Reaction of α-(trialkylstannyl) acetylenes with metallic sodium

-Trialkylstannylacetylenes react under mild conditions with metallic sodium at the Sn-C(sp) bond to give hexaalkyldistannanes and sodium acetylalkynides inca. 65–85 % yields.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1109–1110, June, 1994.     

Synthesis of 2-amino-4,4-bis(trifluoromethyl)-3-cyano-4,5-dihydro-1H-1,5-benzodiazepine

Conclusions The reaction of 1,2-phenylenediamine with 2,2-bis(trifluoromethyl)-1,1-dicyanoethylene leads to the formation of 2-amino-4,4-bis(trifluoromethyl)-3-cyano-4,5-dihydro-lH-l,5-benzodiazepine, whose structure was established by x-ray diffraction analysis.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 8, pp. 1920–1922, August, 1988.     

Investigation of mechanism of initiation of polymerization of cyclic acetals by protic and aprotic acids

The kinetics of polymerization of 1,3-dioxolan and degradation of polydioxolan catalyzed by boron trifluoride etherate have been studied in methylene chloride solution. The S-shape kinetic curves is found to be due to the autocatalytic action of the macromolecules formed. Effective participation of macromolecules in the initiation process has been confirmed on the basis of the relationship of the rate constants of boron trifluoride etherate reactions with cyclic monomer and with the polymer chain as well as by the decrease of the induction period on addition of the polymer or its low molecular weight analog, methylal, to the polymerization system.     

Structural Investigations of Argon Hydrates at Pressures up to 10 kbar

Neutron diffraction patterns of three argon hydrates which exist at the pressures up to 10 kbar has been studied; Rietveld refinement of their structures has been done. The phase which is stable from 1 bar to 4.6 kbar appears to be typical cubic structure II gas hydrate with variable degree of filling of the large cavities. Stoichiometry of this compound under high-pressure conditions has been determined for the first time and appears to be ArW4.5H₂O and Ar·4H₂O at 3.4 and 4.3 kbar, respectively. Gas hydrate existing in the pressure range of 4.6–7.7 kbar has a hexagonal structure (hexagonal structure III, so-called structure H). Refinement of the structure has shown that the best agreement between calculated and experimental pattern can be reached in the case of accommodation of five (!) argon atoms in the large cavity. Indexing of the neutron diffraction pattern of the hydrate stable in the 7.7–9.5 kbar range leads to the primitive tetragonal unit cell with parameters a = 6.342 Å, c = 10.610 Å at 9.2 kbar, which does not correspond to any known type of gas hydrates. The water framework of this structure was found by idealizing the structure of pinacol semiclathrate hydrate. This hydrate belongs to a new, earlier unknown, tetragonal structural type of gas hydrates. It contains only one type of polyhedral cavities with 14 faces. This type of polyhedrons are space-filling; two argon atoms occupy each cavity. This structure gives the first example of the gas hydrate water framework which contains only one type of polyhedral cavities.     

C-alkylation of indoles by 1,1-bis(trifluoromethyl)-2,2-di-cyanoethylene and 2-trifluoromethyl-3,3-dicyanoacrylic acid esters

Indole and its derivatives with various substituants in the 1 and 2 positions of the indole ring react with 1,1-bis(trifluoromethyl)-2,2-dicyanoethylene and 2-trifluoromethyl-3,3-dicyanoacrylic acid esters to give C³-alkylation products.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 5, pp. 1193–1195, May, 1991.     

Calculation of the quadrupole splitting in 2H NMR spectra of polymeric networks

On the basis of current theories of electric quadrupole effects in NMR, we have calculated the quadrupole splitting in ²H NMR spectra for simple models of polymeric networks. We have considered the effect on of several types of anisotropic motions which are rapid on the NMR time scale: segmental motion; rotations of the deuterium-labeled group about an axis which is fixed relative to the polymeric segment (rotations which are independent of other types of motions); spatially restricted random motion of units of the network relative to their average positions. The calculation predicts an inverse proportionality between and the number of segments of the chain connecting two adjacent units of the network. For the considered systems, in contrast to polycrystals, the lineshape should not depend on the electrostatic field asymmetry parameter which may affect only the magnitude of the splitting . The theory allows us to explain the appearance of an absorption signal of unusual shape in ²H NMR experiments on cross-linked polymers.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 21, No. 1, pp. 56–61, January–February, 1985.     

Certain reactions of tris(α,α,ω-trihydroperfluoroalkyl) phosphites

Conclusions Certain properties of tris(1,1,3-trihydroperfluoropropyl), tris(1,1,5-trihydroperfluoropentyl), and tris(1,1,7-trihydroperfluoroheptyl) phosphites were studied, and it was shown that the presence of the,,-trihydroperfluoroalkoxyl groups determines their behavior as the result of an increase in the v-acceptor and decrease in the n-donor ability of the phosphorus atom.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 1, pp. 163–169, January, 1979.