Electrochemical preparation of colloidal fluorescent graphite

Colloidal graphite having nano- and microparticles and exhibiting fluorescence properties was prepared by the destruction of the glassy carbon anode in the electrolyte containing hydrochloric acid and α-olefin C₁₆-C₁₈.     

Design of ecologically safe and science intensive electrochemical processes

This review discusses the results of and prospects for studies aimed at design of new science intensive, environmentally safe technologies for the synthesis of organophosphorus compounds by halogenation of α-olefins, including modification of rapeseed oil; it also considers methods for the production of some other intermediates for chemical industry. New synthetic applications have been developed, using combined methods of classical organic chemistry and electrochemistry, for processes based on electrochemical generation of catalysts (mediators)—complexes of metals in low oxidation states, halogen complexes, etc. Selective electrochemical procedures are suggested for the synthesis of triphenylphosphine, trialkylphosphates, and nanosized transition metal phosphides from white phosphorus.     

Inelastic deformation of glassy polyaryleneetherketone: Energy accumulation and deformation mechanism

The plastic deformation of glassy non-annealed polyaryleneetherketone (PAEK) was investigated via deformation calorimetry and thermally stimulated recovery of residual strain. Polymer samples were deformed at room temperature under uniaxial compression up to ε_def =–(40?50)% at a rate of 0.04 min^?1. It was found that PAEK behaves in the deformation process similarly to many other glassy polymers: It stores internal energy excess at loading and contains two types of different inelastic strain carriers, namely the delayed elastic (ε_de) and plastic (ε_pl) strain carriers. The maximum level of the accumulated energy in PAEK reaches ≈ 8.3 J/g, which is close to those for glassy polystyrene and polycarbonate. Nearly all the deformation energy stored in PAEK is carried by the delayed-elastic strain. The carriers of plastic strain carry no extra energy or a very small amount of it. The inelastic deformation of glassy PAEK proceeds in two stages. The carriers of ε_de are nucleated at the first stage of the deformation process, and the carriers of ε_pl are nucleated at the second stage. It was shown that, during glassy-polymer loading, the molecular level structures carrying ε_pl never appear by themselves, but appear only as a result of spontaneous reorganization of ε_de. In other words, the plastic deformation appears in PAEK owing to the two-step process. This situation is typical for all glassy polymers.     

Effect of the Chemical Structure of Heat-Resistant Thermoplastics on the Friction on Steel

A general approach to understanding the complex nature of the friction of friction-resistant heatresistant thermoplastics has been developed. This approach made it possible to idenify two main factors determining the basic character of the friction of these polymers on steel: the dispersion component of the intermolecular interaction energy and the molecular weight. Specific properties of some polymers can be used to refine the friction behavior.     

Synthesis of Spiroheterocyclic Systems from Barbituric Acids and <Emphasis Type="Italic">N,N</Emphasis>-Disubstituted <Emphasis Type="Italic">o</Emphasis>-Aminobenzaldehydes

Reactions of barbituric, 1,3-dimethylbarbituric, and 2-thiobarbituric acids with 2-(1-pyrrolidinyl)benzaldehyde, its 6- and 7-membered homologs, and 4-phenylpiperazine and morpholine analogs lead to formation of fused systems with a spirocyclic 2,4,6-trioxopyrimidine fragment. The process involves intermediate formation of labile 5-arylmethylidenebarbituric acids which exhibit t-amino effect and undergo spontaneous isomerization to give the final products. The observed spirocyclizations are characterized by an anomalously high rate.__________Translated from Zhurnal Organicheskoi Khimii, Vol. 41, No. 6, 2005, pp. 920–925.Original Russian Text Copyright © 2005 by Krasnov, Kartsev.     

Stereoselective cyclization of alkyl N-phthaloyl-4-bromoglutamates to cyclopropane derivatives

The kinetics of the reactions of alkyl N-phthaloyl-4-bromoglutamates with Et₃N and KOH was investigated. The reactions proceed stereospecifically to form alkyl 1-phthalimidocyclopropane-r-1,t-2-dicarboxylates. In alcohols, the reactions are accompanied by transesterification. The concerted mechanism accounting for the stereospecificity of these reactions is proposed.     

