Why is Carbon Dioxide Most Often the Media of Choice for SFR?
The properties which make supercritical carbon dioxide an attractive solvent for extraction also apply to its use as a medium for reaction chemistry. A fluids most important physical and transport properties that influence the kinetics of a chemical reaction are intermediate between those of a liquid and a gas in the supercritical carbon dioxide. The reactants and the supercritical carbon dioxide frequently form a single supercritical fluid phase. Supercritical fluids share many of the advantages of gas phase reactions including: miscibility with other gases, low viscosities, and high diffusivities, thereby providing enhances heat transfers and the potential for fast reactions. Supercritical fluids are especially attractive as reaction medium for diffusion-controlled reactions involving gaseous reagents such as hydrogen or oxygen.
The properties which make supercritical carbon dioxide an attractive solvent for extraction also apply to its use as a medium for reaction chemistry. A fluid’s most important physical and transport properties that influence the kinetics of a chemical reaction are intermediate between those of a liquid and a gas in the supercritical carbon dioxide. The reactants and the supercritical carbon dioxide frequently form a single supercritical fluid phase. Supercritical fluids share many of the advantages of gas phase reactions including: miscibility with other gases, low viscosities, and high diffusivities, thereby providing enhances heat transfers and the potential for fast reactions. Supercritical fluids are especially attractive as reaction medium for diffusion-controlled reactions involving gaseous reagents such as hydrogen or oxygen. An example of using supercritical fluids as a reaction medium is the hydrogenation of pharmaceuticals to promote enantio selective hydrogenation to favor a
