Chemical elements
  Carbon
    Isotopes
    Energy
    Production
    Application
    Physical Properties
    Chemical Properties
      Methane
      Ethylene
      Acetylene
      Coal-Gas
      Carbon Tetrafluoride
      Tetrafluoromethane
      Carbon Tetrachloride
      Tetrachloromethane
      Carbon Tetrabromide
      Tetrabromomethane
      Carbon Tetraiodide
      Tetraiodomethane
      Carbon Oxychloride
      Carbonyl Chloride
      Phosgene
      Carbon Oxybromide
      Carbonyl Bromide
      Carbon Suboxide
      Carbon Monoxide
      Carbon Dioxide
      Percarbonic Acid
      Carbamic Acid
      Carbamide
      Urea
      Carbon Disulphide
      Carbonyl Sulphide
      Carbon Oxysulphide
      Thiocarbonyl Chloride
      Thiocarbonic Acid
      Thiocarbamic acid
      Thiourea
      Thiocarbamide
      Perthiocarbonates
      Carbon Monosulphide
      Carbon Subsulphide
      Carbon Sulphidoselenide
      Carbon Sulphidotelluride
      Carbon Nitrides
      Cyanogen
      Dicyanogen
      Hydrocyanic Acid
      Prussic Acid
      Cyanogen Chloride
      Chlorocyanogen
      Cyanogen Bromide
      Bromocyanogen
      Cyanogen Iodide
      Iodocyanogen
      Polymerised Cyanogen Halides
      Cyanamide
      Cyanic Acid
      Cyanuric Acid
      Cyamelide
      Fulminic Acid
      Thiocyanic Acid
      Sulphocyanic Acid
      Isoperthiocyanic Acid
      Cyanogen Sulphide
      Thiocyanic Anhydride
    Diamonds
    Graphite
    Amorphous Carbon
    Coal

Carbon Tetrachloride, CCl4





Preparation of Carbon Tetrachloride

Carbon tetrachloride, CCl4, is the final chlorination product of methane, but it is generally prepared by the action of chlorine on carbon disulphide through the catalytic agency of a chlorine-carrier. Thus Hofmann dissolved antimony trichloride in carbon disulphide, and passed dry chlorine through the solution. The trichloride became pentachloride, which then reacted with the carbon disulphide, thus:

CS2 + 2SbCl5 = CCl4 + 2SbCl3 + 2S.

Other catalysts which may be employed are chloride of bromine, chloride of iodine, phosphorus pentachloride, molybdenum pentachloride, and aluminium chloride.

Carbon tetrachloride is also prepared in several ways by the action of chlorine on carbon in the electric furnace.


Physical Properties of Carbon Tetrachloride

Carbon tetrachloride is a colourless liquid which smells like chloroform; it does not mix with water, though it appears to form an unstable hydrate; it dissolves in many organic liquids, and is itself a useful solvent. The properties of mixtures of ethyl alcohol, carbon tetrachloride, and water have been examined by T. H. Hill. Its density at 0° C. is 1.5947, and at 32.5° C. is 1.56834; its boiling-point is 76.65° C. at 760 mm. pressure. The critical temperature is 282.1° C., and the critical pressure 57.57 atm. The specific heat of liquid carbon tetrachloride rises from 0.2010 at 0° C. to 0.2031 at 70° C.; that of the vapour falls from 0.140 at 0° C. to 0.115 at 70° C. Solid carbon tetrachloride is trimorphous, the melting-points of the three modifications being -28.6° C., -23.77° C., -21.2° C. The depression constant, when camphor or ethyl benzoate is used as solute, is found to be 47 or 48.

Chemical Properties of Carbon Tetrachloride

When the vapour of carbon tetrachloride is passed through a red-hot tube chlorine is split off and the compounds C2Cl4 and C2Cl6 result. From the latter compound, hexachlorethane, trichloracetic acid is formed by aqueous hydrolysis in the presence of sunlight, and this is reduced by nascent hydrogen to acetic acid. Since carbon tetrachloride can be obtained from its elements by way of carbon disulphide, this compound marks a stage in the synthesis of acetic acid.

Chemically, carbon tetrachloride is the chloride of the hypothetical orthocarbonic acid, C(OH)4, just as the analogous silicon compound is the chloride of orthosilicic acid, Si(OH)4. Although carbon tetrachloride, unlike the silicon halide and acid chlorides in general, is not attacked by water at atmospheric temperature, this halide is capable of some reactions which reveal its relation to carbonic acid. When heated with oxygen and water under pressure at 250° C. it yields phosgene gas, COCl2, and carbon dioxide, CO2, and a similar change is brought about by certain acidic oxides, e.g.:

2CCl4 + P2O5 = COCl2 + CO2 + 2POCl3
3CCl4 + 2P2O5 = 3CO2 + 4POCl3
CCl4 + 2SO3 = COCl2 + S2O5Cl2.

When heated with alcoholic potash carbon tetrachloride is completely hydrolysed, yielding carbonate and chloride, thus:

CCl4 + 6KOH = K2CO3 + 4KCl + 3H2O.

It reacts with acetylene, with liberation of finely divided carbon, thus:

CCl4 + 2C2H2 = 5C + 4HCl.

Its vapour readily chlorinates various oxides, and may on this account be used in mineral analysis.
© Copyright 2008-2012 by atomistry.com