Theoretical modeling of the mechanism of aniline oxidation by singlet O<Subscript>2</Subscript>

The mechanism of aniline oxidation by singlet oxygen was studied by the DFT-PBE/L2 method. According to the calculations, aniline endoperoxide cannot participate in the reaction because of its energy instability. The addition of ¹O₂ to aniline proceeds with the simultaneous proton transfer to the oxygen molecule from the NH₂ group (for the syn-approach of oxygen) or from the aromatic ring (for the anti-approach). For the syn-approach of the ¹O₂ molecule, the HNC₆H₄(H)OOH intermediate is formed, whose decomposition leads to aniline p-hydroperoxide (predominantly) or p-iminoquinone. In the case of the anti-approach, the ¹O₂ molecule is inserted at the C–H bond to form aniline p-hydroperoxide (H₂NC₆H₄OOH). The decomposition of aniline p-hydroperoxide with the formation of p-aminophenol and H₂O₂ molecule proceeds via concerted mechanism.     

The influence of metal and carrier natures on the effectiveness of catalysts of the deoxygenation of fatty acids into hydrocarbons

The activity and selectivity of palladium, copper, platinum, and nickel catalysts in the decarbonylation of stearic acid into hydrocarbons were studied at a 14 atm hydrogen pressure and temperatures of 300-350°C. If ??-alumina was used as a carrier, the catalysts formed the series Pd > Cu > Pt > Ni according to desired product yields. Quantum-chemical simulation was performed to show that the free energy of activation increased in the same series. The same metals deposited on mixed tungsten and zirconium oxides catalyzed decarbonylation with a low yield of C₁₇ hydrocarbons, likely because such a superacidic carrier could catalyse cracking of olefins or their oligomers formed.     

On calculation of integrals over spherical domains

We construct cubature formulas for the computation of integrals over spherical domains containing less nodes as compared with known ones. __________ Translated from Ukrains’kyi Matematychnyi Zhurnal, Vol. 58, No. 6, pp. 859–864, June, 2006.     

Quantum chemical study of the mechanism of catalytic [2+2+2] cycloaddition of acrylic acid esters to norbornadiene in the presence of nickel(0) complexes

The mechanism of the [2+2+2] cycloaddition of ethyl acrylate to norbornadiene (NBD) catalyzed by Ni⁰ complexes was modeled in terms of the density functional theory (DFT) at the PBE level. The formation of the first C—C bond between the coordinated NBD and ethyl acrylate molecules is the rate-determining step of the process. The low stereoselectivity of the reaction is due to the close matching of the activation barriers for the formation of exo- and endo-cycloadducts (25.6 and 24.9 kcal mol^?1, respectively).