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relation between the ash and total impurities. Once this relation is known the translation of per cent ash into terms of purity offers no difficulty. The calculation is, of course, not valid if there is an abnormally high adsorption of ash within the sugar crystal or a contamination of the sirups with ash from sources other than beets. Results Some results showing the effect of sugar concentration on the-specific conductance are given in the accompanying table. Variation of Speci5c Conductance x 10-5 with Concentration SUGAR Pure A
B
CONCENTRATION, GRAMS PER 100 a.
5
0.025 2.2
. ..
10
15.0
20
25
35
50
0.035 0.039 0.039 0.037 0.021 .. . 3.9 5.2 6.1 6.6 6.7 6.4 14.0 18.3 21.5 22.9 23.7 19.1
The pure sugar was prepared by recrystallization from alcohol according to the modified method of Bates and Jack-
VOl. 19, No. 2
Sugar A is an ordinary grade of granulated beet sugar and B a very poor grade. It will be observed that the conductance is near the maximum a t a concentration of 25 grams per 100 ml. and that the variation of conductance with concentration is very slight. This fact influenced the choice of this concentration for regular use because extreme accuracy in weighing and dilution is obviously unnecessary. Practically all the writer’s efforts have been directed toward developing the method from the standpoint of its practical application t o the estimation of the ash content and purity of beet sugars. There remains to be determined, however, some very interesting fundamental data concerning the effect of sugar on the dissociation constant, and of other factors such as viscosity which influence the conductance of solutions of inorganic salts. Undoubtedly a study of these factors will lead to wider applications of the method in refinery and beet-house practice. Bur Standards, Circ. 44.
The Gelatinization of Lignocellulose’ 111-The Viscose Reaction By A. W. Schorger C. F. BURGESS LABORATORIES, MADISON,WIS.
ROSS, Bevan, and Beadle,2 who applied the thiocarbonate reaction t o thin beach shavings, stated that the resulting product showed none of the characteristic properties of viscose. Hancock and Dah13 found that the pithy stem of Aeschynomene aspera became gelatinous and 20 to 30 per cent went into solution. I n the case of elder pith, less than 10 per cent was rendered ~ o l u b l e . ~ The reaction has also been used to gelatinize wood.6 It is temerity to assert that lignin has yet been isolated from wood in a state even approximately unchanged. One of the hopes for the thiocarbonate reaction was the complete removal of the carbohydrates from wood. If successful, the residual lignin would a t least have been free from the effects produced by high temperatures and the use of strong acids. This end was not attained in one treatment. Such diEculties were encountered in filtration that the small quantities of material finally used precluded a repetition of the reaction on the residue. Experimental
C
SOLUTIOK-TOdetermine if raw wood would show some of the properties of viscose when subjected to the thiocarbonate reaction, 25 grams of white pine passing a 20-mesh sieve were added to a solution consisting of 25 grams of sodium hydroxide in 130 cc. of water and allowed to stand overnight. With thorough stirring, 20 cc. of carbon bisulfide were added, and after 3 hours sufficient water was added to give a volume of 500 cc. Most of the wood settled rapidly to a volume of about 300 cc. The vessel was allowed to stand several days to permit spontaneous coagulation. I n time the wood underwent syneresis. There was 1 Presented before the Division of Cellulose Chemistry at the 72nd Meeting of the American Chemical Society, Philadelphia, Pa., September 5 to 11, 1926. * J . Chcm. SOC.(London), 67, 444 (1895). 8 Chem. News, 72, 18 (1895). 4 Cross and Bevan, “Researches (lS95-1900),”p. 137. 6 Lach, English Patent 12,324 (1912); “Portolac” Holzmasse Ges.. Austrian Patent 64,798(1914); de Cew. U. S. Patent 1,140.799 (1915).
