Microwave heating and chemistry: what can be expected of them?

In industrialised countries economic necessity and environmental problems lead increasingly to gradual substitution of refined for heavy chemistry. Among the repercussions is the development of increasingly selective syntheses (a single product contaminated by secondary ones) by very-high-performance processes: efficiencies close to 100% with given operational conditions. The challenge is to reduce costs and pollutant wastes. The general trend is towards reduction of separation and isolation procedures which consume energy and generate effluents whose treatment and recycling by the former methods are no longer economic. Microwave heating could be at least a partial answer to this problem; it is shown to be selective between competing and parallel processes.