Oxidation of olefins with H₂O₂ catalyzed by gallium(III) nitrate and aluminum(III) nitrate in solution

Soluble gallium and aluminum nitrates (simple salts of non-transition metals) are good catalysts for the epoxidation of olefins (cyclooctene, dec-1-ene) including terpenes (carvone, limonene) with hydrogen peroxide in ethyl acetate or tetrahydrofurane (THF). Typically, the gallium salt is more efficient in comparison with the aluminum derivative. Products are formed in yields up to 93%, turnover numbers (TONs) attained 40. Addition of trifluoroacetic acid or pyrazine-2-carboxylic acid (PCA) accelerates the reaction and improves the yield. In striking contrast, added 2,2′-bipyridine or phenanthroline dramatically inhibit the oxidation

Mechanistic implications of the active species involved in the oxidation of hydrocarbons by iron complexes of pyrazine-2-carboxylic acid

The reactivity towards H2O2 of the complexes [Fe(pca)2(py)2]·py (1) and Na2{[Fe(pca3)]2O}·2H2O·CH3CN (2) (where pca− is pyrazine-2-carboxylate) and their catalytic activity in the oxidation of hydrocarbons is reported. Addition of H2O2 to 1 results in the formation of a dinuclear Fe(III)–(µ-O)–Fe(III) species characterized spectroscopically and by cyclic voltammetry. By contrast, treatment of 2 with H2O2 results in the formation of mononuclear iron(II) complexes, [Fe(pca)2(solvent)2]. The experimental results indicate that the catalytic activity of the starting complexes 1 and 2 is strongly dependent on the species formed in solution.