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E. WEST,W. S. MACGREGOR, T.H. EVANS,I. LEVIAND HAROLD HIBBERT
Vol. 65
insoluble product not being obtained by re-ethanolysis of Acknowledgment.-The authors gratefully mafile ether-soluble lignin. acknowledge the kind financial assistance acAs in the case of maple lignin, the water-soluble spruce corded them by the Canadian Pulp and Paper lignin (G’) could be separated into a petroleum etherinsoluble (J’) and a petroleum ether-soluble (K’) fraction Association. and the latter separated further into a bisulfite (L’), an Summary acid (M‘), a n alkali (N’) and a neutral (0’) fraction. I . Successive re-ethanolyses of ethanol ligFrom the bisulfite and alkali fractions 1-(4-hydroxy-3nins extracted from maple wood under very mild methoxyphenyl)-1,2-propanedioneand Z-ethoxy-l-(4-hyconditions, namely, short-period successive redroxy-3-methoxyphenyl)-l-propanone,respectively, were isolated and identified by the usual methods.3 ethanolyses, bring about depolymerization to low Thus re-ethanolysis of both spruce and maple ethanol molecular weight units to a much greater extent lignin fractions yields the same products as isolated by use than does similar treatment of ethanol lignins of the standard wood ethanolysis procedure and there isolated by the more drastic conditions hitherto would seem t o be no doubt but that the extraction of ligemployed by Hibbert and co-workers in ethanolynin by the action of ethanolic hydrogen chloride involves the previously-discussed’ concurrent polymerization-de- sis extractions of lignin. polymerization changes. The amount of polymerization 2. The results obtained by the re-ethanolysis is evidently greater, and the depolymerization less, in of maple and spruce ethanol lignins support the spruce (a gymnosperm) than in maple (an angiospermi. The fact that l-(4-hydroxy-3-methoxyphenyl)-l,2-pro-theory t h a t t h e action of ethanolic hydrogen chlopanedione and 2-ethoxy-l-(4-hydroxy-3-methoxyphenyl)-ride on wood involves both polymerization and 1-propanone from spruce wood and these two derivatives depolymerization changes. together with their 4-hydroxy-3,5-dimethoxyphenylhonio3. Depolymerization of isolated ethanol liglogs from maple wood are the only, as yet, isolable cleavnins by the action of ethanolic hydrogen chloride age products of each ethanol lignin fraction indicates that they are either primary cleavage products or, as now seems yields the same lignin building units as are obmore probable, stabilized end-products formed from much tained by use of the customary wood ethanolysis more reactive lignin progenitors or units. Hibbert h3-s procedure, viz., 1-(4-hydroxy-3-methoxyphenyl)recently suggested certain chemical structures for the 1,2 - propanedione; 2 - ethoxy 1- (4 - hydroxy - 3 building units of, ligninzb and favors a polymeric form of methoxypheny1)-1-propanone and, in addition, l-hydroxy-3-(4-hydroxy-3-methoxyphenyl)-Z-propanone as best in accordance with the experimental facts, but points for hardwoods only, their 4-hydro~y-3~5-dimethoxyphenyl homologs. out that such structures cannot account for the formation of the 1,Z-diketones. 4. X direct relationship between these simple A more satisfactory hypothesis would now seem to coii- propylphenol units and the more complex ethanol sist in the assumption, based on as yet unpublished work, lignins is established by the isolation of the former that lignin is made up in greater part of units of the from the latter by ethanolysis. hydroxy- and dihydroxyconiferyl alcohol types united t)y oxygen linkages.ab MONTREAL, CAXAuA RECEIVED FEBRUARY 23, 1 9 U 3
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/ C O N T R I B U T I U X FROM T H E
DIVISION OF
I N D U S T R I A L A N D C E L L U L O S E CHEMISTRY,
MCGILLcNIVE,RSIT\’]
Studies on Lignin and Related Compounds. LXVI. The Ethanolysis of Maple Wood B Y €3. WEST,b‘.S. RZACGREGOR, T. H In previous communication^^^^^^ descriptions were given of methods for the isolation of watersoluble ethanolysis products from spruce and maple woods. These “water-soluble oils” represented a mixture of distillable oils (essentially monomeric) and non-distillable resinous material. The presence of the resins was found t o interfere with the fractionation of the oils and to facilitate (1) Cramer, Hunter and Hibbert, THISJOURNAL, 61, 509 (1939). (2) Hunter, Cramer and Hibbert, ibrd , 61, :lG (1930) L 1 ) I
