1924).

48. C. D. Hodgman, "Handbook of Chemistry and Physics," 40th Ed.,
Chemical Rubber Publishing Company, Cleveland, Ohio,
1958, p. 787.

49. C. D. Hodgman, ibid., p. 1265.

50. C. D. Hodgman, ibid., p. 1263.

51. C. D. Hodgman, ibid., p. 1261.

52. C. D. Hodgman, ibid., p. 1081.















BIOGRAPHICAL SKETCH


Paul Otis Sanderfer was born in Union City, Tennessee, on

March 1, 1937. In 1955, he graduated from Union City High School

and entered Union University. From that institution he received

the degree of Bachelor of Science and entered the Graduate School

at the University of Florida in 1959. During his graduate work at

the University of Florida he has held a graduate assistantship and

an interim instructorship in the Department of Chemistry.

Mr. Sanderfer is married to the former Miriam Watt and is

the father of a son, Van. He is a member of the American Chemical

Society, Gamma Sigma Epsilon and Alpha Tau Omega.











This dissertation was prepared under the direction of the

chairman of the candidate's supervisory committee and has been

approved by all members of that committee. It was submitted to

the Dean of the College of Arts and Sciences and to the Graduate

Council, and was approved as partial fulfillment of the requirements

for the degree of Doctor of Philosophy.



August 14, 1965



Dean, College of Arts and Sciences



Dean, Graduate School


Supervisory Committee:



Chairman



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