Water as Solvent and Solvent-free Reactions
In the fi eld of chemistry and in close collaboration with the US Agency for Environmental Protection (“US EPA”), Paul Anastas and John Warner introduced the concept of “green chemistry” and promoted catalysis among 12 principles (Anastas and Warner 1998). One of the key principles of “Green Chemistry” is to limit the use of volatile organic solvents in industrial processes. Indeed, these solvents are often toxic, expensive and problems are inherent to their disposal and reprocessing. A major research effort has been devoted in recent years in developing new synthetic methods that are more environmentally friendly. Among the classical non-usual solvents, water seems to be the best choice because of its abundance and nontoxicity. Nevertheless, the development of solvent-free processes during reactions and/or purifi cation remains an idealistic solution.