Continuous flow organic chemistry using microreactors has gained a lof of attention in recent years due to the numerous advantages associated with this technology. One striking feature deriving from the miniaturization of the device is the enormous increase in the surface-to-volume ratio which can be exploited in catalysis both in terms of catalyst loading and reagent-catalyst interaction.Here we present the functionalization of the inner walls of glass microreactors with organic and nanometallic catalysts and its use in the catalysis of different types of reactions. First, the inner surface of a microstructured reactor was functionalized by a monolayer of strong perfluoro sulfonic acid by a single step reaction with the surface silanol groups. The system turned out to be highly active in the catalysis of different reactions, i.e. hydrolysis, Friedlander formation of quinolines, and cyclizations.In another work, sulfonic acid-bearing polymer brushes were grown onto the inner surface of the microreactor starting from an ATRP initiator. Polymer brushes are of interest for surface functionalization due to their versatility and the possibility to control their growth. By using randomly mixed poly-2-hydroxyethyl methacrylate (PHEMA) and poly-3-sulfopropyl methacrylate (PSPM), a remarkable improvement in the activity and stability of the sulfonic acid catalysts was observed, due to the stabilizing influence of the PHEMA OH groups exerted on the PSPM active sites, thanks to the proximity effect created within the brush architecture.Furthermore, palladium nanoparticles (PdNPs) were grown and stabilized by using the dendrimer encapsulation approach. Subsequently, the so-formed PdNPs were successfully used in the Suzuki-Miyaura cross-coupling reaction. To this end, PAMAM dendrimers were attached onto a pre-functionalized microreactor inner surface. Afterwards, the NPs were grown and stabilized in situ by the tertiary amino groups present inside the dendrimer template along with retaining their catalytic activity.

Supported organic and metallic catalysts within glass microreactors

248th National Meeting (2014)

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