Reaction of 2-methyl-3-ethoxycarbonyl-4-hydroxythiophene with hydrazines

2-Methyl-3-ethoxycarbonyl-4-(N,N-dimethylhydrazino)thiophene (II) and 2-methyl-3-ethoxy-carbonyl-4-(N-phenylhydrazino)thiophene (III) are formed by the action of substituted hydrazines — N,N-dimethylhydrazine and phenylhydrazine — on 2-methyl-3-ethoxycarbonyl-4-hydroxythiophene (I). At the same time, the thiophene ring of hydroxythiophene I undergoes hydrazinolysis under the influence of hydrazine hydrate to form 3-mercaptomethyl-4-ethoxycarbonyl-5-methylpyrazole (IV). Structure IV was proved by IR, UV, and PMR spectroscopy and by hydrogenolysis of IV to the known 3,5-dimethyl-4-ethoxycarbonylpyrazole (V).Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 759–761, June, 1971.     

Synthesis of 2-methylthie no [3,2-b]thieno-[2,3-d]thiazole

A new heterocyclic base — 2-methylthieno[3,2-b]thieno[2,3-d]thiazole — was synthesized by heating 2-acetamido-3-hydroxythieno[3,2-b]thiophene with phosphorus pentasulfide.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1039–1041, August, 1976.     

Catalytic methods for obtaining thiophene and alkylthiophenes from petroleum refining products and sulfur-containing organic compounds

This review is devoted to catalytic methods for obtaining thiophene and alkylthiophenes from C₂-C₆ hydrocarbons and from various organosulfur compounds — aliphatic sulfides, mercaptans, alkylthiophenes, thiophane, and sulfones. Multicomponent chromium-containing catalysts have considerable activity in the majority of the reactions. The catalytic method for obtaining thiophene and alkylthiophenes by the reaction of C₂-C₆ hydrocarbons with hydrogen sulfide may be the most promising one.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1299–1312, October, 1971.     

Quantum-chemical investigation of the 1,2-proton shift in protonated five-membered aromatic heterocycles

Calculations of the energetics of the 1,2-proton shift in protonated five-membered aromatic heterocycles — pyrrole, furan, and thiophene — have been carried out by the SCF MO LCAO method in the MINDO/3 approximation and nonempirically on the OST-3GF (OST-3GF*) basis. The general features of this process, and also the influence of solvation and of taking into account the vacant d-AOs of the sulfur atom in the protonated form of thiophene on the results of the calculation are considered. The results obtained have been used for a discussion of the activity and selectivity of the heterocycles considered in aromatic electrophilic substitution reactions.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1186–1190, September, 1984.     

Study of kinetics and mechanism of sulfonation of thiophene and its derivatives by complex compounds of sulfuric anhydride

By quantitatively studying the sulfonation of thiophene and its homologs by complexes of sulfuric anhydride with ethers, amides, and trialkyl phosphates it was possible to determine kinetic and thermodynamic parameters of the process, to propose a S_E2 type reaction mechanism and also to reveal a quantitative dependence of the rate constant of the sulfonation reaction of thiophene on the basicity of the complex-forming agent: The sulfonating activity of the complexes studied increases in the series — amides < trialkyl phosphates < ethers, which is the reverse of the increase in the basicity series of a donor.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 34–39, January, 1986.     

Basicity and structure of α, β -unsaturated heterocyclic ketones

The protolytic equilibrium constants of chalcone and its furan and thiophene analogs have been measured spectrophotometrically in sulfuric acid — glacial acetic acid solution. It is shown that the furan ketones are more basic than the thiophene ones, basicity depending on the position of the carbonyl group in the conjugated chain. In the systems studied, 2-furyl exhibits an appreciably greater positive dynamical conjugation effect than 2-thienyl, but as compared with the latter it gives rise to less steric hindrance to solvation of carbonium ions.For Part II see [2].     

