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A composition–property relationship has been developed that makes it possible to select the optimal values of the standard entropy of alkali metal borates, for which available experimental and reference data vary in wide ranges. This relationship allows one to estimate the standard entropy of unstudied alkali metal borates with sufficient validity. To ensure the reliability of the relationship, a critical analysis of the initial data borrowed from reference books and original experimental works has been carried out. Experimental measurements of low-temperature heat capacity were processed to verify the reliability of the standard entropy values of alkali metal borates presented in the literature. [ABSTRACT FROM AUTHOR]

A structure–property correlation was developed that makes it possible to choose the optimal values of the standard heat capacity of alkali metal borates, for which, according to the data of various experimental works and reference publications, wide variations are observed. This correlation enables one to estimate the standard heat capacity of unstudied alkali metal borates with sufficient validity. To ensure the reliability of the correlation, a critical analysis was made of the initial data taken from reference publications and original experimental works. Our own processing of experimental measurements of the heat capacity and the enthalpy increment was performed to verify the reliability of the literature values of the standard heat capacity of alkali metal borates. [ABSTRACT FROM AUTHOR]

Two ways for the synthesis of new representatives of non-symmetric organic phosphites with polyfluoroalkyl substituents were developed based on organic dichlorophosphites. The reaction of polyfluoroalkyl dichlorophosphites with allyl alcohol, proceeding at a temperature of –10–22°C (2 h) in the presence of triethylamine, gave diallyl polyfluoroalkyl phosphites in a yield of 75–77%. Under similar conditions (–30–22°C, 2–4 h, Et3N), alkyl (or aryl) dichlorophosphites reacted with polyfluoroalkanols to form alkyl (or aryl) bis(polyfluoroalkyl) phosphites (yield 56–67%). Unlike diallylpolyfluoroalkyl- and alkylbis(polyfluoroalkyl) phosphites, arylbis(polyfluoroalkyl) phosphites are symmetrized under storage conditions (room temperature, inert atmosphere), forming the corresponding triaryl- and tris(polyfluoroalkyl) phosphites. [ABSTRACT FROM AUTHOR]

Secondary phosphine chalcogenides, R2PX (R═(CH2)2Ph, Ph; X = S, Se), react with divinyl chalcogenides, (CH2═CH)2Y (Y = S, Se, Te), at the 2:1 molar ratio (80–82°C, 56–80 h) in the absence of both catalysts (initiators) and solvents to quantitatively afford the corresponding anti-Markovnikov diadducts. Even at the equimolar reactant ratio, the diadducts are the major products, though monoadducts are also formed. When Y = Te, vinylphosphine chalcogenides and metal Te are obtained, thus showing that divinyl telluride behaves as the vinylating agent. [ABSTRACT FROM PUBLISHER]

ABSTRACT A series of tertiary phosphine sulfides and selenides have been synthesized in excellent yields (88-99%) via a three-component reaction between secondary phosphines, electron-rich alkenes (styrene, vinyl chalcogenides), and elemental sulfur or selenium, proceeding under solvent-free conditions (80-82°C, 4-44 h). The interaction occurs via initial oxidation of secondary phosphines with elemental sulfur or selenium followed by noncatalyzed anti-Markovnikov addition of the generated R2P(E)H (E = S, Se) species to alkenes to afford the corresponding adducts with high chemo- and regioselectivity. [ABSTRACT FROM AUTHOR]

Secondary phosphine sulfides and phosphine selenides react with vinyl selenides under mild conditions (80–82°C, without catalyst and solvent) to form regioselectively functionalized anti-Markovnikov adducts in high yield. [ABSTRACT FROM AUTHOR]

ABSTRACT Alkyl vinyl selenides react with diverse secondary phosphines and elemental selenium in a 1.1:1:2 molar ratio (120-124°C, 20-40 min, 1,4-dioxane) to afford selectively earlier unknown diselenophosphinic Se-esters, R2P(Se)SeCH(Me)SeR´, in 82-99% yield. This three-component atom-economic reaction proceeds via intermediate formation of diselenophosphinic acid R2P(Se)SeH (generated from secondary phosphine and selenium), which adds to the double bond of vinyl selenide in a Markovnikov manner to give the target products. [ABSTRACT FROM AUTHOR]

