5. Applications as reaction media

Due to their scalable properties, supercritical fluids are particularly attractive reaction media. In organic synthesis, CO ₂ is the most widely used solvent despite its limited solvent power with respect to polar substrates; light alkanes, mainly propane, and dimethyl ether are also employed; water and ammonia are reserved for special applications under extreme temperature and pressure conditions. Finally, the implementation of new polymerization routes using micelles or emulsions in a supercritical fluid (usually CO ₂ ) are also under study.