Efficient Synthesis of Benzaldehyde by Direct Carbonylation of Benzene in Ionic Liquids

The direct carbonylation of benzene to benzaldehyde, for the first time, was achieved in the presence of chloroaluminate ionic liquids, with relatively high yield (up to 91%) and selectivity (ca. 96%). Under this reaction conditions diphenylmethane was the only by-product. The reuse of the ionic liquids was also studied.