The catalytic oxidation of organic substrates utilizing molecular oxygen and peroxides

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Material Information

Title:
The catalytic oxidation of organic substrates utilizing molecular oxygen and peroxides
Physical Description:
xvii, 216 leaves : ill. ; 29 cm.
Language:
English
Creator:
Patton, Douglas E., 1958-
Publication Date:

Subjects

Subjects / Keywords:
Oxidation   ( lcsh )
Peroxides   ( lcsh )
Oxygen   ( lcsh )
Chemistry thesis, Ph. D   ( lcsh )
Dissertations, Academic -- Chemistry -- UF   ( lcsh )
Genre:
bibliography   ( marcgt )
non-fiction   ( marcgt )

Notes

Thesis:
Thesis (Ph. D.)--University of Florida, 1993.
Bibliography:
Includes bibliographical references (leaves 204-215).
Statement of Responsibility:
by Douglas E. Patton.
General Note:
Typescript.
General Note:
Vita.

Record Information

Source Institution:
University of Florida
Rights Management:
All applicable rights reserved by the source institution and holding location.
Resource Identifier:
aleph - 002257683
oclc - 36653754
notis - ALL0526
System ID:
AA00003253:00001

Full Text










THE CATALYTIC OXIDATION
UTILIZING MOLECULAR


DOUGLAS


A DI
OF THE


N OF ORGANIC SUBSTRATES
OXYGEN AND PEROXIDES


PATTON


SSERTATION PRESENTED TO THE GRADUATE SCHOOL
UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT
OF THE REQUIREMENTS FOR THE DEGREE OF














ACKNOWLEDGEMENTS


would


like


express


deepest


appreciation


people


who


are


closest


wife


and


best


friend


, Lynn,


provided me


with


a love


and


support


for which


am forever


indebted.


thins"


always


of graduate


been


there


school


me during


would


like


"thick


to thank my


family


, both


here


Florida


and


Georgia,


their


support


and


encouragement.


Many


thanks


are


the


many


people


Auburn


University


their


advice


guidance


furthering


career


in the


area


of chemistry.


, I


would


like


express


appreciation


Russell


Drago


his


constant


help,


understanding,


enthusiasm


pursuit


a career


in chemistry


Without


advice


guidance,


work


would


have


been


possible.


Many


thanks


are


due


to Dr


. Robert


Stoufer,


James


Boncella,


the


remainder


of my


supervisory


committee


their


help


and


encouragement


in making


work


easier


would


also


like


to thank


members


of the


Drago


Group


their


help


and


suggestions


in my


research


* I j 4


* *.


1 1


__


^







A special


thank


you


is due


to Mr.


Charl


W. Cromwell


advice


assistance


in obtaining


right


chemicals.


Last


, but


no means


least


would


like


thank


many


other people


in the


chemistry


department


helped me


accomplishing


work.















TABLE


OF CONTENTS


ACKNOWLEDGEMENTS. ..... ......................... .


LIST


OF TABLES. ... ............... ........... ....


vii


LIST


OF FIGURES .. .. .. ...... ................


KEY


TO ABBREVIATIONS


AND


SYMBOLS. .....................


xiil


XVI


CHAPTER


GENERAL


INTRODUCTION. .......................


2 A REGENERABLE
FOR CATALYTIC


Introdu
Results


Exper


N-ALKYLAMIDE HYDROPEROXIDE
SUBSTRATE OXIDATION.......


ction..


Gen
Cat
4-B
Alc
Hyd
Oxy
Red
ime
Rea
Ste
Hyd
Sol
Hyd
PPh
Pre
or
Cat
4-B
Alc


erat
alyt
utyr
ohol
rope
gen
ucti
ntal
gent
ady-
rope
vent
rope


30Ox:
para
Mn2+
alyt
utyr
ohol


S
n

a
x
x
o


cussion
of the
Hydrope
ctone a
idation
ide Dec
m Trans
of N-me


.....
s and
State
roxide
S ...
roxid'


idat.
tion
\


Hydroperoxide.
roxide Formatio
nd Isopropyl


S .
omp
fer
thy


position and
Ability....
Isuccinimide


Equipment....
[ROOH] Studie
e Formation in


e


ioni
of


Other


ab......ty Comp.....
ability Comparison


..Na-YM....Co
MNa-Y (M=Co2+


.Fe3+


. .. ... 4


.B.....


n......
* e SC


..o...
n.. ..

....o..
*.. *. ce

.......
* CCC


.....
..* C C C
* C C S S


ic Hydroperoxide Formation.
olactone and Isopropyl
Oxidations.. ..............


N-methylsuccinimide
Conclusions.............


Reductions
..eo.CeCitae


........
*..*'''*
C C
* C C SC C


CHAPTER


.... 4


1
I


Page


ABSTRACT.. .............................. ...........










Introduction.


. 3


Resul













Exper























Concl


1H
Hyd
cis
Oxi
Eff
Sty
1-H
usi


and
loh
ns-
-P-
ven
oca
ect
ive
cti
sib
ybd
exe
nta
gen
loh
ns-
-0P-
ven
oca
ect
idi
ns-
ng
fin
idi


NMR
rop
- a
dat
ect
ren
exe
ons


Dis
exen
S-Me


M
t
r
S


1
e
n
1
t
e
p
M
t
r
s
n
p


P


e

b

S
n
e
n
e


uss
Ox
hyl
1st
ect
Add
Add
ies


Mechan
um-Cata
Oxidat


s a
xen
-Me
eth
Ef
bon
of
e O
-Me
yri


O
ne
S
er
nd
io
o
e
ne


IX


nd
e
th'
vli


on... .
dation.
tyrene
rene Ox


Oxidat ion
Oxidation
idation..


*. .....
*. ......


tions.. ...........
d Pyridine.......
for Mo(0)2(acac)2

istic Pathways for
lyzed Epoxidations


ion...


. .. ...


.


Equipment.......
Oxidations.......
ylstyrene Oxidati
stvrene Oxidation


fects
Addi
Adde
xidat
thyls
dine-


idati


S...
tudy
oxid
Stra
ins i
If Ex
Oxid
Oxi


on.
Pyr
ns.
ren
oxi
Us


of Mo(i
e React
ns-P-Me
n CHC13
cess t-
ation..
dations


idine


e Os
de..
ing


* a a
* a
ft *


*......*
*..*..a.a
..C.Ca.a.
*..a....


* a a a *
..C..
. .


:idations


substituted
.........a.....~a


0)2(acac)2/t-Butyl
ion... .... ..........
thylstyrene
and CC14...........
Butyl Hydroperoxide.


* .. a a. aa
...........


* a *
..a.a.


CHAPTER


4 TRANSITION
THIOETHERS
SOLVENT...


Intro
Resul




Exper


uct
s a
cti
cti
cti
men
eag
ulf
-Viyr


METAL-CATALY
IN 1-METHYL-


ion.
nd D
vati
vati
vati
tal.
ents
ide
trimn


cus
of
of
of

nd
ida


, rn urt


ED OXIDATIONS
-PYRROLIDINONE


sion.. . .
Molecular Oxy
Alkyl Hydrope
H2O22 C *. .

Equipment.....
tions Using
-1 -mothTr1 --9--nnr


gen..
roxid


.......
.....a ..C


rrnl nn inon


Page










Sulfide Oxidations Using
5-Hydroperoxo- l-methyl-2-pyrrolidinone
(pre-generated), t-Butyl Hydroperoxide,
and H202... . . . .


ROOH
Cata
Hydr
Sulf
pyrr
Effe
Stab


an
lys


Solvent
Conclusions.


d H20
t Rec
roxid
Oxid
dinon
of H
ty St
Syst
. .t .


2 Effi
yclab.
e and
ationm
e/H20
20 on
udies
ems..


i


iency Studies...
.ity Using Alkyl
_r-n


s in 1-Methyl-2-
(50/50, V/V).........
Sulfide Oxidations...
of H202 in Various
............ .e. .....S


CHAPTER


PEROXYACID OXIDATIONS OF
1-METHYL-2-PYRROLIDINONE


THIOETHERS
SOLVENT...


Introduction..


Resul



Exper


ts and
Activat
Catalyt
Effect
mental
Reagent


Discussion.....................
ion of H202 by Maleic Anhydride
ic Maleic Anhydride...........
of Transition Metal Catalysts..


.* .
and


Equipment..


... .....
... .....


Peroxymaleic


Concl


H202 Va]
Sulfide
Amounts
Metal-C
Using P
Metal-C
Using H
usions.


riatio]
Oxida


of Male
atalyzed
eroxymal
atalyzed
202 -


Acid Stability......
n Study ..............
tions Using Catalytic


ic
S
ei
S


Anhydride.......
ulfide Oxidations
c Acid...........
ulfide Oxidations


CHAPTER


GENERAL


CONCLUSIONS.........................


BIBLIOGRAOPHY....... .... .............................


BIOGRAPHICAL


SKETCH . . . . . .........


Page














LIST


OF TABLES


Table


Properties


N-Alkylamide


1-Methyl


-2-pyrrolidinone......


Hydroperoxide


Formation


in Other


Solvents.


Heterogeneous
Oxidation....


1-Methyl


-2-pyrrolidinone


NMR


Study


Oxidation....


N-Methylsuccinimide


of Triphenylphosphine
.. ..... .. ............ .. .. 25


Reduction..


S.. ......... 28


Main


Charact


eristics


Homolytic


Heterolytic


Oxidations


Clas


sification


Scheme


Metal-


Catalyzed


Oxidations.


S.... . 41


Cyclohexene


Oxidation...


trans-p-Methylstyrene


cis-p-Methylstyrene


Oxidation............


Oxidation...............


Solvent


Effects


Oxidation


trans


-P-Methyl


Catalyst


styr


ene


with


Mo(O)


(acac


...... 77


Solvent


Effects


in the Oxidation


cis


-B-Methyl


styrene


with


Mo(O)


Catalyst


trans-P-Methyl


styrene


Oxidation


presence


of Halocarbons..


Effect


Added


Pyridine


Mo(O
tran


/ acar


-Catal zed


Ovid rani nn


( / 2 \ etvn..LLy .C2 y....
B-Methvlstvrene............


of
. a. ..


................ ... .... 21


........... 38


. ................... 64


2(acac)2
.............. 79


. .... .. 81


Page







Table


Page


Eff


Mo(0O
cis-


Added


(acac


Pyridine


-Catalyzed


on the


Oxidation


p-Methylstyrene..............


Effect


Added


Pyridine-N-oxide


Mo(0)2(acac)2-Catalyzed Oxidation
trans-P-Methylstyrene............


Effect


of Added


Mo(0)2(acac)2-Cata]
cis-P-Methylstyren


Pyridine-N-oxide


Lyzed


e. .


Oxidation
. .... e. ..


on the
of
.. ...O .....


Pyridine


Oxidations....


3-14


trans


-p-Methylstyrene


Oxidation


Using


Pyridine-N


-oxide


3-15


Use


of Substituted


Pyridines


Oxidation


C'S


- -Methylstyrene


3-16


Use


of Sub


Oxidation


stituted
of trans


Pyridines


in the


- -Methylstyrene


3-17


NMR


t-Butyl


Results
Hydrope


Mo(0)


roxide


(acac)


Reactions...


3-18


CIS-


and


trans


-P-Methylstyrene


Oxidation


CHCl3


and


CCl4. . . . . .


Effect


of Exc


ess


t-Butyl


Hydroperoxide


CIS-


P-Methyl


styrene


Oxidation...


3-20


Eff


of Excess


t-Butyl


Hydroperoxide


trans


-P-Methyl


styrene


Oxidation


Styrene


1-Hexene
1-Methyl


Oxidation........


Epoxidation in
-2-pyrrolidinone..


3-23


1-Hexene


Epoxidation


Using


Mo(0)


(acac)


1-Hexene
[Ru(dmp)


Epoxidation
(H20)2][PF6]


Using


3-25


Utili


zation


in 1-Hexene


Epoxidation.


a 4 ---


FI Elf


)


t--' *


4 l- P .. .


tt-L-,, -








Table


Page


Transition
of n-Butyl


Metal-Catalyzed


Sulfide


Oxidations


Using


5-Hydroperoxo-1-methyl
(in situ) ... ...


-pyrrolidinone


Transition


n-Butyl
5-Hydrop


Transition


n-Butyl


Metal-Catalyzed


Sulfide


Oxidation


Using


eroxo-1-methyl


Metal-Cataly


Sulfide


Using


pyrrolidinone......


zed Oxidation
-Butyl


Hydrop


eroxide


Efficiency


of Alkyl


Hydroperoxide


Utilization..


Catalyst


Recyclability


n-Butyl


Sulfide


Oxidations


Using


4-7


Efficiency


of H202


Utilization..........


Catalyst


1-Methyl
Variatio


-2-pyrrolidinone/H
ns..... ...........


0 Ratio


4-10


Stability
1-Methyl-


of H202 in
-pyrrolidinone....................


4-11


4-12


Stability
1-Methyl-


Stability


of H202 in
-pyrrolidinone/H20


of H202


50/5


H 20.....


Stability
1-Methyl-


of Peroxymaleic
-pyrrolidinone.


Acid


184


5-2


H202 Varia
Oxidations


tion


Usin


in n-Buty:
ig Maleic


Sulfide


Anhydride


n-Butyl
Amounts


Sulfide


of Maleic


Oxidation


Using


Catalytic


Anhydride..


n-Butyl


Sulfide


nf Msl01 o


Oxidations


Using


Catalytic


anhvdri do..


H202 -


Recyclability ....................


H202 .***









Table


Transition


Sulfide
Acid...


