June, 1 9 1 j
TI€E J O
R S A L 0 F I S D CST RI d L A i YD E S G I .I7E E RI S G C H E M I S TR Y
RESCLTS
The results of t h e analysis of seven American woods are summarized in t h e accompanying table. A discussion of t h e results, as well as a discussion of methods of analysis. is given in t h e following paper. FOREST SERVICE FOREST PRODUCTS LABORATORY MADISON,WISCONSIN
THE CHEMISTRY OF WOOD 11-DISCUSSION OF METHODS AND RESULTS B y A. W. SCHORCER Received March 10, 1917
I n order t o obtain a better understanding of t h e reasons for adopting t h e methods given in t h e previous paper, i t is essential t o consider both methods a n d results in detail. DRYIxG-The methods of drying wood a n d other forms of cellulose have received considerable a t t e n tion. Ost a n d Westhoff' believe t h a t a temperature of I 2 0 t o I 2 j O C . is necessary t o drive out all hygroscopic moisture, b u t it is very doubtful if water retained near this temperature should be considered as merely hygroscopic. Winterstein* found t h a t cellulose t h a t h a d been heated a t I o j o for 48 hours gave increased amounts of glucose when boiled with dilute sulfuric acid.3 Suringar a n d Tollens4 obtained 2 t o 3 per cent less cellulose from j u t e t h a t h a d been heated a t 9 j o for 31/? hrs. t h a n from air-dry material. Renker,j however, reached different conclusions. Unbleached sulfite cellulose t h a t h a d been heated a t I o j t o 107' for 48 hrs. showed no difference i n t h e yield of cellulose b y t h e chlorine method of Cross a n d Bevan as compared with t h e air-dry material. Furthermore, unbleached sulfite cellulose t h a t h a d been heated several days a t Ioj t o 107' gave no greater yields of glucose t h a n t h e air-dry cellulose, when hydrolyzed with sulfuric acid. T h e s t a t e m e n t of Hofmanne t h a t unbleached sulfite cellulose lost 8.17 j per cent b y weight i n a vacuum over phosphorus pentoxide a n d 9.36 per cent b y heating a t 100' was not confirmed. Methods of drying should be considered from t h e standpoint of convenience as well as accuracy. Renker7 found t h a t 3 t o 4 weeks are required t o dehydrate cellulose standing over phosphorus pentoxide, b u t b y employing a vacuum t h e time could be reduced t o about 2 0 hrs. for air-dry material; if saturated with water a longer time is required. He agrees with Schwalbe8 t h a t all hygroscopic moisture can be removed by heating a t IO; t o 107' C., a n d in fact this method was employed as t h e s t a n d a r d of absolute dryness. Konig a n d H u h n g also accept this method of drying. ,%ccordingl? heating t o constant weight a t C h e m - Z f g . , 33 ( I Y O Y ) , 197. Z . physiol. C h e m . , 17 (1893). 393 3 Schwalbe ("Chemie der Cellulose," p . 26) is of t h e opinion t h a t t h e results observed by Winterstein were due t o the presence of considerable amounts of oxycellulose in t h e material examined. 4 Z . angew. C h e m . . 9 (18961, 749. 5 "Bestimmungsmethoden der Cellulose," 1910, p. 16. 6 P a p i e r - Z f g . , 1907, p . 2558. 7 "Bestimmungsmethoden der Cellulose," p , 18. 8 Ber., 40 (19071, 1347. "Bestimmung der Zellulose in Holzarten und Gespinstfasern," p. 13. 1
2
j61
~ o t oj 1 0 7 ' may be accepted as reliable except in case of special cellulose derivatives, or when it is desired t o subject t h e cellulose t o a critical subsequent examination as in t h e work of Renker. Some confirmatory experiments were made in t h e drying of sawdust t h a t showed t h a t t h e moisture cont e n t could be determined in t h e oven with sufficient accuracy. Samples of sugar maple sawdust were dried in a n electric 01-en a t I O j t o 1 0 7 O a n d in a vacuum desiccator containing fresh concentrated sulfuric acid for three consecutive, periods of j . 6 a n d 8 l / ? hrs., respectively. The results are given in Table I. TABLE I-DRYIhC
SUGAR ?if APLE S A W D U S T B Y VARIOUS METHODS T e m p Heating Sample Loss I N WEIGHT C. Hours Grams G r a m Per cent Sample APPARATUS 4.0963 0.2811 6 . 8 6 A Electric Oven 105-107 7 0.2128 6 . 6 0 3.2229 Bi Vacuum: Pressure 60 mm. 5 5 7 3.2229 0.2181 6 . 7 7 B2 Vacuum: Pressure 30 mm. 57 6 0.2178 6 . 7 6 3.2229 B3 Vacuum:Pressure30mm. 60 81,'~
The sample heated iri vucuo reached constant weight after 13 hrs. heating; a n d after 2 1 2~ hrs., t h e total loss i n weight is still 0.10per cent less t h a n t h a t produced b y heating for only j hrs. i n t h e electric oven. T h a t drying in t h e oven was more efficient is shown b y t h e following experiment: A sample of spruce sawdust t h a t h a d been digested with dilute alkali a n d t h e n thoroughly washed with hot water was placed in t h e oven for j hrs. The sample t h e n weighed 1.663j g . After remaining in a Hempel vacuum desiccator containing concentrated sulfuric acid for 7 hrs. a t 5 j o C. a n d 6 0 mm. pressure t h e sawdust actually increased i n weight 0.0070 g. After a n additional heating for 6 hrs. a t j 7 O a n d 30 mm. pressure t h e sample weighed 1.6670 g., showing t h a t half of t h e absorbed moisture was still retained. This is in harmony with previous observations t h a t t h e various forms of cellulose have a greater affinity for moisture t h a n t h e reagents ordinarily used for drying.' T h e effect of prolonged heating on t h e weight of wood in a n air oven a t IO j t o 1 0j O was determined i n t h e case of basswood a n d longleaf pine sawdust sufficiently fine t o pass through a 40-mesh sieve. T h e weighing bottles used were of about 40 grams weight. TABLE 11-EFFECT O F PROLONGED HEATINGO N WEIGHT OF HEATED HEATINOHOURS Periods Total 0 0 0 3 4 7
