Study And Application Of Esterification And Hydrolysis Of Chloroacetic Acid

Being an important intermediate,chloroacetic acid has been widely used in organic synthesis field.With increased purity requirements of chloroacetic acid,the preparation of high-purity chloroacetic acid has attracted much attention.In order to solve the problems of traditional purifying process,namely low purity and high environmental pollution,a novel chloroacetic acid refining process was proposed based on heterogeneous reaction distillation technology.The chlorinated liquid obtained after chlorination was esterified,separated and hydrolyzed to obtain high purity chloroacetic acid product.In this thesis,single factor experiments were used to investigate the effects of various factors on the reaction of methyl chloroacetate synthesis catalyzed with cation exchange resin,and the optimal reaction conditions were determined for synthesizing methyl chloroacetate,methyl dichloroacetate and hydrolysis of methyl chloroacetate.Based on the determined optimal reaction condition,the reaction kinetic equation was fitted too.In order to verify the feasibility of the proposed new process,a small-scale experiment of a reactive distillation column was carried out,and the overhead compositions were determined by gas chromatography.Based on the results of experiments,a novel heterogeneous reactive process was designed for separating chloroacetic acid from dichloroacetic acid,whose operating parameters,i.e.column pressure,theoretical tray number,feed position and reflux ratio,were optimized with Aspen plus,under which the composition of chloroacetic acid for the product was more than 99% and the simulation results were in good agreement with the experimental results.In order to further reduce the energy consumption,condense heat of atmospheric column was used to reboil the bottom liquid of lower pressure column,therefore consumption of utility and cost of equipment were decreased,and total annual cost was reduced by about 15%.In this thesis,the esterification and hydrolysis of chloroacetic acid were studied by single factor and kinetics,and then the esterification and hydrolysis reaction were applied to the purification of chloroacetic acid,and a novel purification process for chloroacetic acid was proposed.The product of chloroacetic acid produced by this process can reach more than 99% and meet the requirements of the high-grade product,as validated by the small-scale experiment and the simulation study.More importantly,no mother liquid is produced during the process,so it is more environment-friendly and sustainable.