Kinetics and mechanism of oxidation of chalcones by trichloroisocyanuric acid [TCICA] in HOAc-HClO₄ medium

Abstract

The kinetics and mechanism of oxidation of chalcone and some substituted chalcones by trichloroisocyanuric acid (TCICA) has been investigated at 313 K in HOAc-HClO₄ medium. The reaction has been found to be first order each in [TCICA] and [Chalcone] and fractional order in [H⁺]. There is no kinetic or spectral evidence for the formation of complex between TCICA and Chalcone. The rate increases with increase in percentage of acetic acid and [Cl⁻]. The products of oxidation have been identified as phenyl acetaldehyde and benzoic acid. The reactive species of oxidant have been established as HOCl and H₂OCl⁺. The rate increases with electron releasing groups in the benzaldehyde moety and vice versa with a Hammett’s ρ value of –0.45. A suitable mechanism involving the chalcone molecule and the reactive species of TCICA in the rate determining step has also been proposed.