Scalable and Recyclable All‐Organic Colloidal Cascade Catalysts

Abstract

We report on the synthesis of core-shell microparticles (CSMs) with an acid catalyst in the core and a base catalyst in the shell by surfactant-free emulsion polymerization (SFEP). The organocatalytic monomers were separately copolymerized in three synthetic steps allowing the spatial separation of incompatible acid and base catalysts within the CSMs. Importantly, a protected and thermo-decomposable sulfonate monomer was used as acid source to circumvent the neutralization of the base catalyst during shell formation, which was key to obtain stable, catalytically active CSMs. The catalysts showed excellent performance in an established onepot model cascade reaction in various solvents (including water), which involved an acid-catalyzed deacetalization followed by a base-catalyzed Knoevenagel condensation. The CSMs are easily recycled, modified, and their synthesis is scalable, making them promising candidates for organocatalytic applications.

Upgrading poly(styrene‐co‐divinylbenzene) beads: Incorporation of organomodified metal‐free semiconductor graphitic carbon nitride through suspension photopolymerization to generate photoactive resins

“…Indeed, most of these techniques require corrosive and toxic chemicals, which limits the feasibility and sustainability of final production, that is, to PS‐DVB matrix is boiled by mixture of acetic anhydride and concentrated sulfuric acid to attain sulfonation 56 . Another method to access surface modification requires the addition of a third monomer, such as 4‐chloro styrene and vinyl methl ketone, both that are more prone to modification compared to PS and DVB, or an addition of a monomer which possesses an acidic or basic functionality 57,58 . This is why we intended to develop a remarkably simplified and more sustainable synthesis process, based on hybrids with carbon nitride.…”

Tandem Aldol Reaction from Acetal Mixtures by an Artificial Enzyme with Site-Isolated Acid and Base Functionalities

“…With the amino group on the surface of the nanoparticle, no other basic catalysts were needed and the selective cross aldol reaction could occur in a very “green” fashion, simply in warm water (40 °C) without any other additives. Although tandem aldol reaction is frequently used to test the performance of site-isolated catalysts, ,,− none of the previously reported systems had features to selectively convert a mixture of similarly reactive reactants.…”

“…Examples include star polymers, magnetically separable catalysts, polymersomes, mesoporous materials, polymeric micelles, , microcapsules, graphene oxides, and hyper-cross-linked nanospheres . New materials continue to emerge in recent years such as hierarchically porous materials, monodispersed photonic spheres, and core–shell microparticles to address additional challenges in scale-up and introduce catalytic features mimicking those in biocatalysis.…”

Highly Diastereoselective Synthesis of Tetrahydroquinoline Derivatives via [4 + 2] Annulation of Ortho-Tosylaminophenyl-Substituted Para-Quinone Methides and Cyanoalkenes

“…et al, 2020 ). Substrates 2 ( Ghosh et al, 2021 ) and other cyanoalkenes ( Fioravanti et al, 2012 ; Donckele et al, 2015 ; Zhu et al, 2017 ; Chen et al, 2021 ) were prepared through the Knoevenagel reactions, and all substrates can be stored at 4°C for 25 days without decomposition.…”