Silver(I) catalysis of oxidative deamination and decarboxylation of l-asparagine and l-histidine by platinum(IV) in perchloric acid solutions: A comparative kinetics study

Silver(I)-catalyzed oxidation of two amino acids (AA), namely L-asparagine and L-histidine, with platinum(IV) as hexachloroplatinate(IV) ion (HCP) has been investigated in perchloric acid solutions at constant ionic strength of 2.5 mol dm−3 and at 25 °C. The courses of the oxidation reactions were followed spectrophotometrically. The kinetics of oxidation of both amino acids by HCP are identical, being first order in [HCP] and fractional-first orders with respect to [AA], [H+] and [Ag(I)]. The rates of both reactions decrease with increasing ionic strength and dielectric constant of the media. Addition of small amounts of Cu(II) and Al(III) increases the rates of reactions. Raising temperature enhances the rates. Amino acids are oxidized to form the corresponding aldehydes, ammonium ion and carbon dioxide. The rate law associated with the reaction mechanism is deduced. Activation parameters of the catalyzed oxidation reactions have been evaluated and discussed.