Adipic Acid Route: Oxidation of Cyclohexene vs. Cyclohexane

A cleaner alternative to the current inefficient oxidation of cyclohexane to adipic acid is presented. Direct oxidation of neat cyclohexene by aq. hydrogen peroxide to adipic acid is selectively achieved in good yield (46%), in the presence of the recyclable C-homoscorpionate iron(II) complex [FeCl2{κ3-HC(pz)3}] (pz = pyrazol-1-yl) and microwave irradiation, by a nitrous oxide-free protocol.