Oxidation of saturated hydrocarbons with peroxyacetic acid catalyzed by vanadium complexes

Abstract

Peroxyacetic acid (PAA) oxidizes alkanes in acetonitrile or acetic acid at 60• C if a soluble vanadium(V) salt, n-Bu 4 NVO 3 (1), is used as a catalyst. Corresponding ketones, alcohols and alkyl hydroperoxides are the main products. Methane, ethane, propane, cyclohexane, and other higher alkanes were substrates in the oxidations. The proposed mechanism involves the formation of a complex between (1) and PAA with equilibrium constants 3.3 and 6.8 dm 3 mol −1 for acetonitrile and acetic acid as solvents, respectively. This complex decomposes to produce CH 3 C(=O)OO• radical and a V IV derivative. The latter reacts with PAA to generate a CH 3 C(=O)O • radical which attacks the alkane abstracting its hydrogen atom. An alkyl radical thus formed adds rapidly a molecule of dioxygen which leads finally to the alkyl hydroperoxide and then to the ketone and alcohol. Other vanadium(V) and vanadium(IV) complexes are also active in this oxidation only if the vanadium ion is not shielded with strongly bound bulky ligands.

Homogeneous Functionalization of Methane

“…In the presence of peroxyacetic acid, the vanadium salt n-Bu 4 NVO 3 (and similar vanadium salts) has been demonstrated to have comparable catalytic activity to ligated systems such as [VO(O 2 )(PCA) 2 ] − . 245 Shul'pin and Pombeiro found similar reactivity with NaVO 3 , H 2 O 2 , and H 2 SO 4 for conversion of methane to methyl hydroperoxide in acetonitrile. 246 Under comparable conditions to the hydrocarbon reaction, the vanadium complexes [VO 2 (PCA) 2 ] − and [VO(O 2 )-(PCA) 2 ] − were isolated and characterized (XRD studies) from VO 3 − −PCA−H 2 O 2 247 and were found to have identical reactivity for oxidation of cyclohexane as the precursor VO 3 − − PCA.…”

“…Shul’pin and co-workers have also reported simple vanadium salt systems, without added ligand, that can oxidize methane to methanol in acetonitrile solvent system. In the presence of peroxyacetic acid, the vanadium salt n- Bu 4 NVO 3 (and similar vanadium salts) has been demonstrated to have comparable catalytic activity to ligated systems such as [VO­(O 2 )­(PCA) 2 ] − . Shul’pin and Pombeiro found similar reactivity with NaVO 3 , H 2 O 2 , and H 2 SO 4 for conversion of methane to methyl hydroperoxide in acetonitrile …”

“…It could be that the propagation step is unfavorable and, as such, excess initiator is required. This has been suggested in later publications from the group, , where they propose catalytic activation of H 2 O 2 followed by functionalization with O 2 . Further studies have shown that the efficiency of this system in aqueous medium is improved by increasing the acidity of the solvent, most likely by increasing catalyst stability …”

Reactivity of Peracetic Acid with Organic Compounds: A Critical Review

“…The use of PAA for the degradation of pollutants in wastewater has also been studied by some researchers. In particular, activation of PAA by energy (UV or solar) or catalysts [e.g., Fe­(II/III), Co­(II/III), Mn­(II/III/IV), Ru­(III), V­(IV/V), and activated carbon] creating advanced oxidation conditions has shown high efficiency for the removal of a variety of organic pollutants. ,,,− The enhanced removal of pollutants, compared to PAA alone, is derived from the formation of reactive radical species, such as • OH and CH 3 C­(O)­OO • , which were confirmed by electron paramagnetic resonance (EPR) analysis and/or radical quenching experiments. ,,,,− The reaction mechanism and reactivities of organic compounds with respect to radicals formed from activated PAA should be different from those of direct oxidation by PAA. This review paper focuses on the reaction of compounds by PAA, not by activated PAA.…”

An oxidovanadium(IV) complex with 4,4′-di-tert-butyl-2,2′-bipyridine ligand: Synthesis, structure and catalyzed cyclooctene epoxidation

“…Oxidovanadium complexes containing the V=O moiety are nearly omnipresent in the chemistry of vanadium [1]. They exhibit high catalytic activity in various organic transformations including alkane oxidation [2][3][4][5][6][7][8][9][10], olefin epoxidation [11][12][13][14][15][16][17][18], aromatization of α,β-unsaturated cyclohexanone derivatives [19,20], alcohol oxidation [21][22][23][24][25], C-C bond cleavage of glycols [26][27][28], naphthol coupling [29] and α-oxidation of hydroxyl esters and amides [30] etc. The use of oxovanadium complexes in the oxidation reactions of various substrates, in particular saturated and unsaturated hydrocarbons is due to the following factors:…”