Hydrolysis of oxaziridines. Part I. The kinetics of 2-t-butyloxaziridines in strong acids

Abstract

Both reaction rates and carbonyl products for the acid-catalysed hydrolysis of five 2-t-butyloxaziridines in aqueous perchloric acid at 25° are reported. These accord with a mechanism involving the breakdown of an O-conjugate acid intermediate to give either a carbonium ion or an immonium ion structure, which subsequently reacts with water. The importance of each path depends on the nature of the 3-substituent. Several observations suggest that oxygen is more basic than nitrogen for 2-t-butyloxaziridines, and this unusual reversal of basicity reflects steric congestion at the nitrogen atom: pK values for these compounds, based on the h₀ scale of acidity, depend on the nature of the 3-substituent and lie in the range +0·13 to –1·81.