Exploring the World of Microwave-Promoted Chemistry
Nicholas E. Leadbeater, PhD, Assistant Professor, Dept. of Chemistry, New Synthetic Methods Group, University of Connecticut, Storrs, CT

The use of microwave heating as a tool for preparative organic chemistry is now commonplace; people finding that they can speed up their reactions and improve their product yields. However, as the field develops, new avenues for microwave-promoted chemistry are developing. The aim of our presentation is to show advances we have made in our laboratory in a number of areas:

Advances in organic synthesis: We will report results from our studies of reactions performed under an atmosphere of reactive gas. This will include carbonylation, oxidation chemistry as well as the use of ethene as a 2-carbon unit in synthesis.

In-situ reaction monitoring: We have developed an apparatus for the monitoring of reactions under microwave irradiation using in-situ Raman spectroscopy. Results obtained using this apparatus will be discussed, in particular the use of the monitoring technique for probing kinetics of reactions.

Synthesis of organometallic and inorganic compounds: While synthetic organic chemists have taken advantage of microwave heating in their work, there have been few reports of application in preparative organometallic chemistry. With our in-situ Raman apparatus we can monitor reactions in real time and can carefully control the synthesis of organometallic compounds. In addition, by using gas-loading equipment we can perform reactions under an atmosphere of reactive gases. This has allowed us to prepare a number of key organometallic compounds very quickly and efficiently. Our results will be presented here.

Interaction of microwave energy with biomolecules: There have been a number of reports of rate enhancements in processes such as trypsin digests and other enzymatic transformations. However, there is still not much understanding of the fundamental effects of the interaction of microwave energy with these biomolecules. We will present the results of some studies we have undertaken in order to understand more fully these effects as well as perform thorough comparisons between microwave and conventional heating.

Scale-up of microwave-promoted reactions: If microwave promoted organic synthesis is going to continue to grow, it is going to be necessary to develop methods for scaling up reactions from the milligram to the kilogram level. This is going to require engineering solutions as well as chemistry. In this part of the presentation we will present results from our laboratory directed towards both larger scale batch and continuous-flow processing and will show how we have modified commercially available equipment and found engineering solutions to problems currently faced.