Thiophene Hydrogenation to Tetrahydrothiophene over Tungsten Sulfide Catalysts

Independent reactions of thiophene reduction to tetrahydrothiophene and thiophene hydrogenolysis to form hydrogen sulfide and C₄ hydrocarbons are shown to occur over supported tungsten sulfide catalysts and unsupported tungsten sulfide at an elevated temperature and a high pressure. The highest rate of tetrahydrothiophene formation over the supported catalysts is observed when alumina was used as a support, and the lowest reaction rate is found when silica gel was used as a support. Both catalysts are less active than unsupported tungsten disulfide. The rate of thiophene hydrogenation over tungsten disulfide increases with increasing thiophene concentration and hydrogen pressure and is inhibited by tetrahydrothiophene. The selectivity to tetrahydrothiophene is constant (70–90%) in the whole range up to high thiophene conversions. The high selectivity over tungsten sulfide catalysts is suggested to be due to the reaction pathway through thiophene protonation mediated with the surface SH groups and to the inhibition of hydrogenolysis.     

含硫化合物热解规律的研究

选择丁硫醚、叔丁硫醚、四氢噻吩、乙基苯基硫醚作为模型化合物,在模拟 催化裂化微反装置上考察了含硫化合物热解规律,在热解过程中,烷基含硫化合物转化程度与硫醚烃基结构、反应条件有关。异构含硫化合物比正构含硫化合物容易转化,反应温度升高,转化程度增大,转化产物主要为硫化氢和硫醇,只有少量四氢噻吩发生转化,反应温度升高论程度增加,大部分乙基苯基硫醚发生转化,生成苯硫酚和少量硫化氢;反应温度升高,转化程度增加。含硫化合物热解可能是通过自由基历程进行的。     

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.     

Hydrothiolysis of di(2-thienyl) disulfide

Conclusions The hydrothiolysis of di(2-thienyl) disulfide by hydrogen sulfide at 130–180°C leads to the formation mainly of di(2-thienyl) sulfide. 2-Thiophenethiol is formed as a side-product due to the dissociation of the disulfide at the S-S bond and subsequent reaction of the thiol radicals with hydrogen sulfide. Di(2-thienyl) sulfide also undergoes secondary conversions to 2-thienyl 3-thienyl sulfide and 3-thiophenethiol by the addition of thiol radicals at C-3 of the thiophene ring.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 12, pp. 2783–2785, December, 1985.     

催化裂化过程中含硫化合物转化规律的研究

选择丁硫醚、叔丁硫醚、四氢噻吩和乙基苯基硫醚作为模化合物,在模拟固定床催化裂化微反装置上考察含硫化合物转化和分布规律,在催化裂化过程中,烷基硫醚可以完全转化,转化产物为硫化氢,反应条件对转化程度没有明显影响;环状含硫化合物的转化程度与反应条件、溶剂性质有关,转化产物主要为硫化氢和汪量噻吩,生产的噻吩可进一步发生烷基化反应,反应温度升高,溶剂供氢能力增强,硫化氢的收率增加;乙基苯基硫醚也可以完全转化,转化产物主要为硫化氢和苯硫酚,生成的苯硫酚可进一步发生烷基化反应,反应温度升高,溶剂供氢能力增强,硫化氢的收率增加。     

Thiyl radicals in gas-phase thermolysis of xanthic acid esters

Gas-phase thermolysis of xanthic acid esters and their reaction with acetylene at 250–600°C have been studied for the first time. The direction of the thermolysis is determined by the nature of the substituents at the oxygen and sulfur atoms. The main products of the thermolysis are gaseous hydrocarbons, carbon monoxide and hydrogen sulfide. The yields of liquid products of the thermolysis and of the reactions with acetylene are 4–46%. The role of thiyl radicals in thiophene molecule formation and reaction routes to carbon disulfide, dithiocarbonates, and stilbene are discussed.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 150–153, January, 1996.     

[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.     

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.     

