Performing reactions in
a flowed format, rather than statically in a conventional batch
reaction set up allows for in-process alterations of reaction
conditions, such as reaction optimization and in-line processing
(analysis or purification) of the products. A potential drawback
with flow is that reactions reside in the flow system for a shorter
period of time than in a standard batch reactor. If a reaction
is kinetically slow, the benefits of flow will be offset by the
poor reaction conversion resulting in low yield and purification
problems because the product mixture is contaminated with unreacted
starting materials. Microwave irradiation is known to dramatically
accelerate the rate of chemical transformations; combining microwave
with flow allows the realization of the full benefits of both
techniques. Preliminary experiments have shown that reactions
flowed through small diameter tubes (capillaries) while being
irradiated actually show greater rate enhancement over larger
diameter tubes and, we believe, offers the greatest hope for wide
acceptance of flow synthesis. This proposal also proposes further
advances by combining flow microwave with capillaries loaded with
new supported reagents, catalysts, and scavengers through which
the reactions flow to allow one-sequence synthesis and purification.
Essentially, this amounts to the creation of an automated, multi-step
chemical synthesis machine capable of running multiple reactions
simultaneously through parallel capillaries.
