The Effect of Swstituents at the Carbon and Phosphorus on the Tautomeric Equilibrium in the Phosphoryl-Hydroxyylide Systems

Abstract

It has been established that in the phosphoryl-hydroxyylide systems (I-VIII) the increasing acidity of the carbon atom depending on substituent Y (which is characterized by [sgrave]^? _CH value) shifts the equilibrium to the hydroxyylide form (B).     

Alkylation of Phosphorylmethylenetriphenylphosphoranes

Abstract

Direction of alkylation of phosphoranes (I) depends on the nature of the substituent Y and the alkylating agent. Unsubstituted phosphorane reacts with CH₃J yielding only the product of C-methylation (II), whereas the reaction with Me₂SO₄ proceeds at both ends of the OPC-triad, preferably yielding the O-alkylation product (IIIa, 80%).     

1,3‐Dipolar cycloaddition of unstabilized N‐methyl azomethine ylide to nitrobenzene annelated with azoles

The 1,3‐dipolar cycloaddition of unstabilized N‐methyl azomethine ylide to mononitro benzazoles was studied. Depending on the nature of substituents and annelated azoles, the reaction affords previously unknown isoindole fused heterocyclic systems. The reactivity of the cycloadducts was examined. J. Heterocyclic Chem., (2011).     

Cellular nanostructure of gas hydrates

It is found that the hydrates obtained by reaction of liquid water with a hydrate-forming gas have a cellular structure with a cell ∼10^-5 cm in size. At T ∼ 274 K, the thickness of the walls of the methane hydrate cell is ∼10^-7 cm. Formation of the cellular structure is due to a competition between the bulk (difference between chemical potentials, specific energy of elastic deformation) and surface energies. At positive temperatures, monolithic methane hydrate is formed at pressures higher than 6 MPa. Translated fromZhurnal Struktumoi Khimii, Vol. 38, No. 6, pp. 1103–1107, November–December, 1997.     

Quasiamorphous state of methane hydrate

It is established experimentally that at temperatures above 0°C formation of methane hydrate starts with the appearance of thin films of this substance on the surface of water; during isothermal storage, the films permeate throughout the whole volume of the sample. The maximal content of methane hydrate is several (volume) per cent. The viscosity of the sample is much lower than that of ice and much higher than that of water. A. A. Galkin Donetsk Physicotechnical Institute, Ukrainian Academy of Sciences. Translated fromZhurnal Strukturnoi Khimii, Vol. 39, No. 1, pp. 86–91, January–February, 1998.     

Mechanisms of exchange of isomorphous components between crystal and solution and macrodefectiveness in secondary crystals

A quantitative study of an exchange of components between crystals and solutions upon isomorphous substitutions is described. The process is shown to be a topochemical reaction occurring by synchronous localized events of growth and dissolution of surface microsections. In K(Al, Cr)(SO₄)₂·12H₂O alum, the crystal and the solvent are shown to exchange both isomorphous (Al−Cr) and analogous (K, H₂O) components. Mechanisms of the process and their relationship with crystal defectiveness are discussed. St. Petersburg State University. Translated fromZhurnal Strukturnoi Khimii, Vol. 35, No. 5, pp. 79–83, September–October, 1994. Translated by L. Smolina     

Clay-salt slimes of the “Belaruskali” - novel sorbents for management of liquid radioactive wastes and decontamination of environmental water streams

Journal of Radioanalytical and Nuclear Chemistry - Clay-salt slimes, production wastes from “Belaruskali” (A Belarusian factory, producing potash fertilizers), have been tested as a...     

Complex Formation of [Ph2P(O)I2 C=CH2 and [Ph2 P(O) I2 C=PPh3 with Phosphorus and Tantalum Pentafluorides

Abstract

Reactions of PF₅ and TaF₅ with [Ph₂P(O)]₂ C=CH₂ (I) and [Ph₂P(O)]₂ C=PPh₃ (II) in MeCN and CH₂Cl₂ were studied by means of ¹⁹F, ³¹P, ¹H and ¹³C NMR spectroscopy. It has become evident, that one or two phosphoryl groups in (I) and (II), as well as in cis- and trans-Ph₂P(O)CH=CHP(O)Ph₂, are involved in complex formation. The formation of tetra-fluoro cations PFL and PF₄L along with pentafluorocom-plexes PF₅L and TaF₅L was found. Ligands are coordinated with central ions of complexes as chelates. The trans-atoms F₁ of TaF ₅L are nonequivalent because of nonsymmetric position to the Ph3P-group. The F₁-atoms in PF₄L are supposed to be symmetric to the Ph₃P-group. The formation of tri-fluorocomplexes TaOF₃L was also observed. Since the position of ¹⁹F NMR resonance lines of TaOF₃L is near to that of pentafluorocomplexes, it can be supposed that either the change of Ta coordination number takes place, either oxygen atom comes into complex with inner sphere in the reaction with ligand or during hydrolysis.