Intramolecular Catalysis in Reactions of Hydroxamic Acids

Among hydroxamate ions (typical nucleophiles), anomalously high nucleophilicity relative to 4-nitrophenyl diethyl phosphonate is seen in anions which have general basic catalytic sites that provide anchimeric assistance for proton transfer in the transition state.     

Muon transfer from mesic hydrogen to lithium and the atomic intershell correlations

The rates of the molecular muon transfer from mesic hydrogen to lithium are calculated. The obtained rates are of the order of magnitude 10⁶ s^?1. It is shown, that taking into account the intershell correlations results in a considerable change in the reaction rates for some isotope mixtures. The experimental study of the muon transfer can yield an information about the contribution of the intershell correlations to the rate of the process.     

Molecular diversity management strategies for building and enhancement of diverse and focused lead discovery compound screening collections

This publication describes processes for the selection of chemical compounds for the building of a high-throughput screening (HTS) collection for drug discovery, using the currently implemented process in the Discovery Technologies Unit of the Novartis Institute for Biomedical Research, Basel Switzerland as reference. More generally, the currently existing compound acquisition models and practices are discussed. Our informatics, chemistry and biology-driven compound selection consists of two steps: 1) The individual compounds are filtered and grouped into three priority classes on the basis of their individual structural properties. Substructure filters are used to eliminate or penalize compounds based on unwanted structural properties. The similarity of the structures to reference ligands of the main proven druggable target families is computed, and drug-similar compounds are prioritized for the following diversity analysis. 2) The compounds are compared to the archive compounds and a diversity analysis is performed. This is done separately for the prioritized, regular and penalized compounds with increasingly stringent dissimilarity criterion. The process includes collecting vendor catalogues and monitoring the availability of samples together with the selection and purchase decision points. The development of a corporate vendor catalogue database is described. In addition to the selection methods on a per single molecule basis, selection criteria for scaffold and combinatorial chemistry projects in collaboration with compound vendors are discussed.     

Detection of explosives on solid surfaces by thermal desorption and ambient ion/molecule reactions

A simple, fast and direct method is presented for detecting traces of solid explosives on cotton swabs or in particulate samples: ions are transferred into a mass spectrometer after thermal desorption and corona discharge chemical ionization in ambient air; specificity is enhanced using ambient ion/molecule reactions or by conventional tandem mass spectrometry.     

A physico-chemical study of iron-chromium-molybdenum catalysts

In the study of the Fe_1–xCr_xMo_1·5O₆ system by X-ray, IR and Mössbauer methods the formation of solid state substitution solutions has been detected, which possess similar catalytic properties in methanol oxidation.

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, , Fe_1–xMo_1·5O₆ , .

     

Research in the field of unsaturated derivatives of azoles. 11. Reaction of benzimh)azole-2-thione with 1,2,3-tribromopropane

In the interaction of benzimidazole-2-thione with 1, 2, 3-tribromopropane under conditions of interfacial catalysis in an alkaline medium, 2-(2-bromo-2-propenylthio)benzimidazole is formed; debromination of this compound affords 3-methylthiazolo[3,2-a]benzimidazole, which is subsequently converted as a result of thermolysis to 2-propadienylthio)benzimidazole.For communication 10, see [1].Rostov State University, Rostov-on-Dan 344090. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 567–570, April, 1995. Original article submitted March 11, 1995.     

Mechanical properties and molecular mobility in oriented polyolefines

The static modulus of elasticity (E) and the correlation time of rotation ( _c ) of 2,-2,6,6-tetramethylpiperidine-1-oxyl are studied as a function of the temperature (210<T <350°K) for oriented films of isotactic polypropylene and polyethylene of high and low density.E and _c change both upon heating and polymer orientation; this result indicates that sample properties are influenced by the microstructure of the amorphous phase where probes are localized.