Monolithic Silica Support for Immobilized Catalysis in Continuous Flow

Monolithic and packed‐bed reactors featuring immobilized catalysts are well‐precedented in continuous flow synthesis but can suffer from adverse pressure drops during use due to their small pore sizes and/or structural changes. Herein, we overcome this challenge with the synthesis of a structurally robust silica‐based monolith featuring pore sizes on the millimeter scale. The 3‐dimensional solid support structure is constructed from a polystyrene foam‐based template and features a functional group handle that can be modified to display a reactive catalyst. Here we functionalize the support with palladium(0) for hydrogenation reactions and a modified proline catalyst for the alpha functionalization of aldehydes. Both reactors showed good activity and excellent catalytic longevity when utilized under continuous flow conditions.