Studies On Synthesis Of M-Chlorobenzaldehyde From Benzaldehyde By Direct Chlorination

In the paper,the method of synthesis of m-chlorobenzaldehyde from benzaldehyde by direct chlorination has been studied.According to the references,the capillary column GC quantitative analysis method has been developed to simultaneous determination of the products and the raw material.Anhydrous aluminium is picked out as the better catalyst from many kinds of catalysts.The chlorination rule is researched by experiments and the kinetic equation is built based on the reasonable simplification for the reaction: r=0.6752· exp(-1131.1/T) [Ca] [Wb]. By parameters and orthogonal test,the effects of the concentration of the raw material and the catalyst,reaction temperature and time have been investigated,the optimized conditions for reaction are obtained. The paper also has investigated the process of chlorination,and the results show mat it is a fast reaction and a typical tandem one,the optimized conditions for the reaction are as follows: benzaldehyde 1.33 mol · L-1; anhydrous aluminium 1.70 mol · L-1; reaction time 30min; reaction temperature 50℃.Under the optimized conditions, the conversion of benzaldehyde is over 90%. The overall yield of m-chlorobenzaldehyde is 79% with 88% selectivity and almost have no structural isomer as byproducts.