Chemistry of wood

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Chemistry of wood
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Ritter, George J
Fleck, L. C
Forest Products Laboratory (U.S.)
University of Wisconsin
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U.S. Dept. of Agriculture, Forest Service, Forest Products Laboratory ( Madison, Wis )
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CH[MISTyY ef WOOD

VI. The Results of Analysis of Ieartuuood and Sapuood

of Some American Woods

October 1923






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UNITED STATES DEPARTMENT OF AGRICULTURE
FOREST SERVICE
FOREST PRODUCTS LABORATORY
Madison, Wisconsin
In Cooperation with the University of Wisconsin










Ci.'ISTRY OF? 700CD L


VI -- The Results of Analysis of Heartwood
and Sapwviood of Some American W7oods


By G. J. RITIr., Chemist
and
L. C. FLE,71', Associate Chemist



This report contains the results obtained in the analysis& of heart-
wood and sapwood of ten American woods. The work was undertaken to deter-
mine whether there is any uniform difference in chemical composition be-
tween sapwood and heartwood in either softwoods or hardwoods.

Th- methods of analysis used are the same as given in the preceding
papers in this series.2 All determinations were :,al-e in duplicate and
the average is given in Table 1.


Discussion of Results


Ash content.--There is no general agreement in the relative ash con-
tent of sapwood and heartwood in the species examined.

E.tractive content.--In general, the extracts of ether, cold water,
hot water, and 1 percent sodium hydroxide are lower in the sapwood than in
the heartwood of the softwoods. In the hardwoods the extractives are lower
in the sapwood than in the heartwood of yellow birch, white oak, and yellow;
poplar, but the reverse is true of white ash and pignut hickory. Thus,
from the standpoint of extractive content in sapwood and heartwood, the
hardwoods analyzed are divided into two classes -- one class following the
order of the softwood, the other following the reverse course.

Acetic acid.--The acetic acid obtained by hydrolysis is higher in
the sapwood thar, in the heartwood of both classes of woods.

Methoxyl content.--T1', relative percentages of methoxyl in the sar-
wood and heartwood of the species analyzed cannot be arranged in any general
order.

1
-Presented before the Division of Cellulose Chemistry at the 65th meeting of
the American Chemical Society, New Haven, Conn., Apr. 2-7, 1923. Fub-
lished in Jour. Indus. & Eng. Chem., Oct. 1925. 15, 1055.
2
-Jour. Indus. & Eng. Chem., Nov. 1922. 14, 1050.

916






Pentosan content.--There is a tendency toward higher yields of
pentosans in the sapwood than in the heartwood of the species examined.
The difference in yields, however, is slight.

Hethyl pentosan content.--The methyl pentosan content in sapwood
and heartwood of the same class is quite uniform.

Cellulose content.--For the relative cellulose content of sapwood
and heartwood, the species analyzed, with the exception of yellow poplar,
are grouped in a manner similar to that for extractives. All the softwoods
e-.mini:.!d have higher cellulose yields in the sapwood than in the heartwood.
This tends to counterbalance the low extractives in the sapwood. One hard-
wood group, yellow birch and white oak with high extractives" in the heart-
wood, has high cellulose content in the sapwood. The other group of hard-
woods, white ash and pignut hickory with high extractives in the sapwood,
has high cellulose content in the heartwood. The results obtained from
the two yellow poplar samples, which are an exception to the foregoing
scheme of grouping, can be explained by referring to the condition of the
samples.

Both yellow poplar samples showed slight signs of decay in the sap-
wood. This condition would tend to increase extractives in the sapwood.
The results show slightly higher extractives in the heartwood than in the
sapwood, which indicates that on the basis of extractives yellow poplar is
strictly a member of the first group of hardwoods. If it belongs to the
first group, the cellulose content should be higher in the sapwood than in
the heartwood, which is not the case. This can also be explained on the
basis of the decayed condition which decreases the cellulose content in
the sapwood, the reverse of what would be expected in sound yellow poplar.

Lignin content.--In softwoods, with the exception of white cedar,
the lignin content is higher in the sapwood than in the heartwood. In the
hardwoods all species except yellow poplar have a higher linin content in
the heartwood than in the sapwood.

A study of the ratio between methoxyl and li7nin is shown in Table 2.
A stni.1- of the results, reveals the fact that the mebhoxyl-lignin ratio is
a'-].rioximately 50 percent higher in hardwoods than in softwopds. This ratio
.2
averages less than 13 percent in bald cypress. In Paper V of this series-
it was shown that the methoxyl content of isolated redwood and live oak
lignins was approximately 17.5 percent. Bald cypress lignin could not meet
these specifications and, consequently, it must differ in chemical composi-
tion from redwood and live oak lignins.