Catalyst activity in alkylthiophene dealkylation

The transformations of 2-alkylthiophenes on various catalysts were studied. In the presence of oxide and sulfide catalysts, 2-methylthiophenes and 2-isopropylthiophenes underwent dealkylation to thiophene. The reaction was complicated by isomerization to 3-alkylthiophene and cracking. The dealkylation of 2-ethylthiophene occurred only in the presence of oxide catalysts. Side-chain dehydrogenation resulting in the formation of 2-vinylthiophene primarily occurred under the action of sulfide and some oxide catalysts. Acid catalysts (amorphous aluminosilicate and zeolites in the form of hydrogen) were the most active and selective in the dealkylation of 2-alkylthiophenes. It is believed that the dealkylation reaction of 2-alkylthiophenes on these catalysts occurs by means of a protolytic mechanism.Translated from Kinetika i Kataliz, Vol. 46, No. 1, 2005, pp. 97–103.Original Russian Text Copyright © 2005 by Mashkina, Chernov.     

Catalytic Hydrogenation of Thiophene to Thiolane in the Gas Phase

The hydrogenation of thiophene in the gas phase in the presence of palladium-sulfide catalyst leads to the production of thiolane and hydrogenolysis products (butane and hydrogen sulfide), which are formed during the decomposition of the thiophene and thiolane. The hydrogenation rate of thiophene increases with increase of its content in the reaction mixture and also with increase of the hydrogen pressure and is reduced by thiolane. The yield of thiolane calculated on the reacted thiophene is 70-90% with 30-60% conversion of the thiophene.     

Mechanism of recyclization of furans to thiophenes and selenophenes under acid catalysis. 1. Kinetic studies of the reaction of 2,5-dialkylfurans with hydrogen sulfide in the presence of hydrochloric acid

The transformation of 2,5-dialkylfurans to thiophenes by reaction with hydrogen sulfide in the presence of hydrochloric acid was studied. The reaction was found to be first order with respect to the furan; the rate of consumption of the furan did not change with increasing length of one of the alkyl substituents. Recyclization in the presence of acid proceeds in two independent directions: through the formation of an intermediate dicarbonyl compound, and by direct conversion of the furan to a thiophene. Kinetic data showed that the reaction occurs mainly by the second route.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1333–1337, October, 1989.     

Synthesis of some thiophene derivatives

The synthesis of thiopene derivatives from diacetylenic hydrocarbons has been described [1]. We have examined for the first time the reaction of diacetylenic diesters with hydrogen sulfide and with NaHS. The diacetylenic diesters react readily with hydrogen sulfide or NaHS in acetone at pH 9–10 to give 2,5-disubstituted thiopheries (see Table 1).Translated from Khimiya Geterotsiklicheskikh Soedinenii, Vol. 6, No. 5, pp. 713–714, May, 1970.     

The insertion and extrusion of heterosulfur bridges. IX: Sulfur bridging in 2-phenylnaphthalene

Sulfur bridging of 2-phenylnaphlhalene ( 3 ) to form benzo[b ]naphtho[2,1-d]thiophene ( 5 ) (main product) and the isomeric benzo[b]naphtho[2,3-d]thiophene ( 4 ) is effected by means of hydrogen sulfide, benzene (solvent), and a sulfided cobaltous oxide-molybdic oxide-alumina (CMA-1) catalyst at 450–630° in a flow system (maximum yield 33% at 500°). The low yield is ascribed to decompositions of both 4 and 5 under reaction conditions.     

HIGH TEMPERATURE REACTIONS OF HYDROGEN SULFIDE AND THIOLS WITH ORGANIC COMPOUNDS

Abstract

The high temperature reaction of hydrogen sulfide with chloro- and bromosubstituted aromatic and heteroaromatic compounds is a convenient method for synthesis of the corresponding thiols and sulfides. The reaction of hydrogen sulfide with ortho-dihalosubstituted aromatic compounds may be directed toward the formation of thianthrene or dibenzo thiophene and their derivatives. The high temperature reaction of thiophenol with chloro- and bromoderivatives of aromatic and heteroaromatic compounds affords the corresponding mixed sulfides. The reaction with ortho-substituted halogen derivatives leads to formation of the sulfur heterocycles of the thianthrene, thioxanthene and dibenzothiophenene series.

