Research on 1-aza two-ring systems

Reduction of 5-[2-(methoxycarbonyl)ethyl]-1,3-dihydropyrrolizines with lithium aluminum hydride gave 5-(-hydroxypropyl)-1,2-dihydropyrrolizines (in 70–90% yields), which have intramolecular -hydrogen bonds in dilute solutions. The parameters of the -hydrogen bonds were determined in the IR spectra, and their enthalpies were found. The data obtained (_OH 95–99 cm^–1, –H 3.05 kJ·mole^–1) show that among compounds with an aliphatic hydroxyl group and a system of electrons, 5-(-hydroxypropyl)-1,2-dihydropyrrolizines have some of the strongest intramolecular -hydrogen bonds.See [1] for communication XVI.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 359–363, March, 1978.     

The occurrence of an implication in finitely valid,intuitively improvable formulas of propositional logic

Kabakov has proved that for the finite validity (in Medvedev's sense) of intuitively unprovable propositional formulas it is necessary that an implication occur in the premise or else in the inference of some subformula of the type ( ), and, consequently, that at least two implications be present. Here we prove that every finitely valid, intuitively unprovable formula contains the occurrence of an implication necessarily in the premise of some subformula of the form ( ) and we also present an example of a similar formula containing exactly two implications.Translated from Matematicheskie Zametki, Vol. 20, No. 3, pp. 383–390, September, 1976.     

Furan compounds

By reductive amination, starting from furfural, 5-methylfurfural, β-(2-furyl)acrolein, and monoethanolamine, we have obtained N-furfurylaminoethanol, N-(5-methyl-2-furfuryl)aminoethanol, and N-[1-(α-furyl)-3-propyl]aminoethanol. By reductive amination combined with the subsequent hydrogenation of the furan ring we have obtained N-tetrahydrofurfurylaminoethanol and N-(5-methyltetrahydro-2-furfuryl)aminoethanol.     

Reaction of benzimidazole-2-thione with cyanoacetylene alcohols

Conclusions 2-Iminobenzimidazo-1,3-thiazines containing a hydroxyl group were obtained by the reaction of benzimid-azole-2-thione with tertiary cyanoacetylene alcohols. It was observed that they have enhanced stability toward alkalis.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 8, pp. 1903–1904, August, 1984.     

Acetylenic condensation of 1-alkoxy- and 1-alkylthio-1-buten-3-ynes with substituted iodobenzenes

Conclusions New -arylenyne ethers and thioethers were prepared by the acetylenic condensation of 1-alkoxy-(1-ethylthio)-1-buten-3-ynes with a series of substituted iodobenzenes in the presence of CuI.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 3, pp. 692–693, March, 1976.     

Radiation degradation of lignin

An analysis is given of literature information on the radiation degradation of lignin. The following questions are discussed: 1) the formation of radicals in the radiolysis of lignin and compounds modeling it; 2) the chemical properties of irradiated lignin; 3) the low-molecular-mass products of the radiolysis of lignin; and 4) the radioprotector properties of lignin.All-Union Scientific Research Institute for the Hydrolysis of Plant Material, Leningrad. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 3–15, January–February, 1990.     

Research on 1-azabicyclic systems

Epimeric 3-methylpyrrolizidines were separated preparatively. Competitive quaternization of the mixture of isomers with n-propyl iodide and catalytic isomerization were used to obtain trans-3, 8-H-3-methylpyrrolizidine. cis-3,8-H-3-Methylpyrrolizidine was isolated from the mixture by quaternization with benzyl chloride and subsequent hydrogenolysis of the resulting quaternary salt. The pK_a values of trans- and cis-3,8-H-3-methylpyrrolizidines, pyrrolizidine, and indolizidine were measured. It is shown that in a series of saturated amines with a tertiary nitrogen atom pyrrolizidine and 3-methylpyrrolizidines are among the strongest bases.See [1] for communication XII.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1060–1064, August, 1976.     

Synthesis of Dialkyl 1-Methyl-2,2-dichlorocyclopropylcarbonylphosphonates and Alkyl (1-Methyl-2,2-dichlorocyclopropylcarbonyl)arylphosphinates

Russian Journal of General Chemistry -     

Numerical prediction of turbulent boundary layer noise from a sharp-edged flat plate

An efficient hybrid uncorrelated wall plane waves–boundary element method (UWPW-BEM) technique is proposed to predict the flow-induced noise from a structure in low Mach number turbulent flow. Reynolds-averaged Navier-Stokes equations are used to estimate the turbulent boundary layer parameters such as convective velocity, boundary layer thickness, and wall shear stress over the surface of the structure. The spectrum of the wall pressure fluctuations is evaluated from the turbulent boundary layer parameters and by using semi-empirical models from literature. The wall pressure field underneath the turbulent boundary layer is synthesized by realizations of uncorrelated wall plane waves (UWPW). An acoustic BEM solver is then employed to compute the acoustic pressure scattered by the structure from the synthesized wall pressure field. Finally, the acoustic response of the structure in turbulent flow is obtained as an ensemble average of the acoustic pressures due to all realizations of uncorrelated plane waves. To demonstrate the hybrid UWPW-BEM approach, the self-noise generated by a flat plate in turbulent flow with Reynolds number based on chord Re_c = 4.9 × 10⁵ is predicted. The results are compared with those obtained from a large eddy simulation (LES)-BEM technique as well as with experimental data from literature.