Homogeneous catalysts have many advantages, including high activity and selectivity, while they generally induce problems at the separation stage of a process, both in product purification and in catalyst recovery. Biphasic systems have provided a new approach to solve these problems. The biphasic catalysis systems using supercritical carbon dioxide (scCO₂) as the continuous phase and poly(ethylene glycol) (PEG) as the stationary catalyst phase are described herein for the chemical reactions. This biphasic system has the especial advantage that combines reaction and separation into only one integrated process easily, in other words, reaction and separation can be completed simultaneously. Recent progress in this field is re-viewed.

Key words: poly(ethylene glycol), biphasic system, supercritical carbon dioxide, homogeneous catalysis, phase behavior