The synthesis of ethyl 2-chloropropinate catalyzed by acidic imidazolium ionic liquids

The synthesis of ethyl 2-chloropropanoate in acidic imidazolium ionic liquids was studied.Four imidazolium ionic liquids were prepared and employed as catalysts in the esterification.Their acidities were measured by Hammett method and the acidity-catalytic activity relationship was investigated.HSO4 was found to be the most efficient catalyst.The effects of reaction time,reaction temperature,the molar ratio of alcohol to acid,the amount of ILs on the yield of n-butyl benzoate were investigated.The optimum esterification conditions were obtained:reaction time was 2h,n(2-chloropropanoic acid)∶n(IL)∶n(ethanol)=1∶1∶2 and reaction temperature was 90℃,The yield of ethyl 2-chloropropanoate was 85.5%and the purity of product detected by GC was 99%under the optimum conditions.Even if the catalyst was repeatedly used for 5 times,the catalytic activity maintains stable.The reusability of the IL was excellent and it could be reuse 5 times without obviously catalytic activity decrease.