Adipic cyclohexane transformation

The total hydrogenation of benzene derivatives represents an important industrial catalytic transformation, in particular with the conversion of benzene into cyclohexane, a key intermediate in adipic acid synthesis, which is used in the production of Nylon-6,6 (Scheme 1). This reaction is still the most important industrial hydrogenation reaction of monocyclic arenes [1]. 

Oxidation of Cyclohexane. The synthesis of cyclohexanol and cyclohexanone is the first step in the transformation of cyclohexane to adipic acid, an important compound in the manufacture of fibers and plastics. Cyclohexane is oxidized industrially by air in the liquid phase to a mixture of cyclohexanol and cyclohexanone.866 872-877 Cobalt salts (naphthenate, oleate, stearate) produce mainly cyclohexanone at about 100°C and 10 atm. The conversion is limited to about 10% to avoid further oxidation by controlling the oxygen content of the reaction mixture. Combined yields of cyclohexanol and cyclohexanone are about 60-70%. 

Adipic acid is a most important petrochemical product which is mostly used for the synthesis of nylon 6.6 from its condensation with hexamethylenediamine. Cyclohexane is transformed to adipic acid in two steps (a) oxidation of cyclohexane to a cyclohexanol-cyclohexanone mixture (ol-one) via the formation of cyclohexyl hydroperoxide followed by (b) oxidation of the ol-one mixture to adipic acid by nitric acid (equation 239). 

---