Bulky monophosphite ligands for ethene hydroformylation

A wide range of monophosphite ligands was investigated in rhodium-catalyzed ethene hydroformylation. A stoichiometric gas mixture CO/H2/ethene 1:1:1 was used, the reaction being thus 100% atom economic. The reaction was found to be very selective and only propanal was formed under the reaction conditions studied. The most efficient catalytic system was L1-modified rhodium, and reaction parameters were optimized for this ligand. Under optimized catalytic conditions, reaction rates 10–15 times higher than those of the triphenylphosphine-modified system were obtained, demonstrating the high suitability of π-accepting ligands for this reaction. Stability tests, resistance toward water and acids in particular, showed the good stability of the selected phosphite L1. Notably, L1 was more stable than cyclic phosphites L6 and L13.

The rhodium-catalyzed hydroformylation of ethene was studied using a library of 25 bulky phosphite ligands. Taking in account activity, selectivity, stability and cost, ligand L1 was found the most suitable ligand for potential industrial applications.Figure optionsDownload high-quality image (36 K)Download as PowerPoint slideHighlights
► The influence of bulky phosphite ligands on rhodium-catalyzed ethene hydroformylation was studied.
► Mixture CO/H2/ethene 1:1:1 were used to ensure 100% atom economy.
► Very fast and selective reactions were obtained.
► Best performing ligand was chosen according to activity, selectivity, stability and cost.
► Cheap and available ligand L1 showed high activity, excellent selectivity, surprisingly good stability.