Micellar Nanoreactors

As clearly described in the series of illustrative examples reported above, the use of micellar environments in catalysis is not just a soapy version of homogeneous catalysis.71 Micelles behave much more as nanoreactors characterized by unique features with all the extra advantages intrinsic in the use of water as solvent. Micellar catalysis has been demonstrated to be suitable to almost all classes of chemical transformations, in particular for a wide range of reactions promoted by metal complexes or organometallic species, also with impressive examples in asymmetric catalysis. The great advantage of using catalysts already developed for use in organic media without the need of ligand modifications to make the catalyst compatible with water, together with the self-assembling nature of surfactants, is the key factor for the success of micellar catalysis with metal species. The surfactant is not just a spectator as usually the solvent is believed to be, rather it directs the overall system. A critical balance between catalyst, substrate, and surfactant properties must be analyzed in detail in order to ensure high yield, selectivity, and recyclability. It can be predicted that, thanks to their generally low cost, surfactants will soon find some applications in large-scale synthetic methods suitable for industrial applications.