Metal


Oxidations


-Catalyze


Using


d n-Butyl
Peroxymal


eic


Transition


Metal-Cataly


zed Oxidations


n-Butyl


Sulfide


Using


H202 . .


Page













LIST


OF FIGURES


Figure


Positions


Autoxidation


Various


Amide


S .


... ............ 5


Amine


Autoxidation


Mechanism ..............


Metal-Catalyzed


Oxidation


1-Methyl-2-pyrrolidinone.


S.. ........ 11


Catalytic


Cyclic


Hydrogenation


Anhydride s


Mechanism


Imides


..... 13


1-Methyl-2-pyrrolidinone


Catalytic


Cycle....


Compari


sion


pyrrolidinone
Hydroperoxide


-Hydroperoxo-1-methyl
) and t-Butyl


Formation


-Hydropero


xo-


1-methyl


pyrrolidinone


.......... ... .... 19


Haber-Weiss


Mec


hanism


Decompos


ition


Alkyl


Hydrop


erox


ides


. ... .... 43


Radical
Epoxide


Fenton


-Chain


Mec


hanism


Formation...


Chemistry


Leading
0......


Mechanism..................


Peroxymetallocycle


Mechanism


....... .. ... 48


Sharpless


Coordination


Epoxidation


Modes


Mechanism .............


Alkylperoxo


Ligands..


.......... 54


Oxygen
Metal


Atom


Transfer


Alkylperoxo


from


Complexes.


Transition


....... .. .. 55


Homolytic


Epoxidation


Pathway for


Page







Figure


Page


Competitive
Oxidation..


Reactions


in Cycloh


exene


S...... 66


3-10


Epoxidation


Pathways.


S...... 74


3-11


Stereo
polar


ective


Epox


idation


Solvents


Non-


. ...... 99


Benz
Solv


3-13


aldehyde
ents....


Benzaldehyde
Solvents....


Formation


Formation


Non-polar


Non-polar


Non-stereose


ective


Epoxidation


Polar


Solvents


3-15

3-16


Benzaldehyde

Benzaldehyde


Formation

Formation


Polar

Polar


Solvents

Solvents


3-17


Ben


zaldehyde


Villiger-Type


Formation by
Mechanism..


a Baeyer-


ective


Mol


ecular


Oxygen


Oxidation


Thio


ethers


Mec


hanism


for


RuX


SO)4


Catalyz


Sulfide


Oxidations


Formation


Sulfide


of Metal


Oxidations


Alkylperoxo


Side-On


Species


Bonded


Metal


eroxo


Compl


exes


Catalytic
Class IVa


Hydrop
Metal


eroxide


Formation


Via


Catalysts


5-1


Thio


ether


Oxidation


Using


Organic


Peroxya


Formation


of Peroxymaleic


Acid


1-Methyl


-2-pyrrolidinone.













KEY


TO ABBREVIATIONS


AND


SYMBOLS


Abbreviation


or Symbol


Definition


acetylacetonate


acac

a


alpha


beta


carbon


carbon


carbon-13


degrees


chemical


sius


shift


DEGS


diethylene glycol


succinate


DIPT


diisopropyl


tartrate


DMA


dimethylacetamide


dimethylformamide


2,9-dimethyl-1
phenanthrolene


dmso


EtOH


dimethylsulfoxide


epoxide


to benzaldehyde


enantiomeric


excess


ethanol


flame


ionization


detector


gamma

gas c


carbon


hromatograph


grams








Abbreviation


or Symbol


Definition


g/cm3


grams per cubic centimeter


proton


hfacac


hexafluoroacetylacetonate


hrs.


hours


molarity


maleic


anhydride


megahertz


min.


minutes


milliliters


methylstyrene

nanometers


NMP


1-methyl-2-pyrrolidinone


NMPD


1-methylpyrrolidine


NMP-5-OOH


5-hydroperoxo-l-methyl
pyrrolidinone


NMR


nucl


-2-


ear magnetic resonance


OAc


acetate


octoate


2-ethylhexanoate


oxidant


to substrate


phosphorus-31


pfb


perfluorobutyrate


ppm


parts


per


million


percentage


psig


pounds


per


square


inch








Abbreviation


or Symbol


Definition


R2SO2


sulfone


silica


t-BuOOH


t-butyl


hydroperoxide


tetramethylenesulfone


TPP


tetraph


enylporphyrin


UV/vis


ultraviolet/visible


v/v


volume


volume


omega


carbon














Abstract


of Dissertation


Presented


Graduate


School


of the


University


Requirements


of Florida


for


the


Degree


in Partial
se of Doctor


Fulfillment of
: of Philosophy


CATALYTIC


UTILIZING


OXIDATION


MOLECULAR


OF ORGANIC


OXYGEN


SUBSTRATES


PEROXIDES


Dougl


August


. Patton

1993


Chairperson


Major


: Russell


Department


: Chemi


Drago
stry


The


employing


use


1-methyl


molecular


-2-pyrrolidinone


hydrogen


and


in a catalytic


oxygen


cycle


presence


transition


metal


catalysts


cribed.


Under


mild


conditions

alkylamide


catalytic


hydroperoxide


cycle


provides


organic


substrat


regenerative

e oxidations


Under


mild


conditions,


the


ability


N-alkylamide


hydroperoxide,


5-hydroperoxo-l1-methyl


-pyrrolidinone


oxidi


alkenes


thioethers


inves


tigated


sence


of transition metal


catalysts


Mechanistic


pathways


for these


metal


-catalyzed


reactions


are


presented.


Transition


metal


-cataly


thioether


oxidations


are


inves


tigated


under


ambient


conditions


1-methyl


pyrrolidinone using the alkyl hydroperoxides,


-hydroperoxo-1


methyl


-2-pyrrolidinone


and


t-butyl


hydroperoxide.


These







metal


catalysts


N-alkylamide


hydroperoxide


system.


Using


1-methyl-2-pyrrolidinone


, the activation of H202 by


transition


maleic


metal


anhydride,


catalysts


and/or


investigated


peroxyacid


under


ambient


precursor,


conditions.


This


oxidant


exhibits


enhanced


stability


1-methyl-2-


pyrrolidinone.













CHAPTER


GENERAL


INTRODUCTION


oxidative


transformations


functional


groups


are


basic


organic


chemistry


with


oxidations


being


extensive


used


laboratory


synthesis


fine


organic


chemi


well


manufacture


large-volume


petrochemicals


Industrially,


the


majority


processes


employed


involve


use of transition metal


comply


exes


, using molecular oxygen,


alkyl


hydroperoxides


as the


primary


oxidants


These


catalytic


pro


cesses


are


advantageous


over


their


non-catalytic


counterparts


because


they


ceed


efficiently


under


mild


conditions


leading


more


energy


efficient


recesses.


Furthermore,


catalytic


processes


are generally more


selective


resulting


optimal


utilization


starting


raw


materials


most


part,


catalytic


processes


are


environmentally


endly


they


involve


small


amounts


effluents,


whi


are


becoming


increasing


more


difficult


dispose


res


ult,


a gr


eater


empha


S1S


must


be placed


the


development


new


improved


catalytic


processes


the


oxidative


transformations


organic


substracts


major


potential


objective


applications


this


of the


work


industrially


present


important


several

solvent,


As


H202







that


make


a desirable


solvent


catalytic


applications


Table


1-methyl


-2-pyrrolidinone is


completely miscible


with


water


, lower


alcohols


lower


ketones


ether


ethyl


acetate,


chloroform


, and


benzene


is moderately


soluble


aliphatic


hydrocarbons


and


dissolves


both


organic


inorganic


compounds.


view


high


boiling


point,


many


reaction


products


can


be separated


distillation.


Recently,


1-methyl


-pyrrolidinone


replaced


other


solvents


poorer


stability,


higher


vapor pressures


, greater


toxicities


or more


facil


skin


penetration.


Large


amounts


1-methyl


medium


-2-pyrrolidinone


polymer


are


zation


used


the polymer


and


solvent


indus


finished


polymers;


thereby,


making


thi


cyclic


N-alkylamide


very


important


solvent


industrial


chemical


applications.







Table


Properties


1-Methyl-2-pyrrolidinone.


Property Value

freezing point -24.40C
boiling point 202C
density 1.028 g/cm3
flash point 95C














CHAPTER


A REGENERABLE


N-ALKYLAMIDE


HYDROPEROXIDE


FOR


CATALYTIC


SUBSTRATE


OXIDATION


Introduction


The oxidation


been reported in


five-


Alkenes


ethers


of amides to their


literature


six-membered


undergo


corres


straight


lactams

similar


ponding


chain


(cyclic

oxidation


imides


alkylamides


amides)

pathway


which


a hydrogen


atom


is abstracted


from


a carbon


atom


that


adjacent


ether.


double


10,11


bond


Hydrogen


alkene


atom


or the


abstraction


oxygen


from


atom


carbon


adjacent


nitrogen


atom


in an amine


rate


constant


much


higher


than


those


alkenes


isostructural


ethers.


photooxidation


of N-alkylamides,


oxygen


attack


occurs


on the


methylene


group


adjacent


amide


nitrogen.


oxidation


straight


chain


alkylamides


characterized


autoxidation


at the


primary


carbon


atom


of the


hydrocarbon


chain,


while


carbon


atoms


ketone


chain


are


affected


Figure


2-1).


case


five-


six-


membered


lactams,


the oxidation


takes place


at positions


in the


five-


six-membered


rings,


respectively


(Figure









II
R-CH2-NH-C-R


N-R


N-R







autoxidation


amides


proceeds


a peroxy-radical


mechanism


similar


amine


autoxidation


mechanism


reported


Beckwith


(Figure


however,


oxidation


occur


amides


because


their


corresponding


nitrogen


very


amine


weakly


oxides


basic


does


donor


atom.


13 During


this


reaction,


most


common


oxidation


product


was


the


imide


Needles


and


Whitfield


attempted


oxidize


five-


six-membered


lactams


with


peroxysulfates


their


ring-opened


products,


o-aldehydoamides;


however,


these


reactions


yie


Aided


imides


as the


products.


For


example,


oxidation


1-methyl-2-pyrrolidinone


with


peroxysulfate


yielded


N-methylsuccinimide.


When


reacted


with


equimolar


amounts


of ruthenium


tetroxide,


amides


are


again


oxidized


their


corresponding


imides.


selective


oxidation


amides


imides


been


reported


using


alkyl


hydroperoxides


peroxyacids


the


presence


transition


metal


catalysts


(i.e.,


Mn(II),


or Mn(III)).


2-pyrrolidinone


oxidations


produced


of 2-pyrrolidinone


succinimide


1-methyl-


and N-methylsuccinimide,


respectively.


Imides


have


been


obtained


electrochemical


oxidations


of their


corresponding


amides.


14,15


During


some


these


reactions,


amido-alcohol


was


produced.


use


of molecular oxygen


in the


autoxidation


of amides


been


shown


to yield


both


corresponding


hydroperoxides
















N- R


N-R


I


N-R


N-R


N--R


N-R


N--R


N-R


02H


N-02

02


molecular products


C


-+ -


--t


02'


--+


02.


---- n








imides.


Using


catalysts


, KMnO4,


oxidation


methyl


-2-pyrrolidinone with molecular oxygen yielded N-methyl


succinimide.


In a


very thorough investigation into


the autoxidation


various N


-alkylamides


, Lock and


Sagar observed


three


principal


overall


reactions:


Formation


of N-acylamides


from


N-n-alkylamides


O


R-C-NH-CH2-R


II II
R-C-NH-C-R


Formation


N-formylamides


from


N-n-alkylamides


res


of C1-C


bond


scission:


O
II
R-C-NH-CH2-R


O O
II II
R-C-NH-C-H


Oxidative


dealkylation


to yield


carbonyl


compounds


R-C-NH-CH2-R --, R-C-NH2


0

+ R-C-H.


autoxidation


tertiary


amide


1-ethyl


pyrrolidinone,


principle


was


stable


performed


products


at 131


were


C under molecular


1-acetyl


oxygen.


-2-pyrrolidinone


.1%)


pyrrolidinone


, and


N-ethylsuccinimide


thereby,


indicating


that


attack


times


more


probable


ring methylene


group


ace


nt to the


nitrogen atom


than at


--+


-+


_







N-ethylsuccinimide


can


explained


decomposition


hydroperoxides


produced


during


the


reaction.


formation


2-pyrrolidinone


result


oxidative


dealkylation process.


The formation of these N


-acylamides


can


explained


terms


peroxy-radical


mechanism


Abstraction


a hydrogen


atom,


from


carbon


adjacent


nitrogen


atom,


an initiator,


such


as a


1-amidoalkoxy-


radical


from


breakdown


of the


amide


hydroperoxide


during


thermal


oxidation,


or by


an added


radical


initiator


butyl


hydroperoxide,


benzoyl


hydroperoxide,


a,a-


azobi


s(isobutyronitrile


(AIBN)


would result in the formation


-amidoalkyl


-radical,


which


would


form


corresponding peroxy-radical


rapid


reaction


with molecular


oxygen.


Depending


the


reaction


conditions


, these


peroxy-radicals


may


then


either


be removed


from


system by


mutual


interaction


propagate


chain


reaction


abstraction


a hydrogen


atom


from


another


molecule


substrate


kineti


autoxidation


these


alkylamides


initiated


thermally


or by


radical


initiators


established


that


the


oxidation


proceeds


radical


-chain


mechanism


analogous


oxidation


to the


amines


mechanism


proposed


Furthermore,


Sagar


Beckwith


reported


for

that


radical


initiators


and


transition


metal


salts


.e.


