This paper describes an investigation of the alkane oxidation with hydrogen peroxide in acetonitrile catalyzed by iron(III) perchlorate (1), iron(III) chloride (2), iron(III) acetate (3) and a binuclear iron(III) complex with 1,4,7-triazacyclononane (4). The corresponding alkyl hydroperoxides are the main products. Nevertheless in the kinetic study of cyclohexane oxidation, the concentrations of oxygenates (cyclohexanone and cyclohexanol) were measured after reduction of the reaction solution with triphenylphosphine (which converts the cyclohexyl hydroperoxide to the cyclohexanol). Methane and ethane can be also oxidized with TONs up to 30 and 70, respectively. Chloride anions added to the oxidation solution with 1 activate the perchlorate iron derivative in acetonitrile, whereas the water as additive inactivates 2 in the H 2 O 2 decomposition process. Pyrazine-2-carboxylic acid (PCA) added to the reaction mixture decreases the oxidation rate if 1 or 2 are used as catalysts, whereas compounds 3 and 4 are active as catalysts only in the presence of small amount of PCA. The investigation of kinetics and selectivities of the oxidations demonstrated that the mechanisms of the reactions are different. Thus, in the oxidations catalyzed by the 1, 3 PCA and 4 PCA systems the main oxidizing species is hydroxyl radical, and the oxidation in the presence of 2 as a catalyst has been assumed to proceed (partially) with the formation of ferryl ion, (Fe IV O) 2 . In the oxidation catalyzed by the 4 PCA system (TONs attain 240) hydroxyl radicals were generated in the rate-determining step of monomolecular decomposition of the iron diperoxo adduct containing one PCA molecule. A kinetic model of the process which satisfactorily describes the whole set of experimental data was suggested. The constants of supposed equilibriums and the rate constant for the decomposition of the iron diperoxo adduct with PCA were estimated.

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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.

The synthesis and characterisation of 4-(3',4',5'-trialkoxybenzoyloxy)pyridines (1a-e), and of their corresponding palladium(II), (2a-e), and platinum(II), (3a-e), complexes are described. The pyridine-based ligands are not mesomorphic, but upon complexation to PdCl 2 or PtCl 2 , new hexacatenar mesogens are formed which show exclusively the hexagonal columnar mesophase. The mesomorphic behaviour of the complexes was characterised by polarised optical microscopy, differential scanning calorimetry and X-ray diffraction. The metal seems to influence the crystal phase and mesophase stability as well as the mesomorphic temperature range.