Structural insights into the alkali lignins involving the formation and transformation of arylglycerols and enol ethers
Structural insights into the alkali lignins involving the formation and transformation of arylglycerols and enol ethers
复制标题
对碱木质素涉及芳基甘油和烯醇醚的形成和转化的结构见解
DOI：
10.1016/j.ijbiomac.2020.02.241
复制
发表时间：
2020
影响因子：
8.2
通讯作者：
Lu Fachuang
中科院分区：
文献类型：
--
作者：
Zhao Chengke;Li Suxiang;Zhang Han;Yue Fengxia;Lu Fachuang
碱法制浆是造纸工业中最重要的制浆工艺之一，碱法生产的大量碱木质素可用于生产大量的生物燃料、芳香化学品和原料。然而，结构和尺寸相关的异质性和复杂性阻碍了这些方向的发展。在此，我们报告了新的见解，碱木质素的结构，通过调查的形成和转化的烯醇醚和芳基甘油结构是显着负责的结构转变从天然木质素到碱木质素。用2D HSQC NMR方法鉴定了阔叶木碱木质素中由G/S结构单元组成的4种烯醇醚。采用2D HSQC NMR、31 P NMR和凝胶渗透色谱（GPC）对不同温度下桉树纤维素酶木质素碱处理后得到的一系列碱木质素进行了分析。通过分析和相关模型化合物的研究，发现天然β-O-4键形成的芳基甘油有氧化的趋势，芳基醚键进一步降解，烯醇醚键在空气中易水解或氧化。这些见解提高了对碱木质素的结构演化和多样性的机理理解，并将有助于进一步开发木质素的增值策略。
Soda process is one of the most important pulping processes in paper industry producing large quantities of alkali lignins that can afford plenty of biofuels, aromatic chemicals and materials. However, the structural and size-related heterogeneities and complexities hinder the development in these directions. Herein, we report new insights into the structure of alkali lignin, through investigating the formation and transformation of enol ether and arylglycerol structures that are significant responsible for the structural transformation from native lignin to alkali lignin. Four-type enol ethers composed of G/S units in hardwood alkali lignin were identified by 2D HSQC NMR. A series of alkali lignins prepared by alkali treatment of eucalyptus cellulolytic enzyme lignin under various temperatures were analyzed by 2D HSQC NMR,31P NMR and gel permeation chromatography (GPC). Upon these analyses and related model compound studies, it was found that the arylglycerols formed from native β-O-4 linkages tends to be oxidized with the further degradation of aryl ether bonds, and that the enol ether linkages are facile to be hydrolyzed or oxidized in the air. These insights improve the mechanistic understanding for the structural evolution and the diversity of alkali lignins and will aid the development of further lignin valorization strategies.