Kinetic Studies on the N,N-Type Smiles Rearrangement

Abstract

Abstract The Smiles rearrangement reaction of Dl-2-aminododecanoic acid N-methyl-p-nitroanilide to Dl-2-(p-nitrophenyl)aminododecanoic acid N-methylamide has been investigated in aqueous alkaline media containing 0–50% (v/v) acetonitrile or ethanol at 25 °C. It was found from the pH-rate profile that the reactive species is the free base form of the substrate. Acetonitrile content in the medium appreciably affected the rate with a maximum at ca. 20% in the acetonitrile content. The cationic CTAB micelles accelerated the rate 4.4-fold at pH 10, while the anionic SDS micelles suppressed the reaction almost completely. These effects of solvent and micelles were qualitatively correlated with the transition state of the reaction. A plausible mechanism for this reaction is the Smiles type rearrangement in which a spiro σ-complex is involved. The activation parameters obtained and suppression of the reaction rate by Cu(II) ion are in line with the proposed reaction mechanism.