Solvent effects in hydroformylation of long-chain olefins

Abstract

Abstract With the increasing concern about climate change, a transformation of chemical processes from petrochemicals towards renewable, sustainable feedstock is indispensable. This transition, however, requires a careful assessment of the transferability of kinetic and thermodynamic data and reaction mechanisms. Here, the rhodium-catalyzed hydroformylation reaction of a long chain olefin (1-decene) from renewable resources with synthesis gas (CO/H2) is investigated. The bidentate phosphite ligand (BiPhePhos) shows a high degree of selectivity towards the desired n-aldehyde. This selectivity can be rationalized by kinetic discrimination at the branching point, i.e. the transition state of the hydride insertion step. Formation of the iso-aldehyde is kinetically and thermodynamically discriminated. The complex multi-step reactions of the desired hydroformylation reaction pathway with respect to the side-reactions such as olefin isomerization and hydrogenation are elucidated in detail. The solvent effects of a mixed polar/non-polar thermomorphic solvent system (DMF/dodecane) on chemical equilibria and activation energies were investigated using the COSMO-RS solvent model. Solvent screening for the overall rate-determining step gives a perspective as to solvent control of the process.