Selective on-line deuteration in gas chromatography - mass spectrometry for the investigation of dissociative ionization of silicon-containing compounds

A method for specific gas-phase deuteration of unsaturated silicon-containing compounds over pre-heterogenized Wilkinson's catalyst (a solution of (Ph₃P)₃RhCl in Carbowax 20M coated on Chromaton) in the reaction column connected to the mass spectrometer is described. This method was employed to study the dissociative ionization of the corresponding saturated analogues. With the aid of the mass spectra of the dideutero derivatives thus obtained, the main electron-impact-induced reactions of 1,1-dimethyl-1-silacyclopentane, 1,1,2,2-tetramethyl-1,2-disilacyclohexane, 1-methyl-1-ethyl-1-silacyclobutane and ethyl triethoxysilane were elucidated.     

From 1,4-diketones to N-vinyl derivatives of 3,3′-bipyrroles and 4,8-dihydropyrrolo[2,3-f]indole in just two preparative steps

Dioximes of hexane-2,5-dione and cyclohexane-1,4-dione react with acetylene in an autoclave (KOH/DMSO, 100 °C, 1 h, initial pressure 14 atm) to give 2,2′-dimethyl-1,1′-divinyl-[3,3′]bipyrrole and 1,5-divinyl-4,8-dihydropyrrolo[2,3-f]indole in 12% and 6% yields, respectively, thus exemplifying a very simple, straightforward route to inaccessible or unknown pyrrolic assemblies.     

Optical properties of cadmium sulfide nanoparticles on the surface of polytetrafluoroethylene nanogranules

The spectral characteristics in the visible range of synthesized nanocomposites based on cadmium sulfide and ultradispersed polytetrafluoroethylene are investigated experimentally. Local perturbations are found in the long-wavelength regions of the reflection and absorption spectra, which are related to the optical transitions between the critical points of the valence and conduction bands of the nanocomposite. The dispersion relations for the refractive index and the absorption coefficient are obtained for undoped and managanesedoped nanocomposites. The following important parameters of the nanocomposites are obtained from the spectral measurements: the fundamental optical absorption edge (the band gap), the refractive index (ω → 0), and the absorption coefficient. It is shown that doping with managanese affects changes in these parameters.     

Luminescence of Pr,Nd and Yb ions implanted in GaAs and GaP

New experimental data on luminescence spectra of Pr and Nd ions implanted into GaAs and GaP crystals and the results on luminescence kinetics of Nd doped GaP are presented. The results show that RE ions form different complexes in measured samples.     

DBU as a scaffold for the synthesis of [1,3]oxazolo[2’,3’ : 2,3]pyrimido-[1,2-a]azepines: annulation with aromatic cyanopropargylic alcohols

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2,4,6-Trisubstituted 3,4-dihydropyrans from acetylene and ketones: deacetylation in the KOBut/DMSO system

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Reaction of 1-(het)aryl-3-bromoprop-2-ynones with furans in solid metal oxides or salts: cross-coupling or cycloaddition?

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Multicomponent transformation of salicylaldehydes, 2-aminoprop-1-ene-1,1,3-tricarbonitrile,and pyrazolin-5-ones into substituted 2,4-diamino-5-(5-hydroxy-3-methyl-1H-pyrazol-4-yl)-5H-chromeno[2,3-b]pyridine-3-carbonitriles

Russian Chemical Bulletin - A new multicomponent reaction, namely, a one-pot transformation of salicylaldehydes, 2-aminoprop-1-ene-1,1,3-tricarbonitrile, and 2-pyrazolin-5-ones in the presence of...     

Chloro(bromo)vinyl ketones and 2,2-Dichloroacrolein in Reactions with Hydrazines

Reactions of 2,2-dichlorovinyl and 2,2-dibromovinyl ketones with alkylhydrazines afford respectively 1-R-3-alkyl(aryl)-5-chloro- or 5-bromopyrazoles in preparative yields. The dichloroacrolein forms with alkylhydrazines and dimethylhydrazine only the corresponding hydrazones. Quantum-chemical calculations were performed characterizing the structure of the obtained ketones and dichloroacrolein alkylhydrazones, of dichloroacrolein dimethylhydrazone, of 1-alkyl-5-chloropyrazolinium halides, and 1-alkyl-5-chloropyrazoles.     

Effect of the nature of titania on the activity of Cu?Ti?O catalysts for selective catalytic reduction of nitrogen oxides with ammonia

The activity of Cu–Ti oxide catalysts has been studied in the selective catalytic reduction of NO with ammonia. We have elucidated how the nature ofstarting titania affects the catalyst activity in this reaction.