Chemical elements
    Physical Properties
    Chemical Properties
      Carbon Tetrafluoride
      Carbon Tetrachloride
      Carbon Tetrabromide
      Carbon Tetraiodide
      Carbon Oxychloride
      Carbonyl Chloride
      Carbon Oxybromide
      Carbonyl Bromide
      Carbon Suboxide
      Carbon Monoxide
      Carbon Dioxide
      Percarbonic Acid
      Carbamic Acid
      Carbon Disulphide
      Carbonyl Sulphide
      Carbon Oxysulphide
      Thiocarbonyl Chloride
      Thiocarbonic Acid
      Thiocarbamic acid
      Carbon Monosulphide
      Carbon Subsulphide
      Carbon Sulphidoselenide
      Carbon Sulphidotelluride
      Carbon Nitrides
      Hydrocyanic Acid
      Prussic Acid
      Cyanogen Chloride
      Cyanogen Bromide
      Cyanogen Iodide
      Polymerised Cyanogen Halides
      Cyanic Acid
      Cyanuric Acid
      Fulminic Acid
      Thiocyanic Acid
      Sulphocyanic Acid
      Isoperthiocyanic Acid
      Cyanogen Sulphide
      Thiocyanic Anhydride
    Amorphous Carbon

Cyanuric Acid, (CONH)3

Cyanuric Acid, (CONH)3, is produced by the condensation of cyanic acid vapour above 150° C.,by the action of ammonia on phosgene, COCl2, and by heating urea above its melting-point as long as ammonia is evolved (Wohler). The reaction

3CO(NH2)2 = (CONH)3 + 3NH3

depends upon the formation of ammonium cyanate, followed by the loss of ammonia and polymerisation of three molecules of cyanic acid thus set free. The use of anhydrous zinc chloride promotes the formation of cyanuric acid. Cyanuric acid is also produced by chlorinating or brominating urea, and hydrolysing the resulting cyanuric halide. The acid crystallises from concentrated sulphuric acid in anhydrous quadratoctahedra, and from water in dihydrated monoclinic prisms.

The formation of this acid from urea suggests that it possesses an imidic rather than a hydroxylic constitution, and this view is borne out by the character of its absorption spectrum. Cyanuric acid is therefore, probably, tricarbonimide:

Anhydrous cyanuric acid has a density of 1.768 at 0° C.; it does not melt, but sublimes above 150° C., producing cyanic acid vapour; at 350° C. it decomposes.

The heat of formation of cyanuric acid from liquid cyanic acid is 37,000 calories, and from its elements 166,400 calories; its heat of combustion is 220,000 calories. One hundred parts of water dissolve 0.125 parts of cyanuric acid at atmospheric temperature, and 4 parts at 100° C.; the acid is readily soluble in alcohol.

Cyanuric acid is a very weak tribasic acid whose aqueous solution does not affect indicators; its tri- and di-alkali salts are much hydrolysed by water, and are converted by carbon dioxide into the mono-salt.

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