Co(II),


Cu(II)


Fe(III))


low


concentrations


failed


increase


already


low maximum


hydroperoxide


concentration.


Higher


.e. ,







accelerated


transition


decomposition


metal


hydroperoxides


catalysts.


From


the


experimental


evidence


presented,


can


inferred


a peroxy


other


that


-radical


observed


thermal


mechanism


products


oxidation


. Both


these


of the


the


amides


proceeds


hydroperoxide s


thermal


oxidations


and


can


explained


subsequent


terms


heterolyti


peroxy


decompo


-radical


sition


mechanism


hydroperoxides


produced


during


reactions.


More


recently,


uncatalyzed


oxidation


1-methyl


pyrrolidinone


molecular


oxygen


under


mild


conditions


sig),


750C)


was


found


form


approximate


concentration


an oxidizing


agent,


which


was


characterized


various


NMR


and


mass


spectral


methods


to be


hydroperoxide


-hydroperoxo-


1-methyl


-2-pyrrolidinone


In the


presence


of peroxide


decomposition


catalysts,


such


Co(BPI)


(where


BPI=1


3-bi


-pyridylimino)i


soindolene


Mn(TPP)Cl


(where


TPP=tetraphenylporphyrin),


hydroperoxide


was


converted


N-methylsuccinimide


(Figure


These


findings show that the hydroperoxide 5


-hydroperoxo-


1-methyl


pyrrolidinone,


is the undetected intermediate


for the


reported


oxidations of 1-methyl


-pyrrolidinone to N-methylsuccinimide.


Another


intere


sting


aspect of


the chemistry


of amides


imides


the


difficulty


hydrogenating


cyclic


imides


their


corresponding


cyclic


amides


(lactams


Even


thought


















N-CH3


N-CH3


catalyst


OOH


I-CH3


H20


02







hydrogen,


attempts


obtain


similar


reaction


with


succinimide


were


successful.


18,19


carbonyl


functionalities


in phthalimide


succinimide


are


unaffected


on attempted hydrogenation at


room temperature and atmospheric


pressure


over


platinum


oxide


catalyst.


20 Attempts


hydrogenate


N-methylsuccinimide


l-methyl-2-pyrrolidinone


with


this


catalyst


at 750C


under


55psig


of hydrogen


were


only


marginally


successful


with


only


small


amounts


1-methyl


pyrrolidinone

Hydrogenation


being


detected

Simide


after


ring


hours


these


reaction.


compounds


can


accomplished


under


such


mild


conditions


an acetyl


or other


acyl


group


attached


imide


nitrogen


atom.


Based


on the


reported


results


hydrogenation


seri


cyclic


McCrindle


propo


anhydrides


sed a mechanism


cyclic


for the


imides,


McAlees


hydrogenation of


cyclic


anhydrides


and


imides


at the


catalyst


surface


(Figure


-4).


initial


step


involves


nucleophilic


attack


catalyst


imide


anhydride)


carbonyl


carbon


atom


substrate molecule


absorbed


on the


catalyst


surface on


ess


-hindered


side


(species


with


concomitant


ring


opening


produce


species


This


acyl


group


cleavage


step


followed


hydrogenolysis


the


metal


-carbon


bond


give


aldehydo-functionality


, followed


rotation


of thi


functionality


aldehyde


through


carbonyl


1800


oxygen


give


a species


atom step


(iii).


absorbed


Ring


through


closure of















o x


(Ill)


(IV)


X=0 or NCOR
*=catalyst surface


OH







hydrogenation


of the


aldehydo-functionality


generated


in step


(ii)


determine


whether


products


further


reduction


are


obtained


Thus


the


N-acyl


succinimide


series


, where


ring


closure

imide


would be


groups


expected

the ir


to be slower


intermediate


since

(III)


the

are


aldehydo-


rigidly


unstrained


a manner


favoring


interaction


, the


main


product


an alcohol,


or products


derived


therefrom.


Hydrogenoly


siS


oxygen-bound


species


(IV)


desorption


gives


hydroxy-lactone


hydrogenolysis


or hydroxy-lactam,


a similar


which


pathway


can


give


undergo


the


further


corresponding


lactone


or lactam


reduction


-pyrro1idinone


of succinimide


was


to the


accomplished


corresponding


presence


amide,

ammonia


using a


catalyst,


such


as cobalt


, nickel,


palladium


, platinum,


ruthenium,


supported


carbon


silica


gel.


Another


reported


cess


preparing


2-pyrrolidinone


involved


reduction


of succinimide


supported


hydrogen


palladium


elevated


in an aqueous


system


catalyst.


temperatures


Higt


are


in the

pres


required


presence


:sures


these


proce


sses.


Results


Discussion


Our


interest


in the oxidation and hydrogenation reactions


N-alkylamides


involved


using


1-methyl


-2-pyrro1idinone


catalytically


in a cycle


that


used


only molecular


hydrogen






oxygen to form the corresponding hydroperoxide,


5-hydroperoxo-


l-methyl-2-pyrrolidinone,


which


can


used


selectively


oxidize


variety


organic


substrates


producing


methylsuccinimide


byproduct


(Figure


2-5,


path(a))


Hydrogenation


methyl-2-pyrrolidinone


N-methylsuccinimide


allowing


would


effect


regenerate


, to function


a catalyst


oxidation


organic


substrates


using


only


molecular hydrogen and molecular oxygen under mild conditions.

The preparation of 5-hydroperoxo-l1-methyl-2-pyrrolidinone


from


direct


molecular


oxygen


reaction


750C


1-methyl


makes


-2-pyrrolidinone


inexpensive,


and


easily


obtainable


source


compare


of hydroperoxide.


stability


this


was


hydroperoxide


interest


with


commercially


available


hydroperoxide


stability


solution


5-hydroperoxo- -methyl


-2-pyrrolidinone


was


compared


with


a t-butyl


hydroperoxide


solution


of comparable


hydroperoxide


concentration


under


ambient


conditions


iodometric


titration.


seen


in Figure


2-6,


stability


5-hydroperoxo-l-methyl-2-pyrrolidinone,


secondary


hydro-


peroxide,


comparable


that


t-butyl


hydroperoxide,


tertiary


hydroperoxide.


Generation


HvdroDeroxide


improved


synthesis


5-hydroperoxo-1-methyl


pyrrolidinone


involves


increasing the


conversion


of 1-methyl-

















N-CH3


N--CH3


OOH


O

ON-CH3

0


so


CH3


OH
















1.55


1.50


1.45


1.40


1.35


1.30


1.25


1.2B.o0


16.00


4.00 8.00 12.00
Time (Days)







accomplish


these


objectives.


formation


of hydroperoxide


function


time


shown


Figure


uncatalyzed


direct


reaction


with


molecular


oxygen.


autoxidation


mechanism


suggested


because


observed


induction


period.


shown


Figure


2-7,


hydroperoxide


reaches


maximum


concentration


at approximately


reaction


1-methyl-2-pyrrolidinone


with


molecular


oxygen


psig)


750C was


analyzed


at various


time


intervals


NMR,


along with

spectra and


iodometric


titrations.


corresponding


integrated


iodometric


titrations


periodically


drawn


samples


showed


that


hydroperoxide


concentration


remained


constant


after


hours,


concentration


N-methylsuccinimide


increased


steadily.


steady-state


hydroperoxide


concentration


attained


in this


system


when


rates


hydroperoxide


formation


decomposition


become


equal.


attempt


was


made


decrease


observed


induction


period


carrying


out


reaction


1-methyl


pyrrolidinone


with


molecular


oxygen


psig


hours


100C


then


decreasing


temperature


750C


remainder


of the


reaction.


Although


induction


period


was


decreased


using


higher


initial


reaction


temperature,


lower


maximum


hydroperoxide


concentration


resulted.


The uncatalyzed reaction of


1-methyl-2-pyrrolidinone with

























1.60



L?


1.20






0.80






0.40


Ir









I
I
S L II I l l


20.00
Time


40.00 60.00
(Hours)


fen-


i


tU


Cu.uu


0.00.


__


|I L


!.







formation


would


occur.


Both


systems


were


found


form


corresponding


hydroperoxide;


however,


lower


steady-state


hydrope


roxide


concentration


was


attained


than


observed


oxidation


neat


1-methyl-2-pyrrolidinone


(Table


Experimental


results


given


Table


indicate


that


formation


hydroperoxide


5-hydroperoxo-l1-methyl


pyrrolidinone,


the


solvent,


CH3CN,


proceeds


more


readily


than


H20.


pure


1-methyl-2-pyrrolidinone,


methyl-2-pyrrolidinone


converted


corre


spending


hydroperoxide


steady-state


conditions.


50/50


10/90


1-methyl-2-pyrrolidinone/CH3CN


systems


9% and


6% of the


1-methyl-2-pyrrolidinone


were


converted


N-alkylamide


hydroperoxide


,respectively.


In all


solvent


after


72 hours


reaction,


further


increases


the


hydroperoxide


concentrations


were


observed,


an indication


of the


attainment


of a steady-state


Catalytic


hydroperoxide


Hydroperoxide


concentration.


Formation


Attempts


were


made


eliminate


induction


period


observed


uncatalyzed


autoxidation


l-methyl-2-


pyrrolidinone


using


various


homogeneous


transition


metal


complexes,


17 such


Co(octoate)2


(where


octoate=


ethylhexanoate),


Co(BPI)


(where


BPI=


,3-bis (2-pyridylimino)


isoindolene),


and Mn(TPP)Cl


(where TPP= tetraphenylporphyrin),


which


are


known


catalyze


Class


radical


chain







Tabl


N-Alkylamide
Solvents.


Hydroperoxide


Formation


Other


I-i -- _I


NMP/H


[ROOH]


(V/V,%/%) (M)

100/0 1.33
90/10 1.00
50/50 0.01
10/90 0.00


NMP/CH3CN
(V/V,%/%)


[ROOH]
(M)


90/10 1.12
50/50 0.46
10/90 0.06


Note:


Reaction


conditions


: 50 psig


of 0


750C;


50mL


total


Reaction


solution


time:


volume.
72 hours







inated,


hydroperoxide


extensive


decomposition


to N-methylsuccinimide


N-alkylamide


was


observed.


Additional


attempts


focused


metal


ion


exchanged


zeo


lites,


such


CoNa-Y,


FeNa-


, and


MnNa-Y


When


heterogeneous catalyst,


CoNa-


, is used


to oxidize


1-methyl


pyrrolidinone


, the


reaction


occurs


as a faster


rate


greater


extent


than


observed


uncataly


reaction


hour


induction


period


observed


uncataly


reaction of


this


hetero


cyclic


amide


is eliminate


d with minimal


hydroperoxide


decomposition


occurring


comparison


hydroperoxide


formation


with


without


metal


-ion


exc


hanged


zeo


lite


cataly


is shown


(Table


2-2) .


contrast


CoNa-


Na-Y


decreases


amount


hydroperoxide


formed


solution.


This


result


shows


that


Co(II)


with


hindered access


sibility,


plays


role


cataly


zeolites


zing hydroperoxide


, such


formation.


FeNa-Y


Other metal


MnNa-Y


-ion exchanged


eliminate


induction


period


and


catalyze


reaction


increasing


hydroperoxide


concentration


relative


uncatalyzed


reaction.


4-Butvrolactone


Isopropvl


Alcohol


Oxidations


Several


other potential


hydroperoxide


-forming


substrates


were


evaluated


using


the


CoNa-


catalyst


When


reacted


with


molecular


oxygen


psig)


750C,


both


uncatalyzed







Tabi


Heterogeneous
Oxidation.


1-Methyl


-2-pyrrolidinone


Hydroperoxide Concentration (M)

Time Blank Na-Y CoNa-Y FeNa-Y MnNa-Y
(hrs)

0 0.00 0.00 0.00 0.00 0.00

6 0.05 0.08 0.50 0.72 0.25

12 0.10 0.11 1.62 1.15 0.66

24 0.18 0.20 2.07 1.35 1.56

48 1.20 0.42 2.30 1.92 2.97

72 1.33 0.50 2.35 2.14 3.00


Note


: Reaction


NMP


were


conditions


In all


cases


employed.


exc


With


50 psig
3pt FeNa-


FeNa-Y,


of 02; 7
-Y. 0.25


f


0.38


'5C
g


'


50 mL of


of catalyst


w







After


hours


reaction,


spectra


reaction


solutions


showed


oxidation


products.


These


compounds


appear


resistant


oxidation


under


conditions


employed


in these


reactions.


Hydroperoxide


Decomposition


Oxvaen


Atom


Transfer


Ability


The decomposition and reaction of 5-hydroperoxo-1-methyl-


2-pyrrolidinone


with


various


substrates


results


formation


of N-methylsuccinimide.


17,21


amido-alcohol,


hydroxy-1-methyl-2-pyrrolidinone,


is expected


form


first


step


an oxygen


atom


transfer


from


5-hydroperoxo-l-


methyl-2-pyrrolidinone


(Figure


2-5,


path


(b))


24 N-


methylsuccinimide


proposed


form


result


facile


oxidation of


amido-alcohol.


To test


this proposal,


pre-generated


solution


5-hydroperoxo-1-methyl-2-


pyrrolidinone


equimolar


l-methyl-2-pyrrolidinone


amount


was


triphenylphosphine


reacted


under


with


inert


atmosphere


hours.


quantitative


yield


triphenylphosphine


oxide


produced


as shown


NMR.


NMR


spectrum


solution


after


reaction


showed


resonances


solvent


, l-methyl-2-pyrrolidinone,


and


triphenylphosphine


oxide,


as well


five


new


peaks


amido-alcohol,


5-hydroxy-1-methyl-2-pyrrolidinone


(Table


resonances


were


detected


solution


either


hydroperoxide


5-hydroperoxo-l1-methyl








Table


13C NMR Study


of Triphenylphosphine Oxidation.


