KINETICS OF THE REACTION OF SULFIMIDES WITH POTASSIUM HYDROXIDE IN METHANOL

Abstract

Abstract The reaction of sulfimides with hydroxide ion in methanol gave the corresponding sulfoxide (the solvolysis product) and/or the corresponding α-methoxysulfide (the Pummerer type product). The pseudo first order rates for the solvolysis reaction and the Pummerer type reaction were determined using a large excess of potassium hydroxide. The rates of the solvolyses are correlated with [sgrave] values and the values of ρ X = +1.2 and ρ Y = +0.8 were obtained for aryl methyl N-aryl-sulfonylsulfimides (p-XC6H4S(NSO2C6H4Y-p)CH3), and both the activation enthalpy and entropy calculated are δH≠ = 18.8 kcal mol−1 and δS≠ = –23.9 e.u. (PhS(NSO2C6H4CH3-p)CH3), respectively. Hammett correlation with [sgrave] values for the Pummerer type reaction gave ρz = +2.0 for N-aryl-sulfonyltetramethylenesulfimides ((CH2)4SNSO2C6H4Z-p), and the activation enthalpy and entropy are δH≠ = 27.9 kcal mol−1 and δS≠ = +13.3 eu ((CH2)4SNSO2C6H4CH3-p), respectively. All these observations suggest that the solvolysis reaction proceeds via the initial nucleophilic attack of hydroxide ion on the sulfur atom of the sulfimide namely via an S N 2 process at the sulfur atom whereas the Pummerer type reaction proceeds by way of the E 1cb mechanism.