Catalysis of chitosan-supported iron tetraphenylporphyrin for aerobic oxidation of cyclohexane in absence of reductants and solvents

Abstract

The chitosan-supported iron(III) tetraphenylporphyrin was prepared and characterized structurally, and its ability to catalyse oxidation of cyclohexane into cyclohexanone and cyclohexanol with air in absence of any reductants and solvents was studied. The research results showed that the amino groups of the chitosan coordinated axially with the iron atoms of chloro[tetraphenylporphinatoiron(III)] to form chitosan-supported ironporphyrin, which has better catalytic power for cyclohexane oxidation with air than the corresponding unsupported ironporphyrin. Under reaction conditions of 418 K and 0.8 MPa, the cyclohexane oxidation catalyzed by chitosan-supported iron(III) tetraphenylporphyrin had 1.40×10 5 catalyst mole turnover (based on the iron atom), 10.48% cyclohexane conversion and the 79.20% cyclohexanone and cyclohexanol selectivity, respectively. The turnover in cyclohexane oxidation catalyzed by the supported ironporphyrin is about 22 times bigger than that by unsupported ironporphyrin and the conversion is about double. The values are also higher than 3.9% conversion and 78% selectivity catalyzed by soluble cobalt catalyst used in industry at present. This paper has also investigated the influences of reaction time, temperature and pressure on the catalyst turnover, cyclohexane conversion and ratio of cyclohexanol to cyclohexanone in the cyclohexane oxidation catalyzed by the chitosan-supported iron(III) tetraphenylporphyrin.