Synthesis, characterization of metal-free, metallophthalocyanines and catalytic activity of cobalt phthalocyanine in cyclohexene oxidation

•Synthesis and characterization of peripherally tetrasubstituted metal-free and metallophthalocyanines.•Investigation of catalytic activity of cobalt and iron phthalocyanine in cyclohexene oxidation.•Determination of substrate, oxidant and temperature effect on cyclohexene oxidation.

In this work, the new phthalonitrile derivative 3 bearing 4-pentylphenol 1, metal-free phthalocyanine 4, metallophthalocyanines 5 and 6 have been synthesized. Metal free phthalocyanine 4 and metallophthalocyanines 5 and 6 bearing four 4-(4-pentylphenoxy) groups on the periphery have prepared by cyclotetramerization of a new precursor, namely 4-(4-pentylphenoxy)phthalonitrile 3 in the presence of the corresponding divalent metal salts [Zn(II), Co(II)]. The new compounds have been characterized by IR, 1H NMR, 13C NMR and MS spectra data. The new cobalt phthalocyanine 6 has tested as a catalyst for the oxidation of cyclohexene with different oxidants, such as tert-butylhydroperoxide (TBHP), m-chloroperoxybenzoic acid (m-CPBA) and hydrogen peroxide (H2O2), in organic solvent. It is seen that complex 6 can selectively oxidize cyclohexene to give 2-cyclohexen-one as major product, 2-cyclohexen-ol and cyclohexene oxide as minor product. Finally, because of the minimal destruction of the catalyst, higher selectivity and conversion, TBHP has found to be best oxidant.

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