Abstract: A process for the hydroformylation of olefinically unsaturated compounds whose hydroformylation products are insoluble or only sparingly soluble in water, comprising reacting the olefinically unsaturated compounds at 60.degree. to 180.degree. C. and 1 to 35 MPa with carbon monoxide and hydrogen in a homogeneous phase in a polar organic solvent and in the presence of a catalyst system comprising a rhodium carbonyl compound and a salt of a sulfonated or carboxylated organic monophosphine or polyphosphine, which salt is soluble both in the polar organic solvent and in water, distilling off the polar organic solvent from the reaction mixture and separating the catalyst system from the distillation residue by extraction with water.

Abstract: In the process for hydroformylation of 1,3-butadiene with carbon monoxide and hydrogen to form pentenals, the improvement comprising effecting the hydroformylation with 1,3-butadiene dissolved in an inert reaction medium at 100.degree. to 180.degree. C. at 5 to 35 MPa in the presence of an aqueous solution of a rhodium/phosphine complex and optionally a further phosphine as catalyst.

Abstract: 1,3-Butadiene is hydroformylated at 60.degree. to 150.degree. C. and 1 to 20 MPa in the presence of an aqueous solution which contains, as catalyst, at least one water-soluble rhodium compound and at least one water-soluble organic phosphine. A pH of 8 to 11 is maintained in the aqueous catalyst solution to increase the selectivity of the reaction with respect to the formation of n-five carbon aldehydes and their secondary products. The latter, in particular, can be hydrogenated to 2-propylheptanol, useful as the alcohol component of phthalic ester plasticizers.

Abstract: Preparation of phosphites which are stable to hydrolysis from organic phosphites or phosphorus-halogen compounds and an ammonium salt of a hydroxysulfonic acid which is insoluble in water and soluble in an organic solvent. The compounds are useful in making catalysts for the hydroformylation reaction.

Abstract: The preparation of aldehydes by hydroformylation of olefinically unsaturated compounds. The reaction is carried out in the presence of a catalyst system which contains rhodium and an ammonium salt of a sulfonated phosphorous acid triester which is soluble in organic media.