Divinyl telluride reacted with 2 equiv of diphenylphosphine sulfide in the presence of AIBN as radical initiator (63-68°C) to give the corresponding anti-Markovnikov adduct in 68% yield with high regioselectivity. Treatment of the addition product with aqueous hydrogen peroxide at room temperature afforded 71% of vinyldiphenylphosphine oxide. Radical addition of diphenylphosphine selenide to divinyl telluride (AIBN, 63-68°C) led to the formation of 1,1,3,3-tetraphenyldiphosphoxane 1,3-diselenide in 82% yield. [ABSTRACT FROM AUTHOR]

Under the conditions of free-radical initiation (AIBN, UV irradiation), divinyl selenide regioselectively reacts with secondary phosphine sulfides and phosphine selenides to afford, depending on the ratio of the reagents, mono- or diadducts mainly of the anti-Markownikoff structure. The conditions which allow obtaining the diadducts in up to 97% yield are found. By the example of 2-{[2-(diphenethylphosphoroselenoyl) ethyl]selanyl}ethyl(diphenethyl)phosphine selenide the diadducts were shown to react with aqueous hydrogen peroxide at 53-56°C to give vinyl(diphenethyl)phosphine oxide in 76% yield. [ABSTRACT FROM AUTHOR]

The article presents a study which focuses on the chemical reaction of the quantitative addition of secondary phosphines with accessible alkyl vinyl selenides. Discussed is the outcome of the solution after dissolving it in diethyl ether. Also explored is the synthesis of functionalized tertiary phosphines.

Sodium sulfide and polysulfides readily (50–55°C, 3 h, aqueous medium) react with alkyl vinyl sulfoxides to afford bis(alkylsulfinylethyl)sulfides and-polysulfides in up to 75% yield. Under comparable conditions the reaction of divinyl sulfoxide with sodium sulfide proceeds by the mechanism of addition-cyclization and results in 1,4-dithiane-1-oxide and 1,4-oxathiane-4-oxide. Microwave activation of the studied reactions allows to increase their rate and efficiency. [ABSTRACT FROM AUTHOR]

The effect of the initial concentration of synthetic surfactant (SSF) in wastewaters on sorption was investigated, and Policon materials were recommended for use in the tertiary treatment stage where the concentration of SSF does not exceed 0.8 mg/dm3. It was noted that increasing the temperature of the effluents by 60° allows significantly extending the period of steady-state flow of the process and the depth of treatment remains high. The selectivity of Policon materials with respect to the SSF contained in synthetic detergents was investigated. The high efficiency of the materials in ultrafiltration of the components of synthetic detergents was demonstrated. [ABSTRACT FROM AUTHOR]

The total fraction of aminoacyl-tRNA synthases from Escherichia coli has been shown to catalyze the synthesis of the bis(5′-nucleosidyl) oligophosphates Ap4AZT, Ap4d4T, Ap43TC, and Ap4ACV, as well as Ap3AZT and Ap3d4T, from [α-32P]ATP and the corresponding nucleoside-5′-tri(or di)phosphate. The resulting compounds, characterized by HPLC, are resistant to alkaline phosphatase. Ap4AZT, Ap4d4T, and Ap43TC are formed with approximately equal efficiency, whereas the efficiencies of the synthesis of Ap4ACV, Ap3AZT, and Ap3d4T are three- to fivefold lower. [ABSTRACT FROM AUTHOR]

Selective monoaddition of carbonodithioate anions to divinyl sulfoxide gives rise to O-alkyl S-[2-(vinylsulfinyl)ethyl] carbonodithioates [ROC(S)SK, R = Et, Bu; 42–50°C, 6 h, NaHCO3, aqueous benzene]. [ABSTRACT FROM AUTHOR]

Results of experimental investigation of the heat exchange in a plasma module which incorporates a mixing chamber and three plasmatrons operating on it are generalized by the methods of physical modeling with the use of regression analysis. It is shown that the heat exchange in such a system is determined by the processes occurring in arc heaters. The most substantial influence is exerted by convection and radiation. [ABSTRACT FROM AUTHOR]

