High-Temperature Synthesis of Thiophene from Bis(2-chloroethyl) Sulfide

Gas-phase reaction of bis(2-chloroethyl) sulfide (Yperite) with acetylene at 550–700°C leads to formation of thiophene in 45% yield, the conversion of the initial sulfide being complete. The yield of thiophene reaches 63–68% in the thermolysis of a mixture of acetylene, bis(2-chloroethyl) sulfide, and lower organic disulfides.__________Translated from Zhurnal Organicheskoi Khimii, Vol. 41, No. 6, 2005, pp. 910–912.Original Russian Text Copyright © 2005 by Voronkov, Levanova, Sukhomazova, Russavskaya, Deryagina, Korchevin.     

Ab initio quantum chemical calculation of the mechanism for molecular addition of chlorine to acetylene in the gas phase

We have investigated the mechanism of gas-phase chlorination of acetylene using anab initio quantum chemical method in a 3–21G° basis. We show that formation ofcis andtrans addition products may be connected with the appearance of carbene in the reaction medium, formed upon addition of a chlorine molecule to one of the acetylene carbon atoms. We have found that intermediate carbene may also be a source for the appearance of radicals in the reaction medium.Institute of Organic Chemistry, National Academy of Sciences of Ukraine, 5 ul. Murmanskaya, Kiev 253094, Ukraine. Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 32, No. 1, pp. 17–19, January–February, 1996. Original article submitted April 6, 1995.     

Plasma Thermal Conversion of Methane to Acetylene

This paper describes a re-examination of a known process for the direct plasma thermal conversion of methane to acetylene. Conversion efficiencies (% methane converted) approached 100% and acetylene yields in the 90–95% range with 2–4% solid carbon production were demonstrated. Specificity for acetylene was higher than in prior work. Improvements in conversion efficiency, yield, and specificity were due primarily to improved injector design and reactant mixing, and minimization of temperature gradients and cold boundary layers. At the 60-kilowatt scale cooling by wall heat transfer appears to be sufficient to quench the product stream and prevent further reaction of acetylene resulting in the formation of heavier hydrocarbon products or solid carbon. Significantly increasing the quenching rate by aerodynamic expansion of the products through a converging–diverging nozzle led to a reduction in the yield of ethylene but had little effect on the yield of other hydrocarbon products. While greater product selectivity for acetylene has been demonstrated, the specific energy consumption per unit mass of acetylene produced was not improved upon. A kinetic model that includes the reaction mechanisms resulting in the formation of acetylene and heavier hydrocarbons, through benzene, is described.     

Synthesis,structure, and thermal destruction of aroxytetraphenylstiboranes

A series of aroxytetraphenylstiboranes, Ph₄SbOAr, were obtained by the reaction of pentaphenylstiborane with phenols at 20 °C. The thermolysis of these compounds givesO- or o-C-phenylation products. The thermolysis of stiboranes, which incorporate aryl groups containing electron-withdrawing substituents (Ar=2,4-Br₂, 2,4-Cl₂, 2-NO₂, 4-OPh) produces predominantly simple diaryl ethers of asymmetric structure in 58 %, 90 %, 32 %, and 60 % yields, respectively.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 958–963, May, 1995.     

Thermolysis of 2-(p-azidocinnamoyl)quinoline

Mass spectrometry was used to study the thermolysis of 2-(p-azidocinnamoyl)quinoline and 4-azidochalcone at 160–230C. The primary thermolysis product of these azides is a nitrene. The reaction of this nitrene in the singlet state gives polymer products, while the triplet nitrene is reduced in the molten azide to give a primary amine and dimerized to give an azo compound.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 3, pp. 685–686, March, 1990.     

Thermal decomposition ofC-iodotetrazoles

Thermal decomposition of 1-substitutedC-iodotetrazoles in melt and solutions has been investigated. Thermal stabilities, kinetic and activation parameters, and compositions of products of thermolysis ofC-iodotetrazolcs depend on the substituent nature. The scheme of thermolysis ofC-iodotetrazoles has been suggested.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 68–71, January, 1996.     

Thermal decomposition of transition metal carboxylates

Thermal solid-phase decomposition of anhydrous copper(ii) formate has been studied at 120–180 ° The rate of gas evolution during the decomposition depends on the depth of conversion and can be presented as the sum of first-order reaction rates and the rate of the autocatalytic process (a second-order reaction). The evolution of the solid phase during thermolysis has been observed by optical microscopy. The decomposition of copper formate is a complex topochemical process, a combination of homogeneous and heterogeneous transformations and dispersion of large crystals.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. l, pp. 72–76, January, 1996.     

