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CONH
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CONH -- See also:NH2. CO2R-> NH2CO• NH •CO2R; by the See also:action of chlorcarbonic See also:esters on See also:urea (H. Schiff, See also:Ann., 1896, 291, p. 367) ; and by the action of urethanes on urea chloride (L. Gattermann, See also:Bee., 1888, 21, p. 293 R). They are readily decomposed by alkalis, yielding cyanuric See also:acid and See also:ammonia. Biuret (allophanamide), NH2•CO•NH•CO•NH2, is formed by See also:heating urea; by the action of ammonia on allophanic ester; and by heating urea to 14o° C. and passing See also:chlorine into the melt at 14o-15o° C. (J. Thiele, Ann., 1898, 303, p. 95 Anm.). It crystallizes in needles which melt at 19o° C. (with decomposition), and is readily soluble in hot See also:water. When heated strongly it is decomposed into ammonia and cyanuric acid. Baryta water hydrolyses it to See also:carbon dioxide, ammonia and urea. With See also:silver nitrate and See also:caustic soda it yields a silver See also:salt, Ag2C2HaN202• With nitric acid in the presence of sulphuric acid it yields a nitro derivative. Thiourea, or sulphocarbamide, CS(NH2)2, is formed by See also:pro-longed See also:fusion of ammonium thiocyanate (E. See also:Reynolds, Ann., 1869, 15o, p. 224), by passing sulphuretted See also:hydrogen into an ethereal See also:solution of See also:cyanamide (E. Baumann, Ber., 1873, 6, p. 1375), or by heating isopersulpho-cyanic acid (F. D. Chattaway, Jour. Chem. See also:Soc., 1897, 71, p. 612). It crystallizes in thick prisms which melt at 18o° C. and is readily soluble in water. When heated for some See also:time with water to 14o° C. in a sealed See also:tube, it is transformed into ammonium thiocyanate, a similar result being obtained by heating the See also:base alone for some See also:hours to 16o-17o° C. On heating alone for some hours to 17o-18o° C. it is converted into See also:guanidine thiocyanate. It is hydrolysed by alkalis, giving carbon dioxide, ammonia and sulphuretted hydrogen. It is readily desulphurized by silver See also:oxide, mercuric oxide or See also:lead oxide. See also:Potassium permanganate oxidizes it to urea (R. Maly, Monats., 1890, 11, p. 278). It acts as a weak base and forms salts with one See also:equivalent of an acid. The alkyl derivatives of thiourea are obtained by the action of ammonia and of See also:primary and secondary See also:amines on the See also:mustard See also:oils (A. W. See also:Hofmann, Ber., 1867, 1, p. 27): CSNR+NH3=NH2•CS•NHR; CSNR+NH2R=R•NH•CS•NHR, or by heating the See also:amide salts of the alkyl dithio-carbaminic acids, viz., NR•CS•S(NH,R). The monoalkyl derivatives are desulphurized by lead hydroxide in the presence of See also:sodium carbonate, the a!3 dialkyl and trialkyl derivatives being unaffected (A. E. See also:Dixon, Jour. Chem. Soc., 1893, 63, p. 325). The dialkyl thioureas when digested with mercuric oxide and amines give guanidines. CS(NHR)2+NH2R+HgO->HgS+RN:C(NHR)2. Thiourea and many of its unsymmetrical derivatives have marked physiological action; thiourea causes a slowing of the See also:pulse and respiration, cardiac failure, and See also:death in See also:convulsions; phenyl-, See also:ethyl- and acetyl-thiourea are actively toxic. The most important derivative pharmacologically is allyl-thiourea, also known as thiosinamine or rhodallin, NH2•CS•NH.See also:CH2.CH:CI-I2. Thiosemicarbazide, NH2.CS•NH.NH2, prepared from See also:hydrazine sulphate, potassium carbonate and thiocyanate (N. See also:Freund, Ber., 1895, 28, p. 946; 1896, 29, p. 2501), crystallizes in See also:long needles, which melt at 181-183° C. The addition of sodium nitrite to an aqueous solution of its hydrochloride converts it into amido-triaz- N- N sulphol S< 1. The hydrochloride with potassium cyanate C(NH2) : N gives hydrazothio-carbonamide, NH2.CO.NH•NH•CS•NH2. See also:Medicine.-Urea has been given in medicine in doses of 10 to 6o grs. either in mixture or hypodermically. It has been used with success as an antiperiodic and antipyretic in See also:ague, and also as a diuretic in See also:gout and See also:kidney affections. Thiosinamine is given internally in doses of z to I gr. in See also:capsule. Larger doses usually upset the digestion. It has been used for the cure of See also:lupus and of keloid, in which See also:case it is administered hypodermically. In keloid 20 minims of a 1o%° solution is injected directly into the See also:part. It causes a See also:local reaction with absorption of the scar See also:tissue. For this See also:reason it is used to remove corneal opacities, deafness due to thickening of the membrane, stricture of the See also:oesophagus and See also:hypertrophy of the pylorus, it has also been successful in the treatment of adhesive parametritis. Fibrolysin is a modified See also:form of thiosinamine made by mixing it with sodium salicylate Fibrolysin is freely soluble and may be given in hypodermic or See also:intra-See also:muscular injection. Like thiosinamine it has a specific action on scar tissue and has been used in urethral strictures. Both these preparations should only be used in cases where it is possible to exclude any tuberculous foci, or by their action in breaking down protective fibrous tissues they may cause a quiescent See also:lesion to become active. In large doses toxic symptoms are produced, death following on See also:coma. Additional information and CommentsThere are no comments yet for this article.
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