CHED 307 |
| Although N-heterocyclic carbenes (NHCs) have become viable organocatalysts for a variety of catalytic nucleophilic reactions, operational problems remain. Namely, NHCs are highly water-sensitive as free carbenes, making them impractical for normal benchtop use. Alternatively, NHCs can be generated in situ from imidazolium salts and appropriate strong bases. However, two drawbacks remain: firstly, the salts are hygroscopic; and secondly, strong bases may be incompatible with sensitive organic substrates. A viable alternative is the use of NHC adducts, which liberate free NHCs (and a neutral chloroform molecule) when heated. The effectiveness of NHC adducts as catalysts is evaluated for primary and secondary alcohol acylation reactions. The temperature dependence of free carbene formation (from an NHC chloroform adduct) is explored via variable temperature NMR data.
|
|
Undergraduate Research Poster Session
2:30 PM-4:30 PM, Monday, August 20, 2007 BCEC -- Exhibit Hall - B2, Poster
Division of Chemical Education |
