Method for producing a 3-trifluoromethyl-benzenesulfonyl chlorides

摘要

PURPOSE:To obtain the titled compound useful as an intermediate for agricultural chemicals, etc., in high yield at a low cost in a short time without forming by-products, by sulfonating benzotrifluorides with fuming sulfuric acid under specific condition and carrying out chlorosulfonylation reaction. CONSTITUTION:Benzotrifluoride expressed by formula I (X and Y are H or halogen) are subjected to sulfonation reaction using fuming sulfuric acid in 20-80%, preferably 30-60% concentration at 30-70 deg.C and then chlorosulfonic acid in an excess amount, preferably in a molar amount of 3-5 times based on the compound expressed by formula I is added to carry out chlorosulfonylation at 20-60 deg.C and afford the aimed 3- trifluoromethylbenzenesulfonyl chlorides expressed by formula II. The above- mentioned method has the following effects. Formation of diphenylsulfones as a by-product, decomposition of trifluoromethyl groups into acid chlorides with the chlorsulfonic acid are suppressed and purification process is not required. equipment cost for waste gas, etc., is low without emitting hydrochloric acid gas and reaction process can be shortened. A low production cost is sufficient, etc.