CARBONYLATION PROCESS OF CONJUGATED DIENES IN THE PRESENCE OF A PALLADIUM CATALYST WITH RECYCLING OF SAID CATALYST

摘要

Esters of beta , gamma -unsaturated carboxylic acids are prepared by (i) carbonylating a conjugated diene with carbon monoxide in the presence of an alcohol, a halogenated hydracid and a palladium catalyst; (ii) distilling the carbonylation reaction product in the presence of an ammonium, phosphonium or arsonium quaternary onium chloride or bromide having a melting point below the temperature at which the carbonylation reaction is carried out, and at a temperature and pressure such that said reaction product separates into a gaseous phase and a homogeneous liquid phase; (iii) recovering said gaseous phase comprising the ester of the beta , gamma -unsaturated carboxylic acid corresponding to the reactant diene and alcohol, any unreacted diene and alcohol, and any volatile reaction products of low molecular weight; (iv) recovering said homogeneous liquid phase comprising a mixture of the quaternary onium chloride or bromide and the palladium catalyst, and any non-volatile reaction products of high molecular weight; and (v) recycling, advantageously after removing any reaction products of high molecular weight, the homogeneous liquid phase comprising said mixture of quaternary onium chloride or bromide and the palladium catalyst, into the carbonylation reaction medium.