Abstract:
Comparative study of the kinetics of oxidation of
phenylpropanolamine hydrochloride (PPA) by chloramine-B (CAB)
and chloramine-T(CAT) catalyzed by Pd (II) chloride in
perchloric acid médium has been studied at 308 K. Addition of mercuric
acetate ions and the reduction product of oxidants,
benzenesulfonamide (BSA),methyl benzene sulphonamide have no
significant effect on the rate of reaction. Reaction follows
first order kinetics in case of oxidants and Pd(II)chloride.Increase
in [H+] showed positive effect in case of chloramines-B
oxidation while showed negligible effect in case of chloramines-T
oxidation.Addition of chloride ions showed negligible effect in
case of Chloramine-B while positive effect in case of
chloramines-T. Phenylpropalamine (substrate) followed zero orde
kinetics in case of both oxidants. The reaction was studied at
different temperatures and the activation parameters have been
computed from the Arrhenius plot. The stoichiometery of the
reaction was found to be 1:1 and the main oxidation producís of
PPA were found to be benzaldehyde and acetaldehyde.Formation and
decomposition constant of Oxidant-PPA complexes in the reaction
scheme have been evaluated. The conjúgate acid C6H5S02NHCl,and
CH3C6H4S02NHCl has
been assumed to be the reactive species of chloramine-B and
chloramines-T respectively.The observed results have been
explained by plausible mechanisms and relative rate law has been
deduced.
Keywords: Phenylpropanolamine hydrochloride, chloramine-B,chloramine-T,
oxidation Kinetics, Pd(II)-catalysis, perchloric acid medium.