磷钨酸离子液体催化合成乙酸苄酯

Synthesis of benzyl acetate with phosphotungstic acid ionic liquid as catalyst

乙酸苄酯的工业合成法中,常使用液体质子酸作催化剂,该方法存在设备腐蚀,酸废液处理操作繁琐和环境污染的问题。新近报道的磷钨酸功能化离子液体催化剂,具有酸活性高,易于与产物分离,可回收再利用等优点。本文以乙酸和苄醇为原料,比较了磷钨酸、磷钨酸质子化咪唑和含丙磺酸基团和磷钨酸杂多基团离子液型化合物,催化合成乙酸苄酯的情况。考察了催化剂用量、酸和醇摩尔比、反应温度和反应时间等因素对合成乙酸苄酯产率的影响。结果表明:磷钨酸离子液体催化剂具有较高的催化活性,其用量为苄醇用量的0.2%摩尔百分比、酸与醇摩尔比为2∶1、温度110℃、反应5h,乙酸苄酯产率可达95.52%。催化剂重复使用五次后,乙酸苄酯产率仍能达到84.15%,为乙酸苄酯的合成提供了一种环境友好的方法。

Various liquid proton acids have been used as catalysts for the industry synthesis of benzyl acetate by esterification.However,these acids are extremely corrosive and contaminative and need to be neutralized at the end of the reaction.The phosphotungstic acid ionic liquid catalyst,recently reported,had the advantages of high acid activity,easy separation of catalyst and product,and the recovery and reuse of catalyst.In this paper,the esterification of acetate acid and benzyl alcohol was carried out using H3PW12O40、[MIM]3PW12O40,,and[MIMPS]3PW12O40as catalysts.The effects of amount of phosphotungstic acid ionic liquid catalyst,mole ratio of reactants,reaction temperature,and time on yields of benzyl acetate were investigated.The results showed that benzyl acetate can be obtained with 95.52% of yield under optimized conditions,0.2mol %catalyst,2 ∶1 molar ratio of acetic acid to benzyl alcohol,and at 110 ℃ for 5 h.Moreover,the catalyst could be reused continuously 5 times to give benzyl acetate in 84.15% of yield.Therefore,an environmental friendly approach for the synthesis of benzyl acetate was developed with the ionic liquid catalysts.