Procédé pour la préparation d'acides dicarboxyliques et de leurs dérivés

1 : 8-Dicyano-2 : 6-octadiene or a mixture of 1 : 8-dicyano-2 : 6-octadiene and 2-vinyl-1 : 6: dicyano-4-hexene is obtained by heating a solution of 1-chloro-4-cyano-2-butene in an inert solvent (e.g. an aliphatic alcohol or nitrile) in the presence of iron powder. The presence of the 2-vinyl-1 : 6-dicyano-4-hexene product may be avoided by using an iron powder produced by reduction of an iron oxide or hydroxide or an iron powder to which has been added a nickel salt. The 1 : 8-dicyano-2 : 6-octadiene and the 2-vinyl-1 : 6-dicyano-4-hexene may be hydrogenated to sebacic nitrile, and ethylsuberic nitrile respectively and the latter compounds may be hydrolysed (e.g. with concentrated hydrochloric acid) to give sebacic acid and ethylsuberic acid respectively. The 1 : 8-dicyano-2 : 6-octadiene may alternatively be hydrogenated to give decamethylene diamine, or hydrolysed to give octa-2 : 6-diene-1 : 8-dicarboxylic acid, which is preferably converted to the alkali metal or ammonium salt prior to subsequent hydrogenation to the corresponding sebacic acid salt.