Production of methyl levulinate from cellulose: selectivity and mechanism study
Production of methyl levulinate from cellulose: selectivity and mechanism study
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从纤维素生产乙酰丙酸甲酯：选择性和机理研究
DOI：
10.1039/c5gc00440c
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发表时间：
2015-01-01
期刊：
影响因子：
9.8
通讯作者：
Wang, Yanqin
中科院分区：
文献类型：
--
作者：
Ding, Daqian;Xi, Jinxu;Wang, Yanqin
研究了在甲醇介质中，纤维素在几种酸催化剂存在下醇解制备乙酰丙酸甲酯的反应。发现一种合成的基于固体铝的磷酸盐催化剂对于ML的产生是高度有效的，达到高达56%的ML产率，高于在与我们先前研究中使用的那些相同的反应条件下在水溶液中的LA产率（52%）（绿色化学，2014，16，3846-3853）。更有趣的是，在水中，非常强的刘易斯酸促进LA的形成;但在甲醇中，布朗斯台德酸促进ML的形成。深入研究发现，纤维素醇解反应的机理和中间产物的类型与水不同，需要高的Bronsted/刘易斯酸比（称为B/L酸比）固体催化剂来防止副产物乳酸甲酯和1，1，2-三甲氧基乙烷的生成。这种受B/L酸比影响的反应机理对设计高效催化剂具有重要的指导意义。
The alcoholysis of cellulose into methyl levulinate (ML) in methanol media was investigated in the presence of several kinds of acid catalyst. One of the synthesized solid niobium-based phosphate catalysts was found to be highly efficient for the generation of ML, reaching an ML yield as high as 56%, higher than the LA yield (52%) in aqueous solution with the same reaction conditions as those used in our previous study (Green Chem., 2014, 16, 3846–3853). More interestingly, in water, very strong Lewis acid promoted the formation of LA; but in methanol, Bronsted acid enhanced the formation of ML. In-depth investigation showed that the mechanism and type of intermediates of cellulose alcoholysis in methanol were different from those in water and a high Bronsted/Lewis acid ratio (known as B/L acid ratio) of solid catalysts is needed to prevent the generation of by-products, namely, methyl lactate and 1,1,2-trimethoxyethane. This new-proposed reaction mechanism affected by the B/L acid ratio was very helpful for the design of efficient catalysts.