Azlactone-functionalized smart block copolymers for organocatalyst immobilization

Yu, Xiaoqian; Herberg, Artjom; Kuckling, Dirk

doi:10.1016/j.eurpolymj.2019.08.034

Cited by 10 publications

(17 citation statements)

References 61 publications

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“…The chain transfer agent 2-(dodecylthiocarbonothioylthio)-2-methylpropionic acid (DMP) was obtained according to a procedure by Lai et al [ 54 ]. Modification of the PEG monomethyl ether ( M n = 5000 g/mol) with 4-cyano-4-pentanoate dodecyltrithio-carbonate was carried out as previously described [ 53 ]. Solketal acrylate (SKA) was synthesized by esterification of isopropylidene glycerol with acryloyl chloride according to literature [ 55 , 56 ].…”

Section: Methodsmentioning

confidence: 99%

“…Solketal acrylate (SKA) was synthesized by esterification of isopropylidene glycerol with acryloyl chloride according to literature [ 55 , 56 ]. (S) - N -(2-Aminoethyl) pyrrolidine-2-carboxamide dihydrochloride (L-prolinamide) was synthesized as previously described [ 53 ]. 2-Vinyl-4,4-dimethylazlacton (VDMA) was prepared via a two-step-synthesis described by Levere et al [ 34 ].…”

Section: Methodsmentioning

confidence: 99%

“…PEG- b -P(NIPAAm- co -VDMA) was synthesized following a previously described procedure [ 53 ]. A Schlenk tube with a septum and magnetic stirrer was charged with PEG-based macro-chain transfer agent (0.25 g, 0.045 mmol), AIBN (1 mg, 0.0121 mmol), NIPAAm (2.14 g, 18.94 mmol), VDMA (138 mg, 1 mmol), and dioxane (5.3 mL) in the ratio of [NIPAAm] 0 /[VDMA] 0 /[PEG-CDPA] 0 = 420/20/1.…”

Section: Methodsmentioning

confidence: 99%

“…Recently, our group reported the synthesis of amino-functionalized L-proline and different L -prolineamides. Subsequent immobilization of these amino-functionalized organocatalysts on azlactone-containing thermoresponsive block copolymers based on PEG and PNIPAAm afforded functional block copolymers for use in micellar organocatalysis [ 53 ]. In this strategy, the same polymer carrier was used for the immobilization of the different organocatalysts, thus allowing the comparison of catalyst activity and selectivity.…”

Section: Introductionmentioning

confidence: 99%

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Micellar Organocatalysis Using Smart Polymer Supports: Influence of Thermoresponsive Self-Assembly on Catalytic Activity

Herberg

Kuckling

2020

Polymers

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Micellar catalysts with a switchable core are attractive materials in organic synthesis. However, little is known about the role of the shell forming block on the performance of the catalyst. Thermoresponsive block copolymers based on poly(N-isopropylacrylamide-co-vinyl-4,4-dimethylazlactone) attached to different permanently hydrophilic blocks, namely poly(ethylene glycol), poly(N,N-dimethylacrylamide), and poly(2,3-dihydroxypropyl acrylate), were successfully synthesized via reversible addition/fragmentation chain transfer radical polymerization (RAFT). Post-polymerization attachment of an amino-functionalized L-prolineamide using the azlactone ring-opening reaction afforded functionalized thermoresponsive block copolymers. Temperature-induced aggregation of the functionalized block copolymers was studied using dynamic light scattering. It was shown that the chemical structure of the permanently hydrophilic block significantly affected the size of the polymer self-assemblies. The functionalized block copolymers were subjected to an aldol reaction between p-nitrobenzaldehyde and cyclohexanone in water. Upon temperature-induced aggregation, an increase in conversion was observed. The enantioselectivity of the polymer-bound organocatalyst improved with an increasing hydrophilic/hydrophobic interface as a result of the different stability of the polymer aggregates.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Micellar Organocatalysis Using Smart Polymer Supports: Influence of Thermoresponsive Self-Assembly on Catalytic Activity

Herberg

Kuckling

2020

Polymers

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“…So far, several strategies have been reported to incorporate derivates of L -proline base catalysts into BCPs, often by synthesizing a Boc-protected L -proline monomer or by post-modification of preformed polymers with functional L -prolines [ 126 , 127 , 128 , 129 , 130 , 131 ]. For instance, the protected 4-vinylbenzoic acid tert -butyl/Boc- L -proline ester was synthesized by esterification of 4-vinyl benzoic acid with tert -butyl/Boc- 4-hydroxy- L -proline [ 127 ].…”

Section: Block Copolymer Micellesmentioning

confidence: 99%

Recent Advances in the Synthesis and Application of Polymer Compartments for Catalysis

et al. 2020

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Catalysis is one of the most important processes in nature, science, and technology, that enables the energy efficient synthesis of essential organic compounds, pharmaceutically active substances, and molecular energy sources. In nature, catalytic reactions typically occur in aqueous environments involving multiple catalytic sites. To prevent the deactivation of catalysts in water or avoid unwanted cross-reactions, catalysts are often site-isolated in nanopockets or separately stored in compartments. These concepts have inspired the design of a range of synthetic nanoreactors that allow otherwise unfeasible catalytic reactions in aqueous environments. Since the field of nanoreactors is evolving rapidly, we here summarize—from a personal perspective—prominent and recent examples for polymer nanoreactors with emphasis on their synthesis and their ability to catalyze reactions in dispersion. Examples comprise the incorporation of catalytic sites into hydrophobic nanodomains of single chain polymer nanoparticles, molecular polymer nanoparticles, and block copolymer micelles and vesicles. We focus on catalytic reactions mediated by transition metal and organocatalysts, and the separate storage of multiple catalysts for one-pot cascade reactions. Efforts devoted to the field of nanoreactors are relevant for catalytic chemistry and nanotechnology, as well as the synthesis of pharmaceutical and natural compounds. Optimized nanoreactors will aid in the development of more potent catalytic systems for green and fast reaction sequences contributing to sustainable chemistry by reducing waste of solvents, reagents, and energy.

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Novel Application of Polymer Networks Carrