杨木自水解液中溶解木质素和胶体木质素的结构特征

Structural Character of Dissolved and Colloidal Lignin in Hydrolysate from Poplar Woodchips Autohydrolysis

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(T_(max)>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）, 1^H, quantitative 13^C, 2D HSQC, and 31^P 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-candensed 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.