Microwave irradiation has been successfully applied in organic
chemistry. Spectacular accelerations, higher yields under milder reaction
conditions and higher product purities have all been reported. Indeed, a
number of authors have described success in reactions that do not occur by
conventional heating and even modifications of selectivity (chemo-, regioand
stereoselectivity). An overview of the application of microwave
irradiation in organic synthesis and the combination with other synthetic
methodologies is included. The effect of microwave irradiation in organic
synthesis is a combination of thermal effects, arising from the heating rate,
superheating or “hot spots”, the selective absorption of radiation by polar
substances and the existence of non-thermal effects of the highly polarizing
radiation – the “specific microwave effect”. Such phenomena are not usually
accessible by classical heating.
Departamento de Química Orgánica, Facultad de Química, Universidad de Castilla-La Mancha, E-13071 Ciudad Real, Spain.