S.4MPLE
4 10 8
15 48 69 98 191 261
11
21 29 44 92 161
259 450 ill
TO 40-MESH BASSWOOD NO. 1 Decrease Weight Per cent Grams .... 3.3487 5.91 3.1517 3.1524 5.89 5.91 3.1517 5.95 3.1504 6.03 3,1476 3,1501 5.96 6.00 3 . I486 6.23 3.1410 3.1491 5.99 6.38 3.1361 6.43 3.1342
WOOD
GROUND
LONGLEAF P I N E S O . 20 Decrease Weight Grams Per cent .... 2.9172 2.7731 4.94 2,7732 4.95 4.94 2.7731 5.05 2.2699 5.13 2.1676 4.98 2,7686 4.23 2 7646 5.65 2.7523 5.56 2.7551 6.04 2.7405, 2.7321 6.35
T h e results given in Table I1 indicate t h a t t h e weights of both woods remain practically constant during 18 hrs. heating. The total loss for t h e longleaf pine during t h e last 7 0 8 hrs. heating is 1.41 per cent. while t h a t for t h e basswood during t h e same period was only o . j z per cent. Since t h e longleaf pine contained 9.23 per cent of resin t h e increased loss in this case is t o be expected. VOLATILE OIL-Determination of t h e volatile oil 1
Jentgen, Z . angew. C h e m , 33 (1910), 1544
T H E J O U R N A L OF I N D U S T R I A L A Y D E S G I S E E R I N G C H E M I S T R Y
562
b y subtracting from t h e total loss in weight b y drying in t h e oven at Ioj t o 107’ t h e a m o u n t of moisture found b y t h e xylol method, gives lower results t h a n if t h e volatile oil is expelled with steam. T h e “pine oil” in longleaf pine is difficult t o expel completely b y heating i n t h e oven. Table 111 presents comparison of t h e amount of volatile oil obtained from longleaf pine b y t h e t w o methods. Longleaf Pine Sample No. 11
13 12 20
TABLE I11 P E R CENT VOLATILE OIL BY METHODOF Heating in Oven Steaming 1.20 1.60 0.98 1.12 0.65 0.Si 1.47 1.60
W A X E S . FATS, REsns-The portion of t h e wood soluble i n ether, consisting of waxes, fats, resins, etc., was determined i n t w o ways: z’iz., loss i n Yeight of t h e wood extracted. a n d direct weight of t h e extract after evaporation of t h e solvent. Only t h e latter method was found t o give reliable results. ALKALI-SOLUBLE-The action of alkali on wood is not specific. Among t h e products rendered soluble are lignin, resin acids, pentosans, a n d other carbohydrates. T h e action of alkali on hardwoods is much more pronounced t h a n on conifers. This is in p a r t due t o t h e slight solubility of t h e pentosans of t h e conifers in alkali as compared with dilute acids. T h e action of alkali is determined b y Cross a n d Bevan’ b y boiling t h e solution containing t h e material t o be examined. This method was not adhered t o since t h e temperature is difficult t o regulate a n d t h e solution bumps violently. T h e material should be washed with dilute acetic acid in order t o remove t h e alkali adsorbed. wAmR-soLmLE-It is necessary, especially in t h e case of hot water, t o limit t h e time of extraction as there is no s h a r p limit .to t h e solubility of m7ood in boiling water. Klason2 found t h a t t h e wood of t h e Norway spruce, which h a d been first extracted with ether t o remove resins, etc., lost about 1 2 per cent of its weight b y alternate extraction with alcohol a n d water. T h e chief materials extracted b y water are tannins, bitter principles a n d carbohydrates. T h e lignin is also partially attacked, methyl alcohol a n d acetic acid being formed. T h e method employed would not be applicable t o woods containing tannins with phlobaphenes rendered insoluble b y boiling. T h e water-soluble portion of the western larch mas found t o consist largely of a galactan, apparently (CsHloOs)zo, t h a t yielded only galactose3 on hydrolysis. Investigation showed t h a t galactans were characteristic of t h e water-soluble portions of the conifers. P E K T O S A N A N D METHYL PENTosAK-The determination of pentosans a n d methyl pentosans as worked o u t b y Tollens a n d his pupils is very accurate so far as duplicating results is concerned. A comparison was made of t h e t w o methods of extracting t h e methyl furfural phloroglucide. Extraction with alcohol in a “Cellulose,” p. 117. “Beitrkge zur Kenntnis der chemischen Zusammensetzung Fichtenholzes.” 8 Schorger and Smith, THISJOURNAL, 8 (1916). 494-9. 1
9
