Study On Synthesis Technology Of N-acetylsulfanilyl Chloride

P-acetylaminobenzene sulfonyl chloride(P-ASC)is an important intermediate for the synthesis of para esters and sulfonamides.In the traditional synthesis process,acetanilide and chlorosulfonic acid are used as raw materials,stirred tank as reactor,batch production mode is adopted,and P-ASC is prepared by sulfonation and chlorination successively.However,the heat release of sulfonation reaction is large,and the material viscosity increases significantly after the reaction.In order to improve the mixing effect and control the temperature of the reaction system,solid acetanilide is slowly added to a large amount of chlorosulfonic acid in industrial production,which not only has low production efficiency,but also produces a large amount of wastewater due to the significant excess of chlorosulfonic acid.In this paper,the solvent is added to reduce the viscosity of the system,and acetanilide is prepared into a slurry to realize the controllable addition of acetanilide materials.In addition,taking the hypergravity reactor as the sulfonation reactor,the micro mixing process between chlorosulfonic acid and acetanilide is strengthened to avoid the generation of local hot spots,and the material circulation heat transfer method is used to control the temperature rise of the system,so as to reduce the dosage of chlorosulfonic acid and achieve the purpose of continuous production.In this paper,the effects of raw material feeding state and solvent addition on P-ASC synthesis process are investigated,and the P-ASC synthesis process in stirred tank reactor is studied.On this basis,the effects of various process conditions on the yield of P-ASC are investigated by using high gravity reactor as sulfonation reactor and stirred tank as chlorination reactor.The kinetic behaviors of sulfonation and chlorination of acetanilide are studied in a stirred tank.The main conclusions are as follows:(1)By comparing the feeding time,sulfonation reaction time,product yield and product purity,the feeding state of powdered raw materials was determined.By comparing the four factors of product yield,product purity,solvent recovery rate and solvent recovery mode,the suitable addition solvent is tetrachloroethylene.(2)The synthesis experiment of p-asc was carried out in a stirred tank.Under the optimal process conditions of 3 mol / L acetanilide slurry with a feeding rate of 19 ml/min and n(acetanilide): n(chlorosulfonic acid): n(thionyl chloride)= 1:2.6:1.2,the yield of p-asc was 85.7%.(3)Taking the high gravity reactor as the sulfonation reactor and the stirred tank as the chlorination reactor,the yield of p-asc is 91.9% under the optimal process conditions of 3 mol/L acetanilide slurry feeding rate of 40 ml/min,RPB and stirred tank rotating speed of 400 rpm,material circulation volume of 24 L/h,n(acetanilide):(chlorosulfonic acid): n(thionyl chloride)= 1:2.6:1.2.(4)The kinetics of sulfonation reaction and chlorination reaction were studied.The reaction rate constants of each reaction at 50 ℃,54 ℃,58 ℃,62 ℃ and 66 ℃ were obtained.The activation energy of sulfonation reaction and chlorination reaction were 61.78 k J/mol and82.76 k J/mol respectively calculated by Arrhenius formula.