Note:


Resonances


for OPPh3


were also observed.







Exposure

intermediate


solution


to molecular


containing


oxygen


room


amido-alcohol


temperature


hours


results


in the


further


oxidation


of 5-hydroxy-1-methyl-


2-pyrrolidinone to N-methylsuccinimide


(Figure


, path


(b)).


combined


results


studies


this


reaction


indicate


that


oxygen


atom


transfer


occurs


with


this


hydroperoxide


via


nucleophilic


attack


peroxide.


absence


molecular


oxygen,


5-hydroxy-l-methyl-2-


pyrrolidinone


results.


the


presence


of molecular


oxygen,


this


product


observed,


oxidized


methylsuccinimide


molecular


oxygen


under


reaction


conditions.


Reduction


of N-methvlsuccinimide


The utility of 5-hydroperoxo-1-methyl-2-pyrrolidinone for


catalytic


oxidation


organic


substrates


would


enhanced


regeneration


1-methyl-2-pyrrolidinone


from


hydroperoxide


decomposition


product,


N-methyl-


succinimide


(Figure


).24


This


would


provide


a recyclable


hydroperoxide


precursor


with


1-methyl-2-pyrrolidinone


becoming


a co-catalyst


a net


reaction


utilizing molecular


hydrogen


oxygen.


Several


homogeneous


methods


this


stage


of the


catalytic


cycle


were


studied.


Since


there


are


literature


reports


homogeneous


reduction


methylsuccinimide


with


molecular


hydrogen,


our


initial


work







selective


reduction


carbonyl


functionalities


several


heterolytic


compounds


to methylene


groups


is reported


literature


The


catalyst,


RuCl


(PPh3)3,


was


reported


Lyons


to hydrogenate


succinic


anhydride


to 4-butyrolactone


with molecular


hydrogen


under mild conditions


28,29


Using this


catalyst,


seven


unsuccessful


attempts were made


to reduce N-


methylsuccinimide


1-methyl


-pyrrolidinone


diff


erent


solvents


Tabl


The


addition


of triethylamine


to these


reactions


did


not


improve


matters.


Reports


use


of Ru


catalysts


hydrogenation


ketones


prompt


investigation


other


comply


exes


and/or


solvent


variations.


30-32


seen


in Tabl


, the


activity


cataly


appear


solvent


dependent


and


in some


cases


show


high


selectivities


to 1-methyl


-pyrrolidinone,


with


yields.


hydrogenation


succinimide


the


corresponding


amide,


2-pyrrolidinone


, has


been


reported


presence


ammonia


using


various


metal


cataly


support


on carbon


silica


reduction


succinimide


corresponding


cyclic


amide


using


a supported


Pd cataly


molecular


hydrogen


aqueous


solution


also


described


reported


hydrogenations


were


run


under


higher


pressures


and


temperatures


than


employed


in our


experiments


Using the


catalyst


Pd on activated


carbon,


only trace


amounts


1-methyl


-2-pyrrolidinone


were


detected








Tabl


N-Methylsuccinimide


Reduction.


Catalyst Solvent (mL) Products
___(%)

RuC, (PPh) ) Toluene (5.0) 0
RuCl(PPh )4 (w/ Et3N) Toluene (5.0) 0

RuCl (PPhg)3 1,4-Dioxane (5.0) 0
RuCl(PPh,)g (w/ EtN) 1,4-Dioxane (5.0) 0

RuClg 3H,0 HO (100) NMP (21)
RuCl3 3H20 Toluene/EtOH 0
(50/50, 10)
cis-RuCl2(dmso)4 Toluene/EtOH NMP (23)
(50/50, 10)
cis-RuC1,(dmso)4 EtOH (10) NMP (8)

[Ru(dmp)2(H20)2][PF6]2 Toluene/EtOH NMPD (<1)
(50/50, 10) NMP (28)
[Ru(dmp),(HO)9][PF6], H,0 (100) 0
5% Pd on C HO (100) NMP (<1)

5% Ru on SG HO (100) NMP (36)

5% Ru on C H, O (100) NMP (57)

5% Ru on C H O (100) NMP(>99)


Note


: The


above
100C.


amounts
4.4x10-5
4.4x10-4


runs


were


first


of sub
moles
moles


state


formed
four s'


used


was
is


under


VS


8


teams li
.8x10-3


added;


Vo psig
sted ti
moles:


when


added


triethylamine.


In
use
was


the
d w


a;


nex
s 4


.0x10-5


t six systems
.0x103 moles


moles


am<


the


Reactions


3unt of
amount


were


substrate
of catalyst


followed


hours.


used


wa


last
s 4.


four
0x10-3


reactions


moles


.The


amount


amount


of substrate


of catalyst


and


reaction


times


were:


5% Pd
5% Ru
5% Ru


on C


on SG


on C


(0.30
(0.59
(0.30


, 24 hours.
). 72 hours.


24 hours


hours.


of catalyst








commercially available catalysts


investigated,


5% Ru on carbon


showed


highest yield of


the corresponding


cyclic


amide,


methyl


-2-pyrrolidinone


(Table


both


catalyze


d reactions,


a high


selectivity to


the


formation of


methyl


-2-pyrrolidinone


was


observed.


Experimental


Reagents


Eauioment


1-methyl


-2-pyrrolidinone


(HPLC


grade),


N-methyl


succinimide


, and triphenylphosphine were obtained from Aldrich


Chemical

obtained


Company

from S


and


trem


used


received.


Chemical


RuCl


other


(PPh3)3


reagents


was

and


solvents


were


obtained


from


Fischer


Scientific


and


were


used


as rece


ived


13C NMR


spectra


were


run


on a General


Electric


Fourier


Transform


Spectrometer


operated


at 300


MHz, respectively


The


samples


were


run


in d6


-benzene


or d1


chloroform


with


tetramethyl


silane


internal


reference.


NMR


spectra


were


run


on a Varian


VXR


Fourier Transform


pectrometer


operated


at 121


samples


were


run


in d6


benzene


using


H3PO4


as an external


reference


A Varian


3700


GC with


an FID


a Hewlett


Packard


3390A


integrator


was


used


analyze


oxidation


reduction


reactions


using


appropriate


column


the


type


-1 -- I .


,,,,,.., ~


1-- _- 1


- -.-- J-- --J-- i


1- _


mi


-. .!_ __ L


_ I


J







ess


otherwi


indicated,


reactions


were


run


in a


Parr


Pressure


Apparatus


the


indicated


temperature


sure.


CAUTION!


Extreme


care


should


be taken


when


working


with


pressurized


apparatus


above


room


temperature


Appropriate


nearby


should


shields must be


elevated


be cooled


room


used and


fire extinguishers


temperatures, the

temperature before


reaction


should


solution


disassembling


pressure


apparatus.


Peroxide


concentrations


were


measured


taking


mL samples


from


pressure


bottle


with


in.


stainl


ess


steel


need


immediate


performing


iodometric


titra-


tions


CAUTION


Many


hydroperoxides


are


shock/temp


erature


sensitive


hydroperoxide


derived


from


1-methyl


pyrrolidinone


should


treated


as potentially


explo


sive


The


cataly


sts,


C1S


-RuCl2


(dmso


34,35


and


dmp)


] [PF


36 were


prepared


literature


methods


Steady


-State


EROOH 1


Studi


1-Methyl


-2-pyrrolidinone


(50mL


, 47g,


.7x10-1


was


ced in


a 250


mL Parr


Pressure


Bottle


equipped


with magn


stirring

reactor


After


was


pressure


purged


times


apparatus

with On


was


assembled,


(50psig)


the

then


ssuri


with


(50psig).


The


reactor


was


placed


75C


bath.


Recharging


the


reactor


with


was








HvdroDeroxide


Formation


Other


Solvents


appropriate


amounts


see


Tabl


2-1)


1-methyl


pyrrolidinone


and


the


solvent


(HO20


or CH3CN)


were


placed


250mL

After


Parr

the j


Pressure


pressure


Bottl


apparatus


equipped


was


with


assembi


magnetic


the


stirring


reactor was


times


with


(50psig)


and


then


pre


ssurized


with


(50psig)


reactor


was


plac


ed in


a 750C oil


bath.


Recharging


reactor


with


was


performed


as needed.


Samples


were


drawn


periodically


analyzed


iodometric


titrations.


HvdroDeroxide


Stability


Comparison


A solution of


5-hydroperoxo-


1-methyl


-pyrrolidinone was


prepared

(50psig)


reaction


750C.


The


1-methyl


hydroperoxide


-pyrrolidinone


with


concentration


ermine


iodometric


titration.


stability


hydropero


xide


solution


was


compared


iodometrically


with


a t-


butyl


hydroperoxide


solution


comparable


hydroperoxide


concentration


under


ambient


conditions.


PPh3


Oxidations


5-Hydroperoxo-1-methyl


-2-pyrrolidinone


(15mL


solution in


1-methyl


-2-pyrrolidinone,


.5x10


and PPh3


.5x10


moles)


were


placed


100mL


round


bottom


flask euipped


with magnetic


stirring


, anN


atmosphere,


Y


r








stirred


hours


that


time


colorless


solution


was


allowed


warm


slowly


room


temperature


reaction


Preparation


solution


of MNa


was


M=Co


analyzed


, Fe


C and


, or Mn2+)


These


heterogeneous


appropriate


chloride


catalysts


salt


were


.0x10


prepared


moles)


placing


distill


(200mL)


a 500mL


Erlenmeyer


flask


equipped with magnetic


stirring


Na-Y


(10g,


Linde


LZY-52


was


added


aqueous


metal-ion


solution.


resulting reaction


slurry was


stirred


70C


(for


or room


temperature


M=Fe3+


or Mn2+)


hours.


After


cation


exchange


slurry


was


filtered


and


washed


with


distilled


H20 until


no chloride


ions


were


detected


AgNO3


testing


filtrates


solid


catalyst


was


dried


under


vacuum


1500C


48 hours


After


cooling


room


temperature


under


vacuum


catalyst


was


ready


use.


Catalytic


Hvdroperoxide


Formation


1-methyl


MNa-Y(M=Co2+

250mL Parr


After


purged


-pyrrolidinone


or Mn2+

Pressure


pressure


times


0.25

Bottle


apparatus


with


(50mL,

M=Fe3+,


equipped


was


Opsig)


47g,


.7x10~1


were


with


magnetic


assembled,


then


and


placed


stirring.


reactor


pressurized


was


with


(50psig).


reactor


was


placed in


75C


bath.







needed.


Samples


were


drawn


periodically,


filtered,


analyzed


iodometric


titrations.


4-Butvrolactone


and


Isopropyl


Alcohol


Oxidations


appropriate


substrate


CoNa-Y


added)

with


were


magnetic


placed


a 250


stirring


mL Parr


After


Pressure

pressure


Bottl


equipped


apparatus


was


ass


embled,


reactor


was


purged


times


with


psig)


and


then


pressurzl


with


psig)


The


reactor


was


placed


a 750C oil


bath.


charging


reactor


with


psig)


was


performed


needed


. S


ampl


were


drawn


periodically


, filtered


and


analyzed


NMR


and


iodometric


titrations.


N-methvlsuccinimide


Reductions


The appropriate catalysts


, substrate


, and solvent(


see


Tabl


were


placed


250mL


Parr


Pressure


Bottle


equipped with magnetic


stirring


After the


pressure


apparatus


was


assembled,


the


reactor


was


purged


times


with


(10OOpsig)


and


then


pre


ssurTz


ed with H


(100psig


reactor


was


plac


100C


bath.


Recharging


reactor


with


(lOOp


sig)


was


performed


needed.


Sampl


were


analyzed


using


foot


stainl


ess


steel


column


packed


with


FFAP(15%)


on Chromosorb


WA/W(80/100


mesh)







Conclusions


This


research


shown


that


approximate


2M solutions


N-alkylamide


hydroperoxide,


5-hydroperoxo-1-methyl


pyrrolidinone


, can be


easily


generated


under mild


conditions.


This


provides


convenient


inexpensive


source


hydroperoxide


oxidation


organic


substrates,


initiation


radical


reactions


, and


variety


bleaching


applications.


Having


stability


comparable


stability


commercially-available t-butyl hydroperoxide


5-hydroperoxo-l-


methyl-


2-pyrrolidinone


can


be produced


direct


reaction


1-methyl-2-pyrrolidinone


with


molecular


oxygen


750C.


When


reacted


with


organic


substrate,


such


triphenylphosphine,


oxygen


atom


transfer


from


hydroperoxide


phosphine


produces


amido-alcohol


intermediate


-hydroxy-1-methyl-2-pyrrolidinone


quantitative


yield


of the


corresponding


phosphine


oxide.


presence


molecular


oxygen,


amido


-alcohol


intermediate undergoes rapid oxidation to N-methylsuccinimide.


Using


appropriate


transition


metal


catalyst,


methylsuccinimide can be hydrogenated


under mild


conditions to


yield


hydroperoxide


precursor,


l-methyl-2-pyrrolidinone.


applications


which


5-hydroperoxo-l1-methyl


pyrrolidinone


is a reactant,


this


recyclable


nature


makes


mot-hsr 1 r 4n-rr nrrrnrl #44 ^ nrnl0 o


all ha^rC*?-l^-








oxidation


reaction


with


the


net


reaction


being


4H2


SO +


2H20.


Another


potential


point


application


interest


this


this


N-alkylamide


research


hydroperoxide


the asymmetric


oxidations of


organic


substrates.


