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THIOPHEN, C4H4S
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See also:THIOPHEN, C4H4S , a See also:compound occurring in small quantities in crude See also:coal-See also:tar See also:benzene, from which it was first isolated in 1883 by V. See also:Meyer (Ber., 1883, 16, p. 1465). The method adopted by Meyer to recover the thiophen was as follows. Ten volumes of the purest coal-tar benzene were shaken for four See also:hours with one See also:volume of sulphuric See also:acid, the acid layer was removed and neutralized with See also:lead carbonate, and the lead thiophen sulphonate obtained was distilled with an See also:equivalent quantity of ammonium chloride. The distillate obtained was diluted with one See also:hundred volumes of ligroin (previously purified by shaking with fuming sulphuric acid) and then shaken for one or two hours with sulphuric acid (using ten volumes of acid to one volume of the distillate), the acid layer diluted with See also:water, neutralized by lead carbonate and the lead See also:salt again distilled with an equivalent quantity of ammonium chloride. The distillate is finally rectified. It may be obtained in small quantity by passing See also:ethylene or See also:acetylene into boiling See also:sulphur; by passing See also:ethyl sulphide through a red-hot See also:tube; by See also:heating crotonic acid, butyric acid or See also:erythrite with See also:phosphorus pentasulphide; by heating succinic anhydride with. phosphorus pentasulphide or See also:sodium succinate with phosphorus trisulphide (J. Volhard and H. Erdman', Ber.; 1885, 18, p. 454); or by heating succindialdehyde with two parts of phosphorus trisulphide (C. Harries, Ber., 19o1, 34, p. 1496). It is a colourless liquid having a faint See also:smell resembling that of benzene and boiling at 84° C. In its See also:chief properties it very much resembles benzene, being readily brominated, sulphonated, and nitrated; also, the See also:side chains in the alkyl thiophens are readily oxidized to carboxyl See also:groups. On passing its vapour through a red-hot tube it yields di-thienyl, CsH6S2. It is completely decomposed by hydriodic acid at 14o° C. It condenses with See also:aldehydes (in See also:chloroform See also:solution) in the presence of phosphorus pentoxide to give dithienyl See also:hydrocarbons (A. Nahke, Ber., 1897, 30, p. 2037). It can be readily recognized by the See also:blue See also:colour produced when a trace of thiophen is added to See also:isatin dissolved in concentrated sulphuric acid (the indophenin reaction). The thiophen See also:ketones'may be prepared by the inter-See also:action of thiophen and its homologues with acid chlorides in the presence of anhydrous See also:aluminium chloride. The thiophen homologues are best prepared by heating the 1.4 See also:diketones with phosphorus pentasulphide, the diketones reacting in the enolic See also:form: ./(CH-cli H . CH\ R C /,CH `OfI HU/C • R FPzs R •Cam__ 3 ./>''C • R. Thiotenol, or oxymethyl thiophene, is prepared by heating laevulinic acid with phosphorus pentasulphide (W. Kues and C. Paal, Ber., 1886, 19, p. 555)• On this See also:group see also V. Meyer See also:Die Thiophengruppc. Additional information and CommentsThere are no comments yet for this article.
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