Environmentally Friendly Synthesis of Benzyl Cinnamate Under Microwave Irrdiation

Water was used as an environmentally benign solvent to directly synthesize benzyl cinnamate from benzyl chloride and cinnamic acid under microwave irradiation. The experiment used K_3PO_4 as a condensing agent and Bu_4NBr as a phase transfer catalyst. The effects of feed amount of raw materials, the microwave irradiation time and the K_3PO_4 concentration on the reaction were investigated. When the microwave power was 750 W, the irradiation time was 30 min, (n(cinnamic acid))∶n(benzyl chloride)∶(n(K_3PO_4))∶n(TBAB) = 1∶2∶1.5∶0.15, the yield is up to 98.6%. Benzyl cinnamate was also surprisingly synthesized by benzyl chloride with cinnamic acid and K_2CO_3 under microwave irradiation and in presence of the phase transfer catalyst without any solvent and inorganic carrier. TBAC solution has the best catalytic capability and the reaction was found to proceed well. When the microwave power was 375 W, the irradiation time was 8 min, n(cinnamic acid)∶n(benzyl chloride)∶n(K_2CO_3)∶n(TBAC)=(1∶2)∶1∶0.075, the yield is up to 98.8%. Hence, this environmentally friendly method of synthesis is quick, convenient and efficient.