Synthesis,reactions, and properties of some selenides of the thiophene,furan, and selenophene series (review)

The review is devoted to the authors' research on the synthesis and study of the reactivities of selenides of the thiophene series, and, to a lesser extent, of selenides of the furan and selenophene series. The properties of the indicated compounds — their capacity for reaction with electrophilic agents and organolithium compounds — and their spectral characteristics are examined in order to compare them with the properties of the corresponding sulfides and alkoxy derivatives.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 723–737, June, 1972.     

Synthesis and spectrophotometric study of some amino derivatives of thiophene analogs of chalcone

Eight amino derivatives of thiophene analogs of chalcone were obtained by reduction of the corresponding nitro derivatives with stannous chloride in concentrated hydrochloric acid, and their UV absorption spectra in dioxane were measured. The long-wave band was assigned to the corresponding fragments of the molecule on the basis of a comparison of the absorption curves of the investigated compounds with the curves of simpler compounds — aminoacetophenone, aminobenzalacetone, acetothienone, etc.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 198–203, February, 1977.     

Activity and selectivity in the electrophilic substitution of five-membered heterorings (review)

Data on the activity and selectivity in reactions involving the electrophilic substitution of five-membered heteroaromatic compounds with one heteroatom are discussed. Chief attention is directed to the reactions of pyrrole, furan, thiophene, and their substituted derivatives. The inconsistency in the change in the activity (reaction rate) — N>O>S — and in the positional selectivity (the ß ratio) — N相似文献   

Autooxidation of methylheterocycles under phase transfer catalysis conditions

The autooxidation of methyl- and dimethyl-substituted N-, S-, and O-heterocyclic compound derivatives has been studied in 1,2-dimethoxyethane—t-BuOK in the presence of 18-crown-6. Mono- and dicarboxylic acid derivatives of pyrazine, pyridine, pyrimidine, and thiophene have been synthesized.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 959–962, July, 1991.     

Pervaporation performance of crosslinked polydimethylsiloxane membranes for deep desulfurization of FCC gasoline: I. Effect of different sulfur species

Crosslinked PDMS/PEI composite membranes were prepared, in which asymmetric PEI membrane prepared with phase inversion method was acted as the microporous supporting layer in the flat-plate composite membrane. The different function composition of the PDMS/PEI composite membranes were characterized by reflection FTIR. The surface and section of PDMS/PEI composite membranes were investigated by scanning electron microscope (SEM). The infinite dilute activity and diffusion coefficients of thiophene, 2-methyl thiophene, 2,5-dimethyl thiophene, n-butyl mercaptan, n-butyl sulfide in crosslinked PDMS were measured in the temperature range of 80–100 °C by inverse gas chromatography. The solubility parameters of thiophene, 2-methyl thiophene, 2,5-dimethyl thiophene, n-butyl mercaptan, n-butyl sulfide were calculated by the group contribution method and the selectivity of PDMS composite membrane for different organic sulfur compounds was investigated. The composite membranes prepared in this work were employed in pervaporation separation of n-heptane and different sulfur forms mixtures. The theoretical results showed good agreement with the experimental results, and the order of partial permeate flux and selectivity for different organic sulfur compounds was: thiophene > 2-methylthiophene > 2,5-dimethylthiophene > n-butyl mercaptan > n-butyl sulfide, which should be significant for practical application.     

The rα-structure of thieno[2,3-b] thiophene. A H-NMR study in a nematic phase including C-satellites in natural abundance

The ¹H-NMR spectrum of thieno[2,3-b]thiophene in a nematic phase has been recorded and analysed. The ¹H,¹³C dipole—dipole couplings were obtained from ¹³C satellites in natural abundance. The indirect ¹H,¹H and ¹H,¹³C spin—spin coupling constants were determined from an isotropic sample. The dipole—dipole couplings were corrected for harmonic vibrational contribution. The corrected dipole—dipole couplings were used to evaluate the r_α-structure of the molecule.     

