摘要:
132 CHEMICAL COMMUNICATIONS A Further Proof of the Identity of Natural and Biosynthetic Lignin BY K. FREUDENBERG and H. NIMZ (Organisch-Chemisches Xnstitut der Universitat Heidelberg, and Forschungsinstitwt f u r die Chemie des Holzes und der Polysaccharide, Tiergavtenstrasse, Heidelberg, Germany) THE detection of aryl benzyl ethers in ligninl prompted us to cleave these labile linkages care- fully so that no subsequent condensations of the condensation products occur. In this way, minute amounts of those dilignols have been obtained from spruce ligni11.~9~ They form the main inter- mediates of the preparation of artificial lignin by dehydrogenation of coniferyl alcohol, viz., de- hydrodiconiferyl alcohol, pinoresinol, and guaiacyl- glycerol /3-coniferyl ether. Degradation of spruce lignin gave in addition a new cleavage product, the crystalline diguaiacylpropanediol (I) .2 9 4 Recently two trilignols and even a tetralignol in which the propanediol (I) occurs have been obtained by degradations.In our opinion, since lignin synthesis follows the same course in vitro and in vivo, (I) ought to occur among the products of dehydrogena- tion of coniferyl alcohol. After the properties of (I) had been studied, a substance was detected, among the numerous products which accompany the crude guaiacyl- glycerol /3-coniferyl ether formed on dehydrogena- tion of coniferyl alcohol, with chromatographic properties which suggested that it was the pro- panediol (I). Vast losses were however incurred during its isolation. The propanediol (I) has a remarkable charac- teristic: on heating in aqueous alkali or acid it loses formaldehyde and water forming 4,4’-di- hydroxy-3,3’-dimethoxystilbene (11), a stable com- pound with a charactistic fluorescence.This material was discovered during alkali treatment ofNUMBER 5, 1966 133 spent sulphite liquors from spruce5 and has since been frequently encountered, most recently as a. conversion product from spruce milled-wood lignhg Apart from its fluorescence the stilbene can be readily recognized by its chromatographic behaviour. It is a central question in lignin chemistry whether lignin is produced in Pu’ature as it is in vitro by dehydrogenation of coniferyl alcohol and its congeners. There are strong arguments in favour of this belief. Here we have another oppor- tunity of testing it, since, if this belief is correct, the propanediol (I) should also occur among the dehydrogenation products or be detectable in the form of the stilbene.This expectation has been fulfilled. Both artificial lignin made from coniferyl alcohol and the fraction of the lignification intermediates sus- pected to contain (I) were treated with alkali. The stilbene (11) was definitely detected in the resultant reaction mixture by its fluorescence and its behaviour on chromatography in three solvent systems. After methylation, the methyl ether of (11) has also been detected. HJCOH & OH (Received, January 26th, 1966; Corn. 048.) K. Freudenberg, J. M. Harkin, and H.-K. Werner, Chem. Bet‘., 1964, 97, 909. K. Freudenberg, C.-L. Chen, J. M. Harkin, H. Nimz, and H. Renner, Chem. Comnz., 1965, 224. H. Nimz, Chem. Ber., 1965, 98, 533. H. Nimz, Chem. Ber., in the press. 5 H. Richtzenhain and C. v. Hofe, Ber., 1939, 72, 1890. 8 I<. Lundquist, A d a Clzem. Scand., 1964, 18, 1316.
ISSN:0009-241X
DOI:10.1039/C19660000132
出版商:RSC
年代:1966
数据来源: RSC