Oxidative cleavage of α, β-unsaturated compounds by pentachlorohydroxoplatinate(IV) in alkaline medium

Abstract

The kinetics of oxidation of a,b-unsaturated compounds by platinum(IV) in the presence of alkali {[OH ) ] ¼ (1-9) · 10 )3 mol dm )3 } have been investigated over the 303-318 K temperature range . The rate of the reaction is dependent on the first power of the concentrations of substrates, oxidant, and alkali. The rate constant increases with an increase in ionic strength and also with increasing dielectric constant of the medium. The oxidation rates follow the order: ACN > ACONH 2 > ACOO ) . The values of the third order rate constant (k 3 ) for the oxidation of acrylonitrile, acrylamide and acrylate are 1.24, 0.826 and 0.628 mol )2 dm 6 s )1 respectively, at 303 K. The oxidations of the substrates by PtCl 5 (OH) 2) take place by an inner-sphere mechanism. Platinum(IV) is reduced to platinum(II) by the substrates in a one-step two-electron transfer process to give reaction products. The major reaction product, HCHO, is identified from the reaction mixture using i.r. spectrometry, n.m.r. and C, H, N analysis. A tentative reaction mechanism, leading to the formation of products, has been suggested. The activation parameters of the reaction have been evaluated.

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

“…Hexachloroplatinate(IV) (HCP), [PtCl 6 ] 2-, has been used to oxidize a limited number of organic [9][10][11][12][13][14][15][16] and inorganic [17][18][19] compounds in different media. Knowledge of the reactivity of Pt(IV) compounds and their reduction by potential bioreductants, such as amino acids, is important for understanding the mechanism of antitumor activity as well as for designing new compounds with fewer side effects.…”

Kinetics and Mechanistic Approach to the Oxidative Behavior of Biological Anticancer Platinum(IV) Complex toward ‐Asparagine in Acid Medium and the Effect of Copper(II) Catalyst

“…The anticancer activity of platinum(IV) complexes is likely to be due to effective Pt IV transport into the cell, followed by reduction to the more reactive platinum(II) compounds. Studies of oxidation of inorganic and organic substrates using platinum(IV) complexes in the form of hexachloroplatinate(IV) (HCP), [PtCl 6 ] 2− , as an oxidant are scarce and limited to a few cases , in which [PtCl 6 ] 2− may behave as one‐ or two‐electron oxidant, depending on the substrate and experimental conditions. The knowledge of the reactivity of platinum(IV) compounds toward their reduction by a potential bioreductant like l ‐asparagine may be important for understanding the mechanism of where antitumor activity as well as for designing new compounds with the least side effect.…”

Oxidative Degradation ofl-Isoleucine by Au3+Complexes in Weakly Acid Medium: A Kinetic and Mechanistic Investigation

“…The intermediate complex undergoes decomposition in a slow rate‐determining step to produce an iminic cation and the latter, through fast hydrolysis, yields the reaction product, 2‐methylbutanal, which was confirmed by 1 H NMR spectroscopy (discussed in the Experimental section). Like Pt(IV) , in this case Au(III) behaves as a two‐electron transfer oxidant and is reduced to Au(I).…”