beaker1 a t 6 0 ° , while more tedious t h a n extraction in a modified Soxhlet as recommended b y Ishida a n d Tollens,2 rras found t o give more accurate results, since b y t h e latter method it is difficult t o determine when t h e extraction is completed. T h e weights of wood chosen ( 2 g. for conifers a n d I g. of hardwoods) give about 0.20 g. mixed phloroglucides. T h e results of extraction of pure furfural phloroglucide (about 0 . 2 0 g.) b y Ellett a n d Tollens3 show t h a t about 0.0014 g. are dissolved during each extraction. A correction cannot be easily applied for this loss since when t h e table? is examined giving t h e amounts of arabinose a n d rhamnose found when known amounts of these sugars were taken, i t is seen t h a t t h e a m o u n t of arabinose found is 3 per cent t o o high a n d t h e rhamnose is 1 . 7 per cent t o o high. I t was also found t h a t 3 t o 4 extractions with alcohol as recommended were usually insufficient t o give even a n approximately colorless extract. I n Table IV are given t h e number of extractions necessary for approximately 0 . 2 0 g. of mixed phloroglucides from t h e various woods a n d celluloses, using 2 0 cc. of alcohol: TABLE IV Douglas Fir 8to9
White Spruce 6to7
Yellow Birch 4to5
Basswood 6to7
Sugar Maple 5to7
Longleaf Western Pine Larch 4to6 5to6
I t is evident t h a t appreciable errors will result from a large number of extractions. These errors might be reduced b y correcting for t h e solubility of t h e f u r f u r a l phloroglucide were it not for t h e fact t h a t t h e amounts of arabinose a n d rhamnose found b y Ellet a n d Tollens were both t o o high in spite of t h e 3 t o 4 extractions. I n view of these facts i t is highly probable t h a t t h e figures given for methyl pentosans especially are t o o high. It would probably be better t o give t h e results as furfural a n d methyl furfural since wood not only contains t r u e pentosans b u t apparently “furfuroids.” Furthermore t h e t r u e pentosans are mixtures o€ a t least arabans a n d xylans, each giving different a m o u n t s of furfural. T h e source of t h e methyl furfural is attributed t o t h e presence of methyl pentosans, though no methyl pentose of methyl pentosan has so far been isolated f r o m wood. T h e various wood celluloses also give considerable amounts of furfural. T o account for this behavior Cross a n d Bevanj have assigned t o wood cellulose a n oxycellulose structure. Konig a n d Huhn6 are firmly of t h e opinion t h a t wood cellulose obtained b y t h e chlorine method contains residual pentosans, a n d t h a t their method of determining cellulose (digestion with glycerin a n d sulfuric acid followed b y oxidation with hydrogen peroxide a n d ammonia) is t h e only one giving t r u e cellulose, i. e . , cellulose free from lignin, pentosans, etc.. It seems essential. however, t o look upon wood cellulose from a broader view-point. Cotton is doubtless t h e typical cellulose of t h e (C8HloOs)ngroup, b u t i t is no more reasonable t o expect cotton t o be t h e only cellulose in n a t u r e t h a n 1 2 3
des
Vol. 9 , No. 6
4 6
1
Ellett and Tollens, J . Land??.,53 (19051, 20. I b i d , 69 (19111, 61. Ibid., 63 (1905), 20. I b i d . , 53 (19051, 22, Table IV. “Cellulose,” p. 82. “Bestimmung der Zellulose, etc.,” p. 50.
June, 1917
T H E J O C R N A L O F I N D r S T R I . I L AiA\-DE N G I N E E R I X G C H E M I S T R Y
glucose t o be the only sugar. It is probab:e t h a t ~x-ood celluloses should be looked upon as definite compounds of hexosans with r a r y i n g amounts of pentosans. The methoxy reaction m a y also be due t o the presence of small amounts of methyl glucosides or similar derivatives. I n t h i s paper cellulose will be de-filled a s the r e s i d u e r e i u i i i i i i i i g a j t e r alternate t r e a t m e i i f xsitlt chloripie gas a n d s n d i z r w sulfite ufi t o t h e fioiiit z , h e r e t l z p c-hloriize-suljile color. reactioti! o r the M a : i l e r e a r t i o i i , c e a s es . -1nalysis has shorn-n t h a t t h e hardwoods can be sharply divided from t h e conifers b y means of the pentosan content of t h e cellulose. I n general. the pentosan content of t h e hard\\-ood cellulose is greater t h a n t h a t of t h e original wood. ivhile with the conifers t h e reverse is true. The pentosan content of Ihe cellulose from t h e conifers varied from j t o I O per cent and t h a t from t h e hardwoods from 24 t o 2 8 per cent. T h e methyl pentosan content of t h e various celluloses is fairly uniform b u t in t h e case of t h e woods there are considerable variations. Douglas fir contains t h e largest amount of methyl pentosan, t h e latter amounting t o 4 2 per cent of t h e total pentosans and methyl pentosans present. I n general t h e conifers contain more methyl pentosan .than the hardwoods. TABLEV-PENTOSAN CONTEXT (PERCENTAGES) OF HARDWOODS
Basswood.. . . . . , . . . . 24 Sugar M a p l e . , . . , , . . . 2 5 Mean 26 Yellow Birch. . . , . . . . 28 \
I
THE
CELLULOSES
CONIFERS
(1907). 1125.
