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

Sulphur Dichloride, SCl2

As explained already, the existence of Sulphur Dichloride, SCl2, has been the subject of much controversy, the view held by some chemists being that the liquid described by others as sulphur dichloride is in reality a mixture of the monochloride with the tetrachloride or with chlorine. A difficulty encountered in the characterisation of such a substance is that molecular weight determinations with the gaseous or dissolved substance do not distinguish between SCl2 molecules and a mixture of S2Cl2 and Cl2 molecules in equal numbers.

The freezing-point curves for mixtures of sulphur monochloride and chlorine containing up to 92 per cent, of total chlorine, as obtained by earlier workers, supplied no evidence of the existence of sulphur dichloride, the only maxima on the curve being found at -80° C. for a composition corresponding with sulphur monochloride, S2Cl2, and at -30.5° C. for the composition of sulphur tetrachloride, SCl4; some indication of a more highly chlorinated derivative such as SCl11 was observable, but there was no suggestion of the existence of SCl2. This result, of course, did not exclude the possibility of the existence of a compound SCl2, or its formation from sulphur monochloride and sulphur at higher temperatures.

Beckmann in 1906, however, by the artifice of employing liquid chlorine as an ebullioscopic solvent, found indication of the existence of SCI 2 molecules; with this solvent a mixture of S2Cl2 and Cl2 molecules will not produce the same effect as simple SCl2 molecules.

In 1927, Lowry succeeded in freezing out some sulphur dichloride from an over-chlorinated equilibrium mixture having its composition adjusted to that of SCl2 by addition of the monochloride. The product was recrystallised from light petroleum, and upon analysis yielded the empirical formula SCl2.

An equilibrium mixture of composition corresponding to SCl2 is most easily prepared by allowing a solution of sulphur monochloride in liquid chlorine to warm to the ordinary temperature; a modification of this process is to saturate the monochloride, cooled in a freezing mixture, with chlorine and subsequently remove excess of the latter gas by a stream of carbon dioxide. Powdered absorbent charcoal acts catalytically in facilitating the action. As prepared in this way, the mixture is a deep, reddish-brown liquid, of density 1.622 at 15° C. It boils at 59° C. under atmospheric pressure, and at -24° C. under 4 mm., but on account of the very considerable dissociation into monochloride and chlorine, the boiling-point is not constant. When cooled, it solidifies near -88° C. and remelts at -78° C.

Sulphur dichloride is decomposed by water, giving hydrochloric and thiosulphuric acids, the latter gradually yielding sulphurous acid and sulphur. This recalls the corresponding behaviour of the monochloride, and, probably on account of the considerable dissociation, even in the liquid condition, the chemical properties of the "dichloride" are generally similar to those of the monochloride.

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