Production of nitriles via hydrocyanation of ethylenically unsaturated organic compounds

A process for the hydrocyanation of an ethylenically unsaturated organic compound into a corresponding nitrile, said ethylenically unsaturated organic compound comprising a diolefin, an ethylenically unsaturated aliphatic nitrile, a monoolefin, or a mixture thereof, comprising (a) reacting said ethylenically unsaturated organic compound with hydrogen cyanide in the presence of an aqueous solution containing a catalytically effective amount of a catalyst which comprises at least one nickel compound and at least one water-soluble phosphine, (b) thereafter separating the resulting organic phase from the aqueous phase, said separated aqueous phase comprising a solid phase formed during the hydrocyanation, and (c) thence treating said separated aqueous phase, or a solid phase removed therefrom, with hydrogen cyanide to partially dissolve said solid phase contained therein or removed therefrom.