二苯甲酰甲烷甲基化反应的微波辐射合成法研究

Microwave-assisted synthesis of α-methyl dibenzoylmethane

目的与方法以苯甲酸乙酯和苯乙酮为原料,经克莱森缩合反应制得二苯甲酰甲烷。在相转移催化剂聚乙二醇的存在下,以固体氢氧化钾为碱,二苯甲酰甲烷与碘甲烷在丙酮中,用微波辐射法合成α-甲基二苯甲酰甲烷。结果与结论优化反应条件为:微波辐射功率80 W,微波辐射时间20 m in,n(二苯甲酰甲烷):n(碘甲烷)=1∶4,产率为82.6%,产品结构经IR、MS和元素分析确证。

Dibenzoylmethane was prepared by Claisen condensation of ethyl benzoate and acetophenone. Methylation was carried out by coupling dibenzoylmethane with methyl iodide in basic condition using PEG 600 as the phase transfer catalyst with assistance of microwave irradiation. The optimum conditions were as following： 80 W of microwave irradiation power, 20 min of reaction time, 1：4 molar ratio of dibenzoylmethane to methyl iodide. The yield of a-methyl substituted dibenzoylmethane was 82.6% and the structure of 2- methyl-1,3-diphenyl-1,3-propanedione was confirmed by IR, MS and elemental analysis.