Cyanoacetylenes in a reaction with benzoxazole-2-thione and benzoxazol-2-one

The reaction of benzoxazole-2-thione and benzoxazol-2-one with substituted cyanoacetylenes was studied. 2-[(3-Phenyl-2-propenenitrile)thio]benzoxazole was obtained by the reaction of benzoxazole-2-thione with phenylcyanoacetylene. Benzoxazol-2-one with phenylcyanoacetylene and a tertiary cyanoacetylenic alcohol gave the corresponding N-adducts.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 6, pp. 1390–1391, June, 1990.     

Synthesis of 1,2,4-triazolo[3,2-b]-1,3-thiazines

1,2,4-Triazolo[3,2-b]-1,3-thiazines were obtained by the reaction of 1,2,4,-triazole-3-thiones with an equimolar amount of 1-phenyl-2-cyanoacetylene in the presence of triethylamine or potassium hydroxide. It is shown that triazolethiones form N,S diadducts upon reaction with a twofold excess of cyanoacetylene. The nature of the heteroatom in the exo position of the heteroring affects the direction of addition to phenylcyanoacetylene. 2,4-Bis(1-phenyl-2-cyanovinylene)-1,2,4-triazol-3-one was synthesized.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1051–1053, August, 1982.     

Regio- and stereospecific addition of phosphines to cyanoacetylenes

Primary and secondary phosphines add regio- and stereospecifically to phenylcyanoacetylene and 4-hydroxy-4-methylpent-2-ynenitrile under mild conditions to form corresponding functionalized secondary and tertiary phosphines of Z-configuration in 70-91% yield. According to ESR and UV data, the addition of primary phosphines to phenylcyanoacetylene involves a single electron transfer process.     

A kinetic study of methane conversion by a dinitrogen microwave plasma

Conversion of CH₄ with a N₂ microwave plasma (2.45 GHz) is studied. The experiments cover the absorbed microwave power range 300–700 W with 17–62% of methane in the gas mixture, with pressures of 10–40 mbar and flow rates of 140–650 ml· min^–1. The yields of C₂ hydrocarbons and dihydrogen are analyzed by gas chromatography. The distance of methane addition downstream of the plasma plays an important role on the composition and the concentration of the products obtained. This distance mainly determines the energy concentrated in the active species of the plasma when they react with methane. Different behaviors for acetylene formation, on the one hand, and for ethane and ethene formation, on the other hand, have been observed, and this finding allows us to propose a kinetic mechanism for the decay of methane and for the formation of C₂ hydrocarbons.     

Addition of thiols at the double bond of methyl esters of 1-alkylcyclopropene-3-carboxylic acids

This is the first report of the addition of propyl and phenyl mercaptans at the double bond in the methyl ester of 1-methylcyclopropene-3-carboxylic acid with the formation of esters of thio-substituted cyclopropanecarboxylic acids in 67–72% yield. The addition of the thio group proceeds selectively at the least substituted atom of the double bond in the position anti to the methoxycarbonyl group.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 1, pp. 220–222, January, 1991.     

Nonempirical calculations of the potential-energy fields of the nucleophilic addition of H− and F− to acetylene and methylacetylene molecules

By using the basis 3–21 + G, the minimum-energy routes for the nucleophilic addition to the F^– ion to methylacetylene have been calculated within the framework of the Hartree-Fock-Roothaan method according to and against the Markovnikov rule with the formation of the 1-fluoropropenyl and 2-fluoropropenyl anions. The results have been compared with data from previous calculations of the nucleophilic addition of H^– and F^– to acetylene with the formation of vinyl and fluorovinyl anions, as well as of the nucleophilic addition of H^– to methylacetylene according to and against the Markovnikov rule with the formation of the 1-propenyl and 2-propenyl anions. It has been established that the reaction with H^– is exothermic, while the reaction with F^– is endothermic. The activation energies of the reactions with F^– are lower than the activation energies of the corresponding reactions with H^–. It is shown that the reactions with H^– have a relatively early transition state, while the reactions with F^– are characterized by a later transition state.Translated from Teoreticheskaya i Éxperimental'naya Khimiya, Vol. 28, No. 1, pp. 5–11, January–February, 1992.     