T h e material placed in beakers was chlorinated in specially designed apparatus of t h e t y p e shown in t h e accompanying figure. This apparatus has several advantages: f o u r samples can be chlorinated a t t h e same time; t h e material is maintained a t a low temperature b y means of a constant stream of cold water; t h e stream of chlorine gas can be regulated by means of the stopcocks; a n d the excess chlorine is carried off b y t h e water. At intervals of 6 t o 7 minutes t h e contents of t h e beakers were stirred with a glass rod and the position of the beakers changed in order t o insure uniformity of chlorination. T h e chlorination was limited t o half-hour periods or fractions thereof in t h e results herewith. -4 first chlorination of one hour, as usually recommended, is too long in some cases. The number of chlorinations or fractions thereof necessary t o obtain the cellulose practically free from lignin were as gi\-en in Table VI. T h e conifers are decidedly more resistant t o the action of chlorine t h a n the broad -le a 1-e d trees R
TABLE \‘I-cHLORIN.4TION
Douglas Fit 4to5
\Vhitc
Spruce 4to5
K € C E S S A R Y Y O ChlT.4IN
Lungleaf Pine 1
Western Larch 5
LIGNIN-FREE CELLULOSE
Yellow Birch 2to3
Basswood 2
Sugar .Maple 2 to 3
To determine the freedom of the cellulose from lignin the yellow color produced b y chlorine a n d particularly
Western Larch. , . . . . .9 Longleaf P i n e . . . . . . 8 Mean Douglas F i r . , . , . , : , 5 8 XVhite Spruce 10 I
f
CELLrLosE-Owing t o t h e work of previous investigators, especially t h a t of Renker.’ no a t t e m p t x a s made t o determine t h e relative merits of t h e various methods of determining cellulose, since t h e chlorine method of Cross a n d Bevan is t h e only one t h a t can be applied satisfactorily t o woods. One of t h e most important points in determining cellulose consists in obtaining t h e sample in t h e proper physical condition. Dean and Tower* rasp t h e wood. This method with dry woods gives mainly dust and even with wet wood t h e use of t h e rasp is tedious and unsatisfactory. In the case of such softwoods as basswood very satisfactory material may be obtained from t h e d a m p wood with a small sharp plane. However, with most woods t h e use of t h e plane is not T O be recommended since t h e resulting material is not of uniform thickness. For t h e purpose of chlorination t h e thickness of t h e material should not exceed 0 . O o j in. The best method of attaining this result for t h e harder woods is b y t h e use of a cabinetmaker’s scraper. which is a thin rectangular steel plate with square edges. Unfortunately, considerable skill is required for the proper use of this tool. Unless t h e user has had a large amount of experience. dust rather t h a n a fine excelsior is obtained. T h e wood t o be scraped should contain 2 j t o 30 per cent moisture. Nearly as good results are obtained with broken window glass as with t h e scraper. Certain soft woods do not scrape well, so t h a t i t is necessary in some cases t o choose a method b y trial. All t h e material t h a t passes through a 40-mesh sieve should be rejected. 1 “Bestirnmunasmethoden der Cellulose.” Berlin (1911)). . .
* J . A m . Chem. SOC.,29
563
APPARATUSFOR CHLORINATIKG Wooo
t h e pink t o purple-red color vihich t h e lignin chloride gives with sodium sulfite were found very sensitive. T h e latter reaction is considerably more sensitive for broad-leaved woods t h a n for the conifers. hlaule’sl reaction t h a t has been considered a very sensitive test for lignin is t h e following: the fibers are covered with a dilute solution of potassium permanganate and allowed t o s t a n d for several minutes; t h e permanganate is t h e n washed out and t h e manganese dioxide adhering t o the fibers is removed b y allowing t h e m t o stand in contact with hydrochloric acid of sp. gr. 1.06. After solution of the manganese dioxide, the fibers are thoroughly washed with water and t h e n a few drops of ammonia are added. I n case lignin is present a deep red coloration is produced. This reaction was found t o be sensitive for the hardwoods b u t in t h e case of t h e conifers no red color was ever obtained. When t h e original wood is given t h e above treatment, it is colored dark brown. ,4s t h e chlorina1
Beitr. z. wissensch. Botanik, 4 (1900), 166.
