Constituents of Extractives from Douglas Fir H. 8%. GRAHAM AND E. F. KURTH Oregon State College, Corvallis, Ore. The samples were individually split into small sticks and then disintegrated in a Greundler Peerless grinder. Microscopic examinations of the wood were made in order positively to identify the species. The over-all percentage composition of Sample 111, as determined by the Technical Association of the Pulp and Paper Industry’s Standard methods of wood analysis (@), is given below:
Investigation of the ether, acetone, and cold-water extracts from three different specimens of Douglas fir heartwood has established the presence of constituents not previously reported. In the ether extract were found oleic, linoleic, lignoceric, and abietic acids, phytosterol, and tannin. The fatty acids were present both in the free and combined states, whereas the resin acids were isolated only as the free acids. From the behavior of the tannin found in the ether extract, it appears that this substance was chemically associated with another component. A pentahydroxyflavanone and a catechol tannin and phlobaphene were isolated from the acetone extract. These substances absorb ultraviolet radiation in similar wave bands which indicates that they are structurally related. Approximately 70% of the cold-water extract was a galactan.
Moisture Ether solubility Alcohol solubility Hot-water solubility Total extractives Ash Lignin (total sample) (40-60 mesh sample) Holocellnlose Pentosan Methoxyl
T
HROUGHOUT the Pacific Northwest are found extensive stands of Douglas fir. Because of its prevalence and excellrnt structural qualities, Douglas fir is the major lumber species in this region and stands second only to Southern yellow pine in the total production of lumber in the United States. I t is the principal species used in the plywood industry, accounting for over 9570 of this country’s past and current softwood plywood production. Although its use as a pulpwood is confined almost entirely to the kraft process, Douglas fir is used extensively in the pulp and paper industry. A more recent industrial use of this wood is in the production of ethanol a t Springfield, Ore., by the fermentation of wood sugars obtained by the saccharification of sawmill wastes. It was in connection with the latter use that it became desirable to develop information on the nature of the extractives. In previous work on Douglas fir wood, Johnson and Cain (15) examined the essential oil. From the resin extracted with alcohol, Frankforter and Brown (10) isolated a crystalline resin acid, C1?H2,02, melting point 143.5’ to 144.5’ C., which they called betic acid. The tannin content of the sawdust was found to be 1.067, (9). A pectin substance (I), a water-soluble arabogalactan, and a mannose-yielding material also have been reported present (13). Recently, attention has been called to the similarity in behavior of Douglas fir and the pines in the sulfite pulping operation (6, 11). In the case of pine heartwood, the difficulty of pulping by sulfite liquor was found by Erdtman (8)to be caused by pinosylvin; 3,5-dihydroxystilbene; and its monomethyl ether, which together constitute only O.Syoof the wood. These inhibiting phenols could not be extracted directly by ether, but when the mood was first extracted with ethanol or acetone, they \?ere then soluble in ether.
9.10 1.32 5.46 2.82 9.60 0.175 30.15 29.35 71.4 10.11 4.75
The soluhilitiea arcs ieported on the basis of the oven-dry unextracted wood and were determined successively in the order, ether, alcohol, and hot water. 1111 other analyses are reported on the basis of the oven-dry extracted wood and were deteimined on extracted wood prepared in accordance with T.A.P.P.I. procedure T12m-46.
ETHER-SOLUBLE COMPOUNDS.Samples I and I1 were used in the investigation of ether-soluble components. Wood meal 3.3 kg. air-dry (3.0 kg. oven-dry weight) were extracted in 800-gram batches in a continuous Soxhlet-type extractor with ether that had been first carefully freed from eroxides. The extract was allowed to accumulate in the boiling &sk, only enough ether being added between changes to compensate for losses. After completion of the extraction, the ether extract was dried over anhydrous sodium sulfate, and transferred to a weighed Erlenmeyer flask, and the ether was distilled. The extract was taken to constant weight by removing the last traces of solvent a t room temperakure under reduced pressure and in an inert atmosphere of burner gas. The P l d of extract from Sample I was 28.2 grams (0.94%) and from ample I1 29.3 grams (0.97%). The weights were assumed to be constant when they did not change more than 0.1 gram over 15 hours. Separation of the extract into component fractions is summarized in Figure 1, and the results are shown in Table I. CHEMICAL NATURE OF THE ETHER-SOLUBLE COMPONENT FRACTIONS
WATERSOLUBLES.After the separation of the neutrals from the acidic materials, some 20% of the ether extract was found to be no longer soluble in ether, and remained in the water layer. When treated with a 1% gelatin solution, this red-colored water layer gave an immediate precipitate indicating the presence of tannin. The solution was treated with hide powder as in the conventional tannin assays ( 3 ) and resulted in complete removal of the red color. The quantitative tannin determination was made by extraction with ethyl acetate, which is a good solvent for tannins. After replacing the ethyl acetate with water and then running the standard tannin determination, it was found that 90% of the water-soluble matter was absorbed by the hide powder. Inasmuch as this material gave a green-black precipitate with ferric chloride, an immediate orange precipitate with bromine
EXPERIMENTAL
In the course of this investigation, three different samples of Douglas fir heartwood were used. Sample I (seasoned for one year) and Sample I1 (recently cut) were taken from large, slow growth, “veneer peelers” logs, and Sample I11 was from a freshly cut, wide-ringed, second-growth tree. Samples I and I1 were yellow-brown in color, whereas Sample 111 had a pink shade.
