Picolinic acid promoted oxidative decarboxylation of phenylsulfinylacetic acid by Cr(VI)

Abstract

ABSTRACT. The kinetics and mechanism of picolinic acid promoted reaction of phenylsulfinylacetic acid (PSAA) with Cr(VI) was carried out in aqueous acetonitrile medium under pseudo first order conditions. The reaction follows Michaelis-Menten type of kinetics with respect to PSAA. The catalytic activity by picolinic acid can be interpreted on the basis of the formation of a highly active oxidizing species, Cr(VI)-PA complex. The mechanism involves the formation of a termolecular complex, Cr(VI)-PA-PSAA by the nucleophilic attack of the sulfur atom of PSAA on chromium of Cr(VI)-PA complex in an equilibrium step followed by ligand coupling in a slow step. Electron releasing substituents in the phenyl ring of PSAA accelerate while electron withdrawing groups retard the reaction rate. The overall rate constants for the para-and meta-substituted PSAAs are found to correlate excellently with Hammett σ constants with a very low reaction constant, ρ. .

Synthesis, Characterization, In vitro Antiproliferative and Cytotoxic Effect of Ruthenium(II)-Bipyridine-Benzoylpicolinic Acid Complex on SK-MEL-28 and Normal L6 Cell Lines

“…Picolinic acid has been detected in various biological mediums that include human milk, pancreatic juice, cell culture supernatants, blood serum, cerebrospinal fluid, and intestinal homogenates [15]. Picolinic acidmetal complexes are now widely introduced as bioactive metals into biological systems [16]. The picolinic acid is a strong chelating agent.…”

Electrophilic and nucleophilic pathways in ligand oxide mediated reactions of phenylsulfinylacetic acids with oxo(salen)chromium(V) complexes

“…Even in majority of cases where ligand oxides are used as additive, no effect is observed in epoxidation [28] and sulfoxidation reactions [29][30][31][32][33]. Further, there was no detailed mechanistic study on the oxidation of phenylsulfinylacetic acid (PSAA) except our recent publications on the proximal effects of nitrogen bases with oxo(salen)Cr(V) + ion [34] and Cr(VI) oxidation of PSAA [35] mediated by cetyltrimethylammonium bromide [36], oxalic acid [37] and picolinic acid [38], though PSAA is a versatile synthetic agent used for the synthesis of antibiotics [39] and various organic compounds [40][41][42][43][44]. Out of our much interest on the oxidation studies of sulfur compounds especially with PSAA in the presence of additives and a significant effect observed with ligand oxides, detailed kinetic investigation on the reactions between PSAAs and oxo(salen)chromium(V) complexes in the presence of triphenylphosphine oxide (TPPO), pyridine N-oxide (PyO) and picoline N-oxide (PicNO) has been carried out.…”