This paper discusses the results of investigations on the kinetics of cumene oxidation to cumene hydroperoxide by molecular oxygen in the presence of N-hydroxyphthalimide as a catalyst. A mathematical model has been developed on the basis of the regularities of hydroperoxide and by-products formation. The model adequately describes changes in all reaction components in the course of the reaction. It has also been established that the role of N-hydroxyphthalimide in the process consists in the creation of a steady-state concentration of N-phthalimide radicals initiating oxidation by interacting with the hydrocarbon. C 2017

96Alkylarene oxidations are the key reactions in the promising methods of obtaining various oxygen con taining organic compounds, namely, alkylphenols and aliphatic ketones, which are widely used in the synthe sis of valuable polymers.Among these reactions, the cumene method of producing phenol and acetone [1] and the simulta neous synthesis of styrene and propylene oxide (Hal con process) [2] have been investigated in detail and widely commercialized. The basic step of these pro cesses is the initiated liquid phase oxidation of isopro pylbenzene or ethylbenzene into the corresponding hydroperoxide. The economic characteristics of the overall process depend directly on the efficiency of this step. It is, therefore, necessary to optimize the oxida tion conditions so as to increase the conversion of the initial hydrocarbon into the hydroperoxide (including through employment of an efficient catalyst) without affecting a high hydroperoxide selectivity and chang ing the existing technology.Kinetic studies of the liquid phase oxidation of iso propylbenzene demonstrated that N hydroxyphthal imide (N HPI) at a concentration of 2-3 wt % increases the hydrocarbon oxidation rate by a factor of 2 relative to the oxidation rate under the standard pro cess conditions. At 120-130°C, the isopropylbenzene conversion is 40-50% in 2-3 h with a hydroperoxide selectivity of 90-95% [3]. Thus, N HPI intensifies the process by increasing the reaction rate and hydrocar bon conversion without reducing the high hydroper oxide selectivity. Considering that phenol is produced in great amounts, this intensification provides means to markedly improve the efficiency of the process.In order to confirm the appropriateness of employ ing N HPI and its structural analogues as agents accelerating the oxidation of isopropylbenzene, we calculated, using the PM3 (unrestricted open shell Hartree-Fock) method, the reactivity index, specifi cally, the difference between the energy of the singly occupied molecular orbital (|E SOMO |) of the substrate (isopropylbenzene) radical and the same energy of the nitrogen containing compound (NC) (|ΔE SOMO |).Japanese researchers [4] recommend to select the catalytic systems, in which the difference between the E SOMO values from 0 to 10 eV, preferably, 0-4 eV. This approach will allow the suitability of a catalyst and the process rate to be estimated a priori, providing a basis for further technological investigation. The |ΔE SOMO | values for the systems examined here fall in the 1-1.5 eV range; therefore, N HPI and its structural analogues are usable in the liquid phase oxidation of isopropyl benzene.N HPI is known to accelerate the oxidation of alkanes, alkylbenzenes, alcohols, ethers, and acetals into oxygen containing compounds (such as ketones and carboxylic and dicarboxylic acids) [5]. It is believed that, in these oxidation processes, the inter action of N HPI with the initiator radical or with the peroxy radical of an oxidizer yields the N oxyphthal imide radical (N OPIR) that is capable of selectively sub...

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