The high temperature reaction of hydrogen sulfide with vinyl chloride gives vinylthiol and thiophene. Hydrogen sulfide initiates pyrolytic transformations of thiophene, aniline and benzaldehyde into dithienyls, 5.10-dihydrophenazine and stilbene, respectively. The reaction mechanism has been discussed.     

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.     

促进剂分子中共轭π键对细胞色素c电化学的影响

比较了具有单功能基团的共轭有机小分子噻吩和四氢噻吩对细胞色素ｃ直接电化学反应的促进作用。发现四氢噻吩不能加速细胞色素ｃ的直接电化学反应。而噻吩是一种很好的促进剂。表明噻吩分子中的共轭π键在加速细胞色素ｃ的电子传递过程中起着重要作用。     

A short and efficient route from tetrahydrothiophene to thieno[2,3-d][1,3,2]dithiazolium salts

A synthesis of thieno[2,3-d][1,3,2]dithiazolium salts from commercial tetrahydrothiophene has been developed. The reaction of thieno[2,3-f][1,2,3,4,5]pentathiepin with LiAlH₄ in THF at −15 °C, after treatment with acetyl chloride, led to 2,3-(bisacetylthio)thiophene in high yield. Bis(acetylthio)thiophene reacted with sulfuryl chloride and then trimethylsilyl azide was added to afford a 1,3,2-dithiazolium chloride which was converted into a soluble tetrafluoroborate. Electrolytic reduction under controlled potential yielded a thieno[2,3-d][1,3,2]dithiazolyl radical which was characterized by EPR in frozen methylene dichloride.     

Gas-Phase Thiophene Hydrogenation to Tetrahydrothiophene over Sulfide Catalysts

Thiophene hydrogenation to tetrahydrothiophene over supported transition metal sulfides is studied. Comparison of the atomic catalytic activity at T = 240°C and P = 2 MPa showed that aluminosilicate-supported PdS is one to two orders of magnitude more active than Rh, Ru, Mo, W, Re, Co, and Ni sulfides on various supports. These metal sulfides are arranged in the following series according to the rate of tetrahydrothiophene formation: Pd Mo > Rh Ru > Re > W > Co > Ni. The reaction over sulfide catalysts is assumed to occur through thiophene activation on proton centers and coordinatively unsaturated cations of metal sulfides and additionally on the proton centers of support in the case of palladium catalysts.     

Investigation of the mechanism of catalytic recyclization of furan to thiophene

Investigation of the formation of thiophene from furan and hydrogen sulfide at various catalysts showed that the activity of the catalysts increases with increase in the strength and concentration of Lewis acid centers. It was found by IR spectroscopy that if the degree of coverage of the aluminum oxide surface with hydrogen sulfide is higher than monolayer its dissociative chemisorption does not occur. Mechanism was postulated wich assume that the reaction takes place through stage with the formation of a surface intermediate, including coordination of the α-carbon atoms of the furan ring with the Lewis acid center and with the sulfur atom of molecular hydrogen sulfide.     

Gas-phase Reaction of 2-Chlorothiophene with Hydrogen Sulfide in the Presence of Alcohols

The effect of methanol and ethanol on the route of the gas-phase reaction of 2-chlorothiophene with hydrogen sulfide, leading to 2-thiophenethiol and to bis(2-thienyl) sulfide, has been investigated. It was found that methanol significantly enhances this reaction and increases its selectivity for the thiol at higher temperatures than without the initiator. The optimal conditions were achieved at 570°C in the presence of 10 mole % of methanol when the conversion of the 2-chlorothiophene in the reaction with hydrogen sulfide reaches 98% and the yield of the thiophenethiol (43%) exceeds that of the bis(2-thienyl)sulfide (31%). In the absence of methanol the 2-thiophenethiol is formed only at 510-540°C in just 17% yield, the basic reaction product being the indicated sulfide (52% yield); the conversion of the 2-chlorothiophene does not exceed 54%.