Sulfooxidation of saturated hydrocarbons,initiated by ozone and hydrogen peroxide

Conclusions The effect of hydrogen peroxide on the ozone-initiated sulfooxidation rate of saturated hydrocarbons was studied. The addition of 0.5–1% H₂O₂ of the hydrocarbon volume leads to an increase in the reaction rate by 5–10 times and the formation of clear reaction products.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 3, pp. 731–732, March, 1978.     

Salt effects in the mercuration of unsaturated compounds. Kinetic evidence for the formation of ion pairs and a solvated ion

The kinetics of mercuration of bornylene and cyclohexene in different solvents in the presence of NaOAc and LiClO₄ has been investigated. Addition of NaOAc sharply decreases the rate of addition reactions of mercuric acetate to bornylene and cyclohexene in alcohols; the main direction of the mercuration of bornylene is the formation of acetoxy-adducts, and the yield of solvo-adducts decreases from 76 % in the absence of NaOAc, to 19 % in the presence of the salt (4·10^–3 mol L^–1). A reaction scheme involving the participation of intermediate ion pairs and a solvated mercurinium ion is suggested and confirmed by a steady-state concentration method. The influence of NaOAc on the rate of the reaction and on product formation is realized through the common ion effect.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 819–826, May, 1994.     

Bromination and iodination of trialkylethynylsilanes

Conclusions The addition of bromine and iodine to trimethyl- and dimethylethylethynylsilanes has been studied. The halogenation of these compounds takes place stepwise. The first molecule of bromine adds at 30–50° and the second at 70–90°. In the case of bromination under UV irradiation, hydrogen bromide is eliminated as a side-reaction. The addition of iodine ceases at the stage of the formation of the diiodovinylsilanes.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 3, pp. 693–694, March, 1967.     

Pyrroles from ketoximes and acetylene. 29. Synthesis of alkylpyrroles from dialkylketoximes and dichloroethane by reaction with KOH-DMSO

Treatment of dialkylketoximes with dichloroethane and KOH-DMSO results in the formation of alkylpyrroles in 31–61% yields. In addition, the corresponding 1-vinylpyrroles are formed simultaneously in yields up to 18%. The corresponding 1,2-bis(alkylideneiminoxy)ethanes are obtained as side products in the reaction; they result from nucleophilic displacement of chlorine atoms by oximate anions.For Communication No. 28, see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 59–62, January, 1985.     

Effect of the addition of indium to alumina-platinum catalysts on the dehydrogenation of higher n-paraffins

Conclusions The addition of 0.2–4.0% indium to alumina-platinum catalysts with 0.05–0.5% platinum suppresses the acidic function of the support, increases catalyst selectivity relative to normal monoolefins, and, in contrast to lithium, increases activity in the dehydrogenation of normal dodecane. The maximum activity is found for catalysts with 1–2% indium.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 9, pp. 2089–2094, September, 1982.     

Thermal transformations of tetrafluoroethylene in the presence of 1,3-cyclopentadiene and hydrogen chloride

Conclusions The thermal transformations of tetrafluoroethylene under flow conditions at atmospheric pressure and 600–710°C in the presence of cyclopentadiene and hydrogen chloride as carbene acceptors lead to the formation of phenyltrifluoromethane in 3.6% yield in the former case and 1,1,1,2-tetrafluorochloroethane in 9.1% yield in the latter case in addition to other products. These results indicate the possibility of an olefin-carbene isomerization of tetrafluoroethylene to trifluoromethylfluorocarbene under these conditions. Hence, the formation of hexafluoropropylene in the thermolysis of tetrafluoroethylene may be the result of the recombination of difluorocarbene with trifluoromethylfluorocarbene.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 6, pp. 1433–1436, June, 1989.     