an annular contraction of 6 mm. (0.25 inch) and the formation of a cylindrical gelatinous mass which now had a volume of 250 cc. Above the wood was a tender mass of jelly, which represented a portion of the wood that had gone into colloidal solution. DETERMINATION OF SOLUBILITY-All attempts to determine by filtration what amount of wood had been actually rendered water-soluble in the various experiments were unsuccessful owing to the gelatinous character of the material. Centrifuging (1200 r. p. m.) was finally employed. To determine the solubility of wood, one gram of the material passing a 100-mesh sieve was treated in a weighing bottle with 5 cc. of 18 per cent sodium hydroxide, allowed to stand overnight, 1 cc. of carbon bisulfide added, and allowed to stand 3 hours with frequent mixing. The mass was diluted with 20 cc. of water, transferred to a 50-cc. tube with 25 cc. of 5 per cent sodium hydroxide, and centrifuged. The supernatant liquid was carefully decanted, the sludge thoroughly mixed with 5 per cent sodium hydroxide solution, filling to the 50 cc. mark, and again centrifuged. In this way the sludge was washed four times with alkali and twice with water. The fourth washing with alkali showed only a faint opalescence when acidified. The sludge was then washed into a beaker, neutralized with hydrochloric acid, made up to 200 cc., 6 grams of sodium sulfite added, and heated to boiling to dissolve any sulfur present. The residue was filtered, washed with hot water, alcohol, and ether, and dried. All results are on the dry, ash-free basis. Under the above treatment the following solubilities were obtained: Aspen (Populus tremdoides) White pine (Pinus strobus)
Per cent 55.82 36.71
EFFECTOF GRINDING-since many of the reactions of cellulose are surface phenomena, numerous experiments were made using wood gelatinized by grinding in a ball mill in low and high concentrations of alkali. Beginning with ((wood flour,” obtained by dry grinding, there was a
INDUSTRIAL AND ENGINEERING CHEMISTRY
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gradual increase in solubility up to the point where the wood was ground in a mercerizing solution of sodium hydroxide. The latter drastic treatment was conducted as follows: 25 grams of wood flour and 600 cc. of alkali were ground for 42 hours; 20 cc. of carbon bisulfide were then added and the grinding continued for 3 hours. The contents of the mill were then made up to a definite volume, and an aliquot part removed for determining the solubility as described above. The results are given in Table I. Table I
LIGNININ : SoLualLrTy
SpECrEs
Per cent 81.80 69.85
Aspen White pine
Insoluble residue
UNDISSOLVED
L I G N ~BASED N
Original ON TOTAL wood LIGNINI N W O O D
P e r cenl 47.97 23.03
Per cent 23.44 29.10
Per cenl 37.2 23.9
ACIDPRECIPITATION-A considerable portion of the wood rendered soluble was not precipitated on acidifying with hydrochloric acid. The following results were obtained with white pine: Residue from thiocarbonate reaction Soluble and precipitated by acid Soluble and not precipitated by acid (by diff.)
Per cenl 30.15 44.64 25.21
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Viscose f r o m Hydrolyzed Wood
It is well known that hydrocellulose is converted into the thiocarbonate more readily and gives a solution of much lower viscosity than does normal cellulose. Twenty-five grams of the material remaining after western white pine had been subjected to hydrolysis under conditions obtaining in the technical production of ethyl alcohol from wood, were ground finely and treated with 100 grams of 15 per cent sodium hydroxide. After standing 2 hours, 20 cc. of carbon bisulfide were added, and the mass with thorough mixing was allowed to stand 3 hours; 50 cc. of water were then added. After standing overnight the material was diluted with 50 cc. of water and 100 cc. of 10 per cent sodium hydroxide, and heated to 40’ C. The solution then passed readily by gravity through fine muslin, giving a clear, darkbrown filtrate. This was neutralized with hydrochloric acid. The precipitated “cellulose” was washed, suspended in 500 cc. of a 5 per cent solution of sodium sulfide, and allowed to stand several days with frequent shaking. The cellulose was then filtered off, washed with water, dilute acetic acid, hot water, and alcohol, air-dried, and analyzed as follows: pentosan 0.63, “lignin” 1.04, and “cellulose” (by difference) 98.33 per cent. The lignin was determined by treating the cellulose with 72 per cent sulfuric acid in the usual way. The residue, however, did not give the characteristic chlorine-sodium sulfite reaction. To determine the extent to which the hydrolyzed wood was rendered soluble by the thiocarbonate reaction, small samples of the hydrolyzed wood of western white pine were treated according to the procedure previously described, using the centrifuge. Eastern white pine was also used, the wood flour having been boiled gently with 2.5 per cent hydrochloric acid under a reflux condenser for 3.5 hours, washed until neutral, and air-dried. The results are given in Table 111.