409
INDUSTRIAL AND ENGINEERING CHEMISTRY
410
Vol. 41, No. 2
Ether solubles
1&0 wash 7 Water insoluble
Water soluble
lcold 20ln I\JaOH I
I
Hot alcoholic KOH followed by acidification 1
Water-soluble acids
Water-insoluble acids Petroleum ether I Petroleum ether Petroleum ether insoluble soluble
I
-
CH30H HzSOj 7 Resin acids
-
Unsaponifiables 'Ftroleum ether Dilute ethanol followed by digitonin I I Petroleum ether Petroleum ether Amorphous Phytosterol soluble insoluble material CHIOH Steam distillation
I
IH*SO,
Methyl esters of fatty acids
Nonvolatile
Resin acids
Volatile oil
Lead acetate
Pb salts of fatty acids Ether I
I
Unsaturated acids Figure 1.
Saturated acids
Separation of Extract into Component Fractions
water, and a red precipitate on boiling with dilute sulfuric acid, Hibbert and Phillips (12) reported a similar phenomenon when attempting to recover the acidic materials from jack pine wood. The amount of the water solubles was determined by the difference in weights of the acids and neutrals from the washed ether exlracl. RESINACIDS. On dissolving the resin acid fractiom, obtained by the preferential esterification method of Wolff and Scholze (H),in hot dilute ethanol and allowing it to stand, a crystalline acid gradually separated. This acid was recrystallized from dilute ethanol until the melting point was not raised by additional recrystallizations. The purified acid had a melting point of 153 O to 155' C., which corresponds to some melting points reported for abietic acid from pine trees. The neutral equivalent was found to be 304 as compared t o the theoretical value of 302.4 for abietic acid. A sample of available abietic acid (Amend Drug and Chemical Company) mas recrystallized to a maximum melting point of 153" to 155" C. and a mixture of this acid with the crystalline resin acid showed no depression of the melting point. Although such resin acid products may be mixtures of isomers, it appears that the crystalline resin acid in Douglas fir is similar to the abietic acid from pine trees. Further, a neutral equivalent of 304 indicates that it cannot have the empirical formula, Cl~Hz4O2, ascribed to the resin acid of Frankforter and Brown (IO). UNSATURATED FATTYACIDS. The unsaturated fatty acid fraction was liquid a t room temperature. Because of the relatively small amounts of these acids which were available, no attempt was made to separate the mixture of liquid acids by distillation. Instead, the mixture was oxidized in a cold alkaline solution with dilute potassium permanganate to obtain the crystalline hydroxy derivatives of the unsaturated acids, which are readily separated because of their different solubilities in water (I?', 19). From the oxidation products a tetrahydroxystearic acid, sativic acid, melting point 160" to 162' C. (literature value 163.5" C.), and a dihydroxystearic acid, melting point 131.5' C. (literature values range from 131" to 137" C.) were isolated.
i t was further classed as a phlobatannin.
Since these acids are obtained from the oxidation of linoleic and oleic acids, respectively, it was concluded that both linoleic and oleic acids were present in the original unsaturated fatty acid fraction. In an attempt to measure the relative amounts of these two acids, the iodine number of the unsaturated fatty acid fraction was rneasurcd. As determined by the Kitufmann method (14) the unsaturated acid mixture from Sample I had an iodine numer of 73.5, whereas that from Sample I1 had a value of 85.6. These values are lower than the theoretical values of oleic and linoleic acids (theoretical iodine number for oleic acid is 89.9, for linoleic acid is 181). The neutral equivalent of the mixture was found to be 297, as compared to the theoretical values of 282 and 280 for oleic and linoleic acids. From these data it was obviously impossible t o estimate the amounts of each acid
TABLE
I.
