Organic sulfur mechanisms. 24. Preparation and reactions of 2-hydroxyethanesulfonyl chloride, the first hydroxyalkanesulfonyl chloride

Abstract

2-Hydroxyethanesulfonyl chloride (1a) is readily made by reaction of an aqueous solution of 2-mercaptoethanol (4a) with chlorine. This is the first clearly proved preparation of a compound which is both an alcohol and a sulfonyl chloride. Reactions of 1a with water and alcohols evidently proceed largely by intramolecular cyclization to the transient β-sultone (2a), which then undergoes nuclcophilic ring opening to form the products. In the presence of tertiary amines a minor but significant part of the reaction is shown by deuterium labelling to proceed via hydroxymethylsulfene (14). the principal reaction of which is simply to add the alcohol or water; only a small part, if any, of the sulfene (14) loses the hydroxy¡ group to give the ethenesulfonate derivatives (13 or 22). Aqueous chlorination of 3-mercapto-1-propanol gave 3-chloro-1-propanesulfonyl chloride (5a) and 1,3-propane sultone (2b) with no sign of any 3-hydroxy-1-propanesulfonyl chloride (1b). A mechanism for the aqueous chlorination process invoking a cyclic chlorooxasulfoxoniuin ion (27) is discussed.