Chapter 11 - Oxidation of organic compounds by molecular oxygen

Abstract

Liquid-phase oxidation of organic compounds is studied at 300- 500 K. Under these conditions, organic compounds are quite stable and their decomposition with dissociation at the C–C bond and in the reaction does not virtually occur. Chain generation in the absence of initiating additives and those formed by hydroperoxide oxidation occurs via the reactions involving dioxygen. It is known from spectroscopy of solutions that O2 forms donor-acceptor complexes with Π-orbitals of aromatic hydrocarbons and unsaturated compounds. However, such complexes cannot be precursors of the transition state of the reaction of O2 with C–H bonds. As shown by the quantum-chemical analysis of the CH4…O2 pair, dioxygen forms an unstable complex with methane. Therefore, for reactions in solution it is hardly possible currently to distinguish the triple collision and the bimolecular reaction of RH with the short-lived encounter complex RH.O2. Both O–O and C—H bonds are non-polar, and the final reaction product H202 is polar. Reaction is endothermic, and the transition state of this reaction is polar according to the Hammond postulate.