Diamino disulphides having the general formula NC-R1-N(R3)-Sx-N(R4)-R2-CN i which R1 and R2 are methylene, alkylmethylene, polymethylene or alkylpolymethylene groups, R3 and R4 are aromatic, araliphatic, aliphatic or cycloaliphatic groups, and x is 1, 2, 3 or 4 are used as vulcanization agents for synthetic rubbers such as butadiene-1:3-styrene or -acrylonitrile copolymers. Exemplary of R1 and R2 are methylene, methyl-methylene, dimethylene, methyl-dimethylene, trimethylene and tetramethylene groups. Exemplary of R3 and R4 are methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, amyl, isoamyl, ter. amyl, hexyl, octyl, decyl, dodecyl, pentadecyl, cyclohexyl, methyl cyclohexyl, cyclohexyl substituted-cyclohexyl, benzyl hexahydrobenzyl, b -phenethyl, phenyl, chlorophenyl, chlorobenzyl, methoxyphenyl, ethoxy phenyl and tolyl groups. Sulphur-containing accelerators of the thiazole type may also be added.ALSO:The invention comprises compounds of the general formula NC-R1-N(R3)-Sx-N(R4)-R2-CN where R1 and R2 are methylene, alkylmethylene, polymethylene or alkylpolymethylene groups, R3 and R4 are aromatic, aralphatic, aliphatic or cycloaliphatic groups and x is 1, 2, 3 or 4. They are prepared by condensing a sulphur halide with an amine of the general formula NC-R1-NHR3. R1 and R2 may be methylene, methyl methylene, ethylene, methyl ethylene, propylene or butylene groups. R3 and R4 may be methyl, ethyl, propyl, isopropyl, n-butyl, sec.-butyl, amyl, isoamyl, ter.-amyl, hexyl, octyl, decyl, dodecyl, pentadecyl, cyclohexyl, methyl cyclohexyl, cyclohexyl-cyclohexyl, benzyl, hexahydrobenzyl, b -phenethyl, phenyl, chlorophenyl, methoxy-phenyl, ethoxyphenyl or tolyl radicals, many amines containing such groups being specified. The sulphides obtained may be converted to higher polysulphides by heating with sulphur or sulphur halides. In examples: (1) four molecular proportions of N-b -cyanoethyl-N-cyclohexylamine are reacted together with one molecular proportion of sulphur monochloride to give N,N1 - di - b - (cyanoethyl) - N,N1 - dicyclohexyldiamino disulphide. Heating one mol. of this product with sulphur yields higher sulphides, e.g. the corresponding tetrasulphide; (2) N,N1 - di - (b - cyanoethyl) - N,N1 - di - (n - butyl) diamino disulphide is obtained by reacting together 4 mols. of N-b -cyanoethyl-N-n-butyl amine with 1 mol. of sulphur monochloride; N : N1 - di - (b - cyanoethyl) - N,N1 - di - (n - butyl) diamino monosulphide (NC-CH2CH2-N(C4H9) -S-N(C4H9) -CH2CH2-CN) is obtained similarly using sulphur dichloride in place of sulphur monochloride; (3) N,N1 - di - (b - cyanoethyl) - N,N1 - diethyl diamino disulphide containing some higher sulphides is obtained by reacting together N-b -cyanoethyl N-ethylamine (1.5 mols.) and sulphur monochloride (0.54 mols.). N,N1-Di-(a - cyanobutyl) - N,N1 - diphenyl diamino trisulphide and N,N1-dicyanomethyl-N,N1-dicyclohexyldiamino trisulphide are also mentioned. The products are of use as vulcanization accelerators (see Groups IV (a) and V) and as insecticides and fungicides.ALSO:Diamino sulphides having the general formula NC-R1-N(R3)-Sx-N(R4)-R2-CN in p which R1 and R2 are methylene, alkylmethylene, polymethylene, or alkylpolymethylene groups, R3 and R4 are aromatic, araliphatic, aliphatic or cycloaliphatic groups, and x is 1, 2, 3 or 4 are used as vulcanization agents for natural and synthetic rubber. Exemplary of R1 and R2 are methylene, methylmethylene, dimethylene, methyl-dimethylene, trimethylene and tetramethylene groups. Exemplary of R3 and R4 are methyl, ethyl, propyl, isopropyl, n-butyl, sec. butyl, amyl, isoamyl, ter-amyl, hexyl, octyl, decyl, dodecyl, pentadecyl, cyclohexyl, methylcyclohexyl, cyclohexyl substituted-cyclohexyl, benzyl, hexahydrobenzyl, b -phenethyl, phenyl, chlorophenyl chlorobenzyl, methoxy-phenyl, ethoxy-phenyl and tolyl groups. Sulphur-containing accelerators of the thiazole type may be employed. An example describes the vulcanization of a natural rubber stock comprising smoked sheet rubber, zinc oxide, stearic acid and N-cyclohexyl 2-benzothiazole sulphenamide with N, N1-di(b -cyanoethyl) N, N1-diethyl diamino disulphide, or with N, N1-di(b -cyanoethyl)-N, N1-di(n-butyl) diamino disulphide as vulcanization agent. Another example describes the vulcanization of stocks comprising smoked sheets rubber, furnace carbon black, zinc oxide, mineral hydrocarbon softener, stearic acid, p-amino diphenyl-acetone reaction product, N-cyclohexyl 2-benzothiazole sulphenamide, with various amounts of N, N1-di(b -cyanoethyl)-N, N1-dicyclohexylamino disulphide as vulcanization agent, and also (for comparision purposes) with sulphur. Comparison of non-scorching properties is made between the vulcanized products of stocks of the above type using N, N1-di(b -cyanoethyl))-N, N1-di(n-butyl) diamino disulphide and sulphur, respectively, as vulcanization agents, a mixture of 2, 4-dinitrophenyl-thiobenzthiazole and diphenyl guanidine phthalate being employed as vulcanization accelerator in place of the sulphenamide. Examples of the preparation of the above-mentioned vulcanization agents and of N, N1-di(b -cyanoethyl)-N, N1-dicyclohexyldiamino tetrasulphide, and N, N1-di-(b -cyanoethyl)-N, N1-di(n-butyl) diamino monosulphide (see Group IV (b)). The application of the agents to the vulcanization of synthetic rubbers is also described (see Group IV (a)).