Chemical elements
    Amorphous Sulphur
    Colloidal Sulphur
    Physical Properties
    Chemical Properties
      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
      Sulphur Trioxide
      Pyrosulphuric Acid
      Sulphuric Acid
      Persulphuric Anhydride
      Persulphuric Acid or Perdisulphuric Acid
      Permonosulphuric Acid
      Amidopermonosulphuric Acid
      Thiosulphuric Acid
      Polythionic Acids
      Dithionic Acid
      Trithionic Acid
      Tetrathionic Acid
      Pentathionic Acid
      Wackenroders Solution
      Hexathionic Acid
      Polythionic Acids
      Sulphur Sesquioxide
      Hydrosulphurous Acid
      Nitrogen Sulphide
      Nitrogen Persulphide
      Nitrogen Pentasulphide
      Nitrogen Chlorosulphide
      Trithiazyl Chloride
      Thiotrithiazyl Chloride
      Dithiotetrathiazyl Chloride
      Nitrogen Bromosulphide
      Thiotrithiazyl Bromide
      Thiotrithiazyl Iodide
      Thiotrithiazyl Nitrate
      Thiotrithiazyl Hydrogen Sulphate
      Thiotrithiazyl Thiocyanate
      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
      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
      Azidodithiocarbonic Acid
      Cyanogen Monosulphide
      Cyanogen Trisulphide
      Sulphur Thiocyanate
      Disulphur Dithiocyanate
      Thiocyanic Acid
      Dithiocyanic Acid
      Trithiocyanuric Acid
      Perthiocyanic Acid

Nitrosulphonic Anhydride, S2O5(NO2)2

Nitrosulphonic anhydride, or nitrous-pyrosulphuric anhydride (the choice of name depending on the view entertained as to the structure of the NO2-group), is formed during the decomposition of nitrosulphonic acid by heat, but it may more conveniently be obtained by the action of dry nitric oxide on sulphur trioxide:

2NO + 3SO3 = NO2.SO2.O.SO2.NO2 + SO2.

It is also formed by the action of nitrogen peroxide on liquid sulphur dioxide under pressure:

2N2O4 + 2SO2 = S2O5(NO2)2 + N2O3.

With both react ants in the liquid state the reaction proceeds according to the equation:

1.5N2O4 + 2SO2 = S2O5(NO2)2 + NO.

The pressure increases slowly at first but after a time a considerable increase suddenly occurs. The anhydride is also formed when the two gases react, only very slowly at ordinary temperatures, but more rapidly at higher temperatures. The reaction is never complete but goes somewhat further in the presence of platinised asbestos. The anhydride may also be prepared by the action of liquid nitrogen tetroxide on pyrosulphuric acid or pyrosulphuryl chloride.

Nitrosulphonic anhydride is a white, crystalline solid, of density 2.14. On heating it undergoes partial decomposition; it begins to melt at 217° C. to a yellow liquid and distils at about 360° C. The heat of formation, calculated from the heat of dissolution in potassium hydroxide, is 112 Calories:

2SO2 liq. + l.5N2O4 liq. = S2N2O9 solid + NO .gas + 112 Calories.

As would be expected from a substance of this nature, water causes rapid decomposition into sulphuric acid and the decomposition products of nitrous acid, whilst sulphuric acid dissolves the substance with formation of nitrosulphonic acid, which crystallises on cooling. With sulphur trioxide the anhydride yields a stable complex of composition 2(S2N2O9).SO3. Gaseous ammonia causes the anhydride to melt and decompose slowly with formation of nitrogen and ammonium hydrogen sulphate:

(NO2)2S2O5 + 4NH3 = 2NH4HSO4 + H2O + 2N2.

The modes of preparation, particularly from pyrosulphuric acid and pyrosulphuryl chloride, and the general properties of nitrosulphonic anhydride, suggest the structure O.NO.SO2.O.SO2.O.NO.

© Copyright 2008-2012 by