COMPO8aTIoX O F ETHER EXTRACT
Material Free acids F a t t y acids Resin acids Petroleum ether-insoluble acids Combined acids F a t t y acids Resin acids Petroleum ether-insoluble acids Total acids Saturated i a t t y acids Unsaturated f a t t y acids Resin acids (abietic) Petroleum ether-insoluble acids Unsaponifiables Phytosterol Volatile oil Nonvolatile material Water-solubles (by difference) Phlobatannins Nontannins
.
Per Cent of Total Extract , Sample I, yield from Sample 11,yield from wood 0.94% wood 0.97% 60.8 63.4 16.5 17.7 9.7 30.7 34.6 5.3 4.5 0.0
0.8 66.1 Trace 21.0 9.7 35.4 9.9
24.0 21.6 2.4
15.0 4.2 3.8 0.0
0.4
67.7 2.7 18.7
30.7 15.4
11.3
3.9 2.4 5.0
21.1 19.0 2.1
February 1949
I N D U S T R I A L A N D E N G I N E E R I N G CHEMISTRY
present in the original mixture. The reason for the discrepancies in the iodine number and neutral equivalent is not too clear. The lead salt-ether method of separating saturated and unsaturated acids is not satisfactory for saturated acids below lauric acid. Although the presence of any of these acids would lower the iodine number, the neutral equivalent would also be low rather than high. Furthermore, the lower members of the saturated acids are somewhat volatile and can be removed by steam distillation. On steam distilling the unsaturated acid fraction the iodine number was not) increased, and no acids were found in the disMate. The methods of treating the acids in obtaining their separation was tried on pure samples of oleic and linoleic acids. Apparently the methods employed leave the acids unchanged, as the treated acids still showed their theoretical iodine number. The most probable explanation for the low iodine number and high neutral equivalent is that some oxidation at the unsaturated linkages had taken place during the seasoning of the wood. Such an action could result ,in a large decrease in the iodine number and a small increase in the neutral equivalent, as observed. The substantiating evidence for this explanation is that the acids from Sample I, which had undergone more extensive seasoning, had an iodine number more than ten points lower than those from Sample 11. SATURATED FATTY ACIDS. The saturated fatty acid fraction obtained from the ether-insoluble lead salts was dissolved in warm ethanol. Water was added until the solution became turbid, the turbidity was removed by warming, and the solution was set aside to crystallize. A white granular fatty acid separated from the solution and on recrystallization from dilute ethanol gave a maximum melting point of 73 O to 73.5" C. The neutralequivalent of the recrystallized product was found t o be 359, which is near that of lignoceric acid ( C ~ ~ H B O molecular ~, weight 368.6, melting point 78' to 83" '2.). The latter, like cerotic acid from beeswax, melting point 77" to 80" C., is not an individual entity but is a mixture of near homologs. It is recognized that mixtures of such homologous acids cab not be separated by crystallization methods (9). PHYTOSTEROL. The crude phytosterol crystals that were separated from the neutral fraction were purified by recrystallization from dilute ethanol until they gave a maximum melting point of 133" to 134" C. When treated with acetic anhydride and sulfuric acid, the crystals gave a violet-red color which changed t.0 blue. This color reaction constitutes a positive Liebermann-Burchard color test for sterols (14). The crystals also gave a precipitate with digitonin. By boiling with acetic anhydride, the acetate of the phytosterol was formed, and it melted at 125' to 126" C. The melting points of the phytosterol and its acetate agreed with those for the phytosterol found in longleaf and shortleaf pines (16). A purified sample of the pine phytosterol was intimately mixed with an equal portion of the phytosterol isolated from Douglas fir and the three melting points were determined simultaneously. All three samples melted together. From these results, it can be concluded that the phytosterol is the same sterol or mixture of sterols that is found in longleaf and shortleaf pines. VOLATILEOIL. The volatile neutral material was a highly aromatic liquid at room temperature. This essential oil has been previously examined by Johnson and Cain (15),and, therefore, was not further investigated in this work. NONVOLATILE NEUTRALS.The nonvolatile neutral material that was left after removal of the phytosterol consisted of an orange-brown amorphous, solid mass from which no crystalline products could be isolated. It was possibly a polymerization product of the terpene hydrocarbons Kith which it was associated, ACETONE SOLUBLE COMP,ONENTS
