New soluble peripherally tetra-substituted Co(II), Fe(II) phthalocyanines: Synthesis, spectroscopic characterization and their catalytic activity in cyclohexene oxidation

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

New 4-{2-[3-(diethylamino)phenoxy]ethoxy}phthalonitrile 3 was obtained from 2-[3-(diethylamino)phenoxy]ethanol 1 and 4-nitrophthalonitrile 2 with K2CO3 in DMF at 50 °C. The novel iron(II) and cobalt(II) phthalocyanine complexes 4 and 5 were prepared by the reaction of the phthalonitrile derivative 3 with n-pentanol in a standard Schlenk tube in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU). These new phthalocyanine complexes were characterized by the spectroscopic methods (IR, 1H NMR, 13C NMR, UV–vis and mass spectroscopies) Complexes 4 and 5 are employed as catalyst for the oxidation of cyclohexene using tert-butyl hydroperoxide (TBHP), m-chloroperoxybenzoic acid (m-CPBA), aerobic oxygen and hydrogen peroxide (H2O2) as oxidant. It is observed that iron(II) phthalocyanine complex can selectively oxidize cyclohexene to give 2-cyclohexene-1-ol as major product, and 2-cyclohexene-1-one and cyclohexene oxide are minor products. TBHP was found to be the best oxidant since the minimal destruction of the catalyst, higher selectivity and conversion were observed in the products.