Process for the preparation of a carboxylic acid

A process for the preparation of a carboxylic acid of the formula III,

• wherein R1 is aryl, substituted aryl, naphthyl, substituted naphthyl or alkyl, R2, R3, R4 and R5 are independently hydrogen or alkyl, said process comprising the steps of:
• a) reacting formula I or formula II,
• wherein R1, R2, R3, R4 and R5 are as defined above and X is a halogen atom or a —OH group, in the presence of a protonic acid, and/or an alkali metal halide, with a water soluble palladium complex catalyst of formula IV
• wherein R6, R7 and R8 are substituents on the phosphine ligand and selected from the group consisting of alkyl, aryl, arylalkyl, and cycloaliphatic, wherein at least one of R6, R7 and R8 carries a sulfonic acid or sit thereof;
• Y is aryl, alkyl sulfonato, aryl, alkyl carboxylate, formato or a halide;
• is an anionic chelating ligand containing a N donor and O— group, degassed water with or without excess sulfonated phosphine, in a carbon monoxide atmosphere under biphasic conditions, at a temperature ranging between 30 to 130° C., for a period ranging between 0.3 to 24 hrs, at pressures ranging between 50 to 1500 psig;
• b) flushing the reaction vessel with inert gas at an ambient temperature;
• c) separating the aqueous catalyst phase and removing the organic solvent;
• and
• d) isolating the compound of formula III from the organic layer.