CHEMICAL-REACTIONS IN SUPERCRITICAL FLUID S

Most homogeneous catalysts have higher selectivity but lower rates tha n heterogeneous catalysts in gas-phase reactions. An ideal catalyst wo uld have the best of both worlds, high selectivity and high rates whic h may be possible with homogeneous catalysts in supercritical fluids r ather than liquid solvents. These fluids are compressed gases heated p ast their critical point. Preliminary results have confirmed that incr eased rates and selectivities can be obtained because of several unusu al properties of supercritical fluids: high solubility of reactant gas es, rapid diffusion between phases, and possibly weaker solvation of t he catalyst. This review will describe research on organic reactions a nd homogeneous catalysis in supercritical fluids, with emphasis on sup ercritical carbon dioxide and water as reaction media.