Interpretation of the kinetics of general-base-catalysed Smiles rearrangement of 2-(p-nitrophenoxy)ethylamine into 2-(p-nitroanilino)ethanol; rate-limiting deprotonation of a spiro-Meisenheimer intermediate

Abstract

The intramolecular rearrangement of 2-(p-nitrophenoxy)ethylamine to 2-(p-nitroanilino)ethanol occurs by a general-base-catalysed process in aqueous alkali; the attainment of a base-independent rate limit at high base concentration can be attributed to rate-determining formation of a spiro-Meisenheimer intermediate. The reaction kinetics can be interpreted in terms of the specific-base–general-acid-catalysed mechanism or by invoking rate-determining deprotonation of the spiro-Meisenheimer intermediate; the latter inerpretation provides the best explanation of the coefficient β= 0.20–0.35 and curvilinear form of the Brønsted correlation and is consistent with the kinetics of reactions of analogous polynitro systems reported by Bernasconi.