Special Features of Cyclohexane and p-Xylene Oxidations

The general mechanism outlined earlier is followed in the first step of oxidation of cyclohexane. As shown by reaction 8.3.2.1, trace quantities of cyclohexyl hydroperoxide 8.12 can initiate the radical chain by 

There are many product formation steps the termination step (8.3.2.2) deserves special attention. This is one of the major product-forming steps where both cyclohexanol and cyclohexanone are formed simultaneously. The six-membered transition state makes this reaction particularly favorable. 

The catalysts used in cyclohexane oxidation are a mixture of hydrocarbon-soluble carboxylate salts of Co and Mn + or Cr. Due to the better solubility properties, salts of long-chain carboxylic acids such as 2-ethylhexanoic or naphthenic acids are favored. 

The mixture of cyclohexanone and cyclohexanol is oxidized by nitric acid in the presence of and Cu ions. The roles of vanadium and copper are complex and poorly understood. A large number of intermediates, including the diketo compound 8.13, are formed. 

As shown by reactions 8.3.2.3 and 8.3.2.4, the ion VO stoichiometri-cally oxidizes the diketo compound to adipic acid. The VCT+ species thus generated is converted back to by nitric acid. In the absraice of copper, 

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