New ways of synthesis of 1,2-dithiole-3-thione

Two new synthetic approaches to 1,2-dithiole-3-thione are proposed. The title compound is formed by thermolysis of dipropyl polysulfides (n-Pr)₂S_x (x = 3–4) and thermal decomposition of polysulfide dendrimers under reduced pressure. The latter reaction may be recommended for utilization of organochlorine waste products in the manufacture of epichlorohydrin, which are used for the synthesis of dendrimers.Translated from Zhurnal Obshchei Khimii, Vol. 74, No. 11, 2004, pp. 1884–1886.Original Russian Text Copyright © 2004 by Korchevin, Russavskaya, Yakimova, Deryagina.This revised version was published online in April 2005 with a corrected cover date.     

Thermal transformations of allyl 2-thienyl sulfide and selenide

In the gas phase at 350–410C allyl 2-thienyl sulfide is converted to thiophene-2-thiol, di(2-thienyl) sulfide, and 2-methylthieno[2,3-b]thiophene. In the presence of acetylene thieno[2,3-b]thiophene is formed in addition to these products. Allyl 2-thienyl selenide is converted quantitatively to 2,3-dihydro-2-methylselenopheno[2,3-b]thiophene during fractional distillation in vacuo. Thiophene, di(2-thienyl) selenide, di(2-thienyl) diselenide, thiophene-2-selenol, and 2-methylselenopheno[2,3-b]thiophene are formed in addition to these compounds in the thermolysis of allyl thienyl selenide in the gas phase. In the presence of acetylene the thermal decomposition of allyl thienyl selenide is accompanied by the formation of selenophene.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1312–1316, October, 1991.     

Effects of UV light irradiation on propane in an argon plasma

It has been shown that propane conversion into acetylene, by propane cracking in an argon plasma, is increased when the reaction site is irradiated with UV light in the range 220–400 nm. The reactions were carried out between 4500 and 6400 K. A model is outlined following which the propane conversion increase at 6400 K (40%) is tied up to energy absorption by acetylene in the lower wavelengths range (220–250 nm). Also, a combined adsorption-photochemical process, related to precursors and submicron carbon particles, could be responsible for the yield increase observed at 5400 K (45%), around 365.0 nm.     

The Solvent Effect on the Rate of Reaction between Propanethiol and Chlorine Dioxide

The products and kinetics of the liquid-phase oxidation of propanethiol by chlorine dioxide in organic media (n-heptane, 1,4-dioxane, carbon tetrachloride, benzene, diethyl ether, ethyl acetate, acetone, and acetonitrile) at temperatures from –10 to 70°C were examined. The reaction rate constants and activation parameters were measured in the above solvents. A strong solvent effect on the reaction kinetics was found (k= 1.67 × 10^–3or 52.7 l mol^–1s^–1(25°C) in heptane or acetonitrile, respectively). The data were analyzed in terms of the Leydler–Eyring and Koppel–Palm equations. The formation of high-polarity intermediates in the test reaction was suggested.     

Liquid Film Deposition of Chalcogenide Thin Films

Thin films of MoS _x were prepared by liquid film deposition of MoS₄ ^2– solutions in 1,2-diaminoethane (en) and 1,2-diaminopropane (pn) and subsequent thermolysis at temperatures up to 800°C under N₂. As the coatings show a high carbon content of up to 30 at.% that influences the morphology and the physical properties, the precursor thermolysis and the solution properties were analysed in detail and correlated to the coating properties. A reduction of the intermediately formed MoS₃ by organic residues at approx. 300°C was made out as the main cause of the carbon contamination during the thermolysis of the precursor salts (enH₂)MoS₄ and (pnH₂)MoS₄, leading to an immobilisation of the organic carbon. In the corresponding solutions cations of the form [RNH₂...H...NH₂R]⁺ could be detected, that result in an incorporation of additional diamine with 3–4 molecules per MoS₄ ^2– ion in the wet films. This cross-linked structure on the one hand reduces the tendency of the precursor salts to crystallise and thus makes it easier to obtain amorphous precursor films, but on the other hand increases the content of organic residues before thermolysis.     

