Strain effects in acyl transfer reactions. Part I. The kinetics of hydrolysis of some N-aryl-lactams

The hydroxide ion-catalysed hydrolysis of nine N-aryl-β-lactams have been studied at 298 K with [OH–] ranging from 10–2 to 1M. All show first-order dependence on hydroxide ion at high pH. Their reactivity is markedly increased by electron-withdrawing substituents and correlates well with the Hammett σ– function to give ρ–+ 1·225. The relative rates of hydrolysis of N-methyl-p-nitroacetanilide and of N-p-nitrophenyl δ-,γ-, and β-lactams are 1, 1·5, 14, and 110 respectively. It appears from these data that amides are activated in both steps of hydroxide-catalysed hydrolysis, as a result of angular deformation.