Uronic (hexenuronic) acid profile of ethanol–alkali delignification of giant reed Arundo donax L.

The effect of process variables on uronic acids (UAs) and hexenuronic acids (HexAs) in the annual crop Arundo donax L. during ethanol–alkali pulping has been examined. A substantial loss of UA moieties (up to 90%) was observed by the end of pulping (target kappa number 18) performed with 25% NaOH and 40% EtOH (by volume) within the temperature range of 130–150 °C. At the same time, the progressive formation of HexA in pulp was detected from the early phases of delignification. The proportion of HexA in the residual UA of the final pulp was found to be 84%, indicating almost complete conversion of 4-O-methylglucuronic acid side groups (MeGlcA) of heteroxylan into HexA. The kinetics of UA degradation and HexA formation has been described in terms of three consecutive first-order reaction stages. The overall rate of UA degradation was one order higher than the rate of UA conversion into HexA. The values of apparent activation energy were estimated as 68.6 and 94.7 kJ mol^–1, respectively. The reaction medium alkalinity was shown to be the controlling factor for UA and HexA stability during ethanol–alkali pulping. An increase in alkali charge from 5% to 35% (as NaOH) led to UA loss of 40%, but promoted HexA formation from 11.8 to 20.1 mol g^–1. The addition of organic solvent to the alkaline pulping solution had a similar effect, and about 10% of UA was lost and the content of HexA increased from 6.9 to 10.9 mol g^–1 with an increase in ethanol proportion in the liquor from 20% to 60%.     

Nitriding of titanium with plasma jet under reduced pressure

The nitriding of titanium with argon-nitrogen (3%) and argon-nitrogen (3%)-hydrogen (2%) plasma jets at pressures of 190 torr was studied. The reaction kinetics obeyed mainly a parabolic law. The parabolic kinetic constants were 10^–10–10^–8 g² cm^–4 s^–1, which were 2–3 orders of magnitude larger than those in R.F. discharges. From emission spectroscopy, nitrogen atoms in the excited states were observed. The nitrogen atoms can promote the nitriding reaction. The effect of the addition of hydrogen to nitrogen is also briefly discussed.     

Utility of the ion-pair formation for spectrophotometric determination of terfenadine in pure form and in some pharmaceutical formulations

A spectrophotometric procedure for the determination of terfenadine and a number of its pharmaceutical preparations has been developed that offers advantages of simplicity, rapidity, sensitivity and stability indication over the official USP (1995) method. The proposed method is based on the formation of ion-pairs by the reaction of terfenadine with some chromotropic acid mono- and bis-azo dyes. Different variables affecting the ion-pair formation were studied and optimized. At the maximum absorption of 557, 521, 592 and 543 nm, Beer's law is obeyed in the range 0.2–18.6, 0.2–16.4, 0.2–25.0 and 0.2–22.2 g ml^–1 on using reagents I, II, III and IV, respectively. The stoichiometric ratio and stability of each ion-pair were estimated and the mechanism of the reaction is discussed. The molar absorptivity and Sandell sensitivity of the produced ion-pairs were calculated in addition to Ringbom optimum concentration ranges. Statistical treatment of the experimental results indicates that the procedures are precise and accurate. Excipients used as additives in pharmaceutical formulations did not interfere in the proposed procedures. The reliability of the methods was established by parallel determination against the official USP method. The procedures described were successfully applied to the determination of the bulk drug and its pharmaceutical formulations by applying the standard addition technique.     

