U. S. Department of Agriculture, Forest Service

a 4.3 /// /

FOREST PRODUCTS LABORATOR YIn cooperation with the University of Wisconsi n

MADISON, WISCONSI N

ci

EFFECT OF PARTIAL HYDROLYSIS ON THE

ALKALI SOLUBILITY OF WOO D

By

L . F . Hawley, Principal Chemis tand

W . G. Campbell, Commonwealth Fund Fello w

Published inIndustrial & Engineering Chemistry

June, 1927

test was Sitka spruce 'tts composition and it stment were first determi :

tained with hydrolyzed~e .

god is given i ncoy+•osition of theer cent caustic soda

erature .

Table I .--Analysis of o',iz'tnal wood

(Results on basis of Weight of original , dry wood )

per,c4nt

Water soluble . ,i 4i8 4 . 1Ether soluble 114 .

. 7Alkali soluble 12 . 0

Cellulose 62 . 5Lignin 29 . 3Methoxyl 4 . 8Total pentosans 9 . 9Pentosans not in cellulose 6 . 2

Table II .--Analysis of wood residue aftertreatmentwith 1 percent NaOH for 1 hour a t100° C .

(Results on basis of weight of original dry wood )

Per cent

Loss on alkali treatment 13 . 7

Cellulose 59 . 2Lignin 27 . 7Methoxyl 4 . 3Total pentosans 7 . 4Pentosans not in cellulose 3 .9

tables tnalysi so

det ese an

pentosansical dat

th eForme ter

Experimental

In studying the alkali solubility of the hydrolyze dwood, the general plan was to subject samples to differentdegrees of hydrolysis, analyze them, treat them with causti csoda, and analyze the residue . It has frequently been found ,however, that on account of the difficulty of obtaining thesame , conditions throughout the mass, a chemical reactio nwhich takes place with small quantities of wood, such asthe sample for analysis, can not be reproduced exactly whe nlarger quantities are used . For this reason it was notattempted to hydrolyze enough wood so that the residue woul d

ent for an analysis, alkali treatment, and th ealysis of the resid . Instead, two samples wer eunder as nearl a_sossible the same conditions ,

lysis and thermORe analyse seight on hydrol-tables shows

is obtained b y

ose, 1~, and .. pent :

cellulerminedfrom tIa ~ JOiilyses of the origi rate wood (Tae, .

a 1 of then s

'e r hydrolysis,, to whin'h is also owed th wate rsolu

in the original wood, on the assump+% ion that this i sall 16lbved by hydrolysise It is immediately noticeable'hat the calculated loss is always considerably higher than

. *hat actually determined. This difference can be explained

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yz . wood

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uents'

the ' ~:1 03A.the Wrtlti

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•le ': II :cent of tio'implylose, lignin, o peslioul4 ada u,pwood totals wte

140 TAP vrWt a

.1- the partly hyzed samples to considerably less than i . ■ per cent, theis good reason to 'assume the presende of Some material i ' . ~ .the . laistwhich was not present in the or j,gi r

andsdoes not show in any of the determination .

eve substance, there is evidence thatit is la, 1ge.ly gOit;MO

the alkali treatment, in t,?aat . the sums of .the - htft •constituents de-t,erlmL'ned on 'a aa. al•i=,tr-e.stdiv~ - ~d

!

all come very c'1oar to 100- Pg-r Bent of the. aeto _iveiglt o fresidue, the extreme variati me being betwe'en 04.0 ad 100 . 5per cent .

-

r

',!,he figures 'in Table III, aside from the di

ence sbetween determined and calculated. losses, give little infor-mation that has ,wt been available previously . Thg., s

t _effect of hydrolysis on th-e amount of lin and , ~and the continuous but not complete rye ,al of tii , p1G.f>> an shave been shown in pa ge-vious wok . This . set ef-

a

.: - sfurnished mainly for compar isom with $Ole IV in $4*r t oshow the qus.ntit g41we effect of the a1 1i treatmem 4Table IV gives '*e loss in weight of- t duplicate saris le son hydrolyai s, heir laD+g-s in weight ''x- a:1-ali treatment , andthen the analysis of th'e residues afitOT t g Mcal i treatment .The alkali-treatment ms identical wit .4 .ttl t. , ed ii banalytical de'te- izii a,' .Nmn of the alkali-MI-kW a ~? s ? ., Hof theoriginal wood --

4 ; 4.weatment with I per

saeahydroxide at boili water temperature for 1 Sour .

