Design and manufacture of an electrochemical flow reactor, and its application in organic electrosynthesis

Organic electrosynthesis is recognised as a green enabling methodology to perform reactions in an efficient and straightforward way. Electrons are used as the reagent to form anion and cation radical species from neutral organic molecules achieving oxidations and reductions by replacing toxic and dangerous reagents. Within this field, the use of microreactors in continuous flow is also concurrent with electrochemistry because of its convenient advantages over batch, such as: i) low loading or no supporting electrolyte at all, due to the small distance between electrodes, providing significant advantages in downstream processing; ii) high electrode surface-to-reactor volume ratio; iii) short residence time; iv) improved mixing effect. In this thesis, a novel easy-to-machine flow electrochemical reactor has been designed and fabricated. This reactor can be made either of aluminium or polymers, if additive manufacturing employed. The efficiency of the reactor has been shown in the electrosynthesis of nitrogen-containing heterocycles. The products obtained have been further functionalised in a single two-step flow system connected to the electrochemical reactor: For the electrochemical synthesis of benzothiazoles from N-arylthioamides in flow a catalyst- and supporting electrolyte-free method has been developed. A library of benzothiazoles was synthesised only in the presence of solvent and electricity: Finally, a new synthetic method for the electrochemical formation of benzoxazoles from easily accessible and inexpensive resorcinol and nitriles was discovered: In conclusion, flow electrosynthesis has shown to be a promising tool for electroorganic synthesis, improving the outcome of standard batch cells