Oxidation of Cyclohexene to Adipic Acid
The combination of aqueous hydrogen peroxide and a molecular sieve catalyst (titanium aluminophosphate number 5 in the IZA classification, TAPO-5) allows slow oxidation of cyclohexane to adipic acid in the absence of organic solvent (Lee S-O et al, Angew Chem Int Ed, 2003, 42, 1520). The mechanism is via cyclohexane oxide and cyclohexanediols but more than one mechanism may operate.
100% conversion can be achieved at 80o for 72 hrs with a turnover number of 310, but as yet selectivity is 30%. The paper describes experiments designed to understand the mechanism more fully.