Synthesis of Adipic Aldehyde by <i>n</i>‑Selective Hydroformylation of 4‑Pentenal

Several phosphine and phosphite ligands were tested in the hydroformylation of 4-pentenal to adipic aldehyde, a versatile starting material for industrially very relevant compounds. By varying the ligand structure we were able to increase the selectivity toward adipic aldehyde to >95%. Additionally, two molecular structures of important catalytic intermediates [(bisphosphite)­RhH­(CO)<sub>2</sub>] and one structure of a previously unknown catalyst decomposition product were obtained.