The kinetics and mechanism of the acid-catalysed hydrolysis of N-vinylpyrrolidin-2-one

Abstract

The kinetics and mechanism of the acid-catalysed hydrolysis of N-vinylpyrrolidin-2-one (1) has been studied using n.m.r. spectroscopy and spectrophotometry. At temperatures near 0 °C N-(1-hydroxyethyl)pyrrolidin-2-one (3) is the main product. At higher temperatures this decomposes into acetaldehyde and pyrrolidin-2-one (4) and the latter reacts with an excess of N-vinylpyrrolidin-2-one to give 1,1-bis-(N-2-oxopyrrolidinyl)ethane (5). The rate-determining step of the hydrolysis reaction has been established as proton transfer to N-vinylpyrroldin-2-one and the reaction conforms to a general acid catalysis mechanism. A Brønsted exponent value of 0.68 ± 0.03 was obtained with a series of carboxylic acids.