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IMIDAZOLES, or GLYOXALINES

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Originally appearing in Volume V14, Page 332 of the 1911 Encyclopedia Britannica.
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IMIDAZOLES, or GLYOXALINES , organic chemical compounds CH=CH containing the See also:ring See also:system HN< , l • Imidazole itself was CII=N first prepared by H. Debus(See also:Ann. 1858, 107, p. 254) by the See also:action of See also:ammonia on glyoxal, 2C2H202+2NH3=C3I-I4N2+H2CO2+2H20. The compounds of this See also:series may be prepared by the condensation of ortho-See also:diketones with ammonia and See also:aldehydes R•C-N R•CO•CO•Rd-2NH,+R'•CHO=3H2O+ fl ~C•R ; R.C-NHS from thioimidazolones by oxidation with dilute nitric See also:acid (W. Marckwald, Ber., 1892, 25, p. 2361); by See also:distillation of hydrobenzamide and similarly constituted bodies; and by the action of See also:phosphorus pentachloride on symmetrical dimethyloxamide, a methylchlorglyoxaline being formed (O. Wallach, Ann., 1877, 181, P. joo). The glyoxalines are basic in See also:character, and the imide See also:hydrogen is replaceable by metals and alkyl See also:groups They are See also:stable towards reducing agents, and acidyl groups are only introduced with difficulty. Irnidazole (glyoxaline), C3H4N2, crystallizes in thick prisms which melt at 88-89° C. and See also:boil at 2J3° C., and are readily soluble in See also:alcohol and in See also:water. It is unaffected by chromic acid, but See also:potassium pe-manganate oxidizes it to formic acid. It forms salts with acids.

CeH;•C-N Lophine (triphenylglyoxaline), II 2C•C6Hy, is formed CbHS•C-NH by the dry distillation of hydrobenzamide, or by saturating an alcoholic See also:

solution of benzil and See also:benzaldehyde (at a temperature of 4o° C.) with ammonia. It crystallizes in needles which melt at 275.° C. It is a weak See also:base. When heated to 300° C. with hydriodic acid and hydrochloric acid, in the presence of some red phosphorus, it yields benzoic acid. The keto-glyoxalines are known as imidazolones and are prepared by the action of acids on acetalyl thioureas (W. Marckwald, Ber., 1892, 25, P. 2357). Benzimidazole, See also:C6H4\ NH >CH, is the simplest representative of the benzoglyoxalines and is prepared by the condensation of formic acid with ortho-phenylene diamine. It forms rhombic crystals which melt at 17o° C. It is basic in character, and on oxidation with potassium permanganate yields a HOOC•C-N small amount of glyoxaline dicarboxylic acid, II HOOC•C-NH' (E. See also:Bamberger, Ann., 1893, 273, p. 338).

End of Article: IMIDAZOLES, or GLYOXALINES

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