CS2

CARBON BISULPHIDE  , a chemical product first discovered in 1796 by W . A . Lampadius, who obtained it by heating a mixture of charcoal and pyrites . It may be more conveniently prepared by passing the vapour of sulphur over red hot char-coal, the unccndensed gases so produced being led into a tower containing plates over which a vegetable oil is allowed to flow in order to absorb any carbon bisulphide vapour, and then into a second tower containing lime, which absorbs any sulphuretted hydrogen . The crude product is very impure and possesses an offensive smell; it may be purified by forcing a fine spray of lime water through the liquid until the escaping water is quite clear, the washed bisulphide being then mixed with a little colourless oil and distilled at a low temperature . For further methods of purification see J . Singer (Journ. of Soc . Chem . Ind., 1889, p . 93), Th . Sidot (Jahresb., 1869, p . 243), E .

Allary (

Bull. de la Soc . Chin., 1881, 35, p . 491), E . Obach (Jour. prak . Chem., 1882 (2), 26, p . 282) . When perfectly pure, carbon bisulphide is a colourless, some-what pleasant smelling, highly refractive liquid, of specific gravity 1.2661 (18°/4°) (J . W . Briihl) or 1.29215 (0°/4°) (T . E . Thorpe) . It boils at 46•o4° C .

(T . E . Thorpe, Journ . Chem . Soc., 188o, 37, p . 364) . Its

critical temperature is 277.7° C., and its critical pressure is 78.1 atmos . (J . Dewar, Chem . News, 1885, 51, p . 27) . It solidifies at about -116° C., and liquefies again at about -110° C .

(K . Olszewski, Jahresb., 1883, p . 75) . It is a mono-molecular liquid (W .

Ramsay and J . Shields, Jour . Chem . Soc., 1893, 63, p . 1089) . It is very volatile, the vapour being heavy and very inflammable . It burns with a pale blue flame to form carbon dioxide and sulphur dioxide . It is almost insoluble in water, but mixes in all proportions with absolute alcohol, ether, benzene and various oils .

It is a

good solvent for sulphur, phosphorus, wax, iodine, &c . It dissociates when heated to a sufficiently high temperature . A mixture of carbon bisulphide vapour and nitric oxide burns with a very intense blue-coloured flame, which is very rich in the violet or actinic rays . When. heated with water in a sealed tube to 15o° C. it yields carbon dioxide and sulphuretted hydrogen . Zinc and hydrochloric acid reduce it to tri-thioformaldehyde (CH2S)3 (A . Girard, Comptes rendus, 1856, 43, p . 396) . When passed through a red-hot tube with chlorine it yields carbon tetrachloride and sulphur chloride (H . Kolbe) . Potassium, when heated, burns in the vapour of carbon bisulphide, forming potassium sulphide and liberating carbon . In contact with chlorine monoxide it forms carbonyl chloride and thionyl'.chloride (P . Schiitzenberger, Ber., 1869, 2, p .

219) . When passed with carbon dioxide through a red-hot tube it yields carbon oxysulphide,

COS (C . Winkler), and when passed over sodamide it yields ammonium thiocyanate . A mixture of carbon bisulphide vapour and sulphuretted hydrogen, when passed over heated copper, gives, amongst other products, some methane . Carbon bisulphide slowly oxidizes on exposure to air, but by the action of potassium permanganate or chromic acid it is readily oxidized to carbon dioxide and sulphuric acid . By the action of aqueous alkalis, carbon bisulphide is converted into a mixture of an alkaline carbonate and an alkaline thiocarbonate (J . Berzelius, Pogg . Ann.,1825, 6, p . 444), 6KHO -+CS2 = K2CO3+2K2CS3+3H20 ; on the other hand, an alcoholic solution of a caustic alkali converts it into a xanthate (A . Vogel, Jahresb., 1853, p . 643), CS2+KHO+R•OH = H2O+RO•CS•SK . Aqueous and alcoholic solutions of ammonia convert carbon bisulphide into ammonium dithiocarbamate, which readily breaks down into ammonium thiocyanate and- sulphuretted hydrogen (A .

W .

Hofmann), CS2+2NH3-NH2•CSS•NH4- H2S+NH4CNS . Carbon bisulphide combines with primary amines to form alkyl dithiocarbamates, which when heated lose sulphuretted hydrogen and leave a residue of a dialkyl thio-urea, CS2+2R•NH2– R•NH•CSS•NH3R–)CS(NHR)2+H2S; or if the aqueous solution of the dithiocarbamate be boiled with mercuric chloride or silver nitrate solution, a mustard oil (q.v.) is formed, R•NH•CSS•NHiR+HgCIi-Hg(R•NH•CSS)i- 2RNCS+HgS+H2S . Carbon bisulphide is used as a solvent for caoutchouc, for extracting essential oils, as a germicide, and as an insecticide . Carbon monosulphide, CS, is formed when a silent electric discharge is passed through a mixture of carbon bisulphide vapour and hydrogen or carbon monoxide (S . M . Losanitsch and M . Z . Jovitschitsch, Ber., 1897, 30, P . 135) .