EXTRACTION. In general, ether extraction of plant materials isolates the fats, resins, sterols, and volatile oils. The tannins, phlobaphenes, and crystalline coloring materials are removed
7ok
I\
I. FLAVANONE 2. TANNIN
411
0.0032 GRAM 1100 MlLLlLliERS 0.0037
L
220
860
300
-
3
D
WAVE LENGTH MlLLlMlGRONS
Figure 2. Ultraviolet Absorption Spectrum
by more polar solvents, such as alcohol or acetone. Acetone, which can be easily removed from the extract at low temperatures, is well suited for the extraction of these materials. Accordingly, 1.5 kg. of room-dried wood meal with a moisture content of 8.0% from Sample I11 was extracted directly with acetone at room temperature in a large lass jar. After soaking for 2-day periods, the acetone was draine! off, and fresh solvent was added to the wood meal. After three such extractions, the acetone was not appreciably colored, and the extract was then concentrated to 580 ml. by removing the solvent on a water bath. To estimate the amount of extract obtained, a 20-ml. aliquot of the concentrated solution was dried to constant weight in a vacuum oven. The dry residue which did not change more than 0.05 gram in 15 hours was 1.78 grams. Therefore, the total extract was 51.6 grams or 3.85451, of the oven-dry weight of the wood. SEPARATION O F EXTRACT INTO COMPONENT FRACTIONS. On pouring the concentrated acetone extract into 200 ml. of water, a turbid solution was obtained. The remainder of the acetone was then removed under reduced pressure and the water-insoluble components were flocculated by the addition of a very small amount of sodium sulfate. After the water-insoluble material had settled, the clear water solution was decanted from the insoluble material. In order to remove the ether-soluble components, both the water-soluble and -insoluble fractions were extracted exhaustively with ether. In this manner, the acetone extract was separated into ether-soluble, ether-insoluble-watersoluble and ether- and water-insolub,le fractions. .4s expected from the solubility characteristics of tannins, the water solution, when treated with 1% gelatin solution, gave an immediate flocculent precipitate. In order t o isolate the tannin, the ether-extracted water solution was extracted with ethyl acetate. The bulk of the tannin was removed by this solvent, the remainder being removed by concentrating the water solution under reduced pressure to a small volume and salting out the tannin with sodium chloride. The water- and ether-insoluble phlobaphene fraction, originally obtained as a heavy tar, was purified by dissolving in acetone and reprecipitating into ethyl ether. after several such treab ments, the product was filtered off as an amorphous powder and weighed. In addition to the components investigated in the first part of this work, the ether-soluble fraction of the extract was found to contain a large amount of a new crystalline product, which was later found to be a flavanone. The most convenient way found for separating this product from the ether solubles was by fractional precipitation of the ether solution with petroleum ether. An amorphous mass of impurities came down first and was.
INDUSTRIAL AND ENGINEERING CHEMISTRY
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TABLE11. INTERPLANAR SPACINGSASD ISTEK~ITIW OF DOUGLAS FIRFLAVANOWE 12.38 (d) 11.36 (m) 9.50 (v.f.) 8.23 (7.f.) 7.50 (f) 6.17 (m)
3.88 3.71 3.60 3.45
(f)
(f)
(i) (d) 3.36 (m) 3.29 v.f.) 5 . 8 4 (v.f.) 3.22 1n1) 5.66 (f) 3.05 f ) 5 . 2 6 (m) 2.79 (E) 5.03 (f) 2.70 (f) 4.87 (E) 2.35 ( f ) 4 . 7 1 (v.f.1 2.26 (ii 4 . 1 9 (m) 2.03 (f) 2.00 (v.f.1 '2 Relative intensities determined visually and shown in ~~tircnthcseu, d = r i m a e , m = medium, f = faint, and v.f. = very faint.
