4063-99-4Relevant academic research and scientific papers
Mechanisms of hydrolysis and related nucleophilic displacement reactions of alkanesulfonyl chlorides: pH dependence and the mechanism of hydration of sulfenes
King,Lam,Skonieczny
, p. 1743 - 1749 (2007/10/02)
pH-rate profiles, primary kinetic isotope effects, deuterium substitution patterns, and pH-product ratios in the presence of added nucleophiles provide evidence for the following overlapping set of mechanisms for the hydrolysis of methanesulfonyl chloride (1) (in 0.1 M KCl at 25 °C): (a) pH ≤ 1-6.7, reaction with water by direct nucleophilic attack on the sulfonyl chloride; (b) pH ≥ 6.7-11.8, rate-determining attack by hydroxide anion to form sulfene (2), which is then trapped by water in a fast step; and (c) pH ≥ 11.8, sulfene formation and sulfene trapping by hydroxide anion; careful inspection showed no sign of sulfene formation in the reaction with water or of direct displacement by hydroxide anion. This pattern, with appropriate variations in the values of pHi (the pH at which two competing mechanisms have the same rate), is apparently general for simple alkanesulfonyl chlorides having at least one hydrogen on the carbon bearing the sulfonyl group. Azide and acetate anions react with 1 below pHi for 1 (6.7) by direct nucleophilic substitution at the sulfur, but above pHi by trapping of the sulfene. 2-Chlorophenoxide anion reacts with 1 below pH 6.7 by both (a) direct displacement to form the ester and (b) elimination to form the sulfene. Above pH 6.7, sulfene is formed from the sulfonyl chloride by reaction with either 2-chlorophenoxide or hydroxide ion; this is followed by trapping of the sulfene with 2-chlorophenoxide, water, or hydroxide. The possibility of the 2-chlorophenoxide anion acting as a general base promoting the reaction of water with either 1 and 2 was examined, but no sign of either process was detected.