For


example,


oxidation


of alkenes


a chiral


alkyl


hydroperoxide


non-chiral


transition


metal


complex


may


duplicate


results


observed


Sharpless


co-workers


without


problems


caused


unstable


chiral


transition


metal


complexes


Further


hydroperoxides


suggested


would


work


this


involve


area


more


regenerable


depth


study


alkyl


into


another N-alkylamide


hydroperoxide


precursor,


1,5-dimethyl


pyrrolidinone,


which


been


shown


to form


corresponding


hydroperoxide,


5-hydroperoxo-1,5-dimethyl-2-pyrrolidinone.


This


hydroperoxide


should


decomp


ose


corresponding


amido-alcohol,


5-hydroxy- 1


,5-dimethyl-2-pyrrolidinone.


potential


regenerable


hydroperoxide


system


would


provide


more


efficient


use


molecular


oxygen


oxidative


step,


a more


efficient


use


of molecular


hydrogen


subsequent


hydrogenation


step.


Here


again,


potential


asymmetric


applications


exists


as well.


.502+ S --













CHAPTER


TRANSITION


METAL


-CATALYZED


OXIDATIONS


USING


AN N-ALKYLAMIDE


HYDROPEROXIDE


Introduction


interest


direct


oxidation


alkenes


epoxides


high


indus


with


during


trial


transition


years


intermediates


metal


since


for the


complexes


ese


remained


compounds


preparation of


a wide


very


are


vari


chemicals


, such


alkanolamines


, glycol


, and


polymers


like


polyesters


, polyurethanes


epoxy


resins


vapor


phase


three


fields


epoxidation


more


being


alkenes


always


obtained.


with


been


For


carbon


difficult


example


chain


with


, the


length


epoxide


oxidation


propyl


ene


with


molecular


oxygen


over


smuth


molybdate


460C


afforded


high


selectivity


acrolein


38-40


presence


ammonia,


this


catalyst


promotes


ammoxidation


of propylene


to acrylonitrile.


41-43


Currently


industrial


method


making


propylene


oxide


based


on organic


hydroperoxides.


Arco


Oxirane


Halcon)


process


is used


oxidation


of propyl


ene


solution.


44-46


this


process,


alkyl


hydroperoxides


, t-


butyl


hydroperoxide


ethylben


zene


hydroperoxide


are







respective


These


alkyl


hydroperoxides


are


prepared


separate


step


under


air


molecular


oxygen


(150


psig)


around

catalys


with


1400C.

t, the


an excess


epoxide.


In the


presence


-generated


olefinic


eas


ibility


iof the

alkyl h


appropriate


Lydroperoxide


substrate


Arco


900C


Oxirane


epoxidation


reacted


to produce


cess


dependent


demand


co-product


alcohol


Another


advantage


thi


process


attainment


of high


selectiviti


elds.


Arco


Oxirane


proc


ess


, the


selectivity


to epoxide


formation was


greatly


enhanced by the


choice


of metal


comply


ex.


When


various


rhenium


comply


exes


were


employed


100%


conversion


the alkyl


hydroperoxide


was


observed


with


only


a 10%


efficiency


for the


formation


of epoxide


Molybdenum


and


tungsten


complex


hydroperoxide


xes


with


converted


a 65 to


the


efficiency


for the


alkyl


formation


propylene


oxide.


Vanadium


comply


exes


have


been


employed


these


olefinic


oxidations


well.


use


molybdenum,


tungsten,

epoxide


vanadium


yields.


When


comply

the


exes


generally


result


oxidant


in higher

tungsten


comply


exes


are


the best


catalysts.


The molybdenum and


vanadium


comply


exes


are


more


effective


when


alkyl


hydroperoxides


are


used


oxidant


Sheldon and Kochi conveniently designate


ed metal


-catalyzed


oxidations


organic


substrates


either


homolytic


H202







Table


Main Characteristics
Oxidations.48


of Homolytic


Heterolytic


Homolytic oxidations Heterolytic oxidations

Characteristics

Free-radical No free-radical
intermediates. intermediates.
Outer-sphere oxidations in The reaction occurs in
bimolecular steps. The the coordination sphere
substrate is generally not of the metal.
coordinated. The substrate is
Oxidations generally not generally activated by
very selective and not coordination.
stereospecific. High selectivity and
One-electron oxidation and stereospecificity of the
reduction step of the transformation.
metal. No change in the
oxidation state of the
metal or two-electron
steps.
Transition metals commonly involved.

V /IV CrVI/CrV, Tiv V, CrVI, MoVI W,
,'IIII vfI VII VI -v'III
Mn /Mn Mn Ru Os
Fe /Fe Co111/Co Rh111/Rh Ir11 /Ir ,
Cu" /Cu' PdII/Pdo, Pt /Pt0

Relevant oxidations

Nonstereoselective Stereoselective
epoxidations of alkenes epoxidations of alkenes
(V,Mn,Fe). (Ti,V,Mo,W).
Hydroxylation of alkanes Ketonization of alkenes
and arenes (Rh,Ir,Pd,Pt).
(V, Cr,Fe,Co,Cu).







should


there


be noted


are


that


this


number


classification


borderline


is not


examples


and


rigorous


exceptions.


Even


though


they


are


homolytic


nature


many


enzymatic


oxygenases


containing first


-row metal


as active


centers


function


very


high


reglo-


stereosel


ective


manner.


In this


case


, the


of the


prot


ein


cage


around


active


center


essential


for


substrate


-enzyme


assoc


iation


right


orientation


of the


substrate


toward


the


active


center.


other


cases


, the


free


-radical


intermediates


can


remain


ose


metal


react


concerted


way


before


inversion.


There


are


sev


eral


examples


where


metal


heterolytic


complex


catalyst


can


Using


both


alkyl


homolytic


hydroperoxides


, vanadium


comply


exes


stereoselectively


epoxidize


allylic


alcohols


via


vanadium


alkylperoxo


intermediates


However,


vanadium


alkylperoxo


complexes


, such


V(0)


dipic)(OOR)L


(where


dipi


, 6-pyridinedicarboxylate


and


L=H20),


react


homo-


lytically


site


occur


as a result


comply


In general,


of the


lack


exation


an available


the


homolytic


olefinic


and


heterolytic


coordination


substrate


nature


the


oxidation


determined


the


nature


metal,


nature of


ligands


, the availability


of coordination


sites


the


nature of


subs


trate


and


temperature


conditions


Recently


, Drago


developed


a more


detailed


ass


ification


scheme


homogeneous


metal


-catalyzed


oxidations


of organic







role


the


transition


metal


complex.


26,27


classification


scheme


consists


five


different


classes


Table


Class


reactions


involve


coordination


of molecular


oxygen


the


transition


metal


complex


described


spin


pairing


model51;


thereby


, increasing


both


basicity


radical


reactivity


of the


molecule.


subsequent


oxidation


substrate


occurs


via


reaction


with


coordinated


molecule.


reaction


of a transition metal


complex with molecular


oxygen


can


result


in the


formation


of a high-valent


metal


OXO


species,


molecule


which


to oxidi


efficiently


the


uses


both


substrate


. Thi


oxygen


Class


atoms


II behavior


indicative


dioxygenate


catalysts


26,27


Subsequent


oxygen


atom


transfer


or other


type


reactions


in the


oxidation


organic


substrate by the


high-valent metal


OXO


complex results


regeneration


of the


lower


oxidation


state


of the


metal;


thus


, allowing


the


reformation


high-valent


metal


OXO


species


from


molecular


oxygen.


Class


reactions


involve


generation


of a metal


OXO


speci


reducing


molecular


oxygen


peroxo


complex


xes


alkylperoxo


complexes,


, or


alkyl


hydroperoxides


26,27


Oxidation


substrate


occurs


via


reaction


high-


valent


metal


OXO


species


with


substrate


. For most


these


reactions


only


one


oxygen


atoms







Table


Classification
Oxidations.26,27


Scheme


Metal


-Catalyzed


Class Role of Metal

I Metal-bound Op.
II Metal oxo via Op.
III Metal oxo via peroxides.
IV Metal peroxo systems.

(a) Metal-catalyzed peroxide
decomposition.
(b) Nucleophilic attack on
peroxo and alkylperoxo
complexes.
(c) Other reactions of metal
peroxo complexes.


Metal


-centered


oxidi


zing


I j agents.







reactions


often


exhibit


monooxygenate


behavior


but,


some


cases


, dioxygenate


behavior


can


occur.


Work


Drago


Goldstein


shown


that


complex


[Ru(dmp)


0)2]


[PF6]


oxidized


metal


OXO


comply


exes


through


alkyl


the Ru(III)

hydroperox


to the


:ides


Ru(IV)


generated


Ru(VI)


during


oxidation

induction


states

period


the oxidation


of alkenes


Reaction


between


substrate


Ru(VI)


dioxo


species


results


in the


formation


of the


Ru(IV)


mono


OXO


complex


which


can


reoxidized


back


Ru(VI)


dioxo


species


with


molecular


oxygen.


transition


metal


complex


exhibits


ass


reactivity


with


alkyl


hydroperoxides


form


Ru(IV)


mono


OXO


species


, followed


a Cl


ass


reaction


form


Ru(VI)


dioxo


complex


with


molecular


oxygen.


Unlike


ass


ass


reactions


, which


invol


high-valent


metal


oXO


comply


exes


reactive


inte


rmediates


ass


reactions


involve


alkylp


eroxo


hydroperoxo


transition


metal


comply


exes


intermediates


26,27


ese


metal


peroxo


comply


exes


exhibit


three


types of


reactivity


oxidation


substrate,


resulting


three


subcl


ass


asses

IVa


this


deal


class of

with


reactions


transition


first

metal


subcl


ass


-cataly


decomposition


hydroperoxides


(Haber


-Weiss


and


Fenton


chemi


stry)


homolytic


According


decomposition


Haber-Wei


of alkyl


hydroperoxides


mechanism,


transition


2 i












H
Co(ll) + ROOH -- [Co-O-O-R] Co(Ill)OH + RO*
Co(ll)OH + ROOH-- Co(ll) + ROO* + H20


RO.'+ ROOH- ROH + ROO0
Co(ll) + ROO.-- Co(lll)OOR
Co(Ill)OH + ROOH--Co(III)OOR + H20
2Co(1l) + 3ROOH 2Co(Ill)OOR + ROH+H2O
Co(lIl)OOR- Co(II) + ROO*


"Co(lll III)O" + RO*


RO" + RO2H ROH + RO2j

2ROO- [RO4R] --, 02+ R2C=0 + He







Budnik


Kochi


reported


cobalt-catalyzed


epoxidation


of several


olefins


using


molecular


oxygen


butyl


hydroperoxide.


56,57


mechanism


proposed


olefin


initiation


epoxidations


reaction


using


between


molecular


Co(acac


oxygen


molecular


involves


oxygen


produce


free-radicals.


subsequent


reaction


these


free-radicals with molecular


oxygen


results


in peroxy-radical


formation.


Addition


peroxy-radical


olefinic


bond


leads


p-peroxyalkyl


radical


intermediate,


which


undergoes


fragmentation


give


epoxide


carbonyl


compounds.


Using


t-butyl


hydroperoxide


as the


oxidant


Cobalt(II)-catalyzed


epoxidation


olefins


, Kochi


proposed


radical-chain mechanism


which


homolytic


addition


butylperoxy


-radicals


olefinic


bond


leads


epoxide


formation


Figure


cobalt


catalysis


is associated


with


CoII/CoI'I


cesses


resulting


interconversion


the


formation


one-electron


redox


t-butylperoxo-


radical.


other


hand


, the


transition


metal-catalyzed


decompos


ition of


via


one-electron


redox proce


sses


results


formation


of hydroxyl-radicals


(Figure


3-3).


1,58,59


presence


organic


substrate


these


hydroxyl


radicals


produce organic


free-radicals


which can


undergo dimerization,


oxidation,


reduction


(Figure


3-3)


These


free-radical


processes


lead


to low


yield,


unselective


substrate


oxidations


of t-












t-BuOOH


t-BuOO-


t-BuOO0


H\
C=C


t-BuO*


t-BuOO
HI ,H
+ 'C C
R' R


t-BuOO
H\I
C
R'


t-BuO*


./R
--C


O
C-C


t-BuOOH


. t-BuOH


t-BuO-


+ t-BuOO*










Fe" + H202

Fd" + H202

Fe"+HO.-


Fe'"+HO 2


HO* +H202

RH + HO* -


- Fe'"OH + HO

Fe" +HO + H

Fe'"OH


Fe + 02


- H20 + H02

R. + H2O


+ Fe'"


R. + Fe"-


[Re] + Fe"


[Re] + Fe"' ?"0


products


RH


+ He







Nucleophilic


attack


the


substrate


coordinated


peroxo


or alkylperoxo


ligand


can


be described


as a Cl


ass


reaction.


exhibit


26,27


a high


As noted


degree of


earlier,


product


these


heterolytic


selectivity


reactions


(Table


. Two


mechanisms

epoxidations


ass


have


been


proposed


metal

by Mi


-catalyzed


moun,


olefin


Chong


harpl


ess


and


Sheldon


The


Mimoun


mechanism


involves


dipolar


addition


form


peroxymetallocyc


which


compo


ses


to yield


epoxide


and


the metal


alkoxide


Figure


The


metal


peroxo


complex


regenerated


with


alkyl


hydroperoxide


mechanism


proposed


Sharply


ess61


Sheldon6


invol


ves


the


nucleophilic


attack


olefin


coordinated


peroxo


oxygen


give


the


corresponding


metal


alkoxide


and


epoxide


Figure


regeneration


metal


peroxo


species


with


alkyl


hydroperoxide


subsequent


reaction


with


olefin


give


a metal


alkoxide


result


with


no change


metal


oxidation


state.


