Elucidaton of the formation mechanism and characteristics of acid-soluble lignin, and conversion of lignin into functional material

本论文主要研究了酸溶木质素的形成机理和性质，以及木质素的功能化转化。选择具有高度缩合结构的硫酸木质素（SAL）作为木质素样品。（1）酸溶性木质素的形成机理及特性研究山毛榉酸溶性木质素（ASL）由约一半的氯仿可溶性ASL和约一半的水溶性ASL组成。在72%硫酸溶液中，愈创木基木质素和异戊基木质素模型化合物与碳水化合物反应，表明异戊基木质素与半纤维素缩合生成水溶性的ASL。此外，在72%水杨酸中的降解反应表明，丁香基烷基醚键水解形成氯仿可溶性低分子量的SAL降解产物。（2）木质素的功能化研究为开发酸解木质素的有效利用新方法，对SAL酸解木质素的化学转化进行了研究。首先，在水溶性ASL的模型上，以SAL和72%SAL的酚化SAL（p-SAL）为原料，尝试制备以碳水化合物为亲水性基团的中性表面活性剂。然而，缩合型木质素模型化合物与单糖在72%SA中的反应仅以低收率得到预期的C-糖苷。尝试将羧甲基和二甲基氨基甲基引入SAL和/或P-SAL中，成功地从P-SAL以定量产率分别制备可溶性酸性和阳离子表面活性剂。每C_9-C_6单元（对羟基苯基）愈创木基甲基单元的基团含量分别为1.4和1.3。

This research studied on (1) elucidaton of the formation mechanism and characteristics of acid-soluble lignin, and (2) conversion of lignin into functional material. Sulfuric acid lignin (SAL) with highly condensed structures was selected as a lignin sample.( 1 ) Elucidaton of the formation mechanism and characteristics of acid-soluble lligninAcid soluble lignin (ASL) prepared from beech was composed of about half the amount of chloroform-soluble ASL and the rest half the amount of water-soluble ASL. Reaction of guaiacyl and syringyl lignin model compounds with carbohydrates iin 72% sulfuric acid (SA) suggested that water-soluble ASL is formed by condensation of syringyl lignin with hemicellulose. Furthermore, degradation reaction of syringyl lignin model compounds in 72% SA indicated that syringyl alkyl ether linkages are hydrolyzed to form chloroform-soluble low molecular weight degradation products of SAL.( 2 ) Conversion of lignin into functional materialTo develop new methods for effective utilization of acid hydrlysis lignin, chemical conversion of SAL as a typical acid hydrolysis lignin into funcrional material was investigated. at first, preparation of neutral surfactant with carbohydrate component as a gydrophilic group from SAL and phenolized SAL (p-SAL) in 72% SAL on the model of water-soluble ASL was tried. However, reaction of condensed-type lignin model compounds with monosaccharides in 72% SA gave the expected C-glycosides only in low yields. Attempts to introduce carboxymethyl and dimethylaminomethyl groups into SAL and/or P-SAL were successful to prepare soluble acidic and cationic surfactants from P-SAL, respetively, in quantitative yields. The content of the groups was 1.4 and 1.3 per C_9-C_6 unit (p-hydroxypheny) guaiacyl methyl unit), respectively.