Catalytic effect of nanosized metal oxides on the knoevenagel reaction

The effect of nanosized metal oxides (Al, Mg, Cu, Ni oxides) on the synthesis of chalcones that are key intermediate in the synthesis of Nitrendipine and Felodipine drugs was examined.     

Silver intercalation in PbS1.18(TiS2)n, n=1, 2, misfit layer compounds

The reaction between metallic Ag and PbS_1.18(TiS₂)_n, n=1, 2, misfit layer compounds has been investigated by electrochemical technique, X-ray powder analysis and transmission electron microscopy. It was found that silver intercalation is possible only in the compound with n=2. The thermodynamic behavior and location of phase boundaries were studied in the temperature range 400–650 K. DC-conductivity and magnetic-susceptibility measurements were performed, and the data can be interpreted as an appearance of small polarons during silver insertion.     

A decrease in the ignition temperature of molecular systems during nonequilibrium vibrational excitation of reacting molecules

The nonequilibrium vibrational excitation of reacting molecules can result in a substantial (up to 100%) decrease in the temperature threshold of self-ignition in the H₂ + air system. In this case, dissociation reactions are responsible for the formation of active species that initiate chain combustion. An increase in temperature during the induction period caused by the recombination of oxygen and hydrogen atoms and OH radicals formed plays an important role in the intensification of chain reactions and self-ignition of the mixture at low temperatures (∼300-400 K)     

Dislocations in magnetic garnet crystals

1. Dislocations in magnetic flux-grown garnet crystals (Y₃Fe₅O₁₂ and others) have been observed. As a rule, {110} growth pyramids have more defects than {211} ones. 2. The highest content of defects (dislocation density 10³–10⁴ cm⁻²) is observed in Y₃Fe₅O₁₂ that grows on crucible walls adjacent to the free surface of the solution where the flow of heat is not uniform to the greatest degree. Bottom grown crystals usually have less dislocations. Far fewer dislocations are in wall grown crystals, least of all dislocations are contained in crystals that grow inside the solution. The solution pouring off at the end of the crystallization period increases dislocation density by some dozens. 3. Heat treatment decreases dislocation density. The less dislocation content and the lower ordering are in the initial crystal, the higher heat treatment effectiveness.     

Synthesis of esters of iminocarbonic acid

The first syntheses of asymmetrical esters of iminocarbonic acid are reported. These syntheses were carried out without the separation of intermediates. Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 10, p. 23, October, 1989.     

4-Hydroxyproline containing podands as new chiralcatalysts for the asymmetric Biginelli reaction

The novel C₂-symmetric chiral organocatalysts of (2S,4R)-hydroxyproline containing podand type have been synthesized and evaluated in the asymmetric Biginelli reaction. Combination of polyether spacer with (2S,4R)-hydroxyproline allowed one to enhance the effect of the latter on enantioselectivity of the Biginelli reaction by a factor of 5. The best results have been achieved for salts of (2S,4R)-hydroxyproline containing podands with trifluoroacetic acid.

1. Download high-res image (100KB)
2. Download full-size image

     

Thermally initiated disproportionation of manganese(II) bis(1-hydroxyethylidene)diphosphonate. Formation and properties of the lepidoid structure of manganese(II) (1-hydroxyethylidene)diphosphonate-2-hydroxyethaneaminium whiskers. Agronomical efficiency of the manganese(II) complex with (1-hydroxyethylidene)diphosphonic acid

Russian Chemical Bulletin - The reaction of poorly soluble manganese(II) bis(1-hydroxyethylidene)diphosphonate tetrahydrate (Mn(H3L)2?4H2O) with 2-aminoethanol (H2NCH2CH2OH) in an aqueous...