Synthesis and chiral-optical properties of some benzolactams

Five- and seven-membered benzolactarns — (–)-S-2, 3-dimethyl-2, 3-dihydroisoindolone and (+)-S-5-methyl-2, 3, 4, 5-tetrahydrobenz[c]azepin-1-one — were synthesized. A study of their chiral-optical properties and comparison with the previously studied six-membered lactam (–)-S-4-methyl-3, 4-dihydroisoquinol-1-one showed that their circular dichroism spectra are similar: The spectra contain dichroic absorption bands due to ^* transitions in the aromatic chromophore (270 and 220 nm) and a band of charge transfer in the benzamide chromophore at 240–250 nm. The magnitude of the Cotton effect due to the charge-transfer band increases as the lactam ring becomes larger (five-membered < six-membered < sevenmembered benzolactam). The change in the magnitude of the Cotton effect is explained by the development of a strictly dissymetric chromophore.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 656–662, May, 1978.     

Conversion of furan compounds in the presence of polymeric gel-immobilized catalysts

Based on studies of catalytic oligomerization of furyl alcohol, 2-furfurylydeneacetone and tetrachlorofuran in the presence of gel-immobilized complexes (GIC) Al(OPh)₃, BF₃ and Ti(OBu)₄, an oligomerization mechanism is suggested and supported experimentally.

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(), 2- () () - (), Al(OPh)₃, BF₃ Ti(OBu)₄. .

     

Electrophysical properties and annealing of defects in nuclear transmutation-doped GaAs irradiated by H+ ions

A study has been made of the electrophysical characteristics of nuclear-transmutation-doped GaAs (NTDG) and GaAs doped with metallurgical impurities Sn, Te, Ge, and In, after irradiation by H⁺ ions at fluxes of up to 1.5·10¹⁶ cm^–2. It is shown that the changes in the GaAs produced by irradiation do not depend on the method used to dope the material and can be described on the basis of the known spectrum of E and H traps in GaAs. Crystals of GaAs annealed after irradiation display deep (P1–P3) traps, which are responsible for the high-temperature proton insulation GaAs.V. D. Kuznetsov Siberian Physicotechnical Institute at the State University, Tomsk. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 10, pp. 61–65, October, 1992.     

Rearrangements in methanolysis of bis(2-bromoalkyl)selenides

Addition of selenium dibromide to 1-hexene, 1-octene, and allylic ethers occurs through the formation of intermediate kinetic anti-Markovnikov adducts that further transform into more thermodynamically stable Markovnikov adducts presumably via seleniranium intermediates. The methanolysis of both Markovnikov and anti-Markovnikov adducts leads to the formation of the same products in approximately the same ratio thus showing that the reaction proceeds through seleniranium intermediates.     

Two-dimensional photonic and phononic crystals based on lithium niobate

Specific features of the preparation and application of photonic and phononic crystals containing two-dimensional periodic domain structures are considered. Particular attention is given to the formation of two-dimensional periodic domain structures in oxide ferroelectrics using strongly focused laser beams. Specific features of the nonlinear properties of such two-dimensional structures during the propagation of optical and acoustic beams through them are described.     

Spectral problems for variational inequalities with discontinuous operators

Some spectral problems for variational inequalities with discontinuous nonlinear operators are considered. The variational method is used to prove the assumption that such problems are solvable. The general results are applied to the corresponding elliptic variational inequalities with discontinuous nonlinearities.