T H E J O U R A T z l L O F I N D C S T R I A L AATTD ELVGIAVEERING C H E M I S T R Y
564
tion proceeds, a n d more a n d more lignin is removed, t h e hfaule reaction changes from a brown t o a dirty brownish gray t h a t is not a t all characteristic. Besides being indefinite, t h i s reaction requires considerable time a n d manipulation. T h e reaction of t h e wood fibers with ferric chloride a n d potassium ferricyanide’ has a certain qualitative value, b u t quantitative determinations gave inconsistent results. T h e yields of cellulose do not apply t o material t h a t is absolutely free from lignin. There are invaria b l y present small fragments of wood t h a t are only partially reduced. However, in obtaining t h e cellulose absolutely free from lignin t h e error involved b y destruction of t h e cellulose is out of all proportion t o t h a t caused b y t h e presence of t h e small amount of lignin. I n t h e original method of Cross a n d Bevan? t h e ligneous material was boiled for half a n hour with I per cent X a O H previous t o chlorination. Also t h e chlorinated fibers were boiled for 5 min. with a solution of sodium sulfite containing 0 . 2 per cent X a O H . Renker3 states t h a t in b o t h cases t h e alkali a t t a c k s t h e cellulose a n d reduces t h e yield. These statements have been confirmed. A number ‘of experiments were made t o determine t h e effect of alkali on t h e yield of cellulose. I n t h e results t h a t follow only t h e mean results of duplicate determinations are given. As a n example of t h e effect of preliminary digestion with alkali on t h e yield of cellulose, basswood (Table V I I ) may be t a k e n as a n extreme case. TABI.EVII-YIELD
CELLULOSE FROM BASSWOOD ChloriYield of nations Cellulose PRELIMINARY TREATMENT: Hrs. Per cent 62.92 Extracted with Alcphol-Benzol.. , . , . , , , , , . , , , , , . I/?, l/z Digested with 50 cc. 1% NaOH in water bath for 30 min.. . . . . . ..................... 1/z. 1/z 59.78 Digested wit aOH in water bath for 60 min l/x, 118 58.25 OF
.
.
v01. 9,
NO. 6
Douglas Fir was digested both with acids a n d alkali, t h e result being t h a t t h e yield of cellulose was lowered b y t h e acid hydrolysis b u t not appreciably affected b y t h e alkali in this case. DOUGLAS FIR Cellulose Per cent PRELIMINARY TREATMENT: Extracted with Alcohol-Benzol.,.............................. 62.90 Digested with 50 cc. 1 % NaOH on Steam Bath for 1/z h o u r . . 6 3 . IO Boiled with 100 cc. 2 . 5 % HzSOd for 3 h o u r s . . . . . . . . . . . . . . . . . . . . 5 5 . 1 2 Boiled with 100 cc. 2 . 5 % HzSOd for 3 hours (material that would pass through a 40-mesh sieve was used in this case) 49.00
....
......
The effect of addition of alkali t o t h e sodium sulfite solution in t h e removal of t h e lignin from Douglas Fir is also illustrated b y t h e following: DOUGLAS FIR Chlorinations Cellulose Hrs. Per cent REMARKS: All samples were first extracted with Alcohol-Benzol: a Sulfite Solution without Alkali.. . . . . . . . . . . . . . . I , ‘/a. 1/4 60.53 1, 1/4, ‘ 1 4 59.35 b Sulfite Solution with 0.2 per cent N a O H . .
......
Since sodium sulfite gives decidedly alkaline solutions owing t o hydrolysis it appeared probable t h a t sufficient alkalinity might be developed t o a t t a c k t h e cellulose. Bleached sulfite pulp t h a t h a d been t h o r oughly washed with hot water a n d t h e n dried a t 60’ was employed. I n all cases 2 g. of t h e pulp were heated with I O O cc. of z per cent sodium sulfite solution. T h e moisture i n t h e pulp was determined b y heating a separate sample in t h e air oven a t 1 0 j O a n d t h e samples treated with sodium sulfite were reduced t o t h e dry weight b y calculation. After t r e a t ment with t h e sulfite solutions t h e pulp was washed with dilute acetic acid, hot water, alcohol, a n d e t h e r in succession a n d finally dried a t I O j O for z hrs. Period of Loss in Heating Weight BLEACHED SULFITE PULP Hrs. Per cent MANNER O F HEATING: a Boiling Water B a t h . . ............................... 1/z 1.99 b Steam B a t h . . c Steam B a t h . , . , . .
.................................
Renker4 working with unbleached sulfite cellulose claims t h a t t h e chlorination proceeds as smoothly without t h e preliminary t r e a t m e n t with caustic soda. I n t h e case of basswood t h a t h a d been digested for I hr. with I O O cc. of I per cent N a O H , 90 per cent of t h e fibers showed no lignin reaction ( M a d e ) after t h e first half hour’s chlorination a n d a n additional chlorination of j min. was sufficient t o remove t h e lignin ,entirely. I n all cases t h e preliminary digestion with alkali was found t o assist i n t h e removal of t h e lignin, t h e time of chlorinating being perceptibly shortened. This is especially t r u e of hardwoods. I n t h e case of t h e conifers t h e effect is less evident. As a general rule, however, t h e t r e a t m e n t results in a n appreciable reduction in t h e yield of cellulose. YELLOWBIRCH PRELIMINARY TREATMENT: Extraction with Alcohol-Benzol for 5 hrs.. . . . . . . . 1, Digested with 100 cc. 17G NaOH in Water Bath for 30 rnin.. I,
..............................
Chlorinations Hrs. I/z,
1/z, ‘/z
l/z, 1 1 4
Yield of Cellulose Per cent 61 . 3 3 60.69
T h e effect of t h e alkali on hardwoods is appreciable even in t h e case of fairly thick shavings, as is evident in t h e case of t h e above experiments in which yellow birch was used. 1 Cross and Bevan, “Cellulose,” p. 124; Sherman, J . A m . Chrm. Soc., 19 (1897). 304. 2 “Cellulose,” p . 95. 3 “Bestimmungsmethoden der Cellulose,” p. 44.
