The chemistry of nitroso compounds. Part 13. Decomposition of N-nitroso-2-pyrrolidone under basic conditions, an unusual example of nucleophilic catalysed hydrolysis of an amide derivative

Abstract

Kinetic studies are reported for the decomposition of N-nitroso-2-pyrrolidone in neutral and alkaline aqueous buffer solutions at 25 °C, where only products of deamination (hydrolysis) are obtained. This reaction is shown to be catalysed by basic entities and the Brønsted plot so generated has a slope β= 0.66. The absence of significant catalysis by sterically hindered bases (e.g. 2,6-lutidine), the strong catalysis by imidazole relative to HPO₄^2–(k_Imidazole/k_HPO4^2–= 83) and by hydroxide ion relative to imidazole (k_HO^–/k_Imidazole= 4 300), and the observation of a second-order catalytic term for imidazole {Rate =[N-nitroso-2-pyrrolidone](k_A–[Imidazole]+k′_A–[Imidazole]²} are interpreted in terms of an addition–elimination pathway involving nucleophilic attack by the catalyst at the carbonyl carbon atom. The preference for nucleophilic rather than general base-catalysed hydrolysis is related to the enhanced leaving properties of the N-nitrosamine fragment.