甘蔗渣在离子液体1-烯丙基-3-甲基咪唑氯盐中与马来酸酐进行均相酯化反应过程中的结构变化
Structural Changes of Bagasse dusring the Homogeneous Esterification with Maleic Anhydride in Ionic Liquid 1-Allyl-3-methylimidazolium Chloride.
作者信息
Wang Huihui, Chen Wei, Zhang Xueqin, Wei Yi, Zhang Aiping, Liu Shijie, Wang Xiaoying, Liu Chuanfu
机构信息
State Key Laboratory of Pulp and Paper Engineering, South China University of Technology, Guangzhou 510640, China.
College of Forestry and Landscape Architecture, South China Agricultural University, Guangzhou 510642, China.
出版信息
Polymers (Basel). 2018 Apr 13;10(4):433. doi: 10.3390/polym10040433.
The maleation of bagasse could greatly increase the compatibility between bagasse and composite matrixes, and the percentage of substitution (PS) of bagasse maleates could be regulated in the homogeneous system. However, due to the complicated components and the linkages of bagasse, it was difficult to control the reaction behaviors of each component. In this paper, the detailed structural changes of bagasse during the homogeneous maleation in ionic liquid 1-allyl-3-methylimidazolium chloride (AmimCl) were comparatively investigated with the three main components (cellulose, hemicelluloses, and lignin) from bagasse. The PS of the maleated bagasse was 12.52%, and the PS of the maleated cellulose, hemicelluloses, and lignin were 13.50%, 10.89%, and 14.03%, respectively. Fourier translation infrared (FT-IR) and NMR analyses confirmed that the three main components were all involved in the homogeneous maleation. ¹H-C HSQC analysis indicated that the predominant monoesterification of cellulose, diesterification of hemicelluloses and lignin, and the degradation of the three main components simultaneously occurred. Besides, the quantitative analysis from ¹H-C HSQC revealed the relative PS of reactive sites in each component. P NMR results showed that the reactivity of lignin aliphatic hydroxyls was higher than that of phenolic ones, and the reactivity of phenolic hydroxyls followed the order of -hydroxyphenyl hydroxyls > guaiacyl hydroxyls > syringyl hydroxyls.
甘蔗渣的马来酸化可以极大地提高甘蔗渣与复合基体之间的相容性，并且在均相体系中可以调节马来酸化甘蔗渣的取代度（PS）。然而，由于甘蔗渣的成分复杂且存在连接键，很难控制各组分的反应行为。本文比较研究了甘蔗渣在离子液体1-烯丙基-3-甲基咪唑氯盐（AmimCl）中均相马来酸化过程中甘蔗渣的详细结构变化，以及甘蔗渣的三种主要成分（纤维素、半纤维素和木质素）的结构变化。马来酸化甘蔗渣的取代度为12.52%，马来酸化纤维素、半纤维素和木质素的取代度分别为13.50%、10.89%和14.03%。傅里叶变换红外光谱（FT-IR）和核磁共振分析证实，这三种主要成分均参与了均相马来酸化反应。¹H-C HSQC分析表明，纤维素的主要单酯化、半纤维素和木质素的双酯化以及这三种主要成分的降解同时发生。此外，¹H-C HSQC的定量分析揭示了各组分中反应位点的相对取代度。³¹P NMR结果表明，木质素脂肪族羟基的反应活性高于酚羟基，酚羟基的反应活性顺序为：对羟基苯基羟基＞愈创木基羟基＞紫丁香基羟基。
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