followed by the crystalline material. The crude product was then purified by recrystallization from dilute ethanol and wa5 finally obtained in the form of fibrous white needles containing water of crystallization, which was lost upon heating above 100" C. The anhydrous needles melted with decomposition around 237" C. Optical rotation, [ ~ y ] 2 6 " ~ ' = 3 9.8 * l oin a 507, acetone solution. Molecular weight determination by the ehullioscopic method using absolute ethanol as the solvent gave values of 296, 311, and 293 or an average of 300. The crystals were first obtained from wood Sample I1 by extracting the ether-extracted wood meal with acetone. The amount obtained, however, was very small and, inasmuch as Sample I11 was a richer source, it was extracted directly with acetone in order to obtain a larger quantity of the compound. Approximately 21% of the acetone extract from the rapid growth wood sample (0.8% on the basis of the oven-dry wood) was found to consist of this component. The crystals were found to be only sparingly soluble in cold water but very soluble i'n hot water; very soluble in acetone, methanol, ethanol; moderately soluble in ether; and insoluble in petroleum ether and benzene. I n the presence of bromine water, the compound gave an immediate brown precipitate. On the addition of a drop of ferric chloride solution to a dilute solution of the material, a blue-green color immediately developed vhich quickly changed to a pink-violet on the addition of sodium carbonate. No reaction could be obtained with phenylhydrazine or with 2,4-dinitrophenylhydrazine. The fibrous white crystals that were groan on a microscope slide from dilute alcohol solution were found to have anisotropic character. Under the microscope some of the crystals showed oblique and some parallel extinction, indicating that the crystal system was monoclinic. The extinction angle of those showing oblique extinction was found to be 36' measured on the long edge of the crystal. An inclined optic axis interference figure was obtained, the dark interference band being east-west when the crystal was north-south. From the movement of the Becke line, 8 was estimated to be slightly greater than 1.658. The ultraviolet absorption spectrum (Figure 2) was determined by means of a Beckman Model DU photoelectric quartz spectrophotometer. Ethanol, purified by the procedure suggested by Leighton, Crary, and Schipp (18), was used as the solvent. The compound shows an absorption maximum a t 290 millimicrons, with another very strong absorption band in the neighborhood of 220 millimicrons. An inflection in the curve near 318 millimicrons, indicates a concealed maximurn in this region. An absorption band in this region for various compounds related to lignin has been interpreted as a result of an unsaturated group, either an ethylenic bond or a carbonyl group, in conjugation with a benzene ring ( P I ) . A Debye-Schemer photograph of a powdered sample was taken on an XRD powder camera. Copper Kol nickel filtered radiation from an x-ray tube operated at 32.5 kv. and 18 ma. was used on the oscillating specimen for 90 minutes. The diameters of the diffraction rings were measured, and the calculations of
Vol. 41, No. 2
the interplanar spacings in Llnystroin units are given in Tahle 11. Relative intensities were determined visuall>-arid an' s h o r v n in Table I1 also. Acetylation wit.h an excess of acetic anhydride in the presence of pyridine at room temperature for 24 hours and subsequent di1ut.ion with water gave a white granular product. Attempts at recrystallization from dilute ethanol, ether, or dioxane-water medium were unsuccessful. After washing several times vith hot water and drying in a vacuum desiccator, the product melted at 82" to 85" C. An acetyl determination gave 39.4% acetyl which indicatcd the presence of five hydroxyl groups. Methylation of the compound with diazomethane from nitrosomethylurea in an ether solution, and recrystallization from methanol gave light-yellow crystals insoluble in dilute sodium hydroxide and melting a t 159" to 161" C. Oxidation of this methylated product with hot dilute potassium permanganate solution gave veratric acid. The properties of ihe flavanone are summarized in Table 111.
TABLE ITI. PROFIXTIES OF FLAVANONE 3lelting point
[elyo
O
C.
Molecular weight Acet,ate hlothyl eth$r with diasornothane Ferric chloride solution Solubility Cold water Hot water Acetone Alcohol Ethyl ether Petroleum ether Benzene
?37--8 39.8 * 1°in50C/o acetone 300
M.P. 820 t o 8.50 c. 39.4% acetyl M.p. 157' to 161° C. Blue-green color
Sparingly soluble Soluble Very soluble Very soluble Moderately soluble Insoluble Insoluble
n'hile further n-ork was under way on this compound, Pew (89) reported its structure to correspond to 3,5,7,3',4'-pentahydroxyflavanone. T A S ~ IAND N PHLOBAPHESE. The tannin that was isolated from the water-soluble fraction was for the most part still soluble in water after its isolation. A water solution of the material gave a precipitate with gelatin, a green color with ferric chloride, anc a precipitate on boiling with dilute sulfuric acid. These test indicated the tannin to be of the phlobatannin class. A methovy content of 3.47, was found on the tannin which had been ob tained by salting out from the water solution. Russell (23) ha stated that the small percentages of methoxyl reported on tar nine are due to absorbed solvents and are not an integral part I the tannin. In this sample, however, the presence of methox cannot be attributed to solvents. Because larger amounts o f t corresponding phlobaphene were available, the determination the phenolic nucleus was carried out on it rather than on t tannin. In order to compare the tannin isolated from Doug fir wood with other tannins, the ultraviolet absorption spectri wa5 determined in the same manner as for the flavanone. 7 tannin was found to possess an absorption maximum at 287 m microns and to absorb verv strongly in the neighborhood of ' millimicrons. Compared with the spectra of redwood and mix , shape of this spectral curve is very sim phlobatannins (j)the The purified phlobaphene fraction was obtained as a red-hr powder. In order to asceitain the phenolic nucleus resent i a sample of the phlobaphene was dissolved in 2 5 6 potas hydroxide and methylated with dimethyl sulfate. The me ated product, which precipitated from solution, was filtered then oxidized Kith hot alkaline potassium permanganate. P fication of the filtrate from the oxidation and extraction ether yielded a crystalline dimethoxybenzoic acid meltir 176' to 177" C, Mixed melting point determinations 01 acid vith the dimethoxybenzoic acids melting at thls ten ture showed the product to be veratric acid, 3,4-dimethoxyb acid.
