Patent ID: 7781621

Claim:
In a method for hydroformylating in the liquid phase olefinically unsaturated compounds, comprising conducting continuously: a hydroformylating reaction stage carried out in the presence of at least one non-aqueous ionic liquid comprising at least one salt of general formula Q + A − , wherein Q + represents a cation and A − represents an anion, and of a catalyst comprising at least one cobalt complex with at least one ligand L selected from among the Lewis bases, a depressurization stage, a decantation stage, and a recycling stage wherein the polar phase, which contains at least the ionic liquid and the catalyst, separated from the mixture of products and from the organic solvent in the decantation stage, is sent back to the reaction stage, the improvement comprising adding said ligand L, optionally in admixture with an organic solvent, in a post-reaction stage, to maintain a molar ratio L/Co in said post-reaction stage of above 2, wherein at least a partial addition of ligand L is continuously conducted downstream of the reaction stage and upstream of the decantation stage.