Patent ID: 7348454

Claim:
A process for the hydrocarboxylation of an ethylenically unsaturated carboxylic acid by reacting it with carbon monoxide and a co-reactant selected from the group consisting of water and carboxylic acids in the presence of a catalyst system which consists of: (a) a source of palladium; (b) a bidentate diphosphine of formula I, R 1 R 2 >P—R 3 —R—R 4 —P<R 5 R 6 (I) wherein P represents a phosphorus atom; R 1 , R 2 , R 5 and R 6 independently represent the same or different optionally substituted organic groups containing a tertiary carbon atom through which the group is linked to the phosphorus atom; R 3 and R 4 independently represent optionally substituted alkylene groups and R represents an optionally substituted aromatic group; and (c) a source of anions derived from an acid having a pKa of above 3.