Co(II) and Fe(II) phthalocyanines: Synthesis, characterization and catalytic activity on cyclohexene oxidation with different oxygen source

Abstract

Peripherally tetra-substituted cobalt(II) and iron(II) phthalocyanines bearing [2-(4-methoxyphenoxy)ethoxy] groups have been synthesized and their structures have been verified by IR, 1H and 13C NMR, mass and UV–vis spectroscopy techniques. Fe(II) and Co(II) phthalocyanine complexes were tested as catalyst for the oxidation of cyclohexene using tert-butyl hydroperoxide (TBHP), m-chloroperoxybenzoic acid (m-CPBA), aerobic oxygen, hydrogen peroxide (H2O2) and oxone (potassium peroxomonosulfate) as oxidant. Catalytic activity of Fe(II) and Co(II) phthalocyanine complexes was compared and Fe(II) phthalocyanine was found as the best catalyst with higher product yields and selectivity. Both catalysts can selectively oxidize cyclohexene to give 2-cyclohexene-1-ol as major product, 2-cyclohexene-1-one and cyclohexene oxide are minor products. The influence of substrate/catalyst ratio, temperature, oxidant ratio and oxidant type were also investigated to find optimal reaction on cyclohexene oxidation for getting the highest conversion. All catalytic reactions were carried out using biphasic system (hexane:acetonitrile).