Electrochemical Dehydration in Flow: Fatty Acid Nitriles From Their Carboxamides

We established a sustainable and scalable electrochemical dehydration of highly lipophilic amides to their nitriles in recirculating flow electrolysis conditions, expanding on our previously published work on the electrochemical dehydration of carboxamides in batch-type cells. With our electrochemical flow setup, long-chain aliphatic carboxamides (C14–C18) and related substrates were converted efficiently, affording lipophilic nitriles in yields up to 88% (2.5 mmol) and 86% (4.4 mmol). The method proved robust across different flow reactor designs, including small cells for rapid screening and optimization, larger systems for scale-up, and adapted setups capable of handling suspensions, further highlighting the versatility of the flow approach. Tetrabutylammonium thiocyanate functions as both redox mediator and supporting electrolyte, while hexafluoroisopropanol is crucial to suppress side reactions. The reaction proceeds under mild conditions, avoiding harsh catalysts and temperatures. Importantly, solvent recovery and reuse under recirculating flow operation maintained comparable yields, reinforcing the sustainability and practicality of this flow-based electrochemical process for producing valuable fatty nitriles.