Carbon Subsulphide, C₃S₂

By passing the vapour of carbon disulphide over an electric arc with carbon poles, Lengyel obtained a deep red, tear-exciting liquid which appeared to be C₃S₂. When heated under reduced pressure this liquid partly distilled, and was partly converted into a black, solid polymer. With bromine it formed C₃S₂Br₆, a yellow solid with an aromatic smell.

Carbon subsulphide has more recently been obtained by Stock and Praetorius, who found that the best way to prepare it was to strike an arc between a carbon cathode and an anode consisting of antimony containing 7 per cent, of carbon placed beneath the surface of liquid carbon disulphide. The subsulphide dissolves in the disulphide as it is formed, producing a red solution, and when separated and distilled in a vacuum and condensed in a receiver at -40° C. forms a yellowish-red solid whose melting-point is -0.5° C. At ordinary temperature it is a bright red, strongly refractive liquid; it has a vapour density and a molecular weight in carbon disulphide solution corresponding to the formula C₃S₂, and polymerises at 90° C. With aniline it forms thiomalonanilide; it therefore bears the same relation to thiomalonic acid that carbon suboxide bears to malonic acid; consequently the constitutional formula S:C:C:C:S is attributed to this compound.