An experimental investigation of the electric-field strength along the length of a cascade argon at a pressure lower than atmospheric pressure has been performed. The influence of different processes on the formation of the voltage-current and E-I characteristics of the arc was considered. It is shown that the processes of heat transfer are of primary importance; however, in the region of mixing of the cathode jet with the heated gas the Reynolds number has a marked influence. The generalized characteristics of the voltage across the arc, of the near-electrode voltage drop, and of the electric field strength averaged over the length are presented. [ABSTRACT FROM AUTHOR]

By methods of physical modeling using a linear ridge regression it is established that in direct-current plasmatrons with step electrodes the volt-ampere characteristic of the arc is formed by heat-transfer processes, while gasdynamic factors have a slight effect. Generalized VACs of unilateral- and bilateral-emission plasmatrons in blowing the arc with air and hydrogen are refined. [ABSTRACT FROM AUTHOR]

Using the methods of regression analysis, consideration is given to the influence of various processes on the volt-ampere characteristics (VAC) of an arc discharge in a plasma generator with a hot rod cathode and a cold cylindrical anode with an arc length that is self-adjusting due to the mechanism of shunting. It is shown that heat-transfer processes play a dominant role in VAC formation. [ABSTRACT FROM AUTHOR]

Special features of physical modeling of high-current arc discharges are considered. It is shown that the employment of dimensionless criterial expressions makes it possible to establish only approximate similarity of characteristics for some specific apparatuses which govern arc-discharge conditions. Procedures to select the dominant energy-exchange processes and to find the scale values of plasma properties are presented, whose knowledge permits modeling of the discharges initiated in various media. [ABSTRACT FROM AUTHOR]

A successive selection of the dominant variables in a generalized volt-ampere characteristic of a magnetomovable arc is performed by regression-analysis methods. It is shown that turbulent energy transfer increases in importance with the electrode gap and magnetic induction. [ABSTRACT FROM AUTHOR]

For arcs that are initiated in an air medium in rotation in a ventilated annular gap and move along parallel electrodes under the action of an external magnetic field, the influence of the magnitude of the interelectrode gap and magnetic induction on the discharge voltage is considered. The accuracy of the volt-ampere characteristics of the arc in approximating by means of simple empirical power formulas and with the use of criterial relations between generalized variables is estimated. [ABSTRACT FROM AUTHOR]

Statistical methods of analysis are used to study the influence of a change in the electrode diameter on the accuracy of the volt-ampere characteristics (VACs) of a vortex electric-arc plasmatron operating with technical nitrogen. It is shown that when each initial parameter is allowed for separately and the VACs are represented by an empirical formula, the influence of a change in the diameter is insignificant. When all the initial parameters are allowed for simultaneously in one dominant criterion in the case of approximation of VACs by a generalized expression, the effect of the size factor proves to be substantial. [ABSTRACT FROM AUTHOR]

The effect of the conditions of electric-arc burning in an air flow on the process of thermal destabilization is considered. The considerable role of heat-transfer processes in the development of instability in an arc-discharge column is shown. [ABSTRACT FROM AUTHOR]

The influence of heat transfer processes in arc discharges on the development of thermal instability is considered. A substantial dependence of the process of destabilization on the plasma properties is shown by the example of argon and helium arcs. [ABSTRACT FROM AUTHOR]

Potassium thiolates generated by treatment of thiols with aqueous KOH react with acetylene to give the corresponding vinyl sulfides in 90-95% yields. [ABSTRACT FROM AUTHOR]

A letter to the editor is presented in response to the article on the unexpected reaction pattern of divinyl sulfoxide with potassium carbonodithioates under microwave assistance in the April 2, 2007 issue.

The article describes the microwave induced synthesis of diphenyltiophenes from elemental sulfur and styrene. Styrene reacts with elemental sulfur in the strongly basic medium KOH-DMSO in the presence of hydroquinone under microwave irradiation of 600 watts for four minutes to form a 1: 12 mixture of 2,4- and 2,5-diphenylthiophenes in overall 30% yield.

A letter to the editor is presented about free-radical addition of secondary phosphine sulphides to vinyl sulphides.