-

Despite the small differenees in the loss on .{hydrolysis between the second -column_ of T :'tLe IV aid the secondcolumn of Table III, some eonclua,i:ons may say be

vnfrom a comparison of the analytical d6ke rni,m,a .ons a t.stand . It will be noti'ced -that in every cape 'td

o -weight due to the alkali treatment is r a OP gf

i neach of the constituen - -,=

mined, axed .:toms is als* ethe orig . ., A. -wmod=PI" -"W

ev :-C•

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t

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err ;L.' ,

if• j if

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each constituent is less in Table IV than in the correspond-ing part of Table XII . There is always a decrease in theconstituents shown in Table IV as the severity of the hydrol-ysis increases, with the exception that the lignin during th efirst three hydrolyses remains practically constant .

The largest variations between the two tables,how-ever, are in the cellulose . Comparing the sixth column o fTable IV with the fourth of Table III, it is seen that th ealkali solubility of the cellulose becomes very high afte rthe last four hydrolyses, although there is no orderly in -crease in the alkali solubility with increasing severity o fhydrolysis . The lignin, on the other hand, is rendered onl yslightly solid Z by the hydrolysis, and even after the mos tdrastic'treatment, with 15 per cent hydrochloric acid, onl y3 per cent out of the 26 per cent present after hydrolysi sis removed by the subsequent alkali treatment .

The methoxyl is removed by the alkali treatment i nincreasing amounts as the hydrolysis progresses . Althoughafter the first three hydrolyses the amount of methoxyl de -creases while the lignin determination remains stationary ,this fact should not be considered an indication that themethoxyl was not a part of the original lignin, since thechemical method by which the lignin was isolated has bee nshown to Fesult in the loss of a considerable portion of themethox 1 - _and_ it is in this relatively unstable portion that~y e p

hoxyl loss on alkali treatment may be suppose df occu

' . . }i . ".1 '

„'I : • - O

-a

.1 f

whit

sans in the h

_ ., _

ecreaby the alkali treatment, although in the origin .sans to the amount of 7 .4 per cent were insoluble-(Table II) . This high alkali solubility of the pthe partly hydrolyzed wood was progressive as hydbecame ire severe .

out great in-se, lignin ,

le -effect on the5 per cent pento-

e ntood pento-

al is i n

*I''

r-

gr = -= AL,

ein;

x'

is no

abl '

ver•

A , lubilit

onst i'b¢ OttOMAIW94 tom'= alk 'Itolubility, Table I Ito ttrQ

cpn

. 0 ' Z.otter one' eofis'tx

t with

eel

nex

soluble) . In partly hydrolyzed wood the most soluble con-stituent at all stages of hydrolysis is the cellulose, th eloss in cellulose reaching 12 .8 per cent in two cases . Theli t in, on the contrary, is very little affected by th e

olysis, the lignin of the original wood being almost a se in alkali as the lignin in the hydrolyzed residues .

.

•

Qf . Irsdi►t

- r-~ : . -~x44:

r rp- ;7F= ~I '-rY ~

,

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n w

f v

snc e ,w .

s-ete"rmined as

e analytical re- 'ial might not have '

ic .. } ata on th.'1 w. od

Aed .

ids "

S ±fordedrmi

on .

I

er ex` :

pro;mina ,

hat

icellulose

r

los eas e

sti y

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-Ir ' dct ois o

ans, .

I

p,

or qv

:I Iff ~~ pay . -_ lfr Pillrl~_

acto condit• c_ ' At pape r

en . ac =d, shows an :•; although it is quit ecan no manufacture ligni

d pulp .- Another instanc eht be made from comparativ end in the pulping of woo d

ood

avail !•l ee partly decaye dthQ

s ofte,

••

}' . I

♦ 1 '

4

Hawley and Wise, op . cit ., p . 259 .

%Ming and Statdl, '4r •

Jl. .• ,

-8-

.

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'

•'t,o

Summa Mary

,

. ,

Although- f ft in-nt.

Wf,emt 4** on wood, t.

so far . as removal of cm,st4tuents is

apparentl ythe same as a hydei*ysi6, yet these two ptoeeb6 .a differ intheir effecIt on the alkali solubility of the resi0e .

2. The total alkali solubility of paVtIV decayedwood is much greater than that of wood whioh has been hydrol-yzed to thel same extent (as shown by equal lmssA41 weight) .

3. The solubility of the lrn :n: alkali is veryslightly increased by partial hydVolyas-, wa$sZeaq; decay mayrender the lignin 50 per cent soluble .

4. The solubility of the .reRid4al cellw1o6e i, =con-siderably increased by partial hydrOlyeia l but prObably rootto the same extent as it is by decay .

5. There is .in partially hydrolyzed wood ,s ), terialv-probably a degraaation product of the cellulose, whiff

notdetermined as cellaose, -Iignin, or pentosans . Thi sis soluble in 1 per cent sodium hydroxide .