脱氢二香草醇的合成及LCC的形成机理(Ⅱ)

Synthesis of Condensed Lignin Model Compound and the Formation Mechanism of LCC during Kraft Cooking(Ⅱ)

在合成缩合型木素模型化合物——脱氢二香草醇的基础上,模拟硫酸盐法蒸煮过程,将合成的木素模型物和典型的半纤维素组成部分——木糖进行蒸煮,然后利用酸析沉淀木素、乙酸乙酯抽提等方法将蒸煮后的产物分级,并利用FT-IR、13C-NMR对分级后的各个部分进行分析,探讨传统硫酸盐法制浆过程中木素-碳水化合物复合体(LCC)的形成机理。研究发现,脱氢二香草醇在硫酸盐法蒸煮过程中非常稳定,部分脱氢二香草醇与木糖形成LCC连接,未降解的脱氢二香草醇和新形成的LCC主要存在于乙酸乙酯抽提物中,酸不溶物和酸可溶物内都不存在新形成的LCC结构。

Dehydrodivanillylalcohol was synthesized with a modified method as a type of condensed lignin model compound. The technique of FT-IR and ^1H-NMR were used to identify the chemical structure. After the lignin model compound was synthesized, it was cooked by kraft method in existence of xylose. The products from lignin model compounds cooked by kraft method were separated by acidification and ethyl acetate extraction. The combination of infrared spectra analysis and ^13C-NMR were used to identify the lignin-carbohydrate complexes（LCC） formed during kraft cooking. The results indicated that dehydrodivanillylalcohol was very stable during kraft cooking. Most of undegraed dehydrodivanillylalcohol and newly formed LCC structure existed in ethyl acetate extractive. No newly formed LCC structure was found in the acid insoluble residue and acid soluble residue.