Synthesis Of 3,5-dichloro-benzoyl Chloride

3,5-Dichlorobenzoyl chloride is an important pharmaceutical and pesticide intermediate, the derivatives gained by reacting with amino acid occupy an important position in bioapplication.In this paper, 3,5-dichlorobenzoyl chloride is prepared by decarbonylation reaction or thermal decomposition synthesis method. It have initially got suitable synthetic methods by single factor experiment to study the key factors of each reaction step:3,5-dichlorobenzoyl chloride is prepared from isophthalic acid by acyl chlorination,ring chlorination and decarbonylation.3,5-dichlorobenzoyl chloride is prepared from m-xylene by side chain chlorination,ring chlorination, hydrolysis and decarbonylation.3,5-dichlorobenzoyl chloride is prepared from Benzoic acid by ring sulfonation acyl chlorination, and thermal decomposition.Through the above three methods of single factor experiment and optimum condition is gained:The first method to optimize the process conditions as follows: In isophthalic acid as the raw material, the process of synthesisof isophthaloyl dichloride, the reaction temperature is 60 ℃, n(isophthalic acid): n(thionyl chloride) = 1: 3, m(DMF): m(isophthalate) = 1%, the yield is 87.5%, the purity is 99.6%;In the process of Synthesis of 5-chloro-Isophthaloyl dichloride, the reaction temperature was 280 ℃,m(ferric chloride): m(isophthaloyl chloride) = 1%, the yield is 54.5%, the purity is94.6 %The second method to optimize the process conditions as follows: m-xylene as a starting material, the synthesis process of 1,3-bis(trichloromethyl) benzene, the reaction temperature was 110℃, n(1,3- bis(trichloromethyl) benzene): n(m-Xylene)= 1:1, the yield is 92.5%,the purity is 99.4%,In the process of synthesis of5-chloro-1,3-bis(trichloromethyl) benzene, the reaction temperature was 100 ℃, m(ferric chloride): m(1,3- bis(trichloromethyl) benzene) = 1%, the yield is 82.4%, thepurity is 96.0%;In the process of synthesis of 5-chloro-Isophthaloyl dichloride, the reaction temperature was 130℃, m(ferric chloride): m(5-chloro-1,3-bis(trichloromethyl) benzene) = 1%, the yield is 94.5% the purity is 98.3%;In the process of synthesis of 3,5-dichlorobenzoyl chloride the reaction temperature was290 ℃, m(Pd / Al2O3): m(5-chloro-Isophthaloyl dichloride) = 1%,the yield is 87.5%the purity is 99.2%;The third method to optimize the process conditions as follows: benzoic acid as a starting material,the synthesis process of 3,5-disulfonate acid the reaction temperature was 220 ℃, n(sulfur trioxide) / n(benzoic acid) = 2.2: 1,the yield is86.5%;In the process of synthesis of 3,5-sulfonyl chloride chloride, the reaction temperature is 120 ℃, n(phosphorus oxychloride) / n(benzoic acid) = 3, the yield is80.4%;In the process of synthesis of 3,5-dichlorobenzoyl chloride, the reaction temperature was 140 ℃,the yield is 79.6%.In summary the yield(calculated by the main raw material) and the purity of3,5-dichloro-benzoyl chloride is above 60% and 90%, respectively, and quality satisfies the commercial requirement.For intermediates and products Conducted nuclear magnetic resonance spectroscopy and infrared spectroscopy.