Investigation of the thermolysis of 5-methyl-1-phenyltetrazole by combined derivatography and mass spectrometry

The thermolysis of 5-methyl-1-phenyltetrazole was studied at 20–350°C by derivatography and mass spectrometry, and it was shown that thermal decomposition proceeds with the elimination of a molecule of nitrogen and is accompanied by skeletal rearrangement of the intermediately formed nitrene to 2-methylbenzimidazole or migration of the methyl group to the nitrogen atom with the formation of methylphenylcarbodiimide (MPCD). In addition, symmetrical dimethyl- and diphenylcarbodiimides, methylphenylguanidines, and aniline are formed. It is assumed that the formation of these compounds in the pyrolyzate is due to polymerization of MPCD and subsequent thermal destruction of the polymerization products. A scheme for the thermolysis of 5-methyl-1-phenyltetrazole is proposed. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 265–271, February, 1980.     

Effect of substituent in the benzene ring on the reactivity of aromatic nitro compounds: A quantum-chemical approach

The effective total charges on the nitro groups of m- and p-substituted nitrobenzenes were calculated ab initio by the RHF/3-21G method. The calculated charges were correlated with the Hammett constants of substituents in the aromatic ring. The correlation equations obtained can be used for predicting and evaluating the reactivity of aromatic nitro compounds.     

Integral equation for a strip coil antenna located on a dielectric cylinder

The problem about the distribution of the surface current density in a narrow circular strip antenna as an infinitely thin perfectly conducting ribbon folded in a circle and positioned on the surface of a dielectric cylinder is reduced to a one-dimensional integral equation (IE). A method for solving the obtained IE is proposed. Complex distributions of the azimuthal component of the surface current density over the circular conductor are presented for different values of the dielectric permittivity of the cylinder.     

Theoretical and experimental study of imine-enamine tautomerism of condensation products of propanal with 4-aminobenzoic acid in ethanol

The tautomerism of the reaction products of propanal with 4-aminobenzoic acid in ethanol was studied by J-modulated spin-echo (JMOD) ¹³C NMR spectroscopy and gradient-enhanced heteronuclear (ge-2D) ¹H–¹³C HSQC spectroscopy. The existence of imine and enamine tautomeric forms of the reduced compounds in solution was established. The tautomeric equilibrium of the condensation product of propanal with 4-aminobenzoic acid in ethanol was found to be shifted toward the imine form. Quantum chemical calculations by the density functional theory (DFT) method demonstrated that the 4-(N-propylidene)aminobenzoic acid molecule forms a stronger hydrogen bond with an ethanol solvent molecule compared to the enamine molecule, resulting in a higher stability of the ethanol adduct of azomethine compared to the adduct of enamine.     

Evolution of the characteristics of Parametric X-ray Radiation from textured polycrystals under different observation angles

The Parametric X-Ray radiation (PXR) spectra and yield dependencies on the orientation angle are measured during the interaction of 7 MeV electrons with a tungsten textured polycrystalline foil for different observation angles. The effects of PXR spectral density increase and PXR yield orientation dependence broadening in the backward direction is shown experimentally for the first time. The experimental results are compared with PXR kinematical theories for both mosaic crystals and polycrystals.     

Hydrogenation catalysts based on platinum- and palladium-containing nanodiamonds

Platinum and palladium nanoparticles of 4–5 nm size applied at nanodiamonds have been shown to efficiently catalyze liquid-phase hydrogenation of different organic compounds (nitrocompounds, azomethines, and unsaturated hydrocarbons and alcohols) under mild conditions (T = 318 K, hydrogen pressure of 0.1 MPa, solution in ethanol). Using of palladium on nanodiamond containing 3 wt % of metal has been most efficient.     

Stationary and photostimulated luminescence of ionic-covalent crystals with adsorbed low-atomic silver and copper clusters

Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 55, No. 5, pp. 763–767, November, 1991.