稻壳高沸醇木质素的制备与结构分析

稻壳高沸醇木质素(RHL)是通过高沸醇溶剂法制备得到的,借助化学组分分析、红外吸收光普、氢质谱和碳质谱分析法分析其结构性质.把稻壳与70%(90%的丁二醇水溶液混合后,放入高压釜中,在一定的固液比下,加热至200(220℃,保持1.0(3.0小时.加水沉淀后,就可以得到水不溶的RHL.温度越低,木质素的得率也越低;丁二醇浓度越低,木质素得率也将越低.化学分析得到RHL分子量是1939 g(mol-1、残糖量5.12%;核磁共振得到RHL脂肪基对芳香甲氧基的相对强度分别出现在3.5-3.8 ppm和 3.8-4.0 ppm,RHL各单元主要通过β-O-4 和 β-5 碳-碳链链接.利用上述数据计算得到了经典的C9结构模型.

Preparation and characteristic analysis of rice husk high boiling solvent lignin

Rice husk high boiling solvent lignin (RHL) was prepared by high boiling solvent method, and its characteristics was analyzed by using chemical composition analysis, infrared spectroscopy, and ¹H-NMR and ¹³C-NMR spectroscopy. The optimum prepared condition was that the rice husk with 70%–90% aqueous solution of 1, 4-butanediol was mixed with autoclave, under a certain weight ratio of solid raw material and solvent, heated to 200–220°C for 1.0–3.0 h, then water-insoluble RHL was separated from the liquor reaction mixture by water precipitation. Results suggested that the lower digestion temperature and concentration of 1,4-butanediol were both unfavorable for extracting lignin. Chemical weight-average molecular weight of RHL was 1939 g·mol⁻¹, and the residual polysaccharide content was 5.12%. The ¹H-NMR spectra of RHL showed the relative intensity ratio, aliphatic over aromatic methoxyl groups, situated at 3.5–3.8 and 3.8–4.0 ppm, respectively. The results from ¹³C-NMR spectra showed that β-O-4 bond and β-5 carbon-carbon linkage were the major linkages between RHL units. The C₉-formula of RHL was calculated by the experiment data. Foundation items: This study was sponsored by the Research Funding for Key Laboratory of Cellulose and Ligno cellulosics Chemistry, Guangzhou Institute of Chemistry, Chinese Academy of Sciences (No. LCLC-2004-158) and the National Natural Science Foundation of Fujian (No. Z0513015)