Continuous-Flow Ritter Reaction for Sustainable Amide Synthesis Using a Recyclable m-Phenolsulfonic Acid-Formaldehyde Resin Catalyst.

Herein, a rapid and efficient continuous-flow synthesis of amides is described. The Ritter reaction, catalyzed by a reusable solid acid catalyst composed of m-phenolsulfonic acid-formaldehyde resin (PAFR II), was used to convert nitriles and alcohols to amides in up to 90% yield. The continuous-flow system facilitates short reaction times and maintains activity for several weeks. This method is scalable, environmentally sustainable, and enables catalyst recycling.