(31b) C-H Activation By Ozone in Liquid CO2
We demonstrate facile and safe ozonolysis of cyclohexane in liquid CO2 with almost complete selectivity towards cyclohexanone. At 10 celsius, with an ozone: cyclohexane molar ratio of approximately 50%, cyclohexane conversion is between 18-25% with a KA oil yield between 10-12%. The dominant presence of CO2 in vapor phase imparts safety by avoiding flammability at reaction condition. The experimentally observed product selectivity is confirmed by computations predicting that the reaction is initiated through hydrogen abstraction followed by cyclohexanone and hydrogen peroxide formation. The extension of this concept to the selective oxidations of linear alkanes will also be presented.