PRODUCTION OF TRIFLUOROMETHANESUFONYL CHLORIDE

PROBLEM TO BE SOLVED: To obtain a trifluoromethanesulfonyl chloride that is useful as a starting substance for medicines, agrochemicals, functional materials by reaction of trifluoromethanesulfonic acid with phosphorus trichloride and chlorine in the presence of phosphorus oxychloride under normal pressure. SOLUTION: In the presence of phosphorus oxychloride, one mole of trifluoromethanesulfonic acid is allowed to react with, preferably 0.5-2.0 mole of phosphorus trichloride and chlorine under normal pressure to give the objective compound. The amount of the phosphorus oxychloride to be added is preferably 0.2-3.0-fold weight of the trifluoromethanesulfonic acid. The chlorine is preferably introduced at 10-30 deg.C. In a preferred embodiment, the reaction temperature is set to 70-90 deg.C and the reaction is continued for additional 1-2 hours, after the increase of the inner pressure has stopped. In this reaction, the objective compound, phosphorus oxychloride, additionally, trifluoromethanesulfonic anhydride are formed but they can be separated and purified by distillation.