Reversible and Irreversible ElcB Mechanisms in the Hydrolysis of 2,2,2-Trifluoroethanesulfonyl Chloride: Carbanion Intermediates in Aqueous Acid(1).

Hydrolysis of 2,2,2-trifluoroethanesulfonyl chloride (1) is shown to take place by way of the sulfene (CF(3)CH=SO(2)), formed by (a) an irreversible E1cB process over the pH range 1.8-5 with water acting as the carbanion-forming base in the lower pH range and hydroxide anion at higher pH, and (b) a reversible E1cB reaction in dilute acid.