微波辐射杂多酸催化合成7-羟基-4-甲基香豆素的研究

利用微波辐射技术,以乙酰乙酸乙酯和间苯二酚为原料,水为溶剂,磷钨酸为催化剂,通过Pechmann缩合反应合成了7-羟基-4-甲基香豆素(HMC),对结构经熔点仪和红外光谱进行了表征.考察了催化剂用量、原料配比、反应时间、反应温度对HMC收率的影响,确定了适宜的反应条件为:间苯二酚与乙酰乙酸乙酯物质的量之比为1∶1,催化剂用量为2.5%,反应时间为30min,微波炉功率为中高火.在此反应条件下,HMC的收率为94.4%.该合成方法与传统加热法相比,反应速率较大,同时HMC收率从84.5%提高到了94.4%.结果表明,微波辐射作用有效促进了HMC的合成反应.

Synthesis of 7-hydroxy-4-methyl coumarin catalyzed by 12-tungstophosphoric acid under microwave irradiation

12-tungstophosphoric acid was used as catalysts for Pechmann condensation of resorcinol with ethylacetoacetate to synthesize the 7-Hydroxy-4-Methyl Coumarin （HMC） under microwave irradiation in solvent-free condition. The product structure was confirmed by IR and melting point. The results showed that microwave irradiation was contributed to the reaction. Effects of reaction temperature, reaction time, catalyst dosage, mole ratio of resorcinol to ethylacetoacetate on HMC yield were investigated. Under optimal reaction conditions catalyst mass fraction in reaction system 2.5 %, mole ratio of ethylacetoacetate to resorcion 1.0, reaction time 30 min under the conditions of medium-high firepower, yield to HMC is 94.4%. Compared with conventional heat methods, the reaction time was shortened and reaction temperature was decreased and the conversion was increased under the best condition of microwave irradiation method.