固体碱催化酮类化合物与碳酸二甲酯合成β-酮酸酯的反应研究

Synthesis β-ketoesters with the Reaction of Dimethyl Carbonate to Ketones Over Solid Base

以固体酸碱为催化剂,研究了碳酸二甲酯与酮合成β-酮酸酯的反应,并考察了不同固体碱对反应的影响,并探讨了反应规律和反应机理。实验结果表明,固体酸催化剂不利于β-酮酸酯生成,而具有中强碱位的MgO对反应具有较好的催化活性。碳酸二甲酯和酮反应必须要求酮有α-H的存在,而且反应活性与酮的酸性有关,酮的pKa值越低,酸性越强,酮的活性也越高。另外,反应的副产物主要酮自身缩合和酮甲基取代的产物。

The synthesis of β-ketoesters was carried out from ketones and dirnethyl carbonate in the presence of solid base catalysts. The results showed that solid acid catalyst such as Al2O3 and H β were inactive towards the synthesis of β -ketoesters. The solid base catalysts, MgO, which possessed moderate basic strength, exhibited higher catalytic activity. The reactivity of aliphatic and aromatic ketones for the methoxycarbonylation was closely related to their acidities, and the scope of the methoxycarbonylation of DMC with ketones seemed to be limited to the ketones with α -H. The main by-products of the reaction were the self-condensation products of ketones and the methylated products.