固体碱催化丙酮和碳酸二甲酯合成乙酰乙酸甲酯

以碳酸二甲酯(DMC)与丙酮为原料,在固体碱上合成乙酰乙酸甲酯,并考察了反应温度、反应时间、催化剂用量和原料摩尔比等因素对反应结果的影响。结果表明,以固体酸为催化剂时,无乙酰乙酸甲酯的生成,而具有中强碱位的K/MgO对反应具有较好的催化性能。当以K/MgO为催化剂,在反应温度为240℃,反应时间5h,催化剂用量为反应物总质量的1.5%,原料摩尔比为n(丙酮)∶n(DMC)=1∶4时,丙酮的转化率和乙酰乙酸甲酯的选择性分别达到41.2%和50.3%。反应的主要副产物为丙酮自身缩合的产物(二丙酮醇、4-甲基-3-烯基-2-戊酮、4-甲基-4-烯基-2-戊酮)以及醚化产物(2-甲氧基丙烯)等。

Synthesis of Methyl Acetoacetate from Acetone and Dimethyl Carbonate Over Solid Base Catalysts

A novel route for synthesis of methyl acetoacetate from acetone and dimethyl carbonate over solid base catalysts was proposed.The results showed that no products were detected if the catalyst were not presented,and only the aldol condensation products of acetone were detected over solid acids such as Al2O3,which suggested that solid acid catalyst was inactive towards the synthesis of methyl acetoacetate.As for solid base K/MgO,which possessed moderate basic strength,exhibited higher catalytic activity and methyl acetoacetate selectivity than other catalysts,such as ZrO2,La2O3,MgO and CaO.Over K/MgO catalyst,the optimal reaction conditions were: temperature 240 ℃,time 5 h,w(catalyst)=1.5% and n(acetone)∶n(DMC)=1∶4.Under such reaction conditions,the conversion of acetone and the selectivity to methyl acetoacetate reached 41.2% and 50.3%,respectively.The main by-products were the self-condensation products of acetone(diacetone alcohol,4-methyl-3-penten-2-one and 4-methyl-4-penten-2-one) and the etherification product(2-methoxypropene).