GB646966A - Manufacture of an organic dinitrile - Google Patents

Abstract

A process for the manufacture of 1 : 4-dicyano-2-butene comprises reacting hydrogen cyanide with a dihalo addition product of 1 : 3-butadiene or mixture of such products, wherein the halogen atoms are of atomic weight between 35 and 80 in the presence of a suspension comprising water, a copper salt catalyst and a carbonate of a metal of Group II of the Periodic Table in amount sufficient to neutralize the hydrogen halide formed, the hydrogen cyanide being introduced gradually during the reaction into the reaction mixture, said reaction being carried out at a pressure not substantially above atmospheric pressure and at a temperature between 60 DEG C. and the boiling point at atmospheric pressure of the aqueous phase. The hydrogen cyanide and the dihalo addition products of 1 : 3-butadiene may be introduced into the reaction mixture gradually during the reaction. 1 : 4-Dihalo-2-butene and 3 : 4-dihalo-1-butene or mixtures of the isomers, and the crude chlorination products obtained on chlorinating butadiene may be employed as starting materials. The hydrogen cyanide, which may be optionally diluted with water, is preferably added at a rate not substantially faster than its rate of reaction with the dihalo addition product or products. As catalysts may be employed cuprous chloride-alkali metal halide or cuprous chloride-ammonium chloride complexes, cuprous chloride, cuprous cyanide, metallic copper or cupric salts, the latter being converted to catalytic complexes under the reaction conditions. Enough water should be present to avoid excessive cooling by evaporation of the hydrogen cyanide. The reaction medium may contain organic solvents. In the following examples 1 : 4-dicyano-2-butene is produced when (1) 1 : 4-dichloro-2-butene mixed with hydrogen cyanide is run into a heated mixture of cuprous chloride, potassium chloride, copper powder and concentrated hydrochloric acid, to which has been added calcium carbonate, the mixture having been prepared under nitrogen; (2) (1) is repeated but the catalyst is not prepared under nitrogen; (3) 3 : 4-dichloro-1-butene is reacted in a similar process to that described under (1); (4) 3 : 4-dichloro-1-butene in hydrogen cyanide is added to a heated mixture of calcium carbonate, cupric sulphate and water. Similar results are obtained when copper sulphate is replaced by copper nitrate, copper acetate, cuprous chloride, cupric chloride, cupric fluoride or copper acetylacetonate. In addition hydrogen cyanide may be dissolved in water, bubbled in the gaseous form through the reaction mixture, both reactants may be added separately at different rates or the dihalobutene may be added first to the mixture of water, carbonate and catalyst. The presence of an inert atmosphere is not essential. Specifications 646,964 and 646,965 are referred to.