Other


reactions


involving


metal


peroxo


inte


rmediates


belong


ass


IVc.


26,27


For


example


Co(SMDPT)


(where


SMDPT=


s(salicylidene


iminopropyl)methylamine


-catalyz
Ccll-d-Ly


reactions


olefins


with


molecular


oxygen


reducing


solvents


results


oxidation


internal


carbon


double


bond


to give


alcohols


and


ketones


mechanism


suggests


the


formation


a metal


hydroperoxo


species


which


) 60










.0
M I
MO
0


C= C


O
M^)
n
p.
6
S


HC-C
H H


M-O-R


H H
H\ /\ /
C-C












C-


,O
-0


I \
I \
p\


-0


-R


H /
HI


.R
.0


H,

H/


'H



/R


1H


'H


CH

\H


H ,
C
HI







olefin


form


metal


alkylperoxo


complex.


Haber-Wei


decomposition of


the alkyl


hydroperoxide


eads


to the


observed


products.


Class


V reactions


involve


oxidation


of the


substrate


a high-valent metal


complex


, followed by


reoxidation


of the


reduced metal


complex


with mol


ecular


oxygen


or peroxides


26,27


The


oxidation


ethylene


ace


taldehyde


Wacker


process


belongs


this


ass.


64,65


Since


some


metal


catalysts


play


several


reaction


reaction


can


involve


a combination


of the


above


mentioned


asses


26,27


Other reactions discussed


work


will


be described


using


this


recent


classification


scheme


mentioned


earlier,


mechanisms


metal-


catalyzed


epoxidation


of olefins


involving


ass


behavior


have


been


described


Landau


et al


Eber


son


Jonsson,


Parshall,


Mimoun


and


Sharply


ess


Epoxidations


carried


esence


180-enriched


H20 by


Sharpl


ess


al. showed


that


epoxide


oxygen


originated


from


alkyl


hydroperoxide


71 The


mec


hanism


proposed


Mimoun


(Figure

atoms on


does


3-4)

the


catalys


distinguish


t before


the


between


addition


metal

of the


peroxo


oxygen


hydropero


xide


and


those


hydroperoxide


metal


findings


peroxo


Sharp


complex


ess


. suggest


mechanism


involving the


trans


one


of the


peroxo


oxygens


olefin


through


three-membered


ring


transition







intermediate


the


epoxidation


olefins


metal


alkylp


eroxo


comply


exes


mechanism


proposed


Sharpless


provides


a better


explanation


the


epoxidation


allylic


alcohol


with


their


coordinated


hydroxyl


groups70


than


does


Mimoun


mechanism.


53,73


nation


several


metal


alkylperoxo


complexes


Mimoun


co-workers


provided


evidence


the


elimination


of mechanisms


in which


alkyl


peroxide


binds


metal


through


the


oxygen


atom


adjacent


to the


alkyl


group


and


clearly


demonstrated


that


isolated


metal


alkylp


eroxo


complex


ective


epoxidation


catalyst


their


investigation


metal


acetylacetonate-


catalyzed


100%


epoxidation of


selectivity


olefins,


epoxide


Indicator and Brill


oxidation


observed


,4,4-


trimethyl


-1-pentene


using


Cr(acac


, Mo(acac)


, V(0)


acac)


V(acac)3


74 These


ass


26,27


epoxidations


are


stereospecific


with


trans


-4-methyl


-2-pentene


yielding


trans


epoxide


and


-4-methyl


entene


yielding


epoxide


No epoxidation


olefins


the


hydroperoxide


alone


was


observed.


presence


various


amines,


such


pyridine


epoxides


were


selectiv


obtained


from


the


reaction


sev


eral


different


aliphatic


aromatic


efins


with


t-butyl


hydroperoxide


Mo(O)


(acac)


2 in


non-polar


solvent


700C


These


reactions


are


stereosel


ective


with


C1S-


olefins







mec


hanism


which


added


amines


assist


observed


activity


to epoxide


formation


was


elucidated.


epoxidation of


cyclohe


xene


-octene


at 900C using


t-butyl


hydroperoxide


molybdenum


catalysts


, Mo(O


(acac)


and Mo(CO


, resulted in


formation of


1, 2-epoxycyclohexane


,2-epoxyoctane


(64%)


respective


These


findings


suggest


active


cataly


should


be a weak


oxidant


a fairly


strong


Lewis


acid.


High-valent


metal


comply


exes


(i.e

High


. Mo(VI)


, Ti(IV),


selectivity


or W(VI))


meet


formation


these


requirements


epoxide


was


76,77


observed


using


cumene


hydroperoxide


as well.


Several


oxovanadium


comply


exes


have


been


studied


catalysts


olefin


epoxidations


Compared


with


molybdenum


catalysts


, vanadium


comply


exes


have


been


found


poor


catalysts


olefin


epoxidations.


79,80


The molybdenum(VI)-


catalyzed


epoxidations


are


about


times


faster


than


those


cataly


vanadium(V)


comply


exes


1,80


Interestingly


, the


epox


idation


proceeds


allyli


at higher


rates


alcohols


and


using


at higher yie


vanadium

Ids than


catalysts


nigh-valent


molybdenum

lectivity


comply


catalysts.


of epoxidation


exes


The


dependence


reactions


nature


catalyzed


ligand


stereose-


vanadium


present


OXO


50,73,82


2,6-pyridine-dicarboxylate


is present


as a ligand,


butene


ves


mixture


the


cooresponding


C1S-


and


trans-


epoxides


whereas


the


presence


tridentate







Schiff


base


ligand,


-hydroxyphenyl


salicyclideneamine,


epoxidation


CIS


-2-butene


results


only


-2,3-


epoxybutane.


Using


t-butylhydroperoxide


oxidant,


18Q-


labeling


studi


vanadium(V)


OXO


-catalyze


d epoxidations


have


shown


existence


metal


peroxo


intermediate


favor


vanadium (V)


Mimoun


vanadium(V)


alkylperoxo


have


OXO


complex


isolated


alkylperoxo


and


complex


active


ecies


character


possessing


61.84


stable


a triangularly


bound t-butyl


peroxo group and having both


equatorial


adjacent


positions


occupied


tridentate


dipicolinate


ligand


These vanadium(V)


alkylperoxo comply


exes


have been suggested


be the


active


species


epoxidation


alkenes,


with


alkylperoxo


ligand


coordinated


in a monodentate


or bidentate


fashion

The


(Figure


transfer


of the oxygen atom from vanadium alkylperoxo


comply


exes


well


from


other


transition


metal


alkyip


eroxo


and


peroxo


species


received


a great


deal


attention.


Three

first


mechanisms

mechanism,


are

the


shown

metal


in Figure

hydroxo a


ilkylperoxo


complex


other


, resulting


metal


from


oxo)


the


complex


reaction


with


alkyl


vanadium


OXO


hydroperoxide


transfers


an oxygen


atom


electron-rich


olefin


to give


the corresponding


epoxide,


starting metal


oxo complex


, and


alcohol


derived


from


alkyl


hydroperoxide.


This


type










.H


NR


\v


.H


/R

















-R


-c


--C-


+ROH


Io10


0
I \
--C--C--


nV-OR
-I


C=C


I .O
V' r*Or
c \c/
Ci


-C--C--


SV-OR
/I1


N


- -*


/1\


/R
.0


~


~







nucleophilic


peroxo


oxygen


of a metal


attack


of the


alkylperoxo


olefin oi

complex


n the


coordinated


, produced


reaction


high-valent


transition


metal


complex


with


alkyl


hydropero


xide


, leads


to the


epoxide


a metal


alkoxide


Class


IV) .


No change


the metal


oxidation


state


occurs


Figure


-7) .


third


membered


mechanism


peroxometallocycle


mechanism


involves


Figure


occurs


intermediate.


first


coordination


alkene


five-


step


to the


metal


into


center


metal


, followed


-peroxygen


insertion


bond


of the coordinated


give


alkene


peroxymetallocycle


intermediate


metallocycle


subsequent


results


decomposition


formation


peroxy-


epoxide


metal


alkoxide


Class


IV).


26,27


general


, vanadium


complexes


are


ess


efficient


and


selective


catalysts


than


molybdenum


compounds


epoxidation


unactivated


olefins.


Mimoun


co-workers


studied the

from stable


heterolytic


metal


and


alkylperoxo


homolytic


oxygen


complexes


atom

the


transfer

stereo-


selective


oxidation


alkenes.


53,73,82


heterolytic


(Figure


or homolytic


Figure


3-8)


dissociation


mode


vanadium


alkylperoxo


species


controls


nature


catalytic

vanadium(V


oxidation.


OXO


For


alkylperoxo


instance,


Schiff


earlier


base


complex


mentioned


exhibited


high


degree


selectivity


and


stereoselectivity





O
' O
R-
R


vO
0


R-CCi.-R


R
\
-C
AI


r

R H
'C

)


0
C--c


R
C


0
-/\ C
-C.


+ .,


S


"0"







indicative of


epoxidation


Class


C1s-


reactions.


trans


26,27


-2-butene


On the other


vanadium(V


hand,


peroxo


comply


exes


resulted


in mixtures


cis-


trans


-epoxide


These


non-stereoselective


epoxidations


are


characteristic


of a homolytic


process


, which


is suggested


involve


a biradical


vanadium(IV)


alkylperoxo


species


(Figure


3-8)


suggested


intermediate


would


account


isomeri


zation


C1s


alkenes


yield


mixtures


and


trans


epoxides


allowing


rotation


about


carbon-


carbon


bond.


While


much


work


been


done


ective


and


stereosel


ective


metal


-catalyzed


formation


epoxides,


area


asymmetric


using alkyl


transition


hydroperoxides


metal


receive


-cataly

id little


epoxidations


attention.


The


catalytic


asymmetric


epoxidation


unfuntionalized


alkenes


with


large


enantiomeri


excesses


(ee)


proven


very


difficult.


Using


t-butyl


hydroperoxide


oxidant


Otsuka


and


co-workers


obtained


a 10%


ee in


epoxidation


1-methylcyc


lohexane


using


a Mo(0) 2 (acac)


/DIPT


catalyst


ability of metal


alkylperoxo


comply


exes


to sel


ectively


epoxidize


alkenes


een


increased


using


allylic


alcohol


substrates.


mentioned


earli


vanadium


comply


exes


were


found


to be


very


efficient


catalysts


allylic


epoxidations


using


t-butyl


alcohol


hydroperoxide


, vanadium


catalysts


oxidation


favor


allylic


formation







observed


acceleration


rate


and


high


region


electivity


these


reactions


suggest


mechanism


which


alcohol


coordinated


metal


rate


determining


step.


81,89


Chiral


molybdenum90


and


vanadium70


complexes


have


been


appli


ed in


the


asymmetric


epoxidation


allylic


alcohols.


presence


chiral


molybdenum


complex,


Mo(O


(acac)


-alkylephedrinate],


and


cumene


hydroperoxide,


allylic


alcohol


were epoxidized


to the corresponding optically


active


epoxy


alcohol


(maximum


vanadium


hydroxymate


catalyst


generated


situ


from


V(O)(acac


and


chiral


hydroxamic


acids


Enantiomeric


excesses


were


observed


using this


catalyst


while


the chiral molybdenyl


hydroxymate


complexes


exhibited


poor


asymmetric


inductions


under


analogous


experimental


conditions.


Probably


best


known


method


the


asymmetric


epoxidation


allylic


alcohol


invol


ves


the


reaction


mixture


titanium(IV)


alko


xide,


optically


active


tartrate


ester,


and


t-butyl


hydroperoxide


with


allylic


alcohol


form


epoxy


alcohol


good


yield


with


enantiomeric


excesses


generally


greater


than


minus


230C.


33,91-99


Rearrangement


epoxy


alcohols


their


corresponding


diols


results


upon


exposure


epoxy


alcohol


Ti(OiPr) 4


or above


room


temperature


When


using catalytic amounts of the titanium (IV)


alkoxide


- )-N







yields


high


enantiomeric


excesses


90-95%


result


from


addition


of 3A


or 4A molecular


sieves


during


reaction.


33,99


The molecular


sieves


are


thought


to protect


catalyst


from


adventitious


that


may


generated


in small


amounts


during


the


reaction.


Using


the


Sharpl


ess


method


the


kinetic


resolution


racemic


oxidation


allylic


rate


alcohol


93 At


can


rapid


performed


rates


varying


oxidation,


epoxidation


-enantiomer


selective


the


formation


erythro


enantiomer.


slower


asymmetric


epoxidation


of the


-enantiomer


res


ults


in a


selectivity


erythro


epoxy


alcohol


Complexes


diisopropyl


tartrate


and


Ti(OtBu)4


were


found


catalyze


kinetic


resolution


efficiency


racemic


relative


secondary


those


allylic


complexes


alcohol


with


generated


from


Ti(OiPr)4.


In order


active


to gain


catalytic


some


species


insight


, the


into


structure


titanium-catalyz


asymmetric


epoxidation of


allylic alcohols


were


investigated using


linked


s-tartrate


esters


ligands


inability


linked


tartrate


derived


catalyst


to mediate


efficient


kinetic


resolution


secondary


allytic


alcohols


argues


against


intermediacy


against


epoxidation


exclusively


a momomeric


titanium tartrate


species


. A detailed solution


study


this


catalytic


system


suggested


that


asymmetric







of the


titanium


alkoxide


and


the


tartrate


ester.


