The production of alkyl levulinates from furfuryl alcohol (FAL) in alcohol media was investigated at moderate temperature in the presence of Brønsted acidic ionic liquids. The reaction was examined and optimized under batch conditions, where it was found that furfuryl alcohol was rapidly and almost quantitatively converted into intermediate products including 2-alkoxymethylfuran and 4,5,5-trialkoxypentan-2-one, and high alkyl levulinates yield of 95% can be achieved after reaching a steady state in 2 h. An advantage of this catalyst system is that undesired dialkyl ether (DEE) formed by a side reaction of the dehydration of alcohol is negligible. The Hammett method was used to determine the acidities of these ionic liquids, which indicated that the acidity and the molecular structure have strong effects on the catalytic activity of ionic liquids. Based on the experimental results, a possible mechanism for the alcoholysis of FAL is proposed.
在中等温度下,在布氏酸性
离子液体的存在下,研究了在
酒精介质中从
糠醇 (FAL) 生成左旋烷基
乙酸酯的过程。在批处理条件下对反应进行了研究和优化,发现
糠醇可快速且几乎定量地转化为包括 2-烷氧基甲基
呋喃和 4,5,5- 三烷氧基戊-2-酮在内的中间产物,在 2 小时内达到稳定状态后,烷基左旋
维甲酸的收率可高达 95%。利用 Hammett 方法测定了这些
离子液体的酸度,结果表明酸度和分子结构对
离子液体的催化活性有很大影响。根据实验结果,提出了 FAL 醇解的可能机理。