Process for the carbonylation of pentenenitrile

Abstract

Processes to prepare 5-cyanovaleric acid or its ester are provided, by carbonylation of a pentenenitrile, wherein pentenenitrile is reacted with carbon monoxide and water and/or an alcohol in the presence of a catalyst system. The catalyst system contains: (a) a metal of Group VIII or a compound thereof and (b) a bidentate phosphine, arsine and/or stibine ligand, wherein the bidentate ligand has the general formula (I): R1R2-M1-R-M2-R3R4  (I) wherein M1 and M2 are independently P, As or Sb, R is a divalent organic bridging group, which bridging group comprises a chain of 3 to 5 atoms directly connecting the 2 phosphorus atoms, which chain consists of carbon atoms and optionally a nitrogen, oxygen or sulphur atom or a silano or dialkylsilicon group, which alkyl groups independently comprise from 1 to 4 carbon atoms, and R1–R4 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. ε-caprolactam is also prepared by reduction of 5-cyanovaleric acid or ester obtained above to 6-aminocaproic acid or ester, and then cyclisation of the 6-aminocaproic acid or ester to ε-caprolactam.

Dependencies are inferred from the claim text.