Activities of the components of glycerol-water binary solutions at 298.15 K

Based on the assumption that there exists a distribution of hydrates over the hydration number, expressions for the hydration number, activity coefficients of the components, and excess Gibbs energy were obtained. It was demonstrated that the van Laar formula for the activity coefficients corresponds to the Poisson distribution of hydrates. It was established that, at a constant ratio of the variance to the mathematical expectation of the distribution of hydrate, the model’s equations adequately describe the available experimental data on the vapor pressure and water activity for the glycerol-water system over the entire concentration range.     

Electrochemical iodination of C-methyl derivatives of dodecahydro-7,8-dicarba-nido-undecaborate anion

By electrochemical iodination of potassium 7-methyl-7,8-dicarba-nido-undecaborate and potassium 7,8-dimethyl-7,8-dicarba-nido-undecaborate, their monoiodine derivatives (extracted as tetramethylammonium salts) are synthesized. Their structure is confirmed by NMR and IR spectra and also by elemental analysis data.     

Low-temperature oxidative chlorination of methane over supported platinum chloride catalyst

The Pt^II (catalyst)+Pt^IV (oxidant) system with a deficiency of Cl ligands is active in the oxidative chlorination of alkanes not only in aqueous solutions but also in the SiO₂-supported state. In heterogeneous as well as in homogeneous conditions, the reaction proceeds at 100°C through platinum-alkyl intermediates.

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: Pt^II- Pt^IV- Cl-, , SiO₂. , , 100° - .

     

Ethylene Adsorption and Oxidation Kinetics in the Reactions with Pd(II)/SiO2 and Cr(VI)/SiO2: Consideration of Substrate Distribution between the Gas Phase,Silica Gel,and Reaction Centers

The kinetics of ethylene oxidation by PdCl₂ and CrO₃ complexes supported on silica gel (300 K, closed batch reactor) and the adsorption of C₂H₄ by silica gel and metal complex reaction centers (M ⁿ ) were studied. A new version of the kinetic distribution method was applied to determine the rate constants of ethylene reactions with metal complexes with consideration for the equilibrium distribution of C₂H₄ among the reactor gas phase, silica gel, and M ⁿ . The rate constant of a first-order reaction with respect to Cr(VI) (k _e) remained constant as [M ⁿ ] was increased up to 0.15 mol % with the absence of detectable ethylene adsorption by chromium(VI). In the case of Pd(II)/SiO₂, strong ethylene adsorption by palladium(II) was found, and k _e was an exponential function of [M ⁿ ]. This exponential function is indicative of an increase in the specific activity of Pd(II) with palladium concentration on SiO₂. Taking into account the adsorption of ethylene (physisorption on SiO₂ and chemisorption on Pd(II)), we found an analogy between the kinetic behaviors of Pd(II) in reactions with ethylene on silica gel and with ethylene and other hydrocarbons in solutions.     

Kinetics, selectivity, and mechanism of the reactions of arenes with adamantyl carbocations in sulfuric acid

Data on the kinetics, selectivity, kinetic isotope effect, and the effect of the acidity of the medium on the rate of the reactions of benzene and alkylbenzenes in sulfuric acid (59–78 wt.% H₂SO₄) solutions of 1-adamantanol at 30 °C indicate that the direct reagents are the adamantyl carbocations (Ad⁺) that alkylate the arenes. The ortho positions of the benzene ring are not accessible on account of steric hindrances. The rate of attack by the Ad⁺ cation on the accessible para and meta positions of the ring is controlled by the formation of a σ complex. __________ Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 42, No. 1, pp. 14–18, January–February, 2006.     

Thermodynamic interaction functions for 4He and 3He quantum liquids

The method of interaction functions is applied to quantum liquids. The interaction energies at 0 K are found as 14.3 cal/mole for ⁴He and 11.0 cal/mole for ³He. The interaction energy as a function of volume for all temperatures along the saturation line is deduced as an expression common to the two isotopes. The two isotopes have a region of anomaly in the interaction entropy, where the liquid appears less ordered than an ideal gas. These anomalies can be eliminated for ³He by allowance for the spin entropy and for ⁴He via the difference between the concentrations of the component with zero entropy in the liquid and Bose gas.     

Kinetics and Substrate Selectivity of the Oxidation of Saturated Hydrocarbons by Adamantyl Cations in Sulfuric Acid

It was shown that at 70 °C sulfuric acid ([H₂SO₄] > 85 wt.%) solutions of 1-hydroxyadamantane and the solutions obtained in the reaction of adamantane with concentrated sulfuric acid oxidize saturated hydrocarbons (RH). Data on the kinetics, selectivity, kinetic isotope effect, and the effect of the acidity of the medium on the oxidation rate of RH indicate cleavage of the C—H bond in the substrate at the rate-determining stage and the direct participation of adamantyl carbocations.     

Esters of isoxazole- and isothiazolecarboxylic acids and oximes of β-isatin, isoxazole- and ferrocene-containing ketones and carborane alcohols

Oximes of β-isatin, isoxazole- and ferrocene-containing ketones, o- and m-carborane alcohols react with isoxazol- and isothiazolecarboxylic acid chlorides in the presence of triethylamine to afford the corresponding esters.     

Structure of 6,11-dichloro-9-dimethylthio-7,8-dicarba-nido-undecaborane [6,11-Cl2-9-SMe2-7,8-C2B9H9]

A technique is proposed for directed synthesis of 6,11-dichloro-9-dimethylthio-7,8-dicarba-nido-undecaborane [6,11-Cl₂-9-SMe₂-7,8-C₂B₉H₉]. Single-crystal X-ray diffraction is used to identify the molecular and crystal structure of the compound.