Green chemistry: synthesis in micro reactors

The importance of minimizing the impact that chemical processing has on the environment is growing, with an increased appreciation of the need to reduce pollution and the depletion of our finite environmental resources. Optimal use of material, energy and consequent waste management can be recognised as important factors for environmental protection. In the case of minimising waste there are two approaches, the traditional approach aims at reducing waste at the end of the pipeline, for example, decreasing emission by catalytic incineration of exhaust fumes. The second approach is based on minimising waste at the source. In this case, innovative procedures have to be employed to change both the method and the technology used throughout the production cycle. The miniaturisation of chemical reactors offers many fundamental and practical advantages of relevance to the pharmaceutical and fine chemicals industry, who are constantly searching for controllable, information rich, high throughput, environmentally friendly methods of producing products with a high degree of chemical selectivity. Indeed, for pharmaceutical companies an informatics-based approach, that micro reactor chemistry can uniquely deliver, may be the trigger for a step change in processes. This review explores how miniaturisation may revolutionise chemical synthesis, highlighting in particular the environmental benefits of this new technology, which include solvent free mixing, in situ reagent generation and integrated separation techniques. Furthermore, the possibility of preparing the chemicals in the required volume at point of use, negates the need to store and transport hazardous materials.