4
Lac. C i f . , p . 44.
T h e loss b y t h e first t r e a t m e n t , approximately 2 per cent, m a y have been due t o t h e presence of oxycellulose, b u t t h e total loss of Sample b (5.69 per cent) b y t h e four treatments can hardly be a t t r i b u t e d to this one cause. Some experiments were made in which t h e sodium sulfite solution containing t h e chlorinated wood was boiled for 5 min. I n one series t h e boiling solution was maintained s a t u r a t e d with SO2 b y passing i n t h e gas. I n some cases this gave a n increased yield of cellulose while i n others t h e yield was slightly lowered. A marked difference i n t h e r a t e of removal of t h e lignin from spruce was noted when a z per cent N a H S 0 3 solution was used i n place of a 2 per cent N a 2 S 0 3 solution. After each chlorination t h e fibers were heated with I O O cc. of t h e sulfite solutions in a water b a t h for half a n hour. WHITE S P R U C E TREATMENT: a With Sodium S u l f i t e . .. . . . . . . . . . . . . b With Sodium Bisulfite.. . . . . . . . . . . .
Half-hour Chlorinations 311s 6
Cellulose Per cent 63.50 62.80
After three chlorinations a did not show t h e Maule reaction b u t chlorine colored t h e fibers a slight yellow. They were accordingly given an additional chlorination of j min. I n t h e case of b , after t h e third chlorination t h e bIaule reaction was brown; after t h e fifth chlorination t h e AIaule reaction was pale saffron,
T H E J O C R A V A L O F INDC‘STRI.4L A N D E N G I N E E R I N G C H E M I S T R Y
June, 1917
a n d t h e chlorine reaction decidedly yellow; after t h e sixth chlorination there was no Maule reaction b u t chlorine gas gave a pronounced yellow color. T h e fibers were bleached with potassium permanganate, washed as usual a n d dried. T h e cellulose obtained with sodium bisulfite was a dark grayish yellow. T h e sodium bisulfite solutions were never colored more t h a n a pale yellow. This fact, combined with t h e large number of chlorinations required. shows t h a t it is essential t o have a slightly alkaline reaction in order t o render t h e method efficient. A C T I O N O F T H E CHLORISE-The rate a t ivhich t h e chlorine is passed into t h e beaker containing t h e ligneous material does not appear t o have received special attention. Cross a n d Bevan s t a t e t h a t a “slow stream” should be used. It was found t h a t t h e a m o u n t of lignin removed was almost directly proportional t o t h e rate of t h e introduction of t h e chlorine as will be seen from t h e following: WHITESPRUCE Chlorine Bubbles Per cent Loss per Min. in Weight 52 to 53 12.84 7 7 t o 78 16.31 120 t o 122 22.58
YELLOWBIRCH Chlorine Bubbles Per cent Loss Per Min. in Weight 44 t o 45 15.31 72 to 74 21.57 120 t o 122 26.11
According t o Cross a n d Bevan the action of t h e chlorine is mainly additive a n d substitutive. I t is difficult t o conceive of t h e reaction being other t h a n mainly a n oxidation. This is also borne out b y t h e considerable excess of chlorine obtained as hydrochloric acid over t h e chlorine combined with lignin as found b y Heuser and Sieber.1 T h e presence of a chlorine carrier such as iodine appears t o be without effect. Yellow birch wood was saturated with alcohol containing a few crystals of iodine a n d after standing a few minutes washed with cold water. After chlorinating a t t h e rate of 6 4 t o 6 j bubbles per minute for 30 min. t h e wood lost 19.83 per cent b y veight. When this loss is compared with t h e losses in t h e above table i t is evident t h a t t h e iodine di.d n o t improve t h e reaction. There is a n advantage in using a rapid stream of chlorine gas during t h e first half-hour chlorination, b u t during succeeding chlorinations. except possibly t h e second in some cases, t h e rate should not exceed about 40 bubbles (of chlorine per minute. T h e loss in weight during chlorination was followed b y using t h e regular method for determining cellulose. After heating with sodium sulfite solution t h e residue was washed with acetic: acid, alcohol. and ether. After drying a n d weighing. t h e chlorination was repeated. T h e results obtained appear in T a b l e Y I I I . TABLE YIII-ACTIOS WESTERNLARCH 40 Chlorine Bubbles per Minute ______A____>
Chlorination Period 1st 1(’z br. 2nd 1/zhr. 3rd 1/2 hr. 4th I/? hr. 5th I/? hr. Next hr.