Pentosan content of cellulose.--The pentosan content has a slight
tendency to run higher in the ca.,vood cellulose than in the heartwood
cellulose, similar to the results obtained in the original wood.

Methyl pento-rir. content of cellulose.--In. general, the methyl pento-
san content is slightly higher in the heartwood cellulose thpn in the sap-
wood cellulose. A similar relation was found in the heartwood and sapwood
of the original samples.


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-2-






Al ha-, beta-, and gamma-cellulose content of cellulose.--The per-
centages of the three kinds of cellulose in sapwood and heartwood cellulose
cannot be grouped in any definite arrangement.


Conclusions


Fromn a study of the data given in this report the following conclu-
sions may be drawn:

1. In softwoods the water, ether, and alkali extracts are ni her
in the heartwood than in the sapwood, and as a result the cellulose and
lignin are correspondingly lower in the heartwood (except lignin in white
cedar).

2. On the basis of extractives hardwoods are divided into two
groups: (a) those with hiTh extractivos in the heartwood, and (b) those
with high extractive in the sapwood. I;"- former have high cellulose con-
tent in the sapwood; the latter in the heartwood.

3. Acetic acid by hydrolysis is hig-her in the sapnwood than in the
heartwood of both softwoods and hardwoods.


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TABLE I-ANALYSES OF SAPWOOD AND HEARTWOOD OF SOME AMERICAN WOODS
(Results in percentage of oven-dry (105 C.) samples)


SPECIES
White ash:
No. 2 sapwood
No. 2 heartwood
No. 3 sapwood
No. 3 heartwood
Yellow poplar:
No. 1 sapwoodl
No. 1 heartwood
No. 2 h'.artwood

Pirr-'t hickory:

N. 2 herw)od
Yellow birch
N-), 1 sipwi>0(
NM. I hipa it woo

No2 saip wow1
No. 2 heartwood
White oak:
No. 1 sapwood
No. 1 heartwood
No. 2 sapwood
No. 2 heartwood
Bald cypress:
No. I sapwood
No. 1 heartwood
No. 2 sapwood
No. 2 heartwood
White pine:
No. 1 sapwood
No. 1 heartwood
Yellow cedar:
No. 1 sapwood
No. I heart wood
White cedar.
No 2 sapwood
No. 2 heartwood
No. i sapwood
N o. 3 heartwood
Incense cedar:
No. 1 sapwood
No. 1 heartwood


'--SOLUBILITY IN-----
Mois- Cold Hot 1% Acetic
Sample ture Ash Water Water Ether NaOH Acid Methoxyl


179 5.34 0.61 5.81 6.41
180 5.45 0.30 2.24 3.40
11 4 91 0.57 5.25 7.02
182 7.42 0.32 2 12 4.46


187 4
1SS 3,
1 s9, 3
189! 3
190 3.


4S 1.29
39 1.50
36 1 .45
33 1.45


1 98
2. OS
2.51
2.89


1,17 21.77
0.43 19.59
0.88 21.93
0.46 18.97

0.27 16.74
0.43 17.70
0.13 16 91
0.5S 17.57


3,23
2.31
3.70
2.66


191 3 54 0 .0 491 6, 45 0.29 19.11 3 .
1'2 3 90 0.4 2 ,07 2.95 0,36 15.10 3.(-:


207 4.92 0
208 t.7f( 0
213 2 0.
214 4.36, 0.

209 7.71 0.
210 7.70 0.
211 7.09 0,
212 6.99 0.

183 4.72 0
184 5.3(30 0.
185 6.72 0.
186 4.72 0.