Thermal decomposition of acetyl propionyl peroxide in acetone-<Emphasis Type="Italic">d</Emphasis><Subscript>6</Subscript>

The kinetics of thermolysis of acetyl propinyl peroxide in acetone-d ₆ in the temperature range 323–373 K was studied using NMR spectroscopy and the effect of chemically induced nuclear polarization. The peroxide decomposes in acetone at rates comparable with the rates of thermolysis in alcohols, yielding numerous products. In the examined temperature range, the solvent molecules act as efficient donors of deuterium atoms, forming acetylmethyl-d ₅ radicals which recombine to a significant extent with the peroxide radicals. A scheme of the processes involved in decomposition of the peroxide was suggested. The parameters of the Arrhenius equation for the peroxide decomposition were determined.Translated from Zhurnal Obshchei Khimii, Vol. 74, No. 11, 2004, pp. 1847–1854.Original Russian Text Copyright © 2004 by Skakovskii, Stankevich, Tychinskaya, Shirokii, Choban, Murashko, Rykov.This revised version was published online in April 2005 with a corrected cover date.     

Ab initio MP2 calculations of the products of acetylene addition to HgCl2

Gas-phase reaction of acetylene with HgCl₂ resulting in -chlorovinylmercury derivatives and their interaction with Cl^– and I^– anions and KI molecule was studied by the ab initio MP2 method with the Dunning—Hay double zeta basis set and LanL pseudopotential for Hg, K, and I atoms. The reaction was shown to proceed via a -complex of acetylene and HgCl₂ (the calculated enthalpy of formation is –6.5 kcal mol^–1). According to calculations, the activation energy of formation of cis--chlorovinylmercury chloride from acetylene and HgCl₂ is 31 kcal mol^–1. Chloride and iodide anions and KI molecule are readily added to both cis- and trans-isomer of -chlorovinylmercury chloride to give stable species.     

Reaction of pyridine-2-thione with acetylenes

In contrast to 2-pyridone, pyridine-2-thione reacts with acetylene with the participation of one reaction center — the sulfur atom. The reaction with phenylacetylene and diacetylene proceeds stereospecifically to give products with cis structures. The structures of the synthesized compounds were confirmed by chemical and spectroscopic methods.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 364–367, March, 1978.     

Gas-phase pyrolysis of bis(phenylthio) acetylene

Conclusions The main products of the gas-phase pyrolysis of bis(phenylthio)acetylene in either benzene or toluene at 560° are diphenyl sulfide, thiophenol, and acetylene. Benzothiophene and thianthrene are also formed here. The yield of diphenyl sulfide increases when bis (phenylthio)acetylene is copyrolyzed with chlorobenzene (580°).Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No.5, pp. 1188–1190, May, 1983.     

Photoelectron spectral study of the thermolysis of benzofuroxan

Photoelectron spectroscopy data have shown that thermolysis of benzofuroxan vaporin vacuo results in thermal abstraction of the exocyclic oxygen to afford a nonvolatile product, which decomposes to give nitrogen monoxide, carbon monoxide, and carbon dioxide.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2238–2240, December, 1994.     

Production of acetylene by a microwave catalytic reaction of water and carbon

The feasibility of producing hydrocarbons in a microwave induced catalytic reaction of carbon and water was successfully demonstrated. The major reaction products are acetylene, methane, ethylene and ethane. Other significant products include propylene, propyne, cyclopropane, carbon dioxide and carbon monoxide. Relative product yields and their distribution depend on a number of experimental variables, such as irradiation time, incident microwave power, water/carbon ratio and the characteristics of the microwave pulse train. At short irradiation times and low incident power only C₁ — C₂ products were observed, their rates of formation being an exponential function of the incident microwave power. High incident power led to the formation of C₃ to C₆ hydrocarbons at the expense of acetylene. Initial addition of methane and carbon dioxide to the reaction mixture increased the yield of acetylene, whereas addition of methanol to water resulted in a sharp increase in the amounts of both methane and acetylene. Mechanisms are considered to account for these observations.     

Formation of C4 Oligomers in Hydrogenation of Acetylene over Pd/Al2O3 and Pd/TiO2 Catalysts

Selectivity of product formation has been tested in hydrogenation of acetylene over 0.3 wt.% Pd/-alumina and 0.5 wt.% Pd/TiO₂catalysts. Non-steady-state regime of catalyst operation was tested in pulse-flow experiments. Significant carbon poisoning appears to be a necessaryrequisite for selective formation of ethylene. The effect of hydrogen and acetylene partial pressure has been tested on the selectivity of C₄products. At 273–298 K the catalysts showed 26–35% selectivity for C₄ hydrocarbons and <2.5% for ethane production at conversionsof 30–40%. Deuterium distribution in ethylene and 1,3-butadiene and the deuterium content of the surface hydrogen pool have been compared and mechanismof diene formation has been discussed.