Metal-free and iron(II)-assisted oxidation of cyclohexane to adipic acid with ozone: a theoretical mechanistic study

摘要: Abstract Adipic acid has a tremendous applied importance. Its industrial synthesis requires harsh conditions and application/emission of hazardous HNO3 N2O. Here, mechanism ecologically benign neat cyclohexane (CyH) oxidation with ozone into adipic under room temperature radiation-free conditions, both metal-free catalyzed by the iron(II) complex [FeCl2{κ3-HC(pz)3}] (pz = pyrazol-1-yl), was investigated theoretical methods. Relatively high activation barriers rate limiting H-abstractions O3 without catalyst explain experimentally observed low CyH conversion selectivity toward due to efficient accumulation cyclohexanone. The active catalytic form [FeIV(=O)Cl2{κ3-HC(pz)3}] improves because it is much more H-abstractor compared provides facile decomposition cyclohexanone, opens up new route formation ortho-cyclohexanediol then acid, prevents anhydride – one stable intermediates conditions.