Wiad. Chem. 53, 66-93 (1999)
Institute of Polymer Chemistry and Technology,
Politechnika Krakowska,
ul. Warszawska 24, 31-155 Krakow, Poland;
In the last few years there has been a growing interest in the use of microwave
heating in organic synthesis. The use of such nonconvetional reaction
conditions reveals several features like: a short reaction time compared to
conventional heating, ease of work-up after a reaction, and reduction in the
usual thermal degradation and better selectivity. Microwave ovens provide a
clean and cheap alternative to conventional oil baths. The popularity of
microwave heating for organic synthesis has increased to the extent that it now
forms the basis of a number of commercial systems, and has even made its way
into undergraduate laboratory courses.
Microwave heating has been proven to be of benefit particularly for the
reactions under "dry" media (i.e., in the absence of a solvent, on solid
support with or without catalysts) and offers a number of advantages: solvents
are often expensive, toxic, difficult to remove in the case of aprotonic
solvents with high boiling point. Liquid-liquid extraction can be avoided for
the isolation of reaction products. Moreover, the absence of solvent reduce
the risk of explosions when reaction takes place in a microwave oven.
In the present article microwave-assisted organic syntheses are reviewed in the
context of their the most significant examples.