The carbonylation of olefins and alcohols affords acids whose carbon skeletons are one carbon atom longer than that of the substrates. Phosphine–palladium complexes with acidic promoters are the most popular catalysts of this reaction.1 Progress in carbonylation in the past decade is attributed to the use of two- phase systems where water2,3 or ionic liquids, including pyri- dinium, imidazolinium and tetraalkylammonium salts,4,5 serve as the polar phase. The ...