Per M%iiIe cent ReacLoss tion 2 9 . 0 5 Brown 8 . 8 2 Brown 2 . 6 5 Saffron 1.23 S o n e 0.57 S o n e 0 . 9 4 None
CHLORIKATIDS ------YELLOW BIRCH--35 t o 40,Bubbles io Bubbles per min. after per Minute first Chlorination throughout Per ChloriPer Chlorination cent nation cent Period Loss Period Loss 1st 1 2 hr. 2i.il 1st 2nd ‘/?hr. 8.08 2nd 3rd 1 , ~hr. 2 , i 3 ( a )3rd 4th 1/19 hr. 1.10 4th hr 4.38 S e x t hr. 1.35 5th 1 1 2 hr. 1.57 Next hr. 1.45 .. ... ... ( a ) Residual cellulose free from lignin. OF
T h e greatest difficulty of t h e present method of estimating cellulose lies in judging just how long t h e 1
Z. angew’. C h e m , .4ufratzleil., 26 (1913). 805.
565
final chlorination should be in order t o remove all t h e lignin and not attack t h e cellulose. I t is probable t h a t t h e attack of t h e cellulose consists in t h e formation of oxycellulose. a n d possibly hydrocellulose, which are soluble in the sodium sulfite solution. However, Heuser a n d Sieber’ b y using methylene blue found t h a t practically no oxycellulose was formed u p t o t h e point where all t h e lignin mas removed. For analytical purposes formation of degradation products of t h e cellulose would be of little consequence providing t h a t t h e y did not pass into solution. All a t t e m p t s t o accomplish this end were negative. T h e chlorinated fibers, when extracted with 9 j per cent alcohol in a Soxhlet extractor t o remove the lignin chloride, still lost 1.j t o 2 . 0 per cent b y weight for each half-hour chlorination following t h e point where t h e lignin reaction ceased. The accuracy attainable in determining cellulose is dependent largely on folloming t h e same procedure exactly with duplicate determinations. Two halfhour chlorinations followed b y treatment with sodium sulfite are b y no means equivalent t o a one-hour chlorination. Unfortunately check analyses do not necessarily indicate t h a t t h e correct amount of cellulose h a s been secured. T h e results obtained b y different chemists, even if following t h e same directions, may be considered satisfactory if t h e y check within one per cent. T h e results attainable b y experience may be judged from Table I X , t h e figures being t a k e n a t random. TABLEIX-PER CENT CELLULOSE-XOTASH-FREE Sample h-0.: 1 2 3. 4 Sugar Maple , . . . . . . . , , . , . 6 0 . i 5 61.64 60.10 60.58 60.82 61.iO 60.31 60.37 \Vestern Larch . . _ .. , , , , , , 5 7 . 8 2 58.66 61.20 53.34 58.67 58.77 60.82 53.28
T h e conifers invariably are harder t o reduce t h a n t h e hardwoods a n d less satisfactory checks may be expected. I n spite of t h e fairly good agreement it is doubtful if t h e results may he considered as having a n accuracy greater t h a n one per cent. The cellulose content of t h e various species is quite uniform, especially when t h e cellulose is calculated on t h e weight of t h e wood free from material soluble in hot water and ether. On this basis t h e figures in Table X n-ere obtained: TABLEX SOFTWOODS Per cent Cellulose HARDWOODS Per Sugar M a p l e . . . . . Western Larch.. . . , 6 6 . 4 0 Yellow Birch.. . . . . Longleaf P i n e . . . . . . 6 7 . 2 0 Mean Basswood.. , . . . . . . Douglas Fir. , , , . . . 6 6 . 3 0 6 5 . 9 2 White S p r u c e . .. . . . 6 3 . i 9
t
.
cent Cellulose. 6 3 . 4 3 Mean 64.38 64’26 64.97
i
T h e conifers appear t o contain more cellulose t h a n t h e hardwoods. Occasionally t h e cellulose content of a tree will be unusually high or low. For example, t h e cellulose content of basswood No. 3* was only 54.42 per cent; microscopic examination showed no evidence of fungous a t t a c k ; t h e analysis was repeated with t h e same result. On t h e other h a n d , t h e cellulose content of longleaf pine KO. 4 * is high b y several per cent. It was thought t h a t b y subtracting t h e per cent soluble in ether and hot water from a fixed number ( j o in t h e case of longleaf pine) t h e cellulose content of the various species could be approximated 1 LOC.
Cil.
566
T H E J O U R N A L O F I N D U S T R I A L Ail'D EIVGIAVEERIAVGC H E M I S T R Y
with fair accuracy. T h a t marked exceptions may exist is shown b y t h e following: LONGLEAF PINE
Sample No.: Hot water-soluble, . . . . . . . . . . . . . . . . . Ether-soluble.. . . . . . . . . . . . . . . . . . . . . . . . . . Cellulose.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
11 8.20 p.70 53.02
12 6.03 6.70 5i.23
13 20 6,78 7.57 2.65 9.23 61.09 59.31
Total Percentages.. . . . . . . . . . . . . . . . . . 69.92
69.96
i o . 52
________
i 6 . 1I
The analysis of Sample KO. 20 was checked b y several determinations b u t t h e cellulose content remained about j per cent higher t h a n t h e average of t h e remaining three samples, t h e calculations being based on t h e wood free from materials soluble in ether a n d water. ACID HYDROLYSIS-The method of determining t h e acids formed b y hydrolysis was adopted after considerable experimentation a n d , while somewhat tedious, very accurate results may be obtained. Duplicate determinations should agree within 0.1 per cent. It is absolutely necessary t o use low temperatures a n d pressures t o prevent decomposition of t h e carbohydrates, etc., b y t h e sulfuric acid before all t h e volatile acids are removed. T h e distillate obtained in a blank determination remained pink for 30 seconds. when phenolphthalein was used as t h e indicator a n d one drop of N / I O N a O H was added, showing t h a t no sulfuric acid h a d been carried over. T h e distillate consists mainly of acetic acid. The volatile acids formed from a sample of yellow birch amounted t o 4.0 per cent, calculated as acetic acid. After heating on the* s t e a m b a t h with mercuric oxide t o destroy formic acid, 3.6 per cent of acid was recovered. I t is probable t h a t t h e formic acid results from decomposition of carbohydrates a n d not from formyl groups. It is not yet certain t h a t all t h e acetic acid is formed b y hydrolysis of acetyl (CH3CO-) groups. A 2-g. sample of yellow birch b y digestion with I O O cc. of 2 . j per cent &So4 lost 31.41 per cent b y weight, showing t h a t a decided decomposition is produced. I t is accordingly n o t impossible t h a t a portion of t h e acetic acid is formed from acetic acid residues (-CHS.CO-). T h e effect of t h e strength of acid on t h e yield of volatile acids from yellow birch was t h e following: Strength of Sulfuric Acid (Per c e n t ) . . . . . . . . . . . 2 . 5 Yield of Acetic Acid (Per cent), , , . . , , , , , . , . , , 3 . 9 9
.
