| abstract |
Disclosed is an improved carbonylation process for the production of carboxylic acids, carboxylic acid esters, and/or carboxylic acid anhydrides wherein a carbonylation feedstock compound selected from one or more organic oxygenates such as alcohols, ethers, and esters is contacted with carbon monoxide in the presence of a carbonylation catalyst and one or more onium compounds. The carbonylation process differs from known carbonylation processes in that a halide compound, other than the onium salt, such as a hydrogen halide (typically, hydrogen iodide) and/or an alkyl halide (typically, methyl iodide), extraneous or exogenous to the carbonylation process is not fed or supplied to the process. The process can be improved by using a bidentate ligand comprising two functional groups selected from tertiary amines and tertiary phosphines, such as 2,2'-bipyridine and diphosphine derivatives. |