The results illustrate with what extreme tenacity the cellulose remains associated with the lignin in the insoluble residues. The lignin content of the insoluble residue from white pine is even lower than in the case of the original wood, while in the case of aspen it is about twice as great. The insoluble residues were gelatinous and formed a curdy precipitate on acidification, behaving, in fact, as though they were insoluble thiocarbonates. The aspen viscose of the above dilution (2 liters) passed rapidly through a Gooch crucible provided with a disk of Table 111 fine muslin, without leaving a residue; when a filter paper LIGNINI N : disk or an asbestos mat was used in the crucible, only a HYDROLYZED MATERIAL SOLUBLE Insoluble Hydrolyzed few drops of solution would pass through with suctjon. residue wood If the aspen or white pine viscose solutions were acidified P n cent Per cent Per rent with acetic acid and allowed to stand for a few hours for Western white pine 55.67 81.68 47.87 coagulation to take place, a mass of jelly was obtained 40.70 48.30 66.89 Eastern white pine that occupied nearly the same volume as the solution. When the ester was precipitated with alcohol it redissolved in water to give a solution like the original. Allowing Here again, by the methods employed, the carbohydrates roughly for 50 per cent of cellulose in the wood, the viscose were very incompletely removed. solutions prepared from wood have a low viscosity in comSummary parison with viscose prepared from cotton under the same conditions. The dilute solutions from wood showed unBy means of the viscose reaction and simultaneous grinding, usual stability in that they showed no tendency to gelatinize approximately 82 per cent of aspen wood and 70 per cent after standing in stoppered flasks in the laboratory for 2 of white pine were dissolved. The lignin of white pine was weeks. more soluble than that of aspen. Table I1 Cellulose is more easily removable from hydrolyzed than from the original wood. I n no case were the carbohydrates CELLULOSE FREE LIGNIN PENTOSAN FROM PENTOSANS SPECIES separated completely from the lignin. Of the latter, a large (by diff.) part passed into solution with the carbohydrates. ~~
Aspen White pine
~
Pet cent 11.70 22.20
Pn cent
Per cent
10.93 8.32
77.37 60.48
Wood Alcohol Called Methanol
The term “methanol” has been officially adopted by the These dilute solutions after standing 2 weeks had separated into a clear upper layer and a sediment. The supernatant United States Public Health Service as representing “wood alcohol,” and will be used in future in lieu of the latter term in layers were carefully decanted, acidified, and the precipitate all correspondence and regulations. purified in the usual way. The results are given in Table 11. Among the advantages which it is believed will result from the The coniferous lignin is much more soluble than that from substitution of “methanol” for “wood alcohol” is that it will the hardwood. A sample, weighing 1.75 grams, of the tend to protect the “class of people to whom the word ‘alcohol’ suggest a substance suitable for use as a beverage.” It is precipitated cellulose from white pine, when heated on the may hoped by Public Health Service officials t h a t by use of the term water bath with 100 cc. of 5 per cent sodium hydroxide “methanol” the number of casualties caused by the improper for one hour, dissolved to the extent of 14.34 per cent. use of wood alcohol will be reduced.