5 .O 4.31
10.0 4.53
Small amounts of acetic a n d formic acids appear t o be present in some woods in t h e free s t a t e or a t least in very feeble combination. Guijo, a Philippine wood, has a marked corrosive action on metal fastenings. Investigation showed t h a t about 0.2 per cent of acetic a n d formic acids could be leached from guijo sawdust with cold water. T h e silver salts i n aqueous solution were heated on t h e steam b a t h t o decompose t h e silver formate. After filtering off t h e metallic silver t h e filtrate deposited beautiful crystals of silver acetate on cooling. T h e crystals were analyzed as follows: 0 . 2 7 1 2 g. silver salt gave 0.1746 g. Ag = 64.38 per cent Ag. Silver acetate, CH3.COOAg, requires 64.64 per cent Ag. M E T H O X Y GROUPS-The efficiency of t h e apparatus a n d t h e quality of t h e acid were tested b y using a compound, vanillin, t h e methoxy content of which is
v01. 9 , NO. 6
known: Vanillin, C 7 H 5 0 2 . 0 C H 3requires , 20.30 per cent CH30--. Found. 20.26 per cent CH30-. Maple gave t h e highest yield of methoxy groups. T h e yields of methyl alcohol obtained b y destructive distillation are much lower t h a n would be expected from t h e methoxy numbers. YIELD Birch Maple Western Larch Methyl Alcohol (Per c e n t ) . . . . . . . . . 1 , 5 3 ( a ) 1.94(a) 0.65 Methoxy (Per c e n t ) . . . . . . . . . . . . . . 6 . 0 7 7.25 4.95 ( a ) Palmer, Bull. 129, U.S. Dept. Agr., Forest Service.
4 s previously mentioned. t h e low yields are probably due t o t h e formation of methyl ethers. FOREST SERVICE FOREST PRODUCTS LABORATORY MADISON,WISCONSIN
ON THE TOXICITY TO A WOOD-DESTROYING FUNGUS OF MAPLEWOOD CREOSOTE AND OF SOME OF ITS CONSTITUENTS AND DERIVATIVES, TOGETHER WITH A COMPARISON WITH BEECHWOOD CREOSOTE' BY ERNEST J. PIEPER. s. F. .%CREE A N D C. J. H U M P H R R Y Receieed March 7, 1917
Considerable interest has been shown t h e past few years in t h e industrial use of wood creosotes. At t h e present time t h e y are on t h e market t o a certain extent as wood preservatives, b u t their high antiseptic properties render t h e m most useful in general sanitation work a n d for special technical purposes as well. For example, t h e y dissolve rosin a n d linseed oil soaps a n d t h u s form disinfectants which with water give emulsions having coefficients three t o five times, or more, t h a t of phenol. T h e y also have a great a d vantage over coal-tar creosotes in t h a t t h e y do not inflame t h e skin a n d are not toxic or poisonous t o humans or animals. Indeed, hardwood creosote, U.S . P., a n d guaiacol have'long been administered as internal medicines, whereas carbolic acid is a wellknown poison. As toxicity t o fungi a n d bacteria is one of t h e very i m p o r t a n t attributes i n t h e utilization of t h e oils or their several constituents, t h e present s t u d y has been undertaken t o throw light upon their behavior i n this respect. These creosotes are by-products i n t h e destructive distillation of wood a n d can be produced a t a moderate cost. T h e main products of t h e distillation are charcoal, methyl alcohol, a n d acetic acid. T h e toxicity of beechwood creosote, b o t h crude a n d refined,? has been determined b y R. M. Fleming a n d C. J. H ~ m p h r e y of , ~ this laboratory, a n d found t o be much greater, z t o 4 times, t h a n t h a t of t h e coal-tar creosote. T h e toxicity of maplewood creosote a n d of its constituents a n d derivatives has been found in t h e present investigation t o be equally as high. METHOD
Toxicity studies a t t h e Forest Products Laboratory have largely been confined t o t h e petri-dish m e t h ~ d ; ~ 1 T h e present paper is one of four prepared by the junior author in partial fulfilment of requirements for the degree of Doctor of Philosophy in the University of Wisconsin. 2 D a t a on refined product not yet published. 3 THISJ O U R N A L 7 , (19151, 652. 4 Humphrey and Fleming, ti. S. Dept. .4gr., Bull 227 (19151, for general method.
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