Reactions of metal ions with β-ketoamides

Abstract

The kinetics and mechanisms of the reactions of copper(II), iron (III) and dioxouranium(VI) with acetoacetamide have been investigated in aqueous solution at 25 °C and ionic strength 0.5 mol dm^–3 NaClO₄ using stopped-flow spectrophotometry. Mechanisms have been proposed which account satisfactorily for the kinetic data. Unlike β-diketones where in many instances the metal ion reacts exclusively with the enol tautomer, co-ordination of the amide tautomer of acetoacetamide is favoured by increased basicity of the carbonyl oxygen as a consequence of amide resonance.

Cu²⁺ and Fe³⁺ and Fe(OH)²⁺ react with the keto tautomer of acetoacetamide with rate constants of 10.0, 14.1 and 50 dm³ mol^–1 s^–1 respectively.