CAS: New Advances in Sustainable Catalysis

University Of California-Santa Barbara, Santa Barbara CA

Investigators

Abstract

With the support of the Chemical Catalysis program in the Division of Chemistry, Professor Bruce Lipshutz of the University of California at Santa Barbara is studying several approaches to the exclusive use of water as a reaction solvent, rather than the common, waste-generating organic solvents. The key technology enabling this switch to water, which Nature uses for chemical reactions, is based on the formation of nanoparticles (NPs) in the aqueous solutions. The NPs are designed to concentrate reagents and catalysts, thus enabling reactions to occur that would normally fail in water alone. Moreover, given the high concentrations of reactants and catalyst within each NP, high temperatures needed will no longer be required, reducing energetic cost of processes amenable to this system. These new advances are expected to contribute to the shift that organic chemistry, in general, must make to avoid its dependence on petroleum, from which derive many of the organic solvents typically used. To further assist with this transition to a more aqueous-based discipline, a Manual will be created containing experiments, all to be done in water at room temperature, for use in sophomore organic laboratories worldwide. The intention will be to introduce students at a very early stage to chemistry in water. Under this award from the Chemical Catalysis program in the Division of Chemistry, Professor Bruce Lipshutz of the University of California at Santa Barbara and his team will pursue three main research directions: (1) innovations in chemoenzymatic catalysis, where the compatibility problem that has prevented the advancement of this field involving both chemocatalytic and enzymatic processes to be used in water in a single reaction vessel has been streamlined and facilitated by adding small amounts of a surfactant in the buffered aqueous medium; (2) the in situ-formation of selected thio-esters that are then subject to reaction with in situ-generated organozinc reagents, thereby leading to a new route to unsymmetrical ketones, in one pot and in water; and (3) development of a new concept in organic chemistry based on the atypical situation that exists within nano-micellar arrays; that is, high concentrations and limited reactant and catalyst mobility as a means of enhancing enantioselectivities (ee’s), rather than the traditional use of organic solvents at low temperature. Should this discovery prove to be general; that ee’s can be maximized by utilization of aqueous micellar media, potentially reducing dependence upon costly cryogenic reaction conditions to achieve and maintain low temperatures, this will be both an important addition to catalysis and a major step forward in advancing chemistry in water. The PI and his group are engaged with the fine chemical industry, in particular the pharmaceutical industry, so as to bring these advances to practical application. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.