Titanium


comply


exes


containing


tartratee


-like"


ligands,


(3R,


4R)-


diisopropyl


-3,4


-dihydroxyadipate


, 4S) -diisopropyl


dihydroxyglutarate,


and


-diisopropyl


,5-dihydroxy-


adipate


were


found


to be


dimeric;


thereby,


providing


further


support


active


catalytic


species


Metalloporphyrin


complexes


have


been


used


selective


manganese(II)-


oxidation


alkenes.


containing


5,10,15,20


iron(II)-


-tetraphenylporphyrins


are


the most commonly used metalloporphyrins


for the oxidation


organic


substrates.


The


iron(IV)


porphyrins


are


proposed


contain


ferryl


group,


105-108


which


suggested


active


species


difficulty


the epoxidation


formation


of alkenes


ferryl


species


109-112


with


tetraphenylporphyrin


ligand


results


from


tendency


to form


the


peroxy-bridged


metalloporphyrin


complex.


113,114


dimerization


problems


assoc


iated


with


metal


tetraphenyl


porphyrin


complex


can


overcome


using porphyrins


containing


bulki


groups,


110,111


the


addition


nitrogen


ases


stabili


monomeri


cies.


imple


unable


iron(III)


catalyze


and


manganese(III)


epoxidation


porphyrins


alkenes


using


were


alkyl


hydroperoxides


115,116


Mansuy


and


Bartoli


proposed


a "Fenton-


like


" homolytic


cleavage


alkyl


hydroperoxide


oxygen-


oxygen bond


and not


a het


erolytic


cleavage of


this


bond,


which







stabilizing


base,


imidazole


, these


iron(III


manganese(III)-tetraphenylporphyrin


complexes


catalyzed


epoxidation


of several


olefins


using


cumyl


hydroperoxide.


Results


Discussion


During


an earlier


performed


solvent


variation


study


metal-catalyzed


oxidations


alkenes


, the


solvent


methyl-2-pyrrolidinone


exhibited


high


selectivity


epoxide


formation


cobalt


II)-catalyzed


oxidation


of 1-


hexene


with


molecular


oxygen.


This


selectivity


xide


would


thereby,


expected


suggesting the


oxygen


involvement


atom


of the


transfer


solvent by


reactions;


chemical


reaction.


subsequent


study,


direct


reaction


methyl


-2-pyrrolidinone with mol


ecular oxygen at


750C was


found


form


methyl


the


corresponding


-2-pyrrolidinone,


succinimide


the


hydroperoxide,


which


presence


decomposed


peroxide


5-hydroperoxo-1-


N-methyl-


decomposition


catalyst


This


hydroperoxide


quantitatively


oxidized


PPh3


OPPh3


oxygen


atom


transfer


give


amido-alcohol


intermediate


, 5-hydroxy-1-methyl-2-pyrrolidinone,


which


further


oxidi


zes


presence


molecular


oxygen


methylsuccinimide


24.25


Furthermore,


final


decomposition


product,


N-methylsuccinimide,


can


be hydrogenated


under


mild


conditions


using


various


transition


metal


catalysts


hydrop


eroxide


presuror,


1-methyl-2-pyrrolidinone,


to provide







pyrrolidinone,


effect


functioning


as a catalyst


(Figure


24,25


Recently,


we have


reported


applications


situ


generated


alkyl


hydroperoxide


stem


elsewhere.


Employing


a recently


reported


ssifi


cation


scheme


the


metal


-catalyzed


oxidation


organic


substrat


26,27


present


a more


in depth


study


into


of the


transition


metal


catalysts


oxidations


various


substrates


using


thi


hydroperoxide


1-methyl


-2-pyrrolidinone


solvent.


Cvclohexene


Oxidation


Our


initial


investigations


were


performed


using


the


cyclic


olefin,


cyclohexene.


After


72 hours


reaction


, both


the


metal


-catalyzed


and


the


uncatalyzed


olefin


oxidations


1-methyl


-2-pyrrolidinone


showed


a predominance


of the


allylic


products


, 2


-cyclohexen


-1-ol


and


2-cyclohexen-l-one


, which


arose


from


autoxidation


substrate


(Table


Looking


results


given


Table


, the


employment


several


molybdenum


epoxidation


catalysts,


including


Mo(O)


allylic


ass


(acac


alcohol


IVb)


(Class

1 and


26,27


IVb),2

ketone,


showed


6.27


display


while


much


preference


catalyst,


greater


V(0)(acac)


preference


allylic


initiating


products.


pathway


vanadium


ass


catalyst


component),


, with


26,27


radical


appears


catalyze


more


facile


olefini


autoxidation


more


readily








Tabl


Cyclohexene


Oxidation.


Catalyst Epoxide:Allylic Alcohol:
Allylic Ketone Ratio

none 1.0:1.6:9.1

MoO 1.0:3.3:15.3
Na9WO4 2H,0 1.0:3.3:10.8

Na2MoO4*2H20 no epoxide, only allylic
products
Mo(0) (acac)) 1.0:2.0:5.4

V(0)(acac)2 1.0:11.4:27.8


Note:


Reaction
catalyst
substrate


conditions


.0x10
.0x10


moles
moles


NMP
run


under


psig)


75C


hours







results


from


hydroperoxide,


was


detected


within


the


first


24 hours


reaction.


These


combined


observations


show


that


there


is a competition


between


autoxidation


substrate


the


formation


N-alkylamide


hydroperoxide derived from 1-methyl


-2-pyrrolidinone


(Figure


trans


-B-Methvlstvrene


Oxidation


Experiments


in which


trans-


p-methylstyrene


was


used


olefini


substrate


were


performed


(Table


interesting


to note


that


the


uncataly


zed oxidation


showed


epoxide


benzaldehyde


ratio


Furthermore


, the


results


Tabl


-4 show that


the


variation of


transition


metal


catalyst


used


a pronounced


effect


on the


epoxide


benzaldehyde


ratio


well


the


times


complete


consumption


substrate


these


reactions.


The CoCl2 6H


Co(octoate


and Co


OAc)


4H20


three


catalysts


aromatic


, Class


olefin


IVa)


show


26,27


results


a larger


oxidation


activity


epoxidation


substrate


than


other


catalysts


listed.


seemed


anomaly,


until


color


change


catalyst


was


observed

the 1-me


during the


thyl


ligands


reaction.


-pyrrolidinone


cobalt


metal


The

had


color ch

probably


centers


. Thi


iange


indicated


replaced


change


that

other


ligands


radically


increased


selectivity


reaction,


since










OH


0

,,NCH3

'OOH


02


3
9


02


N--CH3








Tabi


trans


- -Methylstyrene


Oxidation.


Catalyst Epoxide:Benzaldehyde
Ratio

none 2.0:1.0 (72 hours)

CoCl *6H, O 6.0:1.0 (12 hours)
Co(octoate), 6.0:1.0 (18 hours)
Co(OAc)9'4HO 6.0:1.0 (16 hours)
FeCl3*6HO0 4.0:1.0 (12 hours)
[Ru3O(pfb)6(Et,0)3] (pfb) 2.3:1.0 (6 hours)
RuC1 *3HO 3.5:1.0 (12 hours)
[Ru(dmp)2(H2O),][PF,]9 1.0:6.0 (12 hours)
Mn(OAc)*-4H O 1.0:2.8 (13 hours)
Mo(0),(acac), 1.0:3.4 (48 hours)
V(0)(acac)9 1.0:4.3 (26 hours)
WO3 1.0:1.8 (35 hours)


Note:


Reaction
catalyst
substrate


NMP
run


under


Substrate


conditions


.3x10
.3x10


mol
mol


02 (50 psig)
consumption


at 750C


times


given


in parentheses.







study


cobalt(II)-catalyzed


reaction


1-methyl


pyrolidinone


with


molecular


oxygen


75C


UV/vis


spectro


scopy


in order


to det


ermine


nature


the


species


involved.


intervals


Looking


, the


at the


absorbance


UV/vi


observed


spectra


taken


at 664


at various time


which


in the


region,


showed


no changes


over


a 24 hour


period,


even


though


solution


went


through


sev


eral


color


transitions


. blue


green


to color


ess


Another


absorbance


at 264


showed


increase


hydroperoxide


decomposition


product


, N-methylsuccinimide,


over


time.


Co(NMP


ears


most


likely


candidate


resultant


highly


selective


catalyst,


functioning


ass


IV26


manner


(Figure


3-2)


Another


behavior


catalyst


similar


, FeC13

that o


*6H O


ass


observed


IVa),


cobalt


exhibit


-catalyze


experiments


Good


generate


, giving


selectivities


epoxide


to epoxide


hydroperoxide


stem


to benzaldehyde


formation


employing


ratio.


in situ


1-methyl


pyrrolidinone


as the


solvent


were


observed


with


ruthenium


cataly


RuCI3 3H


Class


IVa)


26,27


Table


[Ru30(pfb)6(Et


0)3] [pfb]


ass


IVa)


26,27


gave


result


comparable


uncatalyzed


reaction


Tabl


3-4).


Whil


trans


than


other


-P-methylstyrene


uncatalyze


catalysts


showed


d reaction,


employee


lower


the


selectivities


surprising


oxidation


epoxide


to note


that








Another


metal


OXO


catalyst,


V(O) (acac)


exhibited


a slightly


greater


preference


to the


radical


cleavage


product


to its


radical


pathway


ass


IVa).


26,27


Another


metal


OXO


precursor,


[Ru(dmp)


] [PFg]


exhibited


several


interesting


observations


situ


generated 5-hydroperoxo


-1-methyl


-pyrrolidinone


system.


ass


IVa2


6,27


component


of thi


catalyst


to an elimination


the


induction


period


observed


formation


the


hydroperoxide


uncatalyz


reaction


through


metal


catalyzed


radical-chain


mechanism.


The


observed


color


change


from


purple


-red


to yellow


signal


the


oxidation


of the


Ru(II)


complex


the


Ru(IV)(0)


and


the


Ru(VI)(0)


speci


es.


hours


into


the


reaction,


thi


color


change


was


detected.


resulting


Ru(VI) (0)


catalyst


reacts with


substrate a


and i


reduced


to the


Ru(IV)O comply


ex.


The


Ru(IV)(0)


species


then


converted


back


Ru(VI) (0)


species


either


hydrop


eroxide or molecular oxygen


perform further


substrate


oxidation


ass


or Cl


ass


III).


26,27


Using


situ


generated


-hydroperoxo-


1-methyl


pyrrolidinone


system


oxidation


trans-


S-methyl


styrene,


the


epoxide


Ru(VI) (0)


to ben


species


zaldehyde


being


ratio was


regenerat


observed with


either


hydroperoxo-


1-methyl


-2-pyrrolidinone


or molecular


oxygen.


Looking


results


given


Tabl


, the


Class


IVa26,27


catalysts


. ....


Co(II)


Fe(III),


and Ru (


III)







oxidation of trans


-p-methylstyrene


using the


in situ generated


hydroperoxide


system


in 1-methyl


-pyrrolidinone.


When metal


OXO


metal


catalysts


OXO


, such


precursor,


as Mo(O)


[Ru(dmp)


(acac)


(H20


and


S[PF6]i


V(0)(acac)


were


, and


employed


the oxidation


this


olefinic


substrate,


a preference


to the


radical


cleavage


product,


benzaldehyde,


was


observed.


result


these


observations,


nature


these


metal


catalyzed


oxidations


homolytic


. heterolytic


oxygen


atom


transfer)


was


investigated.


major


complications


in obtaining


mec


hanisti


information


on this


type


of oxidative


stem


is the


fact


that


situ


formation


hydroperoxide


from


1-methyl


pyrrolidinone


molecular


oxygen


under


thermal


conditions


proceeds


a peroxy


-radical


mechanism.


Earlier


studies


autox


radi


idation


initiators,


of a number


t-butyl


of N-alkylamides


hydroperoxide,


with


benzoyl


free-


hydro-


peroxide, and a, a


-azobi


s(isobutyronitrile


(AIBN)


under thermal


conditions


support


the


peroxy-radical


mechanism.


5,6,


With


fact


mind


free


-radical


inhibitors,


such


butyl-p-cresol


situ


(DTBPC)


hydroperoxide


or benzoquinone


formation;


, would


thereby


inhibit


resulting


oxidation

radical i.


substrate


nitiator would


Likewi


an accel


use


eration


free-


of the


peroxy-


radical


reaction


form


N-alkylamide


hydroperoxide


subsequent


substrate


oxidation.


These


facts







catalysts


in this


pyrrolidinone


situ


stem


using


generated


a different


-hydroperoxo


olefinic


-1-methyl


substrate.


-6-Methvlstvrene


Oxidation


The aromatic olefini


substrate,


s-p-methylstyrene,


was


employed


the


situ


generated


hydroperoxide


system


methyl


-2-pyrrolidinone


lectivity


the


solvent


epoxide


determine


stereose-


formation


the


elucidation


mechani


pathway


which


these


metal


catalyze


d oxidations


proceed.


It is


interesting to


the


oxidation


note


C1S


that


the results


- -methyl


styrene


given


show


Table


trend


similar


to the


analogous


metal


-catalyzed


oxidations


sted


Tabl


-4 for


trans-P-methylstyrene.


In the


oxidation


of the


cis-olefin,


catalyst,


CoCl


6H20


ass


26.27


was


found


to be selective


to epoxide


formation,


giving


an epoxide


to benzaldehyde


ratio


Another


Class


a26,


catalyst


RuCl3


while


*3H20,


the


exhibited


uncatalyzed


preference


reaction


epoxide


gave


formation,


epoxide


benzaldehyde


ratio.


other


hand,


a high


preference


benzaldehyde


formation


observed


with


metal


oxo


catalyst,


Mo(0)


(acac)


2 (Cl


ass


IVb),


26,27


metal


OXO


precursor


complex,


[Ru(dmp)


][PF6]


2 (Cl


ass


III),


26,27


giving


epoxide


quantities


to benzaldehyde


the


radical


ratio


cleavage


These


product,


observed


benzaldehyde,








Table


- -Methylstyrene


Oxidation.


