Keep the flow: in-line technologies for pure products

Flow reactor technology represents one of the enabling technologies introduced in the last decade to advance the sustainability of organic synthesis and shows many advantages compared with batch methods, including increased safety, high control of reaction parameters, quick reaction optimization, possibility of automation and in-line work-up and purifications. Indeed, flow synthesis cuts across several traditional boundaries within the sequential scaling routes of synthesis such as research scale, re-synthesis, kilo labs and full scale manufacturing/formulation, combining aspects of both chemical optimization and process intensification. Continuous production is often cited as both eco-friendly and economic, mainly due to the higher energy efficiency and reduced consumption of resources that can be achieved in comparison with traditional batch production . Theoretically, if a sequence of stepwise reactions can be set up using the same solvent or simply applying an exchanging solvent mechanism, the firstly well optimized reactions could be processed in tandem. In this way the reaction mixture for the first step becomes the reagent for the next one creating a telescoped sequence. If on one side this ideal scenario is not so easy to perform due to the need to quench reactions, work-up intermediates, and consequently purify the stream between the different transformations, on the other side it is possible to combine other enabling technologies to obtain in-line filtration, in-line extraction, in-line distillation, and in-line purification to maintain a continuous flowing sequence