Litvinov J. N-hydroxyphthalimide catalytic activity in the alkylarenes oxidation reactions

The thesis deals with the study of the mechanism of N-hydroxyphthalimide (NHPI) influence on the oxidation of alkylarenes for optimization of oxygen-containing material synthesis. In the course of investigation it has been shown that a high catalytic activity of NHPI is observed in the acid (acetic acid) or neutral (acetonitrile) medium due to the NHPI as a weak acid behavior. The investigation of the acenaphthene and tetraline oxidation by molecular oxygen in the presence of NHPI shows that the corresponding hydroperoxide is the main oxidation product. The NHPI is allowed to oxidize organic substrates in mild conditions (1 atm, <100 °С) with high conversion (> 50%) and selectivity (> 90%) at high rate. On the basis of the experimental data the kinetic parameters of acenaphthene oxidation and tetraline oxidation are obtained. The H-atom abstraction from substrate by the phthalimide-N-oxyl radical (PINO) generated in situ from NHPI is the one of the main step of oxidation mechanism. To investigate this step the method of PINO generation was developed. The PINO has been generatеd in situ from it's hydroxyimide precursor, NHPI, by oxidation with iodobenzenediacetate. On the basis of the method the rate constants of H abstraction from molecules of substrates with wide range of C-H bond dissociation energy (cycloalkane, ketones, alkylaromatics, alcohols, phenols) by PINO have been determined. For several substrates the activation parameters of this step was calculated. It is shown that quantum mechanical tunneling plays a role in the hydrogen abstraction of the PINO radicals. The reactivity of organic substrates towards PINO radical depend both the enthalpy factor (C-H bond dissociation energy in substrate) and entropy factor. The latter is the ability of reactive group in the molecule of substrate to internal rotation: when reactive С-Н bond binds more tightly to molecule cycle, it loses rotational degrees of freedom and doesn't give the corresponding contribution to the total entropy of activation. Lack of internal rotation leads to a decrease in entropy of substrates, which makes them more reactive due to increased activation entropy.