Reactions of cyclammonium cations

The reaction of 1,2-diaminopyridinium salts with -dicarbonyl compounds or -halogeno ketones forms pyrido[1,2-b][1,2,4]triazinium salts. A methyl group present in position 2 of one of these salts condenses with aldehydes, giving styryl derivatives and reacts with orthoesters to give cyanines.For Communication XXII, see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1266–1270, September, 1973.     

EPR spectra of halogenonitromethane anion radicals

Conclusions It was deduced that fluorine is in a -combined state in the anion radicals we studied; this was based on an analysis of the EPR spectra of a series of fluoronitroalkane anion radicals.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 2, pp. 458–460, February, 1969.In conclusion, the authors express their appreciation to A. A. Fainzil'berg for his interest in our work.     

Synthesis of 1,2-Divinyloxypropenes from Glycerol and Acetylene in the Superbasic System CsF-NaOH-DMSO

Russian Journal of Organic Chemistry -     

Mechanism of Dehydrobromination of 1,2-Dibromo-1-phenylethane under Conditions of Phase-Transfer Catalysis

Selective dehydrobromination of 1,2-dibromo-1-phenylethane to -bromostyrene was effected under conditions of phase-transfer catalysis in systems containing KOH, toluene, and tetraalkylammonium bromides. The high selectivity of the catalytic systems originates from stabilization by lipophilic cation of the phase-transfer catalyst of a E1cb-like transition state in the E2 mechanism. In the presence of a catalytic amount of lipophilic alcohols, phenylacetylene was obtained. Substrate activation by alcohol molecules is explained by enhancement of the acceptor power of halogen atoms due to solvation and by increased mobility of hydrogen atoms.     

Hydrodynamic and conformational properties of cellulose myristate molecules in solution

Cellulose myristate samples with a degree of substitution of 230–250 have been studied by the methods of molecular hydrodynamics (viscometry, analytical ultracentrifugation (flotation), and isothermal translational diffusion) in chloroform in the range M = (56–652) × 10³. The experimental evidence has been interpreted within the framework of the generalized wormlike Yamakawa-Fuji model with the following parameters: the persistence length a = 115 × 10^?8 cm, the chain diameter d = 45 × 10^?8 cm, and the molecular mass per unit chain length M _L = 270 × 10⁸ cm^?1. It has been inferred that the polymer dissolves in chloroform in the form of dimers.     

Fragmental analysis of energies of electronic transition in monosubstituted benzene derivatives. I. A single configuration approximation

Conclusions The analysis of EET in the SC-approximation that has been carried out on the example of MSB showed that the use of the FO basis instead of the AO basis gives additional information on the relationship between the energies of transitions of the chromophoric (benzene) molecule and its substituted derivatives.In the FO basis the decomposition of the EET into the fragmental and interfragmental components becomes natural. The value of the fragmental components is determined by the LN of the transition MO in the separate fragments, while that of the one-electronic energies and the coulombic and exchange integrals of the fragment (the chromophore) are approximately transferable parameters.Since the LN are dependent on the degree of mixing of the FO of the fragments the study of the relationship between the transition energies of the SC-transitions in the chromophoric molecule and the fragmental components in the substituted molecule is reduced to the study of formation the LCFO MO. Moreover, the LCFO MO makes it possible to find a relationship between the SC-transitions even when the LCAO MO of the two molecules are not commensurable. This makes it possible to carry out a classification of the SC-transitions in MSB according to the SC-transitions of benzene.We wish to express our gratitude to A. L. Gineitite for useful comments made during the preparation of the article.Institute of Biochemistry, Lithuanian Academy of Sciences. Institute of Theoretical Physics and Astronomy, Lithuanian Academy of Sciences. Translated from Zhurnal Strukturnoi Khimii, Vol. 33, No. 6, pp. 45–56, November–December, 1992.     

Methane Hydroxylation by Methane Monooxygenase: On the Problem of the Process Dynamics

Published data on the kinetic isotope effects of the hydroxylation of deuterium-substituted methane molecules (CHD₃, CH₂D₂, and CH₃D) by methane monooxygenase are examined in the framework of the two-step nonradical mechanism through the intermediate formation of a complex containing pentacoordinate carbon. The kinetic schemes with the first step involving one, two, and three hydrogen atoms of the oxidized substrate are considered. Contrary to the widely accepted oxygen rebound mechanism, the experimental results obtained for the oxidation of various substrates by methane monooxygenase and cytochrome P450 can be explained from the viewpoint of the dynamics of a general nonradical mechanism.