An innovative sequential flow platform for automated multi-step chemical processes - proof of concept with the separation of amine/alkene model mixtures

Multi-step chemical reactions, automation and membrane-based separations have gained momentum in the field of flow chemistry. However, multi-step processes including work-ups are rare, especially due to excessively complicated set-ups requiring numerous fluidic tools. We propose a new sequential flow strategy, as opposed to in-line continuous flow, that drastically alleviates the practical limitations of the latter, in particular by the means of an original micro-lab platform. This platform displays a minimal spatial footprint (30 cm x 20 cm x 20 cm) and can be used for a large variety of multi-step chemical processes. To demonstrate the operation of the set-up and the implementation of the sequential strategy, we propose a sequence of fluid manipulations executed automatically by a couple of programmable sequential micro-dispensers for the separate recovery of an amine and an alkene, starting from a 1 : 9 amine : alkene molar mixture. Biphasic liquid-liquid extractions, liquid-liquid phase separations and monophasic acid-alkali chemical transformations are used for the separation and recovery of the two species. Extraction yields are similar to that obtained by usual batch protocol. Command lines to be sent via dedicated custom Python script are succinct and readily available with this work. The successful operation of the inaugural example presented in this article establishes a starting point for further use of the methodological framework. In particular, the modularity of the micro-lab hardware and software is promising for the integration of most chemical processes including photochemical, electrochemical and plasma-activated transformations.