Influence of mass transfer at the monomer-water interface on polymerization emulsion

A quasi-spontaneous process of mass transfer takes place at the interface of a monomer and water in the presence of surface-active substances soluble in both phases as a result of their diffusion through the interfacial boundary. This process is accompanied by the formation of a microemulsion whose particle size depends on the emulsifier concentration and its molecular structure. While investigating various nonionic surface-active substances as emulsifiers in the emulsion polymerization of vinyl acetate, it was established that polymerization occurs in droplets of the monomer microemulsion in water, which are formed as a result of mass transfer at the interface.     

High‐spin silicon fullerene Si60 and its oligomers

High‐spin states of the Si₆₀ fullerene and its oligomers are considered semiempirically by using sequential and parallel implementations of the AM1 codes. The states are energetically favorable and nearly degenerated over triplet, quintet, and septet spins. All atoms of the Si₆₀ fullerene are in sp³‐configuration, which is supported by atomic spin density in addition to electron density, the latter to be responsible for the formation of chemical bonds. Spotted distribution of spin density over atoms provides molecular magnetism of the molecule. A similar picture is disclosed for oligomers {Si₆₀}_n with n up to 8, which according to computational results should be magnetic with a fractal‐like distribution of spin density over atoms. Opposite the latter, composites Si₆₀C₆₀ and Si₆₀H₆₀ behave conventionally and are nonmagnetic. A way of the Si₆₀ fullerene synthesizing is suggested via the above composite product as intermediates. The considered oligomers are proposed as a model of silicon nanofibers observed recently. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2002     

Crystal Structure and Properties of Rb4H2I2O10 · 4H2O

Single crystals of the Rb₄H₂I₂O₁₀· 4H₂O were synthesized for the first time and studied by X-ray diffraction analysis. The crystals are monoclinic, a = 7.321(6) Å, b = 12.599(8) Å, c = 8.198(8) Å, = 96.30(7)°, Z = 2, space group P2₁/c. The H₂I₂O₁₀ ^4– anion is formed by the edge-sharing IO₆ octahedra. The anions are united by hydrogen bonds into a chain running along the x axis. The chains are combined by water molecules into a three-dimensional structure through hydrogen bonds. The compound is a proton conductor. The conductivity values measured at 20–60°C vary within 10^–6 to 10^–4 ohm^–1 cm^–1.     

Organylthiochloroacetylenes: VI. Reaction of Alkylthiochloroacetylenes with Sodium Azide

Alkylthiochloroacetylenes react with sodium azide in mild conditions (20°C, DMSO) to give alkylthioethynyl azides and 4-chloro-5-alkylthio-4H-1,2,3-triazoles in a total yield of 72%.     

INS and IR study of intermolecular interactions at the fumed silica-polydimethylsiloxane interphase, Part 3. Sicica-siloxane adsorption complexes

A vibration spectra study of the interphase fumed silica andpolydimethylsiloxane (PDMS) particles highlights the microscopic interactionmechanisms in the system. This study involves an extended examination of bothfree silica and PDMS components as well of their adsorption complexes. Thepresent paper, deals with the vibrational analysis of adsorption complexes ofpolymethylsiloxanes and hydrophilic or trimethylsiloxy silylated fumed silica.Vibrations have been investigated involving both experimental andcomputational approaches. Experiments were performed in the framework ofinfrared (FTIR) and inelastic neutron scattering (INS and AWDS) techniques.Spectral interpretation was carried out on the basis of quantum chemical (QCh)semiempirical calculations using AM1 and PM3 parameterisation, and applicationof an original software program for spectra analysis, COSPECO, involvingdirect and inverse spectral problem solutions and spectrum assignments. Indescribing the silica-PDMS interphase, dodecamethylpentasiloxane (Si5) hasbeen used as a linear model of polydimethylsiloxane; its adsorption atdifferent surface coverages on hydrophilic and trimethylsiloxy(TMS)-silylated fumed silicas has been studied. Both, the PDMS and silicacomponents in the adsorption complexes, have been examined using protonatedand deuterated methyl groups of substrate and adsorbate. Additionalinformation was evaluated from the adsorption of longer chain PDMS polymerson hydrophilic silica. The adxorption has a strong impact on the vibrationspectra of both the silica and siloxane. Additional impacts evolve from thedegree of silylation of the silica surface, and the siloxane coverage . The changes in the spectra can be attributed to immobilisation of theadsorbed siloxane on the silica surface, as well as to a `pressure' effect ofthe TMS units of the silica caused by adsorbed PDMS. In terms of interactionenergies, classical H-bonding shows a minor contribution, while Van-der-Waalsforces mainly govern the system; for the latter Si-O dipole interactions alsopay a dominant role.     

Some derivatives of pregna-D6′-pentaranes as possible antagonists of progesterone

Some derivatives of progestins of the pregna-D₆-pentarane series have been obtained and examined for their possible hormonal and antihormonal activity in the Clauberg-McPhail assay as well as in the pregnancy maintenance test in ovariectomized rabbits. 16, 17-Cyclohexanoprogesterones of the 19-methyl and 19-nor series (1–4) saturated in ring A, which are inactive as progestins, exhibited a remarkable antiprogesterone effect. They decreased the McPhail index under combined administration with progesterone in a dose-dependable manner and completely inhibited the action of the latter in the pregnancy maintenance test.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 564–567, March, 1995.     

Use of a Complete Factorial Experiment for Designing a Gas Sensor Based on Extracts of <Emphasis Type="Italic">Pleurotus ostreatus</Emphasis> Mycelium Mushroom

A gas sensor was developed on the basis of extracts of mycelium mushroom Pleurotus ostreatus for determining phenol in air. The procedure of sensor preparation was optimized using a complete factorial experiment. The quantitative and kinetic parameters were found for the adsorption of some organic compounds (alcohols, ketones, alkyl acetates, phenols, aromatic amines) on films with a biological modifier.__________Translated from Zhurnal Analiticheskoi Khimii, Vol. 60, No. 7, 2005, pp. 759–764.Original Russian Text Copyright © 2005 by Silina, Kuchmenko, Korenman, Tsivileva, Nikitina.     

Synthesis of Pinenylsulfides from <Emphasis Type="Italic">cis</Emphasis>-Verbenol

The reaction of cis-verbenol with thiols in the presence of ZnCl₂ occurred stereospecifically with substitution of the hydroxyl by a sulfide. __________ Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 565–567, November–December, 2005.