N-alkylation of 4-chloro-5-cyano-1,2,3-triazole with orthoformic acid derivatives

The N-alkylation of 4-chloro-5-cyano-1,2,3-triazole with methyl and ethyl orthoformate, and the dimethyl, diethyl and ethylene acetals of DMF has been examined. Methylation gives all three N-methyl isomers, whereas ethylation and hydroxyethylation gives the 2-N-alkyl derivatives only. It has been shown for the first time that it is possible to use DMF ethylene acetal to obtain N-hydroxyethylazoles. The structures of the products were established by¹³C NMR spectroscopy.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 920–924, July, 1988.     

Structure and some properties of tetrazole 5-methylpyrimido[4,5-e]-[1,2,4]triazine-6,8-dione and its azide in different phase states

The structure of the tetrazole, 5-methylpyrimido[4,5-e][1,2,4]triazine-6,8-dione was established by x-ray structural analysis. The tautomeric equilibrium with its azide isomer in solution was examined. The effect of bases on this equilibrium was discovered. Analytical criteria were proposed which permit identification of the tetrazole and the azide forms in the gas phase.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 114–120, January, 1986.     

Reactions of N-alkylazinium cations. 3. Quaternary pteridinium salts. Synthesis,structure, and reactions with simple nucleophiles

4-Morpholinopteridine reacts with triethyloxonium tetra-fluoroborate to give two types of isomeric quaternary salts, viz., 1-ethyl- and 8-ethyl-4-morpholinopteridinium tetrafluoroborates. The structures of the pteridinium cations were proved by the ¹H and ¹³C NMR spectra and also by chemical transformations in reactions with simple nucleophiles.See [1] for communication 2.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1257–1264, September, 1985.     

Slow Kinetics of viscoelastic properties of oil at low-frequency shear vibrations

The results of experiments on the observation of the slow evolution of viscoelasticity moduli of crude oil are presented. Measurements were carried out continuously for 72 h at frequencies of 0.5, 5, and 50 Hz at different temperatures. Based on the Boltzmann statistical approach to determination of the velocity of transition into an equilibrium state, a model differential equation describing slow kinetics of variations in the internal medium parameters is derived. As distinct from the accepted exponential time dependence, the slow kinetics is shown to yield a logarithmic time dependence of perturbation damping.     

13C NMR spectra of the aminoglycoside antibiotics streptomycin and dihydrostreptomycin. Complete assignment of the signals

On the basis of the results of a study of the dependence of the chemical shifts of the¹³C NMR spectra streptomycin and dihydrostreptomycin over a wide pH range (from 1.0 to 10.0) and a comparison with the spectrum of streptidine in an acid medium, a complete assignment of the spectra of the antibiotics investigated has been made. The optimum pH values of solutions at which the clearest separation of the resonance signals in the spectra of streptomycin and dihydrostreptomycin have been determined (pH 1.0–7.0 and pH ≤ 8.6, respectively). All-Union Scientific-Research Institute of Antibiotics, Moscow. I. M. Sechinov 1st Moscow Medical Institute. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 695–700, September–October, 1980.     

Alkaloids ofHypecoum erectum,the structure of hyperectine

The structure of a new spirobenzylisoquinoline alkaloid fromHypecoum erectum L. has been established by spectral methods and also by the x-ray structural analysis of its methiodide. It has been shown that the alkaloid, which has been called hyperectine, has a pentacyclic structure in which the tetrahydroisoquinoline fragment has the sofa conformation and the indan fragment the envelope conformation. The natural alkaloid is a mixture of the enantiomeric C-8(S), C-16(R), and C-8(R), C-16(S) forms.All-Union Scientific-Research Institute of Medicinal Plants, Moscow. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 628–635, September–October, 1984.     

Poloidal inhomogenity of the particle fluctuation induced fluxes near the LCFS at lower hybrid heating and improved confinement transition at the FT-2 tokamak

This paper deals with the new spectral and microturbulence experimental data and their analysis, which show that the radial electric field E _r generated at the lower hybrid heating (LHH) in the FT-2 is high enough to form the transport barriers. The ETB is formed when LHH is switched off. The radial fluctuation-induced E × B drift flux densities near LCFS in SOL are measured at two different poloidal angles. For this purpose two Langmuir probes located at low and high field sides of the torus are used. Registration of the poloidal and radial components of the electric field and density fluctuations at the same time during one discharge permits to measure the poloidal asymmetry of the transport reduction mechanism of the radial and poloidal particle fluxes in the SOL. The absolute fluctuation levels show dependence on the sign of E _r shear. The modification of the microscale turbulence by the poloidal E _r × B rotation shear _{E × B} at the L-H transition near LCFS is also studied by X-mode fluctuation reflectometry. The new data were obtained by spatial spectroscopic technique.Presented at the Workshop Electric Fields Structures and Relaxation in Edge Plasmas, Nice, France, October 26–27, 2004.