Catalytic oxidation with nitrous oxide: oxidation of alcohols, ethers and amines in an aqueous suspension of platinum particles at room temperature

Abstract

Room-temperature catalytic oxidation of alcohols, ethers and amines with nitrous oxide (N₂O) has been performed, along with nitrogen (N₂) evolution, in aqueous suspensions of platinum black (Pt). Appreciable decomposition of N₂O to give N₂ is observed in the co-presence of Pt particles and an appropriate substrate. Ketones are obtained from secondary alcohols, amines and branched ethers, while aldehydes, along with carboxylic acids and nitriles, are produced from primary alcohols and amines, respectively. The oxidative decomposition of diisopropyl ether to yield acetone begins after an appreciable induction period, which disappears on the addition of small amount of propan-2-ol to the reaction mixture. An induction period is also observed in the oxidation of propan-2-ol carried out under neutral or alkaline conditions. However, the oxidation of another portion of propan-2-ol, added after almost complete consumption of the initial portion, occurs without an induction period. Treatment of a Pt suspension with hydrogen (H₂) is also effective for elimination of the induction period. A radical chain mechanism is proposed, in which N–O bond cleavage in N₂O adsorbed on Pt gives rise to a primary intermediate of an α-substituted alkyl radical and the resulting hydroxyl radical abstracts hydrogen from the substrate.