Obtained by oxidation and chlorination of p-xylene. 1. The p-xylene and cobalt naphthenate were added into the reaction pot by catalytic oxidation, heated to 90 ° C by air and reacted at 110-115 ° C for 20 H. Cool to room temperature, filter, filter cake with p-xylene wash, dry, get P-methylbenzoic acid. 2. Chlorination add chlorobenzene and p-methylbenzoic acid to the reaction pot, heating to 40 ° C, into nitrogen, stirring evenly. When the temperature rises Chemicalbook to 60 ° C stop the nitrogen gas, switch to chlorine gas, while the light. When the temperature reached 110 ° C within 1 H, the chlorine was continuously permeated at 110-115 ° C for 8 H, so that the amount of chlorine permeated exceeded the theoretical amount. Then stop chlorotonic chloride. Discharge hydrogen chloride from the material. After stopping nitrogen and heating, discharging at 90 ° C, placing overnight, filtering, washing and crystallization with a small amount of chlorobenzene, then washing with a large amount of water, filtering and drying, the finished product was obtained.