1. (015 1.9I
4 10 5. 69
1.74 2.10
2.76 3. 9

2.55 4,11
7.33 10.15
4 27 5.73
4.76 6.60


.48 0.72
30 2.79
86 1,76
95 3.27


1.42
2.99
2.30
3.49


0 41
0. 8S
0.99

0.46
0.71
0.65
0.62

0.23
4.87
2.80
7 93


193 3.90 0,213 3.55 5.15 5 46
194 2,92 0.42 5.97 7.68 3.62


16 77
20.51
19.78
21. 11

21.11
25.81
21.69
22.67

8 55
10.59
10.63
13 56


4.70
5.36
5.66
5.20

5.81
5.86
5.89
6.03


Methyl
Pento- Pento- Cellu-
san san lose

19.85 2.40 50.38
19.90 2.25 53.56
20 16 2. 63 49 72
19.87 2.46 53.40


IN CELLULOSE
Methyl
Pento- P'ento-
Lignin san sari Alpha Beta Gamma


26.95
27.39
27 39
28.3S

23. OS
22.19
23. 86
23. 69


18.83
16.75
19 67
17.34


5.5> 15 1 S 1 11 56 0,S 21.87 16 .90
5.79 ls.iI4 1 .02 5,.S 1 22.65 16.20


2 I.3 5 ,,66
I 71 5 ,46
3.75 5.47
2. S3 5.27


3. 44t
2.59
2.47
2.97

0.77
0.48
0.65
0 29


17.16 1,68
19.15 1.43


195 3.97 0.28 2.13 3.41 1.00 11.72 2.05
196 4.00 0.1 2.8 4,12 1.32 12.77 1,53


1 7 5,59 O*.>;_ 2 18
19S fi.39 0 21 1 94
191 6.02 0.48 3(02
200 6.48 0.27 2.80


2 82
3.22
3.96
4.01


11 02
11 41
1.44 12.71
1.87 14.14


1 .17
0.84
1 .11
0.74


205 6.46 0.47 1.92 2.97 0.67 11.16 1.33
206 7.27 0.30 4.74 7.08 4.78 19.99 0.68


5.95
6. 18s
6.02
5.64

4.35
3.94
4.99
4.07


0 90 49.53
1 .57 48. 6(S
0 94 53. 18
0.91 52.12

4 38 54 .86
4 49 53. 10
3,34 50.94
3.36 49.18


24 .69
24., _;
2,t, 62
27. 76
28.13

32.34
32.74
31 .14
31.30

35.01
33.06
35.31
32 27


4.16 9.31 2.14 54.25 26.51 6.81
4.60 8 .56 1.00 50.23 26.1.1 7.12

4.40 8 47 1,75 58.12 29 03 7.60
4 S1 8.69 1.85 56.08 28.73 7.78,


5.07
5.00
5.23
5.09


0 94 55.77
1 72 55.19
1 ,16 55. 02
1.56 54,42


29 85
31 39
32.11
32.42


10,35
S 52
,.95
7.97


5.95 12.08 0.45 49.09 34.73 10.14
6.21 12.04 0.56 44.53 33.67 11.68


11.66
10.84
16. 50
24.33


1.30 51 .55 21.92 26. 53
1.3 59.44 23.74 1" I .82


61 17
6 (I i.
52.40
53.56

68.07
67.33
53.81
52.96

76.09
76.83
58.18
57.38


15.27
11.54
22.63
20.41
5.93
3.94
26.91
24.75


16 .66
20.83
23 56
26.63

17.98
19.23
14.91
17.8s7


209 54,56 17.47 27 97
2,02 57.29 22.42 19.29

2 44 54.61 26.59 18S.0
2 73 . 20.17


73,78
61 .47
1;1. 17
6(9.17
55.22


0 099
22,23
14.04
24.74


25 23
16 130
16.79
20.04


1.24 50.69 12.98 36.33
1.31 66.62 11.05 22.33


7zf r I-















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in 2013









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Table 2.--Ratio of mncthoxvl to -li:.ir. on mv.",.-ir" (lr- ". '.. i --.t -t f :.-
wood.


Species


: : Lignin : CHO : C0O x 100
S : : Lignin
: -o - - - :- - - - - - - - - - - -
o .-
:Sapwood :Heartwood: Sapwood._ear t7o od:Sapwood: Heatrtwood


Wi a.(: 2 : 26.95
white ash ........ (: 3 : 27.39


Yellow poplar.... (: 23.0
... (: 2 23-96

Black hickory..... :1 21.87

Red alder........( 1 25.97
( 2 : 26.64

Bald cypress.....( 1 : 501
: 2 35.31
Eatern white pine: 1 26.52

Yellow cedar...... 1 : 29.03

Southern white (: 2 : 29.85
cedar ........... ( 3 32.14

Incense cedar.....: 1 34.73


27.39
28.38

22.19
23.69

22.85

25. 6
25.94
33.06
32.27

26.14

28.73

31.39
32.42

33.67


4.70
5.6b

5.81
5.89

5.5t,

2.29
5.26
4.35
4.99

4.16

4.40

5.07
5.23

5.95


5.36
5.20

5.s6
6.03

5.79

5.33
5.26

3.94
4.07

4.60o

4.S1

5.00
5.09

6.21


17.4
20.0

25.2
24.7

25.4

20.4
19. :

12.4
14.0

15.7

15.1

17.1
16.2

17.1


19.5
1i.3

26.4
25.4


20.1
20.3

11.9
12.6

17.6

16.7

15.9
15.7

1. 4




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