Ready chemical conversion of acid hydrolysis lignin into water-soluble lignosulfonate III: Successive treatment of acid hydrolysis lignin and a lignin model compound by phenolation and arylsulfonation

Abstract

The chemical conversion of red pine sulfuric acid lignin (Klason lignin) (SAL) as an acid hydrolysis lignin sample to water-soluble arylsulfonates of lignin derivation (i.e., phenolized SAL) was investigated. Treatment of phenolized SAL with chlorosulfonic acid followed by alkali hydrolysis gave water-soluble sulfonated products with a sulfonic acid group on their aromatic nuclei quantitatively. The products possess 2.0 SO3Na/C9-C6. In contrast, the content of sulfuric acid group in sulfonated SAL was only 0.33/C9. Chlorosulfonation of 1-guaiacyl-1-p-hydroxyphenylethane as a phenolized guaiacyl lignin model compound revealed that the sulfonyl chloride group was introduced at the para position of an aromatic methoxyl group, the ortho position of a phenolic hydroxyl group, or both. © The Japan Wood Research Society 1999.