Liquid Poly(ethylene glycol) and Supercritical Carbon Dioxide:  A Benign Biphasic Solvent System for Use and Recycling of Homogeneous Catalysts

Abstract

Poly(ethylene glycol) (PEG), having a molecular weight of 900 or 1500, is a solid at room temperature but a nonvolatile liquid at 40 degrees C under CO2 pressure. Homogeneously catalyzed hydrogenation can be performed in the molten PEG, followed by extraction of the product by supercritical CO2. The catalyst-containing PEG phase which remains in the vessel can be reused for hydrogenation without addition of further catalyst or PEG.