Process for preparing an unsaturated carboxylic acid salt

A catalytic process for preparing an α,β-ethylenically unsaturated carboxylic acid salt, the process comprising reacting an alkene and carbon dioxide in the presence of a carboxylation catalyst and releasing the α,β-ethylenically unsaturated carboxylic acid salt with a base,

• wherein:
• the carboxylation catalyst is a transition metal complex comprising a structurally constrained bidentate P,P ligand;
• the P atoms of the P,P ligand are separated by 2 to 4 bridging atoms;
• the bridging atoms are contained in at least one 5- to 7-membered cyclic substructures;
• the base is at least one selected from the group consisting of a hydride, an amide, an alkoxide and an aryloxide;
• the alkene has the following formula:
• and
• Ra, Rb and Rc are each independently hydrogen, C1-12-alkyl, C2-12-alkenyl, or Ra and Rb together with the carbon atoms to which they are bonded are a mono- or diethylenically unsaturated, 5- to 8-membered carbocycle.