Catalyst Epoxide:Benzaldehyde
Ratio

none 2.0:1.0 (120 hours)

CoC1d 6HO 4.0:1.0 (24 hours)
RuCl3 *3HO 3.0:1.0 (24 hours)
[Ru(dmp),(H O),][PF3 ] 1.0:6.0 (24 hours)

Mo(0) (acac)) 1.0:6.0 (72 hours)


Note:


Reaction
catalyst
substrate


conditions


.3x10
.3x10


moles


under


Completion


In all


02 (50
times


reactions


psig)
given
, only


at 750C.


parent


trans


eses


-epoxide


was


observed








suggest


the


possible


involvement


a radical


pathway


in the


oxidation


of olefinic


substrates


with


thi


situ


generated


hydroperoxide


system.


Another


transition


hydroperoxo


important


metal


-1-methyl


factor


determining


catalyst


situ


-pyrrolidinone


system


role


generated


involves


stereose


lectivity


the


formation


epoxides.


seen


Figure


-10,


epoxidation


a cis


-olefin


a cis


-epoxide


should


proceed


heterolytic


oxygen


atom


trans


mechanism,


while


OSS


of stereoretention


would


result


from


a free


-radical


intermediate.


cases,


including


uncatalyzed


reaction,


only


trans


-epoxide


was


detected.


This


lack


of stereoretention


appears


to suggest


involvement


a radical


pathway


formation of


epoxide


using the


situ


generated


hydroperoxide


system in


1-methyl


-pyrrolidinone.


Since a


-olefin yields


a trans


system


-epoxide


must


, the oxidation


allow


of the


opportunity


olefin by this


rotation


oxidative


about


olefinic


carbon-carbon


bond


rotation


would


occur


with


a radical


intermediate.


our


work,


metal


-catalyzed


oxidations


methyl styrene


involving


ass


catalysts


CoCI2


6H20


and


RuCl3


S3H20)


show


a preference


formation


trans


mechanism


-epoxide,


with


these


providing


metal


support


catalysts.


radical


Previous


work by


type

Kochi


IVa26










Oxygen-Atom


Transfer


ROOH


HM

Me


(cis-alkene)


Ph


Me


(cis-epoxide)


Radical


ROOH


H C


Me


Ph


(cis-alkene)


. Ph

NH


Me


(trans-epoxide)


C..
C


Hi.







hydroperoxide


this


mechanism,


cobalt


catalyst


interconverts


between


cobalt(II)


cobalt(III)


the


one-


electron


redox


processes


leading


formation


butylperoxy-radicals.


The


subsequent


formation


epoxide


results


from


homolytic


addition


t-butylperoxy-


radical


carbon-carbon


double


bond.


When


the


metal


OXO


precursor


complex


[Ru(dmp)


(H20)


] [PF6]2,


was employed in the oxidation of


methylstyrene in the in situ generated 5-hydroperoxo-l1-methyl


-pyrrolidinone


system,


large


amount


benzaldehyde


results.


addition


epoxidation


s-ol


the


efin


radical


gave


cleavage


only


product


trans


, the


-epoxide.


The


lack


stereoretention


in epoxide


formation


as well


the


prevalence


carbon-carbon


double


bond


cleavage


during


the


oxidation


olefins


Ru(VI)O2


complexes


can


accounted


homolytic


process


involving


oxygen


atom


transfer


ass


character


with


ass


component)


26,27


type


reactivity


has


been


reported


Kochi


and


CO-


workers


a general


class


neutral,


non-halogen-containing


complexes


type


O2RuL2 Y


(where


L=pyridine


Y=a


carboxylato


ligand).


Mo(O)


(acac)


(Class


been


investigate


as a


cataly


epoxidation


S-methyl styrene


with


butyl


hydroperoxide


700C


Endo


et al


In their


study,


the


stereoretention


was


maintained


result


an oxygen


IVb)26,27







-hydroperoxo-


1-methyl-


-pyrrolidinone


system,


high


selectivity


benzaldehyde


resulted.


This


metal


-catalyzed


reaction


showed


Oss


of stereoretention


formation


epoxide


seem


possessing

reporting


by yielding


suggest


radical

describe


only the


trans-epoxide.


involvement


character,


yet


epoxidations


oxygen


result


atom


earlier


varlou


would


transfer


literature

s olefins


occurring by


heterolytic oxygen atom transfer mechanisms


(Class


IVb)


26,27


result


this


discrepency


, the


effects


solvents


Mo(O)


acac)


cataly


oxidation


ese


olefinic


substrates


were


pursued.


Solvent


Effects


Another


methylstyrene


resting


using Mo(O)


aspect


(acac)


oxidation


as the catalyst


trans


involves


observation


solvent


dependency


epoxide


ben


zaldehyde


ratio


In


number


previous


studies


molybdenl

epoxide


complexes


formation


have


when


been


run


shown


to be highly


non-polar


solven


selective

ts, such


benzene


CCl4.


74,75


The


predominance


benzaldehyde


observed


pyrro1idinone


situ


stem


generated


5-hydroperoxo-


catalyzed


(acac)


1-methyl


2 led


perform


an oxidant/


solvent


variation


study


Looking


at Table


, the


use


polar


solvent


, 1-methyl


-pyrrolidinone,


with either


-hydroperoxo-1-methyl


-2-pyrrolidinone


(in situ or







Table


Solvent


Effects


Methylstyrene


in the


with


Mo(O)


Oxidation


(acac)


of trans-
Catalyst.


Solvent __Oxidant E/B

NMP NMP-5-OOH 1:3.4
(in situ)
NMP NMP-5-OOH 1:2
(pre-generated)
NMP t-BuOOH 1:2
DMA t-BuOOH 1:3
Benzene t-BuOOH 4:1

1,4-dioxane t-BuOOH 7:1
CC14 t-BuOOH 10:1


Note:


Reaction
substrate
catalyst
solvent


conditions


.3x10
.3x10


mol


moles


oxidant


run
(50
E/B


750C


psig).
values


a.3x10
under


moles


, if


, except


48 hours,


except


added)
NMP-5-OOH


NMP-5-OOH


situ)


situ)








analogous preference


to benzaldehyde


formation was observed in


polar


solvent,


dimethylacetamide,


using


t-butyl


hydro-


peroxide.


Using Mo(O)


(acac


and t-butyl


hydroperoxide


non-


polar


solvents,


such


as benzene


, 1,4-dioxane,


or CCl4,


gave


high


activity


the


formation


trans


-1-phenylpropylene


oxide.


comparison


study


definitely


shows


a dependency


epoxide


benzaldehyde


ratio


polarity


solvent.


Even


though


a much


ess


pronounced


solvent


effect


on the


xide


benzaldehyde


ratio


was


observed


Mo(O)


acac


-catalyzed


oxidation


CIS


-P-methylstyrene,


observe


stereoretention


lack


formation


epoxide


shows


solvent


dependency


with


oxidant


t-butyl


hydroperoxide


(Table


3-7).


polar


solvents


dimethylacetamide and


1-methyl


-2-pyrrolidinone,


the oxidation


C1S


-p-methylstyrene


resulted


formation


trans-I


phenylpropylene


oxide.


Thi


observed


lack


stereoretention


formation


corresponding


epoxide


predominance


ben


zaldehyde


formation


seem


suggest


involvement


of a radical


type


mechanism


ass


IVa)


26,27


interesting


note


that


employment


non-polar


solvents


such


as benzene,


CCI4,


or 1


,4-dioxane,


eads


to the


formation


CIS


-1-phenylpropylene


oxide


from


corre


spending


cis


-olefin


(Table


3-7).


The


retention


configuration


seen


these


non-polar


solvents


appear







Tabl


Solvent


ects


Oxidation


Methyl


styrene


with


Mo(O)


(acac)


Catalyst


Solvent Oxidant E/B Epoxide
_(cis/trans)
NMP NMP-5-OOH 1:6 (0/14%)
(in situ)
NMP NMP-5-OOH 1:6 (0/6%)
(pre-gen)_
NMP t-BuOOH 1:7 (0/5%)
DMA t-BuOOH 1:8 (0/5%)
Benzene t-BuOOH 1:5 (5%/0)
1,4-dioxane t-BuOOH 1:4 (8%/0)
CCl4 t-BuOOH 1:2 (12%/0)


Note


: Reaction


conditions


sub


state


catalyst
solvent
oxidant


run
(50


.3x10
.3x10


moles


.3x10


75C under


, except


E added)
NMP-5-OOH


situ)


psig).


Reactions


run


in 48 hours,


except


NMP-5-OOH


situ)







exact


nature


mechanistic


pathway


which


these


Mo(O)


(acac


-catalyze


oxidations


occurs


was


further


investigate


d using the


halocarbons,


CCl4


and


CBr4


to determine


these


reactions


occur


via


a homolytic


(Class


IVa)


26,27


a heterolytic


ass


26,27


process.


Halocarbon


Additions


A seri


experiments


were


designed


to determine


mec


hanistic


pathway


which


the


molybdenum-catalyzed


oxidation


trans-


n-methylstyrene


occurs


polar


solvent


, 1-methyl


-2-pyrrolidinone


Looking


at Tabi


, the


addition


a halocarbon


(CC14


or CBr4)


(acac


catalyzed


olefin


oxidation


using


either


pre


-generated


hydroperoxo-


1-methyl


-2-pyrrolidinone or t-butyl hydroperoxide


as the oxidant


showed


only


formation


of benzaldehyde


trans-


-phenylpropylene


oxide.


No halogenated


products


were


detect


thereby


, ruling


out


radical


cess


This


absence


of halogenated


products


suggests


involvement


heterolytic


oxygen


atom transfer mechanism involving


a lack


stereoretention


polar


solvents


, such


1-methyl


-2-


pyrrolidinone.


above


results


shows


or Cl


ass


behavior


metal


catalyst,


Mo(O)


(acac)


26,27


Effects


Add


ed Pvridine







Table


trans- -Methyl styrene
Halocarbons.


Oxidation


the


Presence


Halocarbon Oxidant Products (%)

CCl4 NMP-5-OOH Benzaldehyde (24)
(pre-gen) Epoxide (12)
CCl4 t-BuOOH Benzaldehyde (24)
Epoxide (10)
CBr4 NMP-5-OOH Benzaldehyde (24)
(pre-gen) Epoxide (12)
CBr4 t-BuOOH Benzaldehyde (28)
Epoxide (12)


Note:


Reaction


conditions:


state


catalyst
halocarbon


oxidant


.3x10-
.3x10-5


.3x10
.3x10


mol


moles
moles
moles


run


under


750C


for


48 hours


No other


products


hydrocarbons,
and 1H NMR.


were


, including


detected


halogenated
v GC or 13C







investigated using 5-hydroperoxo-l1-methyl-2-pyrrolidinone


situ


-generated)


t-butyl


hydroperoxide


solvents


1-methyl


-2-pyrrolidinone


CCl4


under


reaction


conditions


given


Tabl


3-9.


The


comparison


reactions


with


without


show


when


a marked


a catalytic


added


effect


amount


aromatic


on the


amine


epoxide


of pyridine


presented


to benzaldehyde


added


to the


in Table


ratio


reaction.


In the


cases


employing added pyridine,


trans-i


-phenylpropylene


oxide


predominant


product.


It is interesting to


solvent


note


oxidation


that


use


C1S-


trans


of pyridine


-B-methyl


as the


styrene


using


Mo(O)


(acac


t-butyl


hydroperoxide


gave


epoxide


benzald


ehyde


ratios


, respectively


These


results


suggests


a dependence


on the


polarity


solvent.


ects


solvent


polarity


molybdenum-


catalyzed


oxidation


of cis-


3-methylstyrene


show


a notice


able


effect


on the


epoxide


to benzaldehyde


ratio


with


addition


a catalytic


amount


pyridine


(Tabl


3-10).


The


use


the


polar


solvents


like


1-methyl


-pyrrolidinone


lead


lack of stereoretention,


while


the


use


of non-polar


solvents


like


have


CC14


een


show


a retention


previously


of configuration


reported


Endo


Similar


et al. for


results


reaction


C1s-


p-methylstyrene


with


t-butyl


hydrop


eroxide


and


Mo(O)


(acac)


CCl4


at elevate


temp


eratures.


Attempts


were


made


determine


played







Tabl


Effect


Added


Pyridine


Mo(O)


(acac)


Catalyze


d Oxidation


trans-


P-Methylstyrene


Solvent Oxidant Pyridine E/B

NMP NMP-5-OOH No 1.0:3.4
(in situ)
NMP NMP-5-OOH Yes 1.6:1.0
(_in situ)
NMP NMP-5-OOH No 1.0:2.0
(pre-gen)
NMP NMP-5-OOH Yes 1.2:1.0
( pre-gen)
NMP t-BuOOH No 1.0:2.0

NMP t-BuOOH Yes 2.0:1.0

CCl4 t-BuOOH No 10.0:1.0

CC14 t-BuOOH Yes 24.0:1.0


: Reaction
substrate


catalyst
pyridine
solvent
oxidant


conditions


.3x10
.3x10
.3x10


.3x10


moles


added


moles


, if


added)


run


under


at 750C,


exc


NMP


-5-OOH


situ)


psig)


Reactions


run


48 hours,


except


NMP-5-OOH


situ).


Note