Hydrolysis of aryl N-methylaminosulphonates: evidence consistent with an E1cB mechanism

Abstract

The following evidence is consistent with an E1cB mechanism for the hydrolysis of aryl N-methylaminosulphonates: (1) rate constants for the hydrolysis of the title esters are indenpendent of pH in the alkaline region and obey a Brønsted type relationship with a β_1.g.–1·8; (2) the 4-nitrophenyl N-methylamino-ester shows a 10⁸-fold greater reactivity to hydroxide ion than does the corresponding dimethylamino-ester; and (3) increasing the concentration of amine buffer has no effect on the rate constant for the release of 4-nitrophenol from the monomethyl ester but at 1_M-amine concentration all the product is in the form of the sulphonamide.