MODELING OF THE COMPLETE MECHANISM OF OXIDATION OF PHENYL RADICAL UNDER COMBUSTION CONDITIONS

Quantum chemical calculations, computational fluid dynamics (CFD) simulations, and isothermal approximation were applied for the interpretation of experimental measurements of the reaction of С6Н5 + O2 in the high-temperature microreactor and of the pressure drop in the flow tube of the reactor.

Effects of Ultrasounds on Neat nitrobenzene

Neat nitrobenzene was continuously irradiated at two ultrasonic frequencies: 40 and 200 kHz, under air and argon atmosphere, respectively. Samples taken at intervals of 1, 5, 10 and 24 h were analyzed by GC-MS and decomposition products were identified. Possible reaction mechanisms are discussed. Presence of air as dissolved gas leads to oxygenated compounds such as 1,4-benzoquinone, 2,4-dinitrophenol, m-dinitrobenzene while argon inhibits the decomposition of nitrobenzene, especially at sonication times under 5 h. Based on the nature of the compounds identified we advanced a mechanism, involving a divergent splitting of unstable radical cation of NB in air and argon respectively. Thus, under air, the phenyl cation formation is preferred leading to 1,4-benzoquinone nitro-biphenyls and dinitrobenzene, while under argon, the phenyl radical formation seems to be favored, leading to phenol and diphenyl ether. The oxygenated compounds detected under argon clearly are a consequence of the nitro group splitting.

Quantum Chemical and Kinetic Study on Radical/Molecule Formation Mechanism of Pre-Intermediates for PCTA/PT/DT/DFs from 2-Chlorothiophenol and 2-Chlorophenol Precursors

Polychlorinated phenoxathiins (PCPTs), polychlorinated dibenzothiophenes (PCDTs), and polychlorinated thianthrenes (PCTAs) are sulfur analogues of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/DFs). Chlorothiophenols(CTPs) and chlorophenols (CPs) are key precursors to form PCTA/PT/DTs, which can form chloro(thio)phenoxy radical, sulfydryl/hydryl-substituted phenyl radical and (thio)phenoxyl diradicals. The available radical/radical PCTA/DT formation mechanism failed to explain the higher concentration of PCDTs than that of PCTAs under the pyrolysis or combustion conditions. Thus in this work, a detailed thermodynamics and kinetic calculations were carried out to investigate the pre-intermediates formation for PCTA/PT/DTs from radial/molecule coupling of 2-C(T)P with their key radical species. Our study found that the radial/molecule mechanism can thermodynamically and kinetically contribute to the gas-phase formation of PCTA/PT/DT/s. The S/C coupling modes to form thioether-(thio)enol intermediats are preferable over the O/C coupling modes to form ether-(thio)enol intermediats. Thus, although the radial/molecule coupling of chlorophenoxy radical with 2-C(T)P have no effect on the PCDD/PTs formation, the radial/molecule coupling of chlorothiophenoxy radical with 2-C(T)P play an important role in the PCDT/PT formation. Most importantly, the pre-PCDT intermediates formation pathways from the coupling of sulfydryl/hydryl-substituted phenyl radical with 2-C(T)P and the coupling of (thio)phenoxyl diradicals with 2-C(T)P are more favorable to pre-PCTA/PT intermediates formation pathways from the coupling of chlorothiophenoxy radical with 2-C(T)P, which can give reasonable explanation for the high PCDT-to-PCTA ratio in the environment.

Theoretical Determination of Enthalpies of Formation of Benzyloxy, Benzylperoxy, Hydroxyphenyl Radicals and Related Species in the Reaction of Toluene with the Hydroxyl Radical

<p>Reaction of toluene (T) with HO^● produces addition products and the benzyl radical (TR). TR can react with HO^● or O₂ to produce oxygenated species, for many of which there is no experimental information. We present here theoretically determined heats of formation (HFs) of 17 such species using non-isodesmic reactions of TR+O₂ and T+HO^●+O₂. For experimentally known HFs, we obtained a reasonable correlation between experimental and theoretical data for G4 (r2=0.999) and M06/cc-pVQZ (r2=0.997) results. Previously unknown HFs of other radicals (benzyloxy, spiro [1,2-dioxetane benzyl], hydroxyphenyl, and benzylperoxy) and closed shell species (salicylic alcohol, benzo[b]oxetane and p-hydroxy cyclohexa-2,5-dienone) were calculated using these methods. The species studied and the enthalpies of formation obtained were: salycilic alcohol, -69.7 ± 3.4 kcal/mol; benzyloxy radical, 28.4 ± 3.4 kcal/mol; hydroxyphenyl radical, 37.3 ± 3.4 kcal/mol; benzo[b]oxetane, 23.7 ± 3.4 kcal/mol; spiro [1,2-oxoetane phenyl] radical, 57.3 ± 3.4 kcal/mol; p-hydroxy cyclohexan-2,5-dienone, -42.1 ± 3.4 kcal/mol; and benzylperoxy radical, 28.5 ± 3.2 kcal/mol.</p>

Напівемпіричний аналіз взаємодії алкоксипохідних 1,4-бенздіазепіну з ГАМКа-рецептором на підставі даних молекулярного докінгу та фармакологічного ефекту

Introduction. Pharmacological spectrum of 1.4-benzodiazepine 3-alkoxy derivatives, in contrast to classical substances, has more prominent analgesic properties, but even among the synthesized and studied molecules there are compounds with different magnitude of this effect.The aim of the study – to evaluate the molecular docking parameters of the theoretically generated structures of 1.4-benzodiazepine alkoxy derivatives with the GABA receptor complex and to compare these data with the pharmacological activity of the synthesized compounds.The molecular docking procedure was carried out using the iGEMDOCK v2.1 program, optimized structures of already synthesized and theoretically designed molecules with differing substituents in the ortho position of the phenyl radical and the "7" position of the condensed system are generated in the Avogadro program (v 1.2.0). The average effective doses of compounds (penthylenetetrazole-induced seizures, 120 mg/kg, subcutaneously 30 min after compounds administration) were studied in white mice.The binding energy of all the generated structures is within the ranges of 81.6–96.8 kcal/mol. Virtual docking data analysis of substituted alkoxy derivatives allows identifying several binding sites inherent for 7-chloro- or 7-bromo-substituted benzodiazepine derivatives. The greatest influence on the binding of chlorine-substituted alkoxy derivatives have regions with a high polarity amino acids (16-23 D) and similar hydrophilicity and hydrophobicity. The contribution of Van der Waals and hydrogen interactions to the total binding energy is determined by the presence of halogen (chlorine or bromine). In penthylenetetrazole-induced seizures test the compounds containing the chlorophenyl substituent in the hetero ring were most active (ED50 (0.42±0.10) μmol/kg for the propyloxy derivative and (0.51±0.17) μmol/kg for the ethyloxy derivative) while for the compounds with the phenyl radical, the ED50 value were much higher (5.1±2.7) μmol/kg and (17.75±1.93) μmol/kg, respectively). The analgesic effect is mainly due to the lkoxy derivatives possibility of binding to a center containing residues of basic amino acids.

Formation of bicyclic polycyclic aromatic hydrocarbons (PAHs) from the reaction of a phenyl radical with cis-3-penten-1-yne

The formation of PAHs within 4-, 5-, 6- and 7-membered rings on the C6H5 + C5H6 potential energy surface.