From thiophenes

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. 

T system, the PPP a—-tt method (133). The -tt and a net charges and bond orders of thiophene and thiazole are compared in Table 1-5. Whatever the method considered the variation of the indices occurs in the same sense when passing from thiophene to thiazole the replacement in the 3-position of a carbon atom by a nitrogen induces... 

Eurfuryl (for 2-furylmethyl) Eurfurylidene (for 2-furylmethylene) Thienyl (from thiophene)... 

TicarcHHn [34787-01-4] (SB) (52) is a significant penicillin antibiotic that incorporates the thiophene ring system. A number of routes to the required intermediate, 3-thiophenemalonic acid [21080-92-2] have been used over the years. Those from thiophene-based starting materials have involved 3-methylthiophene and 3-bromothiophene. 

Thiophene, which is more stable to acid, is readily sulfonated by shaking with concentrated sulfuric acid at room temperature. Benzene is not reactive under these conditions and this is the basis for the purification of benzene from thiophene contamination. With all three heterocycles, if the a-positions are blocked, then sulfonation occurs at the /3-position. 

Cetylamide [629-54-9] M 255.4, m 106-107", b 235-236"/12mm. Crystd from thiophene-free benzene and dried under vacuum over P2O5. 

Crystd from thiophene-free benzene and dried under vacuum over P2O5. 

Polyethylene [9002-88-4]. Crystd from thiophen-free benzene and dried over P2O5 under vacuum. 

The second thiaaryne is the 2,3-hetaryne derived from thiophene (108). It was obtained by Wittig and Wahl34 by heating bis-(3-... 

About 1 gram of sodamide in fine powder is washed several times vrith benzene and placed in a 200 c.c. fiask. About 50 c.c. of benzene, free from thiophene, is added, and the fiask, attached to a condenser, warmed on the water-bath, and traces of ammonia are removed by a stream of carbon dioxide. From 1 to 2 grams of the phenol-containing oil is then admitted to the fiask through a stoppered funnel inserted through the... 

The synthesis of monocyclic thiepins from thiophene and dimethyl acetylenedicarboxylate is often accompanied by the loss of sulfur. In particular, in cases where room temperature is required for efficient rates of cycloaddition and rearrangement76 (see Section 2.1.3.3.), the desulfurization reaction proceeds rather quickly with the consequence that thiepin formation can be monitored by low temperature HNMR spectroscopy, but the products cannot be isolated.76 - 78 However, in the case of thiepin 1 where R1 = R2 = C02Me and R3 = H, refluxing toluene is necessary for the extrusion of sulfur.78... 

The parent compound 2 is obtained from thiophene-3,4-dithiol (1) and disulfur dichloride.400... 

Loss of C2H2 from thiophene Aromatic compounds Pyrrole... 

Methyl-2,5-dihydrothiophene was converted into the corresponding S-oxide 4 in 57% yield after treatment with 30% excess of hydrogen peroxide for 60 h. By the same procedure the sulphoxides 5 derived from thiophene and its a-substituted analogues were also prepared18. 

ESR experiments employing in situ photolytic decomposition of the peroxydisulfate anion (S20g ) have been carried out to study the reaction of S04 with aliphatic sulfoxides. In the case of dimethyl sulfoxide three radicals are detected ( CHj, CH3 S02, CH2 S(0)CH3), the proportion being pH-dependent. The reaction is assumed to proceed via an initially formed radical cation (not detected) which would be rapidly hydrated to give an intermediate identical with that generated by OH addition on the sulfoxide. Such a process parallels the rapid hydration of radical cations formed from thiophene in their reactions with SO/ and... 

Di-2-thienyl and di-2-furyl ditelluride are prepared from thiophene and furan by lithia-tion with n-buthyllithium, tellurium insertion and oxidative work-up. 

The total synthesis of dibenzothiophene from thiophene is described in Section V, A. 

The total synthesis of dibenzothiophene from thiophene has made available two ketones of potential synthetic interest. Stepwise succinoy-lation and reduction of thiophene in the 2- and 5-positions gave the... 

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