Atom efficiency and catalysis in organic synthesis

The key to waste minimization in fine chemicals manufacture is the widespre ad substitution of classical organic syntheses employing stoichiometric amo unts of inorganic reagents with cleaner, catalytic alternatives. The E fact ors (by waste per kg product) of chemical processes increase dramatically o n going downstream from bulk to fine chemicals and pharmaceuticals, mainly owing to the use of "stoichiometric" methods. The concept of atom efficienc y is a useful tool for rapid evaluation of the amount of waste generated by alternative processes. The general theme of atom-efficient, catalytic proc esses is illustrated with industrially relevant examples. These include cat alysis by solid acids and bases, catalytic reductions and oxidations, catal ytic C-C bond formation, asymmetric catalysis, biocatalysis, and catalysis in novel media (aqueous and fluorous biphasic systems, supercritical fluids , and ionic liquids).