Potential function of the internal rotation of biphenyl

The form of the potential function of the internal rotation of the biphenyl molecule has been found for various states of aggregation and temperatures on the basis of an analysis of experimental data. Some chemical and physicochemical characteristics of biphenyl have been discussed.The new publications [1, 2], in which a similar problem was solved for the biphenyl molecule (in the vapor phase), appeared during the preparation of the present communication for press; the conclusions expressed in these publications are in general agreement with our calculations.Translated from Teoreticheskaya i Eksperimental' naya Khimiya, Vol. 24, No. 2, pp. 197–203, March–April, 1988.     

Similarities between thermolysis and mass spectrometric fragmentation of tetrazoles (review)

Both thermolysis and dissociative ionization of tetrazole and its derivatives form products of the same elemental composition. This similarity permits mass spectrometry to be used to predict thermal conversions and the compositions of thermolysis products.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 723–741, June, 1985.     

Mass spectrometry of nitrogen heterocycles. 4. Mass spectral behavior of triazolo[1,5-a]pyrido[2,3-d]pyrimidines

The electron impact mass spectra of substituted 9-imino- and 9-oxotriazolo[1,5-a]pyrido[2,3-d]pyrimidines were studied. The mass spectral data obtained permitted us to determine the order of the fusion of the triazole, pyrimidine, and pyridine rings as well as the position of the hydrogen atoms at the heteroatoms. Compounds labelled with ¹⁵N and ¹³C atoms were used to check the assignments made.For Communication 3, see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 116–120, January, 1992.     

Synthesis of N-alkyl- and N-(β-hydroxyalkyl)-2-(acylmethylthio)benzimidazoles and their properties

N-alkyl- and N-(β-hydroxyalkyl)-2-(acylmethylthio)benzimidazoles have been obtained by the reaction of N-alkyl- and N-(β-hydroxyalkyl)benzimidazoline-2-thiones with α-haloketones. The structures of the substances synthesized have been confirmed by IR, PMR, and mass spectra. The biological properties of the compounds obtained have been studied.     

The vibrational spectrum of crystalline KSCN

The spectrum is reported for the range 700 to 5000 cm^–1; the internal modes of the SCN^– ion are interpreted in terms of the C_s local symmetry group. The combinations of internal and external (lattice) modes are examined in terms of theD _2h factor group. The frequency of the translational mode is found to be 20 cm^–1.I am indebted to Academician A. N. Terenin for direction and encouragement, and to L. A. Gribov and D. S. Bystrov for discussions.     

Synthesis and reactions of 2-(4-pyridyl)indole anhydro bases

The corresponding anhydro bases are formed from quaternary salts of 2-(4--pyridyl)indole under the influence of a methanol solution of alkali. The 2-(4-pyridyl)indole cation and 1H-4-(2-indolenylidene)-1,4-dihydropyridine were subjected to quantum-chemical calculation, and the possibility of electrophilic substitution of the anhydro bases in the position of indole was predicted on the basis of the results of the calculations. Thus, the reaction of the anhydro bases with acetyl nitrate and a solution of bromine in acetic acid leads to quaternary salts with a substituent in the position of the indole ring, which are reconverted to anhydro bases under the influence of alkali with retention of the substituent in the position. When the anhydro bases are refluxed in nitromethane and cyanoacetic and malonic esters in the presence of triethylamine, they form the corresponding adducts, which give the starting compounds under the influence of alkali, whereas upon reaction with methyl iodide in ethanol they give quaternary salts. All of these chemical transformations were confirmed by the IR, UV, PMR, and mass spectra.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 52–58, January, 1982.     

Mass spectrometry of nitrogenous heterocycles. 1. Mass spectrometric evaluation of stability of tetrahydropyrazines annelated to five- and six-membered heterocycles

Based on a study of electron impact mass spectra of a large number of tetrahydropyrazines, which are joined to five- and six-membered heterocyclic and carbocyclic residues, the trends which characterize the stability of these condensed systems are found. The proposed criteria can be used for evaluation of the chemical stability of these compounds, for example, their propensity toward the reverse dissociation reaction.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 532–538, April, 1989.     

Gas-Chromatographic Analysis of Terpenoid-Maleic Adducts

Conditions were found for separation of a mixture of terpenoid-maleic adducts and maleic adduct of resin acids in the form of methyl esters by gas-liquid chromatography.