Transition metal-catalyzed oxidation of l-asparagine by platinum(IV) in acid medium: a kinetic and mechanistic study

Abstract

Kinetic investigations of Pt(IV) oxidation of L-asparagine catalyzed by transition metals with different valencies, namely Ag(I), Pd(II), Cr(III) and Zr(IV), were studied spectrophotometrically in sulfuric acid medium at constant ionic strength and temperature. The reaction was first order in [Pt(IV)], while the orders with respect to the concentrations of Asn, sulfuric acid and transition metal were less than unity over the concentration range studied. The rate constants decreased with increasing ionic strength and dielectric constant, while increasing temperature enhanced the rate. The order of catalytic efficiency was: Ag(

A Comparative Kinetic Study of Silver(I)-Catalyzed Oxidations of Alanine and Valine by Platinum (IV) in Perchloric and Sulfuric Acids Solutions

“…The observed enhancement of the oxidation rates upon increasing acids concentration with the less than unit order dependences suggests [39] that the protonated forms of the amino acids may be considered as the kinetically reactive species in the rate-determining step, which play the main role in the reactions kinetics. The less than unit order dependences with respect to the concentrations of the amino acids suggests formation of intermediate complexes between amino acids and Ag I catalyst as reported earlier [17,18,21] owing to the availability of the electron pairs on both oxygen atom of the carboxylate group and nitrogen atom of the amine group in the amino acids. Within the protolytic amino acids systems, the carboxylate and amine groups may act as nucleophiles, depending on pH of the medium.…”

“…Platinum (IV) complexes have increased interest in the last decades due to their remarkable anticancer properties [24][25][26][27]. Kinetic studies on the oxidation of inorganic and organic substrates using one of the platinum (IV) complexes such as hexachloroplatinate (IV) complex, [PtCl 6 ] 2-, are scarce and limited to a few cases [15][16][17][18][19][20][21][28][29][30][31], in which [PtCl 6 ] 2-may behave as one or two electron oxidant, depending upon the substrate and experimental conditions. The knowledge of the reactivity of platinum (IV) compounds towards their reduction by potential bioreductants such as alanine and valine may be important for understanding the mechanism of where antitumor activity as well as for designing new compounds with the least side effect.…”

“…Transition metal ions have been widely employed as homogenous catalysts for oxidation of organic and inorganic substrates [12][13][14][15][16][17][18][19][20][21][22] by different reaction pathways such as formation of complexes with the reactants, oxidation of a substrate, or the formation of free radicals [32]. Kinetic investigations on the oxidation of amino acids catalyzed by different metal ions are an important field of chemistry due to the role played by metals in biological systems.…”

Ruthenium(III)-Catalyzed Oxidation of Vanillin by Anticancer Hexachloroplatinate(IV) Complex in Perchloric Acid Solutions: A Kinetic Study

“…Platinum(IV) complex in the form of hexachloroplatinate (IV) (HCP), [PtCl 6 ] 2− , has been used to oxidize a limited number of inorganic [12][13][14][15][16] and organic [17][18][19][20][21][22][23][24][25][26][27][28][29] compounds in different media. Knowledge of the reactivity of Pt(IV) compounds and their reduction by potential bioreductants, like vanillin, is important for understanding the mechanism of antitumor activity as well as for designing new compounds with fewer side effects.…”

“…Transition metal ions have been widely employed as homogenous catalysts for oxidation of organic and inorganic substrates [22][23][24][25][26][27][28][29]31] by different reaction pathways such as formation of complexes with the reactants, oxidation of a substrate, or the formation of free radicals [32]. The present study deals with the oxidative behavior of hexachloroplatinate(IV) with vanillin in the presence of ruthenium(III) catalyst in order to explore the kinetic and mechanistic aspects of such redox reaction in a strong acid medium.…”