CAPILLARY-BASED MICROREACTOR FOR SCREENING PEPTIDE CATALYSTS IN THE ALDOL REACTION
In recent years, the concept of miniaturization has been applied to many areas of chemistry, one of which is the synthesis arena with the development of new microreactor technology. Compared with conventional scale vessels, microreactors are advantageous in many aspects, such as faster mixing, better heat transfer, minimal reagent use and great safety. However, the technology of microreactors is still immature and most organic reactions are simply carried out based on the existing concept and setup of 'lab-on-a-chip'. The analysis-oriented chips are always incompatible with demands of organic synthesis and so the development of synthesis-oriented microreactors is of great need.
Our laboratory developed a novel capillary-based reactor system that was specific for high-throughput synthesis and screening. The computer-controlled reactor system integrated standard HPLC apparatus (autosampler, pump), fused-silica capillaries and GC in which separate zones of reactants and catalysts can be combined and loaded serially into a single reactor capillary, reacted in parallel and ejected serially for online GC analysis.
One of the applications of our microreactor was to study peptide-catalyzed aldol reaction. We chose a model aldol reaction with benzaldehyde and acetone substrates and known catalyst L-proline. Chiral GC separation conditions were optimized for determination of chiral aldol products. The optimum reaction conditions were 10 mol% L-proline catalyst, DMSO and acetone 1:1 (v/v), room temperature and 4 hr reaction time. A little amount of acetic acid was added to increase L-proline solubility in organic solvents. Several peptides were preliminarily screened in the microreactor. Unfortunately, all of them showed poor activities.
The next step is to keep screening active peptide catalysts by our microreactor. Besides, novel solvents will be studied to further increase product yield and selectivity. The microreactor will also be optimized to increase its throughput and efficiency. The optimization process will be based on the combination of mathematical calculation (Mathcad software) and experiments. Moreover, the design of the microreactor will be improved in some units to make the system capable of accommodating more types of reactions such as multi-step reactions, gas-phase reactions or gas/liquid multiphase reactions.
Advisor:Kay M. Brummond; Stephen G. Weber; Shigeru Amemiya
School:University of Pittsburgh
School Location:USA - Pennsylvania
Source Type:Master's Thesis
Date of Publication:09/28/2008