杨木自水解液中溶解木质素和胶体木质素的结构特征

摘要

对不同水解强度下杨木预水解液中溶解木质素和胶体木质素(DCL)进行了分离、纯化和结构表征.结果表明:随着自水解温度的增加(Tmax>170 ℃),杨木预水解液中DCL的缩合程度明显增加,与残留在杨木自水解木片中的木质素相比,预水解液中的DCL组分含有更少的脂肪族羟基、更多的缩合型酚羟基和非缩合型酚羟基,以及更高的 S-OH/G-OH 比率,表明预水解液中的木质素更易发生侧链脂肪族羟基的脱水反应、β-O-4的水解反应和木质素分子间的缩合反应.%The dissolved and colloidal lignin(DCL)under different autohydrolysis levels were isolated and purified from the poplar woodchips autohydrolysis liquor,and their structural features were characterized by series of instrumental analysis,i.e.Fourier transform infrared(FT-IR),1H,quantitative 13C,2D HSQC,and 31P nuclear magnetic resonance(NMR)spectroscopies,and gel permeation chromatography/multi-angle laser light scattering(GPC-MALLS).The condensation of DCL in the poplar autohydrolysis liquor remarkably increased with increasing autohydrolysis temperature(Tmax>170 ℃).Comparing with functional groups of the lignin in the autohydrolyzed poplar woodchips,the DCL had less aliphatic-OH groups,containing more condensed phenolic-OH and more non-condensed phenolic-OH groups,and appearing with higher syringyl OH/guaiacyl OH ratios.These results indicated that DCL underwent more sufficient dehydration of side-chain aliphatic-OH,hydrolysis reaction of β-O-4 linkages,and condensation reaction between each lignin units.