GB661783A - Manufacture of vinyl sulphones - Google Patents

Abstract

Vinyl sulphones RSO2CH : CH2, wherein R is a stable monovalent group containing a carbon atom linked to the sulphur atom, are made by heating a mercaptan RSH with ethylene chlorhydrin in alkaline solution to form RSCH2CH2OH, the hydroxyl group of which is replaced by chlorine by heating with hydrochloric acid and the sulphide is oxidized to the corresponding sulphone which is dehydrochlorinated by reaction with an alkali metal hydroxide in aqueous solution to obtain the vinyl sulphone. R may be alkyl or alkaryl groups or aryl groups unsubstituted or substituted with nuclear halogen or alkyl groups and many such groups are specified together with the sulphones obtained therefrom, including propyl, dodecyl, cyclohexyl, naphthyl, tolyl, chlorphenyl and benzyl vinyl sulphones. Crude mercaptans as obtained from petroleum sources or as foreruns from the preparation of aromatic phosphate esters from cresylic acid, may be used. Reaction of the mercaptan with the chlorhydrin is usually effected by refluxing in water or in an inert organic solvent, e.g. methanol, ethanol or dioxane, using the mercaptan as its alkali metal salt. Conversion to a chloro derivative may be effected by refluxing at 110-120 DEG C. with 1-5 mols, of conc. aqueous HCl. Oxidation may be effected by conventional methods, e.g. by 26 per cent aqueous hydrogen peroxide at about 90-120 DEG C. in acetic acid solution. Dehydrochlorination may be effected with 5 to 40 per cent aqueous sodium hydroxide at 20-80 DEG C., preferably 30-40 DEG C. In examples: (1) thiophenol (as the potassium salt); (2) lauryl mercaptan (as the potassium salt); (3) benzyl mercaptan (as the potassium salt); and (4) crude "cresyl" mercaptans obtained as a petroleum purification by-product are converted into the corresponding vinyl sulphones by the methods outlined above, oxidation in the first three cases being with hydrogen-peroxide-acetic acid and in (4) being with sodium bichromate-sulphuric acid.