INDUSTRIAL AND ENGINEERING CHEMISTRY
February 1949
It can be concluded, then, that the catechol grouping was present in the original phlobaphene. Other workers have shown that phlobaphenes are probably condensation products of the corresponding tannins, since the same phenolic nuclei are found in the two materials. A sample of the phlobaphene, t h a t was boiled three times in water to remove any traces of absorbed organic solvents, was found to have a methoxyl content of 7.7%. This high value of methoxyl compared with the tannin fraction suggests the presence of native lignin in the phlobaphene fraction. I n isolating native lignin, Brauns ( 4 ) purified his material by dissolving in dioxane and precipitating into ether. The phlobaphene fraction isolated here was also soluble in dioxane and was precipitated on the addition of ether. Because of the similar solubilities of the two materials, no method is known by which they can be separated. The ultraviolet aPsorption spectrum of the phlobaphene was measured in the same manner as for the tannin and was found to be very similar to that of the tannin. It also showed a similarity to the spectrum reported for native lignin (6). The spectra of the tannin and phlobaphene are given in Figure 2. The composition of the acetone extract is summarized in Table IV.
413
then treated with acetic acid until a strong odor of acetic acid was obtained. If glucose is present, potassium acid saccharate should be formed under these conditions. None of this material, however, could be isolated. Tests for the presence of mannose were carried out by hydrolyzing the material with 2% sulfuric acid until a reducing sugar determination indicated 94.5% complete hydrolysis, based on galactose. Nearly 14 hours of refluxing in a boiling water bath were necessary to reach this degree of hydrolysis. The hydrolyzate, after neutralization with barium carbonate and concentration under reduced pressure, was treated with phenylhydrazine in acetic acid. After standing in an ice box for 24 hours, no crystals of mannose phenylhydrazone could be obtained. Under identical contitions, the mannose from a known mixture of 90% galactose and 10% mannose could be readily detected. The absence of mannose in this polysaccharide, which appears to be contrary to another report (I@, may possibly be a result of the method of extraction. The present carbohydrate material was obtained by a cold-water extraction. No indication of the method of extraction was given in the other report, but i t is possible that hot water was used. The analysis of the precipitated carbohydrate fraction is given in Table V. SUMMARY AND CONCLUSIONS
TABLE IV.
COMPOSITION OF ACETONE EXTRACT (Yield from wood 3.85%)
% of Total Extract Tannin Phlobaphene and native lignin (1) Ether-soluble Flavanone
1.7 3.7
94.6
21.1
WATER-SOLUBLE COMPONENTS
EXTRACTION AND SEPARATION OF FRACTIONS. The previous
ether and acetone extractions served t o remove the fats, oils, resins, sterols, tannin, +hlobaphene, and crystalline coloring matter from the wood. he extraneous polysaccharide materials in woods, however, are not removed by these solvents, but they can be extracted with water. Accordingly, the acetone-extracted wood from Sample I11 was extracted twice with water at room temperature in large glass jars. On concentrating the extract t o a small volume on a water bath, under reduced pressure, and then adding approximately four volumes of ethanol, more than 70% of the extract was obtained as a flocculent light-colored precipitate. This precipitate was separated by centrifuging. By dissolving the precipitate in a little water, adding ethanol to the point where only a very small amount of recipitate was formed, and then recentrifuging, most of the cogred impurities were carried down with this first precipitate. Subsequent precipitation and separation of the remainder of the material gave a practically ure white substance. After washing the product twice with etEanol and twice with ether, it was obtained as a white powder. The yield was 11.9 grams or 0.89% of the weight of the wood. CHEMICAL NATUREO F PRECIPITATED CARBOHYGRATE. The precipitated white powder showed the following properties: [a]:’ = 23.8 * 1”; it did not reduce a hot Fehling’s