Patent ID: 8173847

Claim:
An improved process for preparing aldehydes in a homogeneous organic phase in the presence of at least one rhodium compound and in the absence of complex-forming organophosphorus compounds in this reaction zone by: a. introduction of an organic solution containing at least one rhodium compound in dissolved form into a reaction zone; and b. reaction of olefinically unsaturated compounds with carbon monoxide and hydrogen, wherein the improvement comprises: addition of at least one organic acid in a total amount, calculated as acid equivalent, of from greater than 3 mol to 3000 mol per mole of rhodium to the rhodium-containing organic solution and subsequent feeding of this solution to the reaction zone, said organic acid being selected from among: saturated aliphatic monocarboxylic acids having from 5 to 13 carbon atoms in the molecule; saturated aliphatic dicarboxylic acids having from 5 to 13 carbon atoms in the molecule; sulphonic acids having from 1 to 12 carbon atoms in the molecule; and combinations thereof.