Conformational analysis of the structure of <Emphasis Type="Italic">p</Emphasis>-butoxybenzylidene-<Emphasis Type="Italic">p</Emphasis>′-propionyloxyaniline at temperatures of crystal → nematic and nematic → isotropic liquid phase transitions

The molecular structure and conformational properties of the p-butoxybenzylidene-p′-propionyloxyphenylaniline molecule in the crystalline state and at temperatures of the crystal → nematic and nematic → isotropic liquid phase transitions were examined by AM1 calculations. It was found that the nematic → isotropic liquid phase transition is accompanied by a change in the molecular conformation.     

Quantum-chemical interpretation of the effect of substitution in the benzene ring on the reactivity of monosubstituted benzenes

The HF/3-21G and HF/6-31G** methods were used to calculate the effective charges on the carbon and hydrogen atoms in the meta and para positions of the aromatic ring in monosubstituted benzenes. The calculated charges are compared with the Hammett constants of the substituents in the aromatic ring. Linear correlations were obtained between the atomic charges and the Hammett constants of the substituents. The resulting equations were shown to be useful for predicting and assessing the reactivity of aromatic compounds.     

Pt- and Pd-containing nanodiamonds in hydrogenation and hydroamination reactions

The catalytic activity of platinum- and palladium-containing nanodiamonds has been investigated in liquid-phase nitrobenzene, allyl alcohol, and cyclohexene hydrogenation and propanal hydroamination with 4-aminobenzoic acid as model reactions. The catalysts suggested are significantly more active than commercial Pd/C. The catalysts with a low metal weight content are the most effective in liquid phase catalytic hydrogenation.     

Disproportionation of hydrogen peroxide in the presence of Mn(III) complexes with various porphyrins and acid anions

The kinetics of homogeneous decomposition of H₂O₂ in the presence of Mn(III) complexes with octaethylporphine or meso-phenyloctaethylporphines and acid anions Cl^?, AcO^?, and SCN^? was studied by volumetry. The ionic-molecular mechanism of the transformation, involving reversible coordination of the H₂O₂ molecule, its irreversible decomposition with the release of H₂O and removal of two electrons from the metal porphyrin, reversible coordination of the second peroxide molecule in the form of HO ₂ ^? , and slow irreversible reduction of the catalyst with the release of O₂ and H₂O was substantiated by electronic absorption spectra. The catalytic activity of Mn(III) porphyrin complexes is independent of the acid anion present as extra ligand, but depends on the structure of the porphyrin ligand, which can be used for controlling the catalytic activity. Unsymmetrical (chloro)(monophenyloctaethylporphinato)managanese(III) is the most active; it increases the rate of O₂ evolution by a factor of 2 at the peroxide: catalyst molar ratio of (3 × 10⁵): 1.