solution, but if first hydrolyzed with a few drops of sulfuric acid, it then showed a strong reducing power; and it darkened noticeably around 255 O C. but did not melt below 285’ C. A standard pentosan determination showed the presence of 4.6% pentosan in the material. Using the method of Dickson, Otterson, and Link (7), the powder gave 0.95% carbon dioxide which indicated only 3.8% uronic acid anhydrides. Oxidation with nitric acid gave mucic acid, melting point 213’ t o 214’ C. Since mucic acid is obtained from the oxidation of galactose, it can be concluded that a galactose-yielding material is present in the white powder. A subsequent analysis, according to the Bureau of Standards method (go), showed that 81.4% of the precipitated carbohydrate material was a galactan. In order t o test for the presence of glucose, the filtrate from the mucic acid determination was neutralized with potassium carbonate and
+
The present investigation of three specimens of Douglas fir heartwood has established the presence of constituents not previously reported, and it has revealed certain interesting phenomena. Materials found in this investigation were: oleic, linoleic, lignoceric, and abietic acids; phytosterol; a crystalline flavanone; a catechol tannin and phlobaphene; and a galactan. I n the ether extract, only the fatty acids were present both in the combined and uncombined‘states, the resin acids being iso-, lated only as the free acids. Inasmuch as tannins are soluble only to a limited extent in ether, the isolation of approximately 20% of the ether extract as tannin indicates that this solvent may not give a true measure of the oil, fat, and resin content. From the behavior of the tannin during its isolation, it appears that it may have been chemically associated with some other component and was extracted with it. The source of tl wood sample that is selected for analysis may have a marked effect on the components isolated. Thus, from a comparison of the ether extract from Samples I and 11, it would appear that seasoning decreases the amount of petroleum ethersoluble resin acids that can be isolated. Another difference is the larger content of the flavanone in the rapidly grown wood.
TABLBV. COMPOSTTION OF WATQR-SOLUBLE POLYSACCHARIDE (Yield from wood 0.89%)
% Pentosan Uronic acid anhydride (COS X 4) Galaotsn Undetermined
4.6 3.8 81.4 10.2
The fact that the flavanone could not be extracted directly from the wood with ether but was easily extracted with ether from an acetone extract of the wood, suggests the possibility that Erdtman’s “membrane substances” prevent the ether from originally dissolving this phenolic constituent. I n Douglas fir, however, these membrane substances appear to be only tannin and phlobaphenes and/or native lignin. The close similarities observed between the crystalline coloring matters in wood and their accompanying tannin has led t o the belief that they are structurally related. It has been observed that the flavanone from Douglas fir wood absorbs ultraviolet radiation in wave bands similar t o t h e tannin and that both materials contain a catechol nucleus.
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414
ACKNOWLEDGMENT
The authors are grateful to x-ray data reported here.
Lambert for Obtaining the
LITERATURE CITED
-4nderson, E., J . Bid. Chem., 165, 233-40 (1946). Assoc. of Official Agr. Chemists, “Official arid Tentative Methods of Analysis,” 6th ed., p. 112, Washington, 1946. ENG.CHEM., 7, Aenson, 13. K., and Thompson, T. G., J. IND. 915 (1915). Brauns, F. E., J . Am. Chem. Soc., 61, 2120 (1939). Buchanan, M . A., Lewis, 11, F., and Kulth, E. F., IND.EKG. CHEM..36 907 (1944). Chidester, G.H.,‘ and McGovern, J. N., Paper Trade J., 113, NO.9,34-8 (Aug. 28, 1941). Dickson, A. D., Otterson, H., and Link, K. P., J . Am. Chem. Soc., 52, 775 (1930). Erdtman, H., Suemic Papperstidn., 42, 344-9 (1939) ; Ann., 539,116-27 (1939). Francis, B., Piper, S. €I., and M a l h n , T., PTOC. Rov. SOC.(Lond o n ) , A128, 214 (1930). Frankforter, G. E., and Brown, H. H., Corn. 8th. Intern. Congr. AppL Chem. (.4ppendiz), 25, 359 (1912). Hatch, R. S . , and Holzer, W. F., T A P P I Monograph KO.4, pp. 153-66, 1947. Hibbert, H.. and Phillips, J. B., Can. J . Research, 4 , 1 (1931).
