Mild Peroxidative Oxidation of Cyclohexane Catalyzed by Mono‐, Di‐, Tri‐, Tetra‐ and Polynuclear Copper Triethanolamine Complexes

Abstract

Abstract:The mono-, di-, tri-, tetra-and polynuclear copper (II) (5), respectively, are highly active and selective catalysts or catalyst precursors for the peroxidative oxidation of cyclohexane, in acetonitrile, to a cyclohexanol and cyclohexanone mixture, by aqueous hydrogen peroxide in acidic medium (liquid biphasic catalysis) at room temperature and atmospheric pressure. The effects on the catalytic activity of various factors, e.g., the relative amounts of cyclohexane, oxidant, catalyst, solvent and nitric acid, reaction time, catalyst recycling and impact of both carbon-and oxygen-centred radical traps (supporting mainly radical mechanisms) were investigated and allowed us to achieve yields and TONs up to ca. 39% and 380, respectively, corresponding to the most active copper systems so far reported for the oxidation of cyclohexane under mild conditions. The catalysts can be reused for recycling and, at least complex 4 maintains almost the same level of activity even after five reaction cycles. The preparation of the new complexes 1, 2b and 2c by self-assembly at room temperature, and their full characterization by IR spectroscopy, FAB-MS þ , elemental and X-ray diffraction structural (for 1 and 2c) analyses are also reported.

Oxidation of Cyclohexane with Molecular Oxygen Catalyzed by SiO2 Supported Palladium Catalysts

“…The other alternative, i.e. the use of peroxides is expensive [8] and accompanied by the formation of the byproducts and therefore it is economically disadvantageous. So the prospect of operate with the ideal ''green'' oxidant, i.e.…”

Copper(II) coordination polymers derived from triethanolamine and pyromellitic acid for bioinspired mild peroxidative oxidation of cyclohexane

“…It bears an active site composed of a multinuclear Cu cluster possessing a NO-environment [14][15][16]. However, although numerous examples of bioinspired copper compounds have been reported [10][11][12]17,18], the synthetic and catalytic (with respect to alkanes) studies on multinuclear copper complexes related to pMMO remain rather scant [19][20][21][22][23].…”

Catalytic activity of a benzoyl hydrazone based dimeric dicopper(II) complex in catechol and alcohol oxidation reactions

“…A plausible mechanism for catecholase like activity promoted by R-Cu 2+ (the nitrate ligand is omitted for the sake of clarity). (Hpic) and 2-pyrazinecarboxylic acid (Hpca), or bases such as pyridine, 3,5-dimethyl-1H-pyrazole, pyridazine, piperidine and triethylamine were tested, since they have been reported [54][55][56][57][58][59][60][61] Fig. 4, entry 1).…”