O-acylated flavonoid glycosides of the needles ofPinus sylvestris I. O-acetylated derivatives of flavonol glycosides

Summary O-Acetylated flavonol glycosides have been isolated for the first time from the needles of the Scotch pine and the following structures have been established for them: 3,45,7-tetrahydroxy-3-methoxyflavone 3-O--D-(6-O-acetylglucopyranoside), 3,4,5,7-tetrahydroxy-3-methoxyflavone 3-O--D-(6-O-acetylgalactopyranoside), and 3,3,4,5,7-pentahydroxyflavone 3-O--D-(6-O-acetylglucopyranoside). The first two compounds have not previously been described in the literature.All-Union Scientific-Research Institute of Medicinal Plants, Moscow. Irkutsk Institute of Organic Chemistry, Siberian Branch of the Academy of Sciences of the USSR. I. M. Sechenov I Moscow Medical Institute. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 193–196, March–April, 1978.     

Metastable high-spin states in chemical ionization in hydrocarbon combustion

The chemical ionization mechanism for HCO ₂ ⁺ is considered from MINDO/3 CI calculations and ones on the spin-orbit interaction elements, which has been employed in examining the sections of the potential-energy surfaces along the reaction coordinates in the formation of HCO ₂ ⁺ and HCO ₂ ⁺ .Karaganda University. Translated from Teoreticheskaia i ksperimental'naya Khimiya, Vol. 27, No. 6, pp. 672–677, November–December, 1991. Original article submitted April 24, 1989.     

Kinetics and mechanism of the hydrogenation of substituted anthraquinones on Raney nickel catalysts

The rate and direction of the hydrogenation of anthraquinone has been established to depend considerably on the nature and position of the substituent as well as on the structure and phase composition of the catalyst. The selectivity of the process is increased by introducing electronaccepting substituents into the anthraquinone molecule or upon doping the Ni–Al alloy by additives increasing the M–H bond energy.

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, . Ni–Al , M–H, .

     

Uncommon transformations of methyl (1S,2S,3R,4R)-2,3-isopropylidenedioxy-5-iodomethyl-2-tetrahydrofurylacetate initiated by bases

Methyl (1S,2S,3R,4R)-2,3-isopropylidenedioxy-5-iodomethyl-2-tetrahydrofurylacetate prepared in two stages from D-ribose acetonide underwent a series of uncommon transformations under the treatment with bases providing the following different products depending on the base applied: methyl 3-(5-acetyl-2,2-dimethyl-1,3-dioxol-4-yl)propionate (DBU), methyl 2,3-isopropylidenedioxy-7-oxabicyclo[2.2.1]heptane-6-carboxylate (t-BuOK), methyl {(5R)-2,2-dimethyl-5-[(2R)-oxiranyl]-1,3-dioxolan-4-ylidene}propionate and methyl-(E)-3-{(4S,5R)-2,2-dimethyl-5-[(1R)-(2-oxiranyl)]-1,3-dioxolan-4-yl}-2-propenoate (t-BuOK and LDA).     

Intramolecular electron transfer in mixed-valence complexes [(NH3)5Ru-L-Ru(NH3)5]5+ (L = N2, pyz, pym, 4,4′-bipy, bpa)

The dynamics of the intramolecular electron transfer from Ru(II) to Ru(III) in binuclear mixedvalence complexes [(NH₃)₅Ru-L- Ru(NH₃)₅]⁵⁺ (L = N₂,pyz, bipy, pym, bpa) is analyzed by the semiempirical CINDO +CI method. Translated fromZhumal Strukturnoi Khimii, Vol. 39, No. 4, pp. 579–590, July–August, 1998.     

Electronic structure, spectrum, and intramolecular electron transfer model of [(NH3)5Ru-(4,4’-bipy)-Ru(NH3)5]5+

The electronic structure of the ground and excited states of the binuclear mixed-valence complex [Ru(NH₃)₅]₂(4,4’-bipy)⁵⁺ is calculated by the semiempirical INDO + CI method, and an electronic spectrum assignment is given. A theoretical model of electron transfer between the Ru(II) and Ru(III) metal centers is constructed on the basis of many-electron wave functions. The dependence of the electron transfer characteristics on the angles between the planes of the pyridine rings and also between the pyridine rings and the planes of cis(NH₃)-Ru-cis(NH₃) is analyzed. Translated fromZhumal Struktumoi Khimii, Vol. 38, No. 3, pp. 447–456, May–June, 1997.     

Structural inhomogeneity types of perovskite-like superconductors. Relation to growth conditions

Literature data and our studies are used to consider three types of structural inhomogeneity in perovskite-like superconductors. Their irregular mixed-layered structures differ in the nature and distribution of impurity layers. A three-dimensional diagram is suggested for each type of defect. A great variety of postgrowth conditions are discussed to choose optimal conditions for obtaining perfect single crystals with the desired content of oxygen and T_s. St. Petersburg State University. Translated fromZhurnal Strukturnoi Khimii, Vol. 35, No. 5, pp. 15–22, September–October, 1994. Translated by O. Kharlamova     

A microbatch anion-exchange technique for matrix separation

Summary A rapid and simple one-vessel microbatch anionexchange method has been developed for matrix separation prior to the AAS determination of the trace elements. The method can be applied to the separation of matrix elements which are strongly sorbed on anion exchangers, e.g. gold, palladium, bismuth a.o. The method was illustrated by the flame or ET-AAS determination of 20 trace elements in pure gold. The limits of detection were from 0.002 to 0.4 g/g, the RSD from 3 to 8% depending on the trace element.     

Synthesis of 3E-tetradecenol, 3E, 9E-tetradecadienol,and their acetates starting from acetylcyclopropane

Stereospecific synthesis of the linear E-olefins mentioned in the title was realized by a general scheme that was worked out earlier by the authors and which includes as key steps homologization of the corresponding aliphatic pentakisnoraldehydes by means of trimethylsilyloxyvinylcyclopropane and ZnBr₂-initiated rearrangement of the intermediate cyclopropylcarbinols under the influence of Me₃SiBr.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 3, pp. 640–644, March, 1991.