Patent ID: 7820849

Claim:
A process for the production of alkylpentenoate by carbonylation of 1,3-butadiene comprising reacting 1,3-butadiene with carbon monoxide and a hydroxyl group-containing compound in the presence of a palladium catalyst system in a reaction zone to produce a reaction mixture with a selectivity to alkylpentenoate reaction product of 87% and higher, said catalyst system comprising: (a) a source of palladium cations, (b) a phosphine process ligand which is at least one selected from the group consisting of 2,3-bis(9-phosphabicyclononyl)butane, 1,2-bis(9-phosphabicyclononyl)ethane, 1,2-bis (9-phosphabicyclononyl) propane, 1,2-bis (carboxymethyl)-1,2-bis(9-phosphabicyclononyl) ethane, 1,2-bis(hydroxymethylene)-1,2-bis(9-phosphabicyclononyl)ethane, 1,2-bis (methoxymethylene)-1,2-bis(9-phosphabicyclononyl)ethane, 1,2-bis(9-phosphabicyclononyl) cyclohexane, 1,2-bis(9-phosphabicyclononyl)benzene, 1,2- bis (9-phosphabicyclononyl)cyclopentane, 3,4-bis (9-phosphabicyclononyl)hexane, 2-bis (dicyclohexylphosphino)-3-(9-phosphabicyclononyl)butane, 1,2-dicyclohexyl-1,2-bis (9-phosphabicyclononyl)ethane and 1-cyclohexyl-1,2-bis(9-phosphabicyclononyl)ethane, and (c) a source of anions containing a carboxylic acid, wherein the process further comprises, feeding the process ligand (b) continuously or periodically into the process as ligand make-up at a temperature of 50° C. or lower, and feeding a second phosphine ligand different from the process ligand (b) continuously or periodically to the process as ligand make-up, wherein said second phosphine ligand contains at least one phosphorous atom which is connected to two aryl groups and is chosen such that a phosphonium salt of the second phosphine ligand is reversible under carbonylation conditions.