A process for the production of ibuprofen.

The invention relates to a method of preparing ibuprofen by carbonylating * (IBPE) with carbon monoxide in an acidic, aqueous medium, the carbonylation reaction being at a temperature of at least about 10C and a carbon monoxide pressure of at least about 500 psig and in the presence of (1) a catalyst complex, consisting essentially of a palladium compound, (2) dissociated hydrogen ions of an acid which is substantially completely ionizable in dilute aqueous solution, and (3) dissociated halogen ions such that the molar ratio of halogen ions added to the reaction zone is at least about zero 15 is carried out. As the source of the hydrogen ions and the halogen ions, a hydrogen halide is advantageously used. The carbonylation is preferably combined with a process for the production of IBPE from isobutylbenzene. ibuprofen; carbonylation; carbon monoxide; Catalyst complex; Palladium compound; Hydrogen ions; Acid; Halogen ions; hydrogen halide; isobutylbenzene}