The Research On Selective Aerobic Oxidation Of Different C-H Bonds Of Alkanes Catalyzed By Metalloporphyrin

Selective oxidation of alkanes is primarily important to petrochemistry, drug design, stuff and synthetical chemistry. Selective oxidation of alkanes is difficult to control for two reasons: (1) The bond strength of C-H bonds places high demands on the reaction condition. (2) Most alkanes have differen C-H bonds. So the selective oxidation of different C-H bonds is important but still remains a challenging question for Chemists. In this thesis, Methylcyclohexane that has three different C-H bonds was oxidated in absence of any solvent and reducer. And the effects on the conversion and selectivity were investigated when conditions of reaction or structure of porphyrins were changed.The contents of this thesis are presented as follows:1. In the introduction, we presented the development of the application of metalloporphyrins in selectivly catalyzing alkanes oxidation.2. The synthesis of eight kinds of porphines and their metalloporphyrins bearing different substituents were presented in the second chapter. The structures of all porphyrins were characterized.3. In the third chapter we introduced the studies of the catalytic oxidation of methycyclohexane. The effects on the conversion and selectivity were investigated when conditions of reaction or structure of porphyrins were changed. And we found that the activity and selectivity are sensitive to the temperature. For example when the temperature was improved from 403K to 423K, the ratio of selectivity between tertiary C-H bonds and secondary C-H bonds was decreased from 5.17 to 3.22. In this chapter the activation energy of different C-H bonds was achieved which are 106kJ/mol for tertiary C-H bonds and 143kJ/mol for secondary C-H bonds.4. In chapter four and five, we discussed the hypothetic mechanism of the methylcyclohexane oxidation catalyzed by metalloporphyrins according to the Hammett relationship of reaction and results of some comparative experiments. We discuss the reasons for the selectivity of oxidation catalyzed by different porphyrins and get a method to control the selectivity of different C-H bonds.5. At last we put forward a new method for the preparation of methylcyclohexanone and methylcyclohexanol. The new method used only one reaction so it is easy to handle.