Ritter Reactions in Continuous Flow Catalysed by a Solid-Supported Sulfonic Acid Catalyst

Abstract

The Ritter reaction allows the 100% atom economical synthesis of amides via acid-catalysed coupling between nitriles and alcohol substrates. However, this reaction has traditionally required harsh acid catalysts which must be separated from the product stream. Here, we demonstrate that commercial polymer-supported Brønsted acids catalyse the Ritter reaction under continuous flow conditions. The products are generated in high yield and free from acidic catalyst impurities. Continuous flow conditions deliver high yields in significantly shorter reaction times compared with batch reactions (1 hour vs. 24 hours) and the catalyst remains effective after 43 hours of continuous operation.