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1989 Fiscal Year Final Research Report Summary

Mechanism and Control of Cleavage of the beta-O-4 Bonds in Lignin

Research Project

Project/Area Number 63560172
Research Category

Grant-in-Aid for General Scientific Research (C)

Allocation TypeSingle-year Grants
Research Field 林産学
Research InstitutionKyushu University

Principal Investigator

SAKAI Kokki  Kyushu University, Department of Forest Products, Associate Professor, 農学部, 助教授 (30015656)

Project Period (FY) 1988 – 1989
KeywordsLignin / beta-Aryl ether / Delignification / Cleavage / Organosolv pulping / Solvent effect / Pulping / beta-O-4 bond
Research Abstract

The beta -omicron-4 bonds in lignin and its model compounds were reductively cleaved to give eugenol and/or isoeugenol during the alcohol-bisulfite pulping at 160 ゚C . The mechanism and the control method of this reductive cleavage has been studied using some dimeric compounds.
1. Mechanism. (1) This cleavage seems to proceed via a quinone method intermediate because non-phenolic, alpha -carbonyl and alpha -methylene models did not produce high yield of isoeugenol. Sulfonation or alkylation at alpha position of the side chain of the quinone method more or less retarded the cleavage reaction under alcohol bisulfite pulping conditions. (2) Cleavage of the beta -syringyl ether was much faster than that of the guaiacyl ether. This strongly suggests that the quinone method formation is not the rate determining step of the cleavage reaction. (3) A reaction mechanism involving single electron transfer from bisulfite anion or from bisulfite radical to the quinone method seems to explain this cleavage reaction well. The possibility of homolytic cleavage is also discussed.
2. Control. (1) The cleavage was extensive in aqueous solutions of some primary and secondary alcohols and in aqueous dimethylformamide but much less extensive in many other solvents including aqueous ethers, tertiary alcohols, ketones, carboxylic acids, amines, a phenol, and a sulfoxide. (2) Concerning solvent concentration, the cleavage proceeded most rapidly in 50 % ethanol. Thus, the cleavage can be controlled to some extents by changing solvents and their concentration. However it is necessary to inhibit sulfonation which is competitive with the cleavage. We should study to solve this problem in the future.

  • Research Products

    (3 results)

All Other

All Publications (3 results)

  • [Publications] 坂井克己: "Cleavage of the β-0-4 Bonds in Lignin Model Compounds by Alcohol Bisulfite Treatment" 木材学会誌. 36. (1990)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] 文星筆: "Wood Processing and Utilisation" Ellis Horwood, 99-104 (1990)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] K. Sakai, T. Takagi, H. Imamura: "Cleavage of the beta-O-4 Bonds in Lignin Model Compounds by Alcohol-Bisulfite Treatment" Mokuzai Gakkaishi.Vol. 36.(1990)

    • Description
      「研究成果報告書概要(欧文)」より

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Published: 1993-03-26  

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