Ph Optimization Of Nucleophilic Reactions And Mechanisms Of Reactions Of Sulfonyl Chlorides

This thesis consists of four chapters all involving the chemistry of sulfonyl chlorides in water.;Chapter 1 describes the mechanisms of the reactions of alkanesulfonyl chlorides with water with and without added nucleophiles. Evidence is provided that the hydrolysis of alkanesulfonyl chlorides proceeds (a) at low pH, by S{dollar}\sb{lcub}\rm N{rcub}{dollar}2-S attack of water, (b) at intermediate pH, by rate determining attack of hydroxide anion to form sulfene which is then trapped by water, and (c) at high pH, by way of sulfene both formed and trapped by hydroxide anion. Among the following pathways observed in the reaction of alkanesulfonyl chlorides with nucleophiles are the following: (i) direct displacement to form RSO{dollar}\sb2{dollar}Nu; (ii) elimination to form RR{dollar}\sp\prime{dollar}C=SO{dollar}\sb2{dollar}; (iii) hydrolysis of the sulfonyl chloride assisted by the nucleophile acting as a general base.;In Chapter 2, a general equation giving pH{dollar}\sb{lcub}\rm max{rcub}{dollar}, the pH giving the highest possible yield of the product for a reaction in water containing both nucleophile and hydrolysable electrophile, is derived. Analogous approximate equations for maximum selectivity for reaction at either of two nucleophilic sites are also deduced. Plots of yield versus pH calculated from related equations accord with observed yields for reactions under pseudo-first-order conditions. Preparative experiments give excellent yields of clean products under conditions optimized in accord with the general equation.;Chapter 3 presents the synthesis and characterization of cyclopropanesulfonyl chloride. The pH-rate profile, primary kinetic isotope effects, and pH-product ratio profiles provided evidence for the sulfene cyclopropanethione S,S-dioxide as the intermediate in the reaction with aqueous hydroxide anion. Reaction with triethylamine and 2-propanol in dichloromethane gave further evidence for the intermediacy of cyclopropanethione S,S-dioxide. No sign of any rearranged cyclopropanethione S,S-dioxide product was seen.;Chapter 4 reports the reaction of trimethylsilylmethanesulfonyl chloride with water with and without other reagents. Evidence is presented that the former reactions proceed (a) at low pH, by S{dollar}\sb{lcub}\rm N{rcub}{dollar}2-Si attack of water to give sulfene, (b) at high pH, silicophilic attack of hydroxide to give sulfene, and elimination to form trimethylsilylsulfene