Continuous micro-reactor rigs with capillary sections in organic synthesis : generic process flow sheets, practical experience, and 'novel chemistry'

The use of microstructured reactors with their benefits especially concerning enhanced mass and heat transfer for organic synthesis can lead for given chemical protocols to process intensification and as important additional aspect enable process chemistry with novel features not feasible so far because of limits of conventional equipment (1-7). Therefore, continuous micro-reactor rigs including conventionally interconnected micro-flow devices are versatile tools because of their simplicity, reliability, and flexibility - as opposed to tailored integrated micro-reactor concepts. This includes combinations of micromixers and heat exchangers and in particular capillary or tube sections (being rather meso- than microstructured). Various generic process flow sheets for such rigs will be proposed to tailor the needs of a class of reactions each grouped by their kinetics. This is illustrated by real-case plants and micro processing engineering at three application examples, the aqueous Kolbe-Schmitt synthesis of 2,4-dihydroxy benzoic acid, the bromination of thiophene, and the synthesis of an ionic liquid. They stand for three novel processing concepts which are the high-p,T processing, all-at-once contacting of hazardous reagents, and solvent-free operation.