Chemical elements
  Sulphur
    Isotopes
    Energy
    Extraction
    Refining
    Applications
    Allotropy
    Crystalline
    Amorphous Sulphur
    Colloidal Sulphur
    Physical Properties
    Chemical Properties
    Detection
    Estimation
    Compounds
      Hydrogen Sulphide
      Metal Polysulphides
      Hydrogen Polysulphides
      Hydrogen Pentasulphide
      Hydrogen Trisulphide
      Hydrogen Disulphide
      Sulphur Monofluoride
      Sulphur Tetrafluoride
      Sulphur Hexafluoride
      Sulphur Monochloride
      Sulphur Dichloride
      Sulphur Tetrachloride
      Sulphur Monobromide
      Thionyl Fluoride
      Sulphuryl Fluoride
      Fluorosulphonic Acid
      Thionyl Chloride
      Sulphuryl Chloride
      Sulphur Oxytetrachloride
      Pyrosulphuryl Chloride
      Chlorosulphonic Acid
      Thionyl Bromide
      Sodium Sulphoxylate
      Sulphur Dioxide
      Sulphurous Acid
      Sulphites
      Sulphur Trioxide
      Pyrosulphuric Acid
      Pyrosulphates
      Sulphuric Acid
      Persulphuric Anhydride
      Persulphuric Acid or Perdisulphuric Acid
      Perdisulphates
      Permonosulphuric Acid
      Amidopermonosulphuric Acid
      Thiosulphuric Acid
      Thiosulphates
      Polythionic Acids
      Dithionic Acid
      Trithionic Acid
      Trithionates
      Tetrathionic Acid
      Tetrathionates
      Pentathionic Acid
      Pentathionates
      Wackenroders Solution
      Hexathionic Acid
      Polythionic Acids
      Sulphur Sesquioxide
      Hydrosulphurous Acid
      Hydrosulphites
      Nitrogen Sulphide
      Nitrogen Persulphide
      Nitrogen Pentasulphide
      Sulphammonium
      Hexasulphamide
      Nitrogen Chlorosulphide
      Trithiazyl Chloride
      Thiotrithiazyl Chloride
      Dithiotetrathiazyl Chloride
      Nitrogen Bromosulphide
      Thiotrithiazyl Bromide
      Thiotrithiazyl Iodide
      Thiotrithiazyl Nitrate
      Thiotrithiazyl Hydrogen Sulphate
      Thiotrithiazyl Thiocyanate
      Thionylamide
      Sulphamide
      Imidodisulphamide
      Sulphimide
      Sulphonic Acids
      Amidosulphonic Acid
      Imidosulphonic Acid
      Nitrilosulphonic Acid
      Hydroxylamine-monosulphonic Acid
      Nitrososulphonic Acid
      Hydroxylamine-disulphonic Acid
      Hydroxylamine-isodisulphonic Acid
      Hydroxylamine-trisulphonic Acid
      Dihydroxylamidosulphonic Acid
      Sulphazinic Acid
      Sulphazotinic Acid
      Dehydrosulphazotinic Acid
      Nitrosulphonic Acid
      Nitrosulphonyl Chloride
      Nitrosulphonic Anhydride
      Nitrosulphuric Acid
      Nitrosodisulphonic Acid
      Sulphonitronic Acid
      Sulphates of Hydroxylamine
      Hydroxylamine Dithionate
      Hydrazine Dithionate
      Hydrazine Amidosulphonate
      Carbon Subsulphide
      Carbon Monosulphide
      Carbon Disulphide
      Thioformaldehyde
      Thiocarbonic Acid
      Ammonium thiocarbonate
      Thiolcarbonic Acid
      Xanthic Acid
      Perthiocarbonic Acid
      Sodium perthiocarbonate
      Carbonyl Sulphide
      Thiocarbonyl Chloride
      Thiocarbonyl Tetrachloride or
      Carbon Hexachlorosulphide
      Trichloromethyl Disulphide
      Thiocarbonyl Sulphochloride
      Carbon Bromosulphide
      Amino-derivatives of Thiocarbonic Acid
      Dithiocarbamic Acid
      Thiocarbamide
      Azidodithiocarbonic Acid
      Thiocyanogen
      Cyanogen Monosulphide
      Cyanogen Trisulphide
      Sulphur Thiocyanate
      Disulphur Dithiocyanate
      Thiocyanic Acid
      Thiocyanates
      Dithiocyanic Acid
      Trithiocyanuric Acid
      Perthiocyanic Acid
      Perthiocyanogen
      Sulphates

Thionyl Bromide, SOBr2






Thionyl Bromide, SOBr2, analogue of thionyl chloride is best prepared by the prolonged action of hydrogen bromide on thionyl chloride:

SOCl2 + 2HBr = SOBr2 + 2HCl.

Sodium bromide or aluminium bromide may be used instead of hydrogen bromide.

It is an orange-yellow liquid, density 2.697 at 15° C., b.pt. 45° C. at 22 mm., 68° C. at 40 mm., and 138° C. (with decomposition) at 773 mm. It decomposes slowly at the ordinary temperature, more rapidly on heating, yielding sulphur monobromide, sulphur dioxide and free bromine:

4SOBr2 = S2Br2 + 2SO2 + 3Br2.

It is readily hydrolysed by water. It reacts with organic acids to form acid bromides. Mercury decomposes the vapour with formation of sulphur dioxide.

The liquid appears to contain associated molecules, as the following data indicate: molecular weight, 234 to 246; surface tension, 43.71 dynes per cm. at 17° C.; Trouton coefficient, 25.2.

Besson, when preparing thionyl bromide by the action of boiling thionyl chloride on hydrogen bromide or aluminium bromide, claimed to have isolated the intermediate compound, thionyl chlorobromide, SOClBr, a more volatile liquid than thionyl bromide and therefore separated from it by distillation under reduced pressure. The product isolated was a yellow liquid, density 2.31 at 0° C., boiling with slight decomposition at 115° C. Mayes and Partington, however, could obtain no evidence of such an intermediate compound in the product from the bromination of thionyl chloride. The physical properties of the product were similar to those of a mixture of thionyl chloride and thionyl bromide. Moreover, the boiling-points of mixtures of the two compounds rise evenly from that of the chloride to that of the bromide, whilst the freezing-point curve of such mixtures is a smooth mixed crystal curve, giving no indication of the existence of any intermediate compound.

The remaining compounds of bromine and all those of iodine corresponding with thionyl and sulphuryl chlorides and chlorosulphonic acid are either unknown or their existence is very doubtful. There is no reaction between sulphur dioxide and bromine analogous to that by which sulphuryl chloride is formed from sulphur dioxide and chlorine; this is true between 100° and 200° C., both in the dark and under strong illumination, also in the presence of likely catalysts.


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