Preparative Synthesis and Structure of 2,2-Bis(hydroxymethyl)propyl and 2,2-Bis(hydroxy-methyl)butyl Phosphites

Conditions were found for selective hydrolysis of bicyclic phosphites derived from 2,2-bis-(hydroxymethyl)-1-propanol and 2,2-bis(hydroxymethyl)-1-butanol to the corresponding dihydrogen phosphites. The latter were isolated as potassium, sodium, and ammonium salts and were characterized by the ¹H, ¹³C, and ³¹P NMR spectra. The structure of the ammonium salt was proved by X-ray analysis.     

Gas-phase electron diffraction and quantum chemical study of the structure of the 4-nitrobenzene sulfonyl chloride molecule

A combined gas-phase electron diffraction and quantum chemical (B3LYP/6-311+G**, B3LYP/cc-pVTZ, MP2/6-31G*, and MP2/cc-pVTZ) study of the structure of the 4-nitrobenzene sulfonyl chloride molecule is performed. It is found that at a temperature of 391(3) K only one conformer with C _s symmetry is present in the gas phase. The following experimental values of structural parameters are obtained: r _h1(C-H)_av = 1.086(6) Å, r _h1(C-C)_av = 1.395(3) Å, r _h1(C1-S) = 1.773(4) Å, r _h1(S=O) = 1.423(3) Å, r _h1(S-Cl) = 2.048(4) Å, r _h1(N-O) = 1.224(3) Å, r _h1(N-C4) = 1.477(3) Å, ∠(C1-S=O) = 109.0(4)°, ∠(Cl-S-O) = 106.7(2)°, ∠C1-S-Cl = 100.2(13)°, ∠O=S=O = 122.9(11)°, ∠O=N=O = 123.6(5)°. The C2-C1-S-Cl torsion angle that characterizes the position of the S-Cl bond relative to the benzene ring plane is 89(4)°. The NO₂ group lies in the benzene ring plane. Internal rotation barriers calculated by B3LYP/6-311+G** and MP2/6-31G* methods are: V ₁ = 4.7 kcal/mol and 5.3 kcal/mol for the sulfonyl chloride group; V ₂ = 4.9 kcal/mol and 6.0 kcal/mol for the nitro group.     

Molecular structure of SmBr<Subscript>3</Subscript> and DyBr<Subscript>3</Subscript> according to the data of simultaneous electron diffraction and mass spectrometric experiment

The saturated vapors of samarium and dysprosium tribromides were investigated for the first time by electron diffraction with mass spectrometric monitoring at temperatures of 1151(10) K and 1141(10) K. Dimer molecules (up to 2 mole %) were found in vapors along with monomer molecules. The SmBr₃ and DyBr₃ molecules have a pyramidal effective configuration with bond angles ∠_gBr-Sm-Br=115.1(9)° and ∠_gBr-Dy-Br=115.3(7)°. The difference between the internuclear distances of SmBr₃ and DyBr₃ (r _g(Sm-Br) = 2.653(6) Å and r _g(Dy-Br) = 2.609(5) Å) coincides with the difference between the ionic radii of Sm³⁺ and Dy³⁺. The insignificant pyramidality of the r _g configuration and the low deformation vibration frequencies of SmBr₃ and DyBr₃ may be indicative of a planar equilibrium geometry of D _3h symmetry. The equilibrium distances r _e(Sm-Br) and r _e(Dy-Br) have been evaluated and compared with the values obtained by quantum chemical calculations.     

The cross-section in <Emphasis Type="Italic">dp</Emphasis>-elastic scattering at the energies of 500, 700 and 880 MeV obtained at the internal target station of Nuclotron

The results on the cross-section of dp-elastic scattering reaction obtained at 500, 700 and 880 MeV at the internal target of Nuclotron are presented. The measurements have been performed using CH₂ and C targets and kinematic coincidence of signals from scintillation counters. The cross-section data are compared with theoretical predictions and results of previous experiments.