Improvements in or relating to the preparation of poly-thiuram disulphides

Polythiuram disulphides are prepared by treating a polar solvent solution of a polydithio carbamic acid derived from a primary or secondary polyamine, with an oxidising agent, the pH of the reaction mixture being maintained in the range of 6 - 7 throughout the reaction (see also Group IV(b)). The polydithio carbamic acids may be derived from polyamines by interaction with CS2 in aqueous or alcoholic ammonia solution ; specified polyamines include ethylene diamine, 1-methyl and 1:2-dimethyl ethylene diamines and polyethylene polyamines. The oxidising agent may be chlorine, bromine, iodine, a hypochlorite, a hypobromite, air, oxygen, H2O2 or nitrous acid obtained from a nitrite and acid. Suitably, acid is added to a solution of a polydithio carbamate to adjust the pH to 6-7, then the oxidising agent is added gradually together with acid as required to maintain this pH. The acid may be a mineral acid or a weak acid, e.g. acetic or boric acid. The polar solvent may be water, an alcohol or an ether. Reaction is suitably effected at up to 50 DEG C.ALSO:Poly thiuram disulphides are prepared by treating a polar solvent solution of a poly-dithio carbamic acid derived from a primary or secondary polyamine with an oxidising agent, the pH of the reaction mixture being maintained in the range of 6-7 throughout the oxidation. The oxidising agent may be chlorine, bromine, iodine, a hypochlorite, a hypobromite, nitrous acid prepared from a nitrite and acid, hydrogen peroxide, air or oxygen. Suitably, acid is added to a solution of a poly-dithio carbamic to adjust the pH to the required value and then the oxidising agent is added gradually, the pH being maintained in the stated range by addition of acid as necessary. The acid may be a mineral acid or a weak acid such as formic, acetic, propionic, butyric or boric acid. The polar solvent may be water or an organic solvent, e.g., an alcohol or an ether. Reaction may be effected at up to 50 DEG C. The poly dithiocarbamic acids may be alkylene bis acids containing 2-10 carbons in the alkylene chain, e.g. ethylene, 1-methyl ethylene and 1 : 2-dimethyl ethylene bis dithio carbamic acids Poly-dithiocarbamic acids derived from poly ethylene polyamines may be used. The preferred dithiocarbamic acids are prepared by reacting the polyamine with CS2 in an aqueous or alcoholic ammonium hydroxide solution. In an Example, ethylene diamine is reacted with CS2 in aqueous ammonia, sulphuric acid is added to adjust the pH to 6,5 and H2O2 is