Process for the preparation of diaryl sulphides and diaryl selenides

摘要

Diaryl sulphides and diaryl selenides of formula:P PAr-- X--ArPPwhere X=S or Se and Ar=aryl are made by the action of sulphur and sulphur dioxide or selenium and selenium dioxide on a compound of formula:PPAr--HPP The process is especially useful for the preparation of phenothiazines of formula ##STR1## in which X=S or Se and Z and Z.sub.1, which may be identical or different, are each hydrogen, halogen, alkyl or alkoxy.