KINETICS AND MECHANISM OF OXIDATION OF L-TYROSINE BY THALLIUM(III) IN PERCHLORIC ACID MEDIUM

The kinetics of oxidation of L-tyrosine by thallium(III) was studied at 50 oC in perchloric acid medium titrimetrically using iodometric method. The reaction was found to be first order dependent on [thallium(III)] and fractional order on [tyrosine]. Rate of the reaction increased considerably with increase in ionic strength whereas change in [H+] and [thallium(I)] did not show any significant effect. The main product of oxidation was confirmed as 4-hydroxyphenyl acetaldehyde. A plausible mechanism was proposed invoking complexation between the substrate and oxidant. The energy of activation, Ea and entropy of activation, ΔS≠ for the rate determining step were calculated using linear least squares method and were found to be 109.92 ± 15.24 kJmol-1 and 16.83 ± 47.18 JKmol-1 respectively