Research Of The Hydroxycyclohexanone Oxidation With Dioxygen Catalyzed By Metalloporphyrin

Adipic acid, one of oxidative products of cyclohexane, is the most valuablediacid among the alkyl diacids as well as the most important industrial product andimmediate. The demand of adipic acid becomes larger along with the development ofthe economy. Because of the complexity of oxidation products of cyclohexane, highconversion of cyclohexane and high selectivity of adipic acid are difficulty to achieveat the same time, so studying the role of hydroxycyclohexanone in cyclohexaneoxidation plays an important role in improving the conversion of cyclohexane andselectivity of adipic acid.Firstly, research progress of the oxidation of cyclohexene or cyclohexanone todiacid catalyzed by metalloporphyrin with dioxygen as oxidant, origin pathways ofthe oxidation of cyclohexane or cyclohexanone to diacid, and hydroxycyclohexanoneoxidation were reviewed.Secondly, a GC and HPLC quantitative analysis method of the products ofcyclohexanone was established according to the demanding of our research, and itwas accurate and repeatable.Thirdly, the oxidation of three kinds of hydroxycyclohexanone which generatedin the oxidation of cyclohexanone was carried out using different catalysts andsolvents. These results show that the main product of2-hydroxycyclohexanoneoxidation is adipic acid, the main products of3-hydroxycyclohexanone oxidation arecyclohexenone and glutaric acid, the main products of4-hydroxycyclohexanoneoxidation are succinic acid and4-acetobutyric acid.Fourthly, the influence of different factors on the selective oxidation ofcyclohexanone to the three kinds of hydroxylcyclohexanone was investigated. Theseresults show that the oxidation of cyclohexanone to2-hydroxycyclohexanone,3-hydroxycyclohexanone and4-hydroxycyclohexanone was parallel, and thesehydroxycyclohexanones are the important initial products of cyclohexanone oxidation.The relative reactive activity of C-H bonds of cyclohexanone was in the order of ortho≈para>meta position. And the lower temperature was in favor of generating2-hydroxycyclohexanone, and the lower concentration of cyclohexanone was in favorof generating4-hydroxycyclohexanone.Fifthly, the hydroxycyclohexanone oxidation was a free radical process involved homolysis of C-O bond by means of methylene blue, bromotrichloromethane radicaltrapping and triphenylphosphine reduction of hydroxyclohexanone oxidation products.Combined with the literature and the studing results above, the origin pathways ofproducts of cyclohexanone oxidation with dioxygen catalyzed by metalloporphyrinwere proposed.