Oxovanadium(IV)-Salen Ion Catalyzed H₂ O₂ Oxidation of Tertiary Amines to N -Oxides- Critical Role of Acetate Ion as External Axial Ligand

Abstract

The oxovanadium(IV)-salen ion catalyzed H 2 O 2 oxidation of N,N-dimethylaniline forms N-oxide as the product of the reaction. The reaction follows Michaelis-Menten kinetics and the rate of the reaction is accelerated by electron donating groups present in the substrate as well as in the salen ligand. This peculiar substituent effect is accounted for in terms of rate determining bond formation between peroxo bond of the oxidant and the N-atom of the substrate in the transition state. Trichloroacetic acid (TCA) shifts the λ max value of the oxidant to the red region and catalyzes reaction enormously. The cleavage of N-O bond by vanadium complex leads to moderate yield of the product. But the percentage yield of the product becomes excellent in the presence of TCA. C 2015 Wiley Periodicals, Inc. Int J Chem Kinet 47: [315][316][317][318][319][320][321][322][323][324][325][326] 2015

Impact of added ligand oxides in the sulfoxidation of phenylmercaptoacetic acids with oxovanadium(IV)‐salen complexes

“…This observation demonstrates the formation of a new vanadium species in the reaction mixture. Appearance of such a broad peak near 570 nm region by the addition of oxidant to the reaction mixture containing oxosalen complex has been already noticed in the oxidation of sulfides, [ 68 ] sulfoxides, [ 22 ] phenol, [ 10 ] tertiary amines, [ 21 ] and PMAA. [ 37,39 ] In all these cases, formation of new peak has been interpreted by the formation of adduct between salen complex and H 2 O 2.…”

“…The advantages of working with VO(salen) are its high stability and simple method of synthesis from commercially available VOSO 4. [20] Oxovanadium(IV)-salen complexes are widely used as catalyst in the oxidation of tertiary amines, [21] phenols, [10] phenylsulfinylacetic acids, [22] benzoin, [23] alcohol, [24] and oxidative coupling of 2-naphthols. [25] Besides catalytic activity, vanadium acts as an insulinenhancing agent either in the form of its inorganic salts or complexes with organic ligands.…”

A Spectroscopy Approach for the Study of the Interaction of Oxovanadium(IV)-Salen Complexes with Proteins

“…The details of synthesis of salen ligands and oxovanadium(IV)-salen complexes and spectral characterization are given our previous reports [59,61] but the spectral data are collected in the supporting information (Tables S1 and S2). The structure of the oxovanadium(IV)-salen complexes synthesized for the present study are shown in Chart 1.…”

“…The ligands [56,57] and oxovanadium(IV)-complexes [58][59][60][61][62][63][64][65] were synthesized by known procedures and characterized by UV-vis, MS, FTIR spectral studies and cyclic voltammetry measurements (Tables S1 and S2). Bovine serum albumin (BSA) and ovalbumin (OVA) were purchased from Ocimum Bioscience and Sigma-Aldrich respectively and used without any further purification.…”

Mononuclear oxovanadium(IV) Schiff base complex: Synthesis, spectroscopy, electrochemistry, DFT calculation and catalytic activity

“…Also, in homogeneous catalysis, vanadium Schiff base complexes formed with chelating ligands involving hetero atoms are found to be used in a variety of systems [14]. Homogeneous catalysts of oxovanadium(IV) complexes induce organic reactions in the oxidation of sulfides and sulfones [24,25], the epoxidation of alkenes [26,27], the hydroxylation of hydrocarbons [28], the oxidation of alcohols to aldehydes and ketones [29,30], phenols [31] and tertiary amines to N-oxides [32].…”