Patent ID: 6946574

Claim:
Process for the preparation of unsaturated or saturated carboxylic acids from compounds comprising an ethylenic or acetylenic unsaturation conjugated with an other unsaturation or an electron-donating group by hydroxycarbonylation reaction with carbon monoxide and water in the presence of a palladium-based catalyst in a reaction medium, which comprises (1) treating the reaction medium comprising said unsaturated or unsaturated carboxylic acids, byproducts, and water, after the end of the hydroxycarbonylation reaction, with a gas to extract carbon monoxide from the reaction medium to obtain a CO concentration in the reaction medium of less than 600 ml of CO per litre, (2) treating the reaction medium with hydrogen to reduce the palladium to the zero oxidation state, and (3) separating precipitated palladium from the reaction medium.