CN3H5

GUANIDINE  or HN: C(NH2)2, the amidine of amidocarbonic acid . It occurs in beet juice . It was first prepared in 1861 by A . Strecker, who oxidized guanine with hydrochloric acid and potassium chlorate . It may be obtained synthetically by the action of ammonium iodide on cyanamide, CN•NH2+ NI14I=CN3H5•HI•; by heating ortho-carbonic esters with ammonia toso° C.; but best by heating ammonium thiocyanate to 18o°-190° C., when the thiourea first formed is converted into guanidine thiocyanate, 2CS(NH2)2=HN: C(NH2)2•HCNS+H2S . It is a colourless crystalline solid, readily soluble in water and alcohol; it deliquesces on exposure to air . It has strong basic properties, absorbs carbon dioxide readily, and forms well-defined crystalline salts . Baryta water hydrolyses it to urea . By direct union with glycocoll acid, it yields glycocyamine, NH2•(HN): C•NH•CH2•CO2H, whilst with methyl glycocoll (sarcosine) it forms creatine, NH2•(NH): C•N(CH3)•CH2•CO2H . Many derivatives of guanidine were obtained by J . Thiele (Ann., 1892, 270, p . I ; 1893, 273, p .

133; Ber., 1893, 26, pp . 2598, 2645) . By the action of nitric acid on guanidine in the presence of sulphuric acid, nitroguanidine, HN:C(NH2)•NH.NO2 (a substance possessing acid properties) is obtained; from which, by reduction with

zinc dust, amidoguanidine, HN:C(NH2)•NH•NH2, is formed . This amidoguanidine decomposes on hydrolysis with the formation of semicarbazide, NH2•CO•NH•NH2, which, in its turn, breaks down into carbon dioxide, ammonia and hydrazine . Amidoguanidine is a body of hydrazine type, for it reduces gold and silver salts and yields a benzylidine derivative . On oxidation with potassium permanganate, it gives azodicarbondiamidine nitrate, NH2• (HN) : C.N: N•C:(NH)•NH2.2HNO3, which,when reduced by sulphuretted hydrogen, is converted into the corresponding hydrazodicarbondiamidine, NH2•(HN):C•NH•NH•C:(NH)•NH2 . By the action of nitrous acid on a nitric acid solution of amidoguanidine, diazoguanidine nitrate, NH2•(HN):C•NH•N2•NO3, is obtained . This diazo compound is decomposed by caustic alkalis with the formation of cyanamide and hydrazoic acid, CH4N5•NO3=N3Hd-CN•NH2+ HNO3, whilst acetates and carbonates convert it into amidotetra- N—N . zotic acid, H2N•C II . Amidotetrazotic acid yields addition \NH—N compounds with amines, and by the further action of nitrous acid yields a very explosive derivative, diazotetrazol, CN6 . By fusing guanidine with urea, dicyandiamidineH2N•(HN):C•NH•CO•NH2,is formed .