Variation of the reactivity of solids near the interface reagent-product of the topochemical reaction

During the topochemical decomposition of ammonium perchlorate and copper hypophosphite an enhanced acid concentration occurs near the reagent-product interface. Concentration profiles of the acid were observed after the treatment of the partially decomposed crystals by indicator solution and by microphotometry. Profiles exhibit the diffusive characteristics. The diffusion coefficient is 10^?10 cm²/sec for ammonium perchlorate and 10^?9 cm²/sec for copper hypophosphite at 20°C. It is concluded that the variation of the reactivity near the interface is due to the enhanced acid concentration.     

Determination of trap parameters by simultaneous measurement of thermostimulated luminescence and thermostimulated conductivity

A method is proposed for processing of thermostimulated luminescence (TSL) curve in the presence of thermostimulated conductivity (TSC) in which no assumption is made as to the smallness of dn_c/dt (n_c is the conduction electron concentration). Results of the theory are applied to study of ZnSAg, Al and ZnSCu single crystals, in which elementary traps are revealed, and their activation energy and the value of the frequency factor determined. For ZnSCu the radiative transition recombination section is calculated.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 6, pp. 94–101, June, 1977.     

Facile one-pot synthesis of BINOL- and H8-BINOL-based aryl phosphites and their use in palladium catalysed asymmetric allylation

Novel P-monodentate aryl phosphite ligands have been synthesised in one step from (R)-BINOL, (R)-H₈-BINOL and (R)-H₈-3,3′-dibromo-BINOL. With the new aryl phosphites, up to 86% ee was observed in the asymmetric Pd-catalysed amination of 1,3-diphenyl-2-propenyl acetate with sodium diformylamide. In the enantioselective alkylation of 1,3-diphenyl-2-propenyl acetate with dimethyl malonate, up to 97% enantioselectivity was achieved.     

A first <Emphasis Type="Italic">P,N</Emphasis>-bidentate phosphite with a chiral ketimine fragment. Catalytic properties of its Rh<Superscript>I</Superscript> and Pd<Superscript>II</Superscript> complexes in comparison with those of phosphine analogs

A chiral P,N-bidentate aryl phosphite ligand containing peripheral (R)-(+)-camphor-derived ketimine and its rhodium(I) and palladium(II) chelate complexes were synthesized for the first time. These compounds were found to be suitable for asymmetric allylic substitution. The Pd-catalyzed sulfonylation of 1,3-diphenylallyl acetate with sodium p-toluenesulfinate gave the product in 73% ee; in the alkylation of the same substrate with dimethyl malonate, the ee was 94%. These ee values are higher than the enantioselectivity achieved with the known phosphine analogs.Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1942–1945, September, 2004.     

Solubility of α-and β-gypsum in aqueous solutions of calcium,magnesium, and sodium chlorides

The interaction of multicomponent water-salt systems including calcium, magnesium, and sodium chlorides, gypsum, air, and water were studied by the methods of thermodynamic modeling. The solubility of α-CaSO₄ · 2H₂O and β-CaSO₄ · 2H₂O were determined in aqueous solutions of calcium, magnesium, and sodium chlorides and their mixtures at 25°C and carbon dioxide partial pressure of 10^?1.53 kPa, metal chloride concentrations of 10^?4 to 1.0 mol/kg H₂O, and their molar ratio of 1: 1.     

Preparation of samples for the α—Spectrometry of transplutonium elements

The electrolytic deposition of the hydroxides of rare earth and transplutonium elements on nickel holders from α-hydroxyisobutyrate solutions of 10⁻⁵ M to 5·10⁻¹ M concentrations has been investigated in the presence of ammonium chloride. It is shown that at total concentrations of ≥10⁻¹² M of rare earth and transplutonium elements, their electrodeposition proceeds with a 90% yield.     

BINOL-derived diphosphoramidites bearing unsymmetrical 1,2-diamine link and their application in asymmetric catalysis

New P,P-bidentate diastereomeric diphosphoramidite chiral ligands with mixed stereogenic elements and a C₁ backbone symmetry have been prepared from (S_a)- and (R_a)-1,1′-binaphthyl-2,2′-diol (BINOL) and (S)-N-benzyl-1-(pyrrolidin-2-yl)methanamine and are fully characterized. The use of these ligands provides up to 84% ee in the Pd-catalyzed asymmetric allylic substitution of (E)-1,3-diphenylallyl acetate and up to 95% ee in the Rh-catalyzed asymmetric hydrogenation of α-dehydrocarboxylic acid esters. The results indicate that the catalytic performance is highly affected by the axial chirality of the binaphthyl moieties of the ligand and the nature of the solvent.     

Reaction of Trialkylphosphine Carbon Disulfide Adducts with Cyclopentadienones

Abstract

It has been known more than for 100 year that triethylphosphine forms the 1:1 adducts with carbon disulfide and isothiocyanates. However, little is know on the reaction of the adducts and the formation of reactive alkylidenephosphoranes was recently reported by the reaction of adducts with electron-poor double bonds.