Microwaves applied to organic synthesis

Microwaves – electromagnetic waves in the microwave range – are capable of generating heat in media that are sensitive to these waves, for example by possessing particular dielectric characteristics. Unlike conventional heating techniques based on conduction or convection, the use of microwaves involves interaction between electromagnetic radiation and matter. Microwave heating of a product is therefore not a thermal transfer, but the conversion of electromagnetic wave energy into heat within the material.

The application of this type of heating to chemical synthesis began almost thirty years ago. While many positive experiments have been carried out, too few have gone beyond the laboratory stage. The implementation of a microwave synthesis process remains complex and requires special attention. The engineer's integrative approach, combining an understanding of the electromagnetic mechanisms involved and their interactions with the medium, the development of specific technologies and the critical analysis of reactions, are all essential to the success of any organic reaction under microwave conditions, and subsequently to its industrialization. This article describes the basic knowledge required, reviews the technologies available, highlights the critical points and, finally, proposes a useful approach to understanding organic synthesis under microwave conditions. It is accompanied by examples of organic syntheses and shows the potential offered by the use of this heating technique, particularly in the context of sustainable development.