Patent ID: 7026473

Claim:
A process for preparing a 5-cyanovaleric acid or its ester comprising reacting pentenenitrile with carbon monoxide and water and/or an alcohol in the presence of a catalyst system, comprising (a) a source of Group VIII metal and (b) a bidentate phosphine, arsine and/or stibine ligand, wherein the bidentate ligand has the general formula (I): R 1 R 2 -M 1 -R-M 2 -R 3 R 4 (I) wherein M 1 and M 2 are independently P, As or Sb, R is a substituted or unsubstituted divalent organic aryl bridging group, which bridging group comprises a chain of 3 to 5 atoms directly connecting M 1 and M 2 , which chain consists of carbon atoms, and R 1 –R 4 represent the same or different optionally substituted tertiary alkyl groups, (c) an acid having a pKa less than 3, as measured at 18° C. in an aqueous solution.