Tetrazole derivatives. 25. Investigation of the synthesis of 1-(5-tetrazolyl)-3,5-diphenylleucoverdazyl. Structure and some properties of the accompanying product — 1,3,7,9-tetraphenyl-5-oxo-5H-1,2,4-triazolo[3′,4′:5,1]imidazo[4,3-c] -1,2,4-triazole

In the reaction of 1,3-diphenyl-5-(5-tetrazolyl)formazan with formaldehyde, in addition to a leucoverdazyl, one can obtain 1,3-diphenyl-1,2,4-triazole and 1,3,7,9-tetraphenyl-5-oxo-5H-1,2,4-triazolo[3,45,1]imidazo[4,3-c]-1,2,4-triazole. The structure of the latter was established from data from the mass spectrum and the ¹H and ¹³C NMR, UV, and IR spectra, as well as from the products of alcoholysis of this compound, which leads to 1,3-diphenyl-1,2,4-triazole and 1,3-diphenyl-5-carbethoxy-1,2,4-triazole. According to the data from the PMR spectra, the leucoverdazyl displays prototropic tautomerism due to the NH proton of the tetrazine ring.See [1] for Communication 24.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 694–700, May, 1981.The author thank V. I. Svergun ans M. B. Smirnov for recording the ¹³C NMR spectra and their assistance in their interpretation.     

Indoles

In a study of the Fischer cyclization of cyclohexanone mono-p-substituted α, α-diphenylhydrazones (in which the substituents were donor and acceptor groups) it was found that isomeric (formed during cyclization at the substituted and unsubstituted rings) indoles are formed in close ratios. The results were interpreted in terms of sigmatropic processes as a confirmation of the Fischer reaction via a scheme involving a sigmatropic shift.     

Configuration of 2-(4-pyridyl)-5-aryloxazole molecules in various states of aggregation

The electronic absorption and emission spectra in the crystals, solutions, vapor, and ethanol-ether (77 °K) were investigated for the series of 2-(4-pyridyl)-5-aryl-substituted oxazoles at various temperatures. The conjugation between the rings of the system was investigated by mass spectrometry. The combination of spectral data shows that the configurations of such molecules both in the ground state and in the excited state depends substantially on the state of aggregation and on the temperature.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 407–412, March, 1986.     

Adsorption Equilibrium of Binary Mixtures in Zeolites and State of Adsorbed Phase

The criterion of ideal behavior of a mixture of a few molecules within a separate zeolite cavity is formulated on the basis of the statistical thermodynamics. The criterion determines the dependence of the Helmholtz free energy, internal energy, and entropy of a molecular aggregate on the ratio of the number of molecules of components 1 and 2. The similarity between this criterion and the criterion of ideal behavior for bulk solutions is shown. Expressions of excess thermodynamic functions of the molecular mixture in a cavity are obtained. The negative magnitude of these excess functions is proposed to be due to rearrangement of molecules under influence of energetic heterogeneity. The calculation procedure of the excess functions has been demonstrated for the system CO₂-C₂ H₆-zeolite NaX, the information of both isotherms and isosteric adsorption heats being used simultaneously. The approach offered allows the state of adsorbed mixture in a separate cavity to be analyzed from pure-component and multicomponent experimental data.     

Laser study of photooxidation of chloranyl-sensitized 1,2,3,4-tetrachlorodibenzo-p-dioxine

The kinetics of quenching of the triplet state of chloranyl (CA) by 1,2,3,4-tetrachlorodibenzo-p-dioxine (TCD) in benzene and acetonitrile was studied by nanosecond laser flash photolysis. The reaction proceedsvia electron transfer (ET) with the rate constants of 1.5·10⁹ and 3.7·10⁹ L mol^?1 s^?1, respectively. In benzen ET results in the formation of short-lived triplet radical ion pairs (lifetime 100 ns). In acetonitrile, relatively long-lived (lifetime ≥10 μs) radical anion CA^.? and radical cation TCD^.? are formed and decay due to bimolecular reactions in the bulk of the solvent accompanied by the consumption of TCD.     

Mechanism of the formation of a diamond nanocomposite during transformations of C60 fullerite at high pressure

The results of an investigation of the transformation of C₆₀ fullerite to diamond under pressure through intermediate three-dimensionally polymerized and amorphous phases are reported. It is found that treatment of fullerite C₆₀ at pressures 12–14 GPa and temperatures ∼1400°C produces a nanocrystalline graphite-diamond composite with a concentration of the diamond component exceeding 50%. At lower temperatures (700–1200°C) nanocomposites consisting of diamondlike (sp ³) and graphitic (sp ²) amorphous phases are formed. The nanocomposites obtained have extremely high mechanical characteristics: hardness comparable to that of best diamond single crystals and fracture resistance two times greater than that of diamond. Mechanisms leading to the transformation of C₆₀ fullerite into diamond-based nanocomposites and the reasons for the high mechanical characteristics of these nanocomposites are discussed. Pis’ma Zh. éksp. Teor. Fiz. 69, No. 11, 822–827 (10 June 1999)     

5-Phenyl-1,3,4-thiadiazole and 5-phenyl-1,2,4-triazoline-3-thione as products of dehydrogenation of cyclic tautomeric forms of benzaldehyde thiosemicarbazone

5-Pkenyl-1,3,4-thiadiazole and 5-phenyl-1,4-triazoline-3-thione are produced from heterocyclic tautomeric forms of benzaldehyde thiosemicarbazone in the gas phase under conditions existing in a mass spectrometer, and also in the solid phase in the course of thermolysis.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1554–1560, November, 1993.