GB897735A - Improvements in or relating to methods of producing aromatic sulphones - Google Patents

Abstract

A method of producing aromatic sulphones comprises reacting a compound of the formula RH with a sulphohalide of the formula R1SO2X where R represents a phenyl, naphthyl or thienyl residue substituted by at least one halogen atom or by at least one hydrocarbon radical or by at least one ether or thio-ether group or represents an unsubstituted thienyl residue, R1 represents a phenyl or naphthyl residue which may be substituted by at least one halogen atom, at least one hydrocarbon radical or at least one ether or thio-ether group and X represents a halogen atom, the compound RH and the sulphohalide containing no free hydroxyl, sulph-hydryl or amino groups, the reaction being carried out in the presence of a metal (other than alkali or alkaline earth metal) salt of ortho-, meta or pyro-phosphoric acid or a mixture thereof, so that sulphones of the formula RSO2R1 are produced. The reaction is preferably carried out by slowly adding the metal salt and/or sulphohalide to the compound RH at a temperature of 100 DEG C.-150 DEG C. and a diluent such as a nitro-alkene or an excess of the compound RH may be used. The reaction is preferably carried out under anhydrous conditions but to enable the reaction to proceed to completion a trace of water may be added to the reactants. In the examples in which silver, zinc and cadmium salts are used, 4-methoxy-, 4,41-dimethoxy-, 4-methyl, 4-methoxy-41 - chloro - and 2,4,5,41 - tetrachloro - diphenyl sulphone and 4-methoxyphenyl thienyl sulphone are prepared. Specification 761,837 is referred to.