Investigation of catalytic activity of new Co(II) phthalocyanine complexes in cyclohexene oxidation using different type of oxidants

•Synthesis and characterization of tetra-substituted cobalt phthalocyanines.•Investigation of catalytic activity of cobalt phthalocyanine.•Determination of substrate, oxidant, temperature effect on cyclohexene oxidation.

In this work, the new phthalonitrile derivatives 4, 5 bearing 1,3-bis(naphthalen-1-yloxy)propan-2-ol and 1,3-bis(naphthalen-2-yloxy)propan-2-ol, cobalt phthalocyanine complexes have been synthesized. The new cobalt phthalocyanines have been prepared by cyclotetramerization of phthalonitrile derivatives 4, 5 in the presence of the corresponding CoCl2 salt in DMAE by using a microwave oven. The new compounds have been characterized by IR, 1H NMR, 13C NMR and MS spectral data. The new complexes have been 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 DMF. m-CPBA is also found as the most successful oxidant in the other oxygen sources. In this sense, the substrate/catalyst ratio, the influence of temperature, oxidant/cat ratio and type of oxidant have been studied. It is observed three oxidation products. First one is 2-cyclohexene-1-ol as dominant product and the others are 2-cyclohexene-1-one and cyclohexene oxide as minor product.

Graphical abstractSynthesis and catalytic activity of cobalt(II) phthalocyanines.Figure optionsDownload full-size imageDownload as PowerPoint slide