Chemical and Photochemical Reactivity in Microemulsions and Waterless Microemulsions

摘要

Relatively little attention has been paid to molecular aggregation phenomena in structured nonaqueous solvents compared to that devoted to such process in aqueous media. This paper is a review concerning our work with formamide in place of water. The following observations showed that formamide has sufficient cohesive force to favor molecular aggregation: 1) critical micellar concentrations (c.m.c.) were determined with various ionic and non-ionic surfactants; 2) the phase diagram of CTAB in formamide shows two mesomorphic phases closely resembling those found in aqueous systems; 3) X-ray scattering demonstrated the presence of molecular aggregates, and gave an indication of their structure, and 4) a variety of microemulsions were prepared in formamide. Such non-aqueous microemulsions represent valuable media for synthetic purposes. For example, Diels-Alder reactions, photoamidation of olefins, and the Wacker process can be carried out readily in such media. The observed discontinuities in reaction selectivity indicate the presence of structured phases. (AW)