3- thiophene-. sodium

Benzenethiol, sodium salt EINECS 213-224-0 HSDB 5771 Sodium benzenethiolate Sodium phenylmercap-tide Sodium phenylsulfide Sodium phenylthiolate Sodium thiophenate Sodium thiophenolate Sodium thio-phenoxide Sodium thiophenylate Thiophenyl sodium salt. 

By treatment with anhydrous aluminium chloride (Holmes and Beeman, 1934). Ordinary commercial, water-white benzene contains about 0 05 per cent, of thiophene. It is first dried with anhydrous calcium chloride. One litre of the dry crude benzene is shaken vigorously (preferably in a mechanical shaking machine) with 12 g. of anhydrous aluminium chloride for half an hour the temperature should preferably be 25-35°. The benzene is then decanted from the red liquid formed, washed with 10 per cent, sodium hydroxide solution (to remove soluble sulphur compounds), then with water, and finally dried over anhydrous calcium chloride. It is then distilled and the fraction, b.p. 79-5-80-5°, is collected. The latter is again vigorously shaken with 24 g. of anhydrous aluminium chloride for 30 minutes, decanted from the red liquid, washed with 10 per cent, sodium hydroxide solution, water, dried, and distilled. The resulting benzene is free from thiophene. 

Benzoic acid and naphthoic acid are formed by the oxidative carbonylation by use of Pd(OAc)2 in AcOH. t-Bu02H and allyl chloride are used as reoxidants. Addition of phenanthroline gives a favorable effect[360], Furan and thiophene are also carbonylated selectively at the 2-position[361,362]. fndole-3-carboxylic acid is prepared by the carboxylation of 1-acetylindole using Pd(OAc)2 and peroxodisulfate (Na2S208)[362aj. Benzoic acid derivatives are obtained by the reaction of benzene derivatives with sodium palladium mal-onate in refluxing AcOH[363]. 

Reduction and Hydrodesulfurization. Reduction of thiophene to 2,3- and 2,5-dihydrothiophene and ultimately tetrahydrothiophene can be achieved by treatment with sodium metal—alcohol or ammonia. Hydrogen with Pd, Co, Mo, and Rh catalysts also reduces thiophene to tetrahydrothiophene [110-01-0] a malodorous material used as a gas odorant. 

Halothiophenes. The biomothiophenes, coimneicially the most impoitant of the halothiophenes, are readily made and can be further derivatized. Manufacture of 2-bromothiophene involves the reaction of thiophene with a solution of sodium bromide/sodium bromate in acid solution. 

Rates of debromination of bromonitro-thiophenes and -selenophenes with sodium thio-phenoxide and sodium selenophenoxide have been studied. Selenophene compounds were about four times more reactive than the corresponding thiophene derivatives. The rate ratio was not significantly different whether attack was occurring at the a- or /3-position. As in benzenoid chemistry, numerous nucleophilic displacement reactions are found to be copper catalyzed. Illustrative of these reactions is the displacement of bromide from 3-bromothiophene-2-carboxylic acid and 3-bromothiophene-4-carboxylic acid by active methylene compounds (e.g. AcCH2C02Et) in the presence of copper and sodium ethoxide (Scheme 77) (75JCS(P1)1390). 

The sodium ethoxide catalyzed rearrangement of readily prepared thiazole derivatives provides a facile thiophene synthesis (Scheme 103) (76JPR343). 

A notable exploitation of this reaction has been used for the preparation of potential anticancer agents. In an attempt to control the water solubility of thiophene analogs, a series of sodium salts of 2,5-dicarboethoxy-3,4-dihydroxythiophene have been produced by condensation between thiodiglycolate esters and diethyloxalate. These condensation reactions consistently proceeded in good yield. 

Thiophene has been thiocyanomethylated to a mixture of 2-thenyl-thiocyanate and 2-thenylisothiocyanate in 20% yield by the use of sodium thiocyanate, formalin, and dilute sulfuric acid, ... 

Dichlorothiophene can also be used for the synthesis of 3-substituted thiophenes, since it can be smoothly acylated and chloro-methylated in the 3-position, and the halogens can then be readily removed at the appropriate stage. 3-Thenylsuccinic acid (28) has thus been obtained by treating 2,6-dichloro-3-thenylsuccinic acid with sodium amalgam. 2-Bromo-3-thenylbromide can be utilized in a similar way. ... 

Thiophene is also metal ated by a benzene-soluble ethyl sodium-diethyl zinc complex. Upon carbonation, 65% of 2-thiophenecar-boxylic acid was obtained. ... 

Thiophenethiols are prepared by reduction of the sulfonyl chlorides or, more conveniently, by the reaction of Grignard rea-gents or thienyllithium compounds with sulfur. They have also been obtained by cleavage or thienyl alkyl sulfides with sodium in liquid ammonia. 3-Thiophenethiol is a by-product in the commercial thiophene synthesis. Thiophenethiols have recently also been prepared by a synthesis involving Friedel-Crafts reaction of 2,4-dinitrobenzenesulfenyl chloride with thiophenes, followed by basic cleavage of the resulting sulfide. ... 

The thenyl cyanides are of great importance for the preparation of thiophene derivatives. Because of the acidifying effects of both the thienyl and of the cyano groups, carbanions are easily obtained through the reaction with sodamide or sodium ethoxide, which can be alkylated with halides, carbethoxylated with ethyl carbonate, or acylated by Claisen condensation with ethyl... 

Thienylacetylenes have been prepared in good yield through de-hydrohalogenation of 1,2-dichloroethylthiophenCs or 1-chlorovinyl thiophenes, which are obtained from acetylthiophenes and PCI5, with sodium amide and in liquid ammonia. " The 3-isomers show... 

Catalytic reduction of thiophenes over cobalt catalysts leads to thiolane derivatives, or hydrocarbons. " Noncatalytic reductions of thiophenes by sodium or lithium in liquid ammonia leads, via the isomeric dihydrothiophenes, to complete destructions of the ring system, ultimately giving butenethiols and olefins. " Exhaustive chlorination of thiophene in the presence of iodine yields 2,2,3,4,5,5,-hexachloro-3-thiolene, Pyrolysis of thiophene at 850°C gives a... 

Complexes 79 show several types of chemical reactions (87CCR229). Nucleophilic addition may proceed at the C2 and S atoms. In excess potassium cyanide, 79 (R = R = R" = R = H) forms mainly the allyl sulfide complex 82 (R = H, Nu = CN) (84JA2901). The reaction of sodium methylate, phenyl-, and 2-thienyllithium with 79 (R = R = r" = R = H) follows the same route. The fragment consisting of three coplanar carbon atoms is described as the allyl system over which the Tr-electron density is delocalized. The sulfur atom may participate in delocalization to some extent. Complex 82 (R = H, Nu = CN) may be proto-nated by hydrochloric acid to yield the product where the 2-cyanothiophene has been converted into 2,3-dihydro-2-cyanothiophene. The initial thiophene complex 79 (R = R = r" = R = H) reacts reversibly with tri-n-butylphosphine followed by the formation of 82 [R = H, Nu = P(n-Bu)3]. Less basic phosphines, such as methyldiphenylphosphine, add with much greater difficulty. The reaction of 79 (r2 = r3 = r4 = r5 = h) with the hydride anion [BH4, HFe(CO)4, HW(CO)J] followed by the formation of 82 (R = Nu, H) has also been studied in detail. When the hydride anion originates from HFe(CO)4, the process is complicated by the formation of side products 83 and 84. The 2-methylthiophene complex 79... 

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