Asymmetric halogenation and hydrohalogenation of ethyltrans-cinnamate in crystalline cyclodextrin complexes

The gas-solid halogenation and hydrohalogenation using microcrystalline cyclodextrin complexes are found to be efficient for production of the optical active halides of ethyltrans-cinnamate in moderate optical yields: On exposure to HBr at 20°C for 15–20 hr, the cinnamate in solid - and -cyclodextrin complexes yields ethyl R-(+)-3-bromo-3-phenylpropanoate in 46% e.e., and S-(–)-enantiomer in 31% e.e., respectively. No addition nor substitution products are obtained with HC1 vapor at 0–50°C for 15–65 hr. Bromination of the -cyclodextrin complex results in the formation of optical active ethylerythro-2,3-dibromo-3-phenylpropanoate, while chlorination gives the optical active mixture oftrans andcis addition products, ethylerythro- andthreo-2,3-dichloro-3-phenylpropanoates in 60–80% yields. Mechanism of chiral induction in the present gas-solid reaction has been proposed on the basis of the crystal structure of the complex.     

Spectrophotometric microgram determination of copper in organic compounds by wet or oxygen flask combustion

Summary Spectrophotometric Microgram Determination of Copper in Organic Compounds by Wet or Oxygen Flask Combustion A spectrophotometric method for the microgram (2–30 ppm) determination of copper in organic compounds after wet digestion or oxygen flask combustion has been developed. The copper content is determined through the formation of the molybdenum blue complex, which is formed by the addition of 1 ml of each of 1% KCN, 1% phosphomolybdic acid and 1M HCl solutions, in the order mentioned. The absorbance is measured at 725 nm. A series of 10 compounds with 10–40% copper gave highly satisfactory results. The total average error is ±0.05% and the overall standard deviation value is 0.220. The method described is rapid, simple and accurate; the reagents required are cheap and readily available.     

Intermediate molybdenum oxides involved in binary and ternary induced electrodeposition

The first stages of Co–Ni and Co–Ni–Mo deposition in sulphate–citrate medium at pH 4.0 were analysed. In both cases, the formation of non-hydrogenated nickel on the electrode before alloy deposition was detected by linear sweep voltammetry and inductively coupled plasma mass spectrometry. Co–Ni electrodeposition was anomalous since the Co/Ni ratio in the alloy was higher than the corresponding [Co(II)]/[Ni(II)] ratio in solution. The adsorption of Co(II) over the initial nickel could explain the anomalous codeposition, which persisted with the addition of molybdate to the Co–Ni bath. However, the formation of intermediate molybdenum oxides also took place. A mechanism has been proposed to describe the sequence of steps for Co–Ni–Mo electrodeposition. Under our conditions, the alloy is formed mainly from free Co²⁺ and Ni²⁺ cations, whereas molybdate is reduced firstly to molybdenum oxide from MoO₄(H₃Cit)²⁻ and, secondly, NiCit⁻ catalyses the subsequent reduction to molybdenum metal of the intermediate [MoO₂–NiCit⁻]_ads species.     

Ammonolysis of technical lignins

The oxidative ammonolysis of hydrolysis lignin, cellolignin, and lignosulfonate takes place effectively with the greatest formation of a water-soluble fraction at 140–150°C in 2 h. On oxyammonolysis, cellolignin forms approximately twice as much water-soluble fraction as hydrolysis lignin, while lignosulfate desulfonates under conditions exceeding the optimum. The maximum amount of nitrogen in the water-soluble fraction of lignin (nitrogen-containing lignin) amounts to 9.0% for cellolignin and is 2–3% less for the others.M. V. Frunze Simferopol' State University. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 275–278, March–April, 1987.     

Addition of methyl dibromoacetate and methyl tribromoacetate to acrylic compounds in the presence of various initiating systems

Conclusions 1. At 70–100° the system, iron pentacarbonyl + dimethylaniline and ferric chloride + dimethylaniline, efficiently initiate the addition of methyl dibromoacetate to methyl acrylate and methyl methacrylate, and also of methyl tribromoacetate to methyl acrylate, with the predominant formation of adducts.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 3, pp. 592–595, March, 1973