Vol. 41, No. 2
(13) Isenberg, I. H , Buchanan, H. A., and Wise, L. E., Paper Ind. and Paper E7orld, 28, No. 6, 816-22 (September 1946). (14) Jamleson, G. S., “Vegetable F a t s and O h , ” A.C.S. Monogiaph No. 58, 2nd ed., pp. 363, 395, New Yolk, Reinhold PublishingCoro.. 1943. (15) Johnson; C. H., and Cain, R, A., J . $m. Pharm. dssoc., 26, 623 (1937). ( 1 6 ) Kurth, E. F., 11,-D. EXG.CHEM.,25, 192 (1933). (17) Lapworth, A., and Mottram, E. N., J . Chem. Soc., 127, 1628 (1925). - - - ,(18) Leighton, P. A., Craw, R. W., and Schipp, L. T., J . Am. Chem. SOC.,53, 3017 (1931). (18) Lewkowitch, J., “Chemical Technology and bnalysis of Oik, Fats, and Waxes,” 3rd ed., p. 360, London, Macmillan Co.,. 1904. (20) Aratat2. Bur. Stundards ( U . 8.1, Circ. C440, $1. 218 (1942). (21) PatterRon, It. P., and Hibbert, H., J . Am. Chem. SOC.,65, 1862 (1943). (22) Pexv, J. C . , paper presented before 112th Meeting of the -4~1. CHBX.SOC., September 18, 1947. (23) Russell, A., Chem. Revs., 17, 155 (193.5). (24) Technical Association of the Pulp and Paper Industry, “Standards and Suggested Methods” (September 1046). (25) Wolff, H., and Scliolze, E., Chem. Ztg., 38, 369-70 (1914j. \ -
RECEIVED October 13, 1947. Published with approval of t h e hlonographs Publication Committee, Oregon State College, Researoll I’npcr No. 130, School of Science, Department of Chemistry.
From Sodium- Catalyze Copolymerizations W.A. SCHULZE, W. W. CROUCH, AND C. S. LYXCH Phillips Petroleum Company, B a r t l e s d l e , Okla.
A study has been made of the sodium-catalyzed copolymerization of butadiene and styrene with emphasis on the preparation of charge ingredients and sodium catalyst to obtain duplicable results from polymerization runs. A careful control of monomer purity, reaction conditions, and quantity and particle size of the catalyst are required. The process is facilitated by the use of a hydrocarbon diluent to control the heat Qfthe reaction and a wash mill to remove residual catalyst from the copolymers. The products are superior to emulsion-polymerized copolymers in flex life and processing characteristics but are inferior to them in low temperature embrittlement.
HE sodium-catalyzed polymerization of butadiene is an old 7 ) for the process has been employed in Europe production of synthetic rubber. However, it appears that in spite of the superiority of butadiene-styrene copolymers prepared in emulsion systems over polybutadiene from the same process, little Drogress has been made in admting the sodium-catalvzed reaction to the production of these copolymers. There is some evidence (8)that the process was studied in Russia with results which led to the classification of styrene along with 2-butene and other olefins said to have the property of shortening the Pohmer chains, or modifying polybutadiene. Recently, however, Marvel and co-workers (2, 3) showed that by the use of carefully purified ingredients, the copolymerization of 1,3-butadiene with styrene is effected readily with sodium catalyst to give an elastomeric copolymer of interesting physical properties. They proposed the name S-BE3 €or t h i s product. This material was produced in larger quantities in this laboratory for more thorough evaluation. In the course of this work there arose a number of problems related to the preparation of the charge ingredients and to the polymerization of S-BS. This re&
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port describes the most satisfactory process developed and presents results of physical tests on the products. The S-BS polymerization process was not adapted to any known type of conventional large scale polymerization equipment. At the start of the polymerization reaction the disper~ed sodium particles became coated with sticky polymer and usually aggregated a t the bottom or in a corner of the reactor in masses of material which grew upward until the whole charge was converted to solid polymer. Agitation of the reaction mixture, which would be required to disperse the catalyst and provide temperature control in a large reactor, would be extremely difficult in the later stages of reaction. Thus, in preparing a 50pound lot of the copolymer, it appeared advantagrous to make the material in a number of small batches in laboratory pressure vessels rather than to attempt to develop an entirely new type of reactor or charge recipe which would permit the reaction in larger For purposes of this study the following modifications of t h e earlier procedure (3) were made:
~I
Larger reaction vessels, either 3 X 11 inch steel bombs or 32-
ounce glass bottles were used.
d low boiling diluent, usually isobutane was used to control the heat of reaction and reduce gel form;tion. The catalyst was prepared in quantities sufficient for a number of charges rather than individually for each charge. A wash mill was used $0 remove sodium and organosodium from the polymers. PURIFICATION OF CHARGE INGREDIESTS
A typical charge recipe was as follows: Butadiene, 75 parts; styrene, 25 parts; isobutane, 75 parts; and sodium catalyst, 0.30 part. To minimize variations in the purity of the chargc ingredients, they were procured in quantities sufficient for several weeks’ ex-