Synthesis of some nitrogen derivatives of the thiophene analog of cinchophen

2-Nitro-5-(4-carboxy-2-quinolyl)thiophene was obtained bynitration of 5-(4-carboxy-2-quinolyl) thiophene. Data from microbiological tests of the nitro-substituted thiophene and its carboxyl-group derivatives are presented.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 183–184, February, 1973.     

Quantum-chemical calculations of the electronic structures of polymethylidyne dyes

The energies of the transitions of unsubstituted and substituted thia-, thiazolo-, and thienothiazolocarbocyanines, as well as quinocyanines and carbocyanines with a condensed thiophene, furan, selenophene, or pyridine ring, to the excited singlet states and their electronic structures were calculated by the MO LCAO method within the Pariser—Parr—Pople approximation. The nature of the long-wave and short-wave absorption bands in the spectra of these dyes and the peculiarities of the color of thieno-, furo-, and selenophenothiazolo- and -pyridocyanines, as well as the effect of substituents on their electronic characteristics as a function of the position in the heteroresidues and the nature of the latter, are discussed.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 626–633, May, 1978.     

Photochromic dihetarylethenes. 14. Synthesis of symmetrical and unsymmetrical dihetarylcyclobutene-1,2-diones

A procedure was developed for the synthesis of symmetrical and unsymmetrical cyclobutene-1,2-dione derivatives bearing thiophene and thieno[3,2-b]thiophene substituents by the Friedel—Crafts reaction of the corresponding heterocyclic compounds with squaric acid dichloride in the presence of AlCl₃. In addition to the target dihetarylcyclobutenediones, monoacylation products of methyl (2,5-dimethylthiophen-3-yl)acetate and methyl 5-methylthieno[3,2-b]thiophene-2-carboxylate with squaric acid dichloride were isolated and characterized.     

[3,3]-sigmatropic rearrangement of allyl 2-benzothienyl sulfide

Allyl 2-benzothienyl sulfide at 20–120 °C undergoes a [3,3]-sigmatropic rearrangement to give 3-allylbenzothiophene-2-thiol. The kinetic parameters of the reaction were studied. Under the experimental conditions the thiol undergoes cyclization to give 2-methyl-2,3-dihydrobenzothieno[2,3-b]thiophene, 2-methyl-benzothieno[2,3-b]thiophene, and benzothieno[2,3-b]dihydrothiopyran. Allyl 3-methyl-2-benzothienyl sulfide does not form a thiol even at 150–190 °C but rather forms only bis(3-methyl-2-benzothienyl) disulfide.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 615–618, May, 1981.     

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.     

Estimation of the activity of catalysts and the reactivity of organosulfur compounds

The kinetics of hydrogenolysis of various classes of organosulfur compounds were studied in the presence of MeAlCl ₄ catalysts (Me=Li, Na, K). The reactions were conducted at 100–250°C without introduction of hydrogen into the reaction zone, but in the presence of hydrocarbons capable of acting as hydride—ion donors; these donors were necessary for H ₂ S formation. A series of catalytic activities and optimal reaction conditions for each catalyst were determined from the rate constants of hydrogenolysis at the C-S bond. Reactivities of mercaptans, sulfides, disulfides, and thiophene were estimated.Institute of Chemistry, Bashkir Scientific Center, Ural Branch, Russian Academy of Sciences, Ufa 450054. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 3, pp. 562–564, March, 1992.     

Catalytic activity of NiMo/TiO2?Al2O3 systems in thiophene hydrodesulfurization

A correlation exists between the number of surface acid sites and the catalytic activity of NiMo/TiO₂–Al₂O₃ systems in thiophene hydrodesulfurization. The catalytic activity for thiophene hydrodesulfurization and surface concentration of Brönsted acid sites increase with the titania content in the TiO₂–Al₂O₃ support.     

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.