sym-triazines. 7. Hydrolysis and cyclization of 1,3,5-triazine series mononitriles

The routes of base and acid hydrolysis of sym-triazine mononitriles has been studied for aqueous or aqueous-alcohol media. Depending on the pH of the medium, the concentration of reagents, and the temperature it was found that the hydrolysis led to the formation of amides, oxo or alkoxy 1,3,5-triazines, or to an unstable sym-triazine carboxylic acid, the latter leading to formation of substituted sym-triazines. A novel series of tetrazolyltriazines has been prepared by the reaction of the mononitriles with sodium azide and their alkylation has been studied. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 731–737, May, 2006.     

Reaction of <Emphasis Type="Italic">N</Emphasis>-sulfonyl-1,4-benzoquinone imines with sodium azide

Depending on the conditions and the order of addition of the reactants, reactions of N-sulfonyl-1,4-benzoquinone imines with sodium azide afforded N-(3-azido-4-hydroxyphenyl)alkane(arene)sulfonamides, N-(3-azido-4-oxocyclohexa-2,5-dienylidene)alkane(arene)sulfonamides, and N-(3,5-diazido-4-hydroxyphenyl)-alkanesulfonamides. Quantum chemical calculations showed that the reactions begin with addition of azide ion to the quinone imine.     

Derivation of an Equation of Phenomenological Symmetry for Some Three-Dimensional Geometries

The main problems of the theory of phenomenologically symmetric (PS) geometries, i.e., geometries of maximum mobility, are their complete classification, the establishing of the fact of existence of their group symmetry, and finding an equation of the phenomenological symmetry for each of them. A complete classification of three-dimensional PS geometries has been already built. Their PS, i.e., the existence of a functional relation between the values of the metric function for all pairs of five points follows from the rank of the corresponding functional matrix. However, not for all such geometries an equation, which expresses the PS, is known in the explicit form. The paper describes methods of finding the equations of PS, which were applied to some three-dimensional geometries. For each of them we give groups of motions that define the group symmetry of degree six.     

Activated sterically strained C=N bond in N-substituted p-quinone mono- and diimines: XIII. Reactions of N-alkyl(aryl, trifluoromethyl)sulfonyl-, N-arylsulfinyl- and N-arylsulfanyl-1,4-benzoquinone monoimines with alcohols

Steric strains arising between the substituent atoms at nitrogen (S, SO, or SO₂) and the methyl group located in positions 3 or 5 of the quinoid ring of 3,5-dimethyl-substituted quinone monoimines lead to the increased angle C=N-S. As a result in these quinone monoimines the reactions of 1,2-addition become thermodynamically possible since the formation of quinolide structures with the sp³-hybridized carbon atom removes the steric strain.     

Observation of polarized positrons from an undulator-based source

An experiment (E166) at the Stanford Linear Accelerator Center has demonstrated a scheme in which a multi-GeV electron beam passed through a helical undulator to generate multi-MeV, circularly polarized photons which were then converted in a thin target to produce positrons (and electrons) with longitudinal polarization above 80% at 6 MeV. The results are in agreement with GEANT4 simulations that include the dominant polarization-dependent interactions of electrons, positrons, and photons in matter.     

Reactions of <Emphasis Type="Italic">N</Emphasis>-arylsulfonylquinone imines with enamines

Depending on the reaction conditions N-arylsulfonyl-1,4-quinone imines with enamines led to the formation of the products of 1,4-addition, derivatives of benzo- and naphthofuran, indole, and benzindole.     

Some Aspects of Seedless Synthesis of Gold Nanorods

Seedless synthesis of gold nanorods with the use of sodium borohydride and hydroquinone as reductants of metal ions has been systematically studied. The effect of reaction system composition on the morphology and optical characteristics of the formed particles has been determined. It has been found that the position of the band of the longitudinal surface plasmon resonance of the nanorods varies nonmonotonically with variations in the concentration of hydroquinone or silver nitrate. The seedless synthesis has been shown to yield high-quality gold nanorods, with the tunable position of their longitudinal surface plasmon resonance in a wide spectral range (from 700 to ~1050 nm). Therewith, the conversion of metal ions is no lower than 78 wt %.