H6P2W18O62/SiO2催化合成4-苯基-6-甲基-5-乙氧羰基-3,4-二氢嘧啶-2(H)-酮

Synthesis of 4-Phenyl-6-methynl-5-ethoxycarbonyl-3,4-dihydropyrimidin-2(H)-ketone usig H6P2W18O62/SiO2 as Catalys

摘要:

采用溶胶凝胶法将Dawson型磷钨酸负载于SiO2上，制备的负载型催化剂H6P2W18O62/SiO2，通过FT-IR，XRD，SEM，TGA等手段对其进行表征。结果表明该Dawson型磷钨酸可以较均匀的分散在SiO2载体上，且在催化合成4-苯基-6-甲基-5-乙氧羰基-3,4-二氢嘧啶-2(H)-酮的Biginelli 反应中表现出较高的催化活性。最佳反应条件为：在固定苯甲醛用量为0.04 mol的情况下，n(苯甲醛):n(乙酰乙酸乙酯): n(尿素)=1:1.5:1.5，催化剂的用量占反应物总质量的2.0%，反应温度为80 ℃，反应时间为75 min。在最优条件下，产品平均收率可达82.3%，催化剂重复利用十次以后收率仍然可达57.2%。

Abstract:

Phosphotungstic acids with Dawson structure(H6P2W18O62) supported on SiO2 were prepared by sol-gel method． The properties of the catalyst were characterized by TGA, FT-IR, SEM and XRD. The results showed that H6P2W18O62 had been well dispersed into the SiO2 support, and the immobilized catalyst exhibited high catalytic activity in the Biginelli reaction for the synthesis of 4-phenyl-6-methyl-5-ethoxycarbonyl-3,4-dihydropyrimidin-2(H)-ketone. The optimized conditions were as follows: fixing benzaldehyde consumption is 0.04 mol， n(benzaldehyde): n(ethylacetoacetate):n(urea)= 1: 1.5: 1.5, the mass ratio of the catalyst to total reactant was 2.0%, the reaction temperature was 80℃, and the reaction time was 75min. The yield of the product could reach 82.3% under the optimum conditions. It also maintained satisfactory catalytic activity for the synthesis of Biginelli compound after 10 rounds of recycling, and the yield was still above 57.2%.