PROCESS FOR PRODUCING 4,4'-DICHLORODIPHENYL SULFOXIDE

The invention relates to a process for producing 4,4′-dichlorodiphenyl sulfoxide comprising: (a) reacting thionyl chloride, chlorobenzene and aluminum chloride in a molar ratio of thionyl chloride:chlorobenzene:aluminum chloride of 1:(6 to 9):(1 to 1.5) at a temperature in the range from 0 to below 20° C., forming an intermediate reaction product and hydrogen chloride, (b) mixing aqueous hydrochloric acid and the intermediate reaction product at a temperature in the range from 70 to 110° C. to obtain a crude reaction product comprising 4,4′-dichlorodiphenyl sulfoxide, (c) separating the crude reaction product into an organic phase comprising the 4,4′-dichlorodiphenyl sulfoxide and an aqueous phase, (d) washing the organic phase with an extraction liquid.