P667: Synthesis of air-stable imidazolium hydrogen carbonates for use as precatalysts in an undergraduate laboratory

Author: Cheri A. Barta, University of Wisconsin-Madison, USA

Co-Author: Laura Ruiz Espelt, M. Fishman, Elizabeth K. Krantz, Angelica Hinchman, Jillian Stegink and Nick Hill, University of Wisconsin-Madison, USA

Date: 8/5/14

Time: 5:15 PM6:30 PM

Room: LIB

Related Symposium: S33

N-heterocyclic carbenes (NHC) are an important class of molecules largely due to their versatility in numerous catalysis applications. Unfortunately, NHC reactions are not often explored in undergraduate laboratories due to their limited stability in aerobic environments, the need for anhydrous reagents, and the use of prohibitively expensive laboratory equipment. Recently, a class of stable NHC hydrogen carbonate salts [NHC(H)][HCO3] that can be used as precatalysts for several different organocatalyzed reactions – such as a benzoin condensation and the ring-opening polymerization of D,L lactide – was reported. This discovery has allowed us to develop a new laboratory experiment for our advanced synthesis course. Utilizing standard undergraduate benchtop techniques, students will synthesize an air stable imidazolium hydrogen carbonate salt that, in solution, generates an NHC that catalyzes transesterification reactions. The synthesis of the precatalyst, its characterization, and its use in organocatalyzed reactions will be presented.