Continuous Flow Nitration in Microreactors: Progress and Future Challenges

Continuous-flow nitration in microreactors has attracted increasing attention as a strategy for improving the safety and controllability of highly exothermic nitration processes. This review surveys more than 40 primary studies reported since 2014 and classifies them according to phase behavior into homogeneous, liquid-liquid heterogeneous, and miscellaneous systems; within each category the literature is further organized by nitrating system, principally mixed-acid and nitric-acid-based approaches. Flow operation has compressed residence times from the hours typical of batch nitration to between roughly 2 s and 30 min: the dinitration of o-toluic acid, for example, affords 96