Process for the hydrocyanation of unsaturated compounds

A process for the hydrocyanation of unsaturated compounds, the process comprising:

• (a) hydrocyanating an unsaturated compound using at least one stage of hydrocyanation, wherein the hydrocyanation is performed in the presence of a catalytic system comprising an organometallic complex formed by one or more organophosphorus ligands of monodentate organophosphite and one or more bidentate organophosphorus ligands, and optionally a Lewis acid promoter, wherein a reaction medium comprising a reactant and a compound formed by the reaction is formed and
• (b) separating a reactant or a compound formed by the hydrocyanation reaction from the reaction medium using at least one stage of separation by distillation of a reactant used in the process or of a compound formed by the reaction from a medium comprising said catalytic system, wherein the reaction medium subjected to the stage of separation by distillation comprises a ratio of the number of moles of organophosphorus ligands, expressed as phosphorus atoms, with respect to the number of metal element atoms of less than or equal to 15 and/or a concentration by weight of metal element forming the organometallic complex of less than or equal to 1.3%, and the distillation bottom temperature of the distillation stage being less than or equal to 180° C.
• wherein the one or more organorhosphorus ligands of monodentate organophosphite is triphenyl phosphite, tritolyl phosphite or tricymenyl phosphite,
• wherein the unsaturated compound is butadiene and/or an unsaturated nitrile compound, and
• wherein the bidentate organophosphorus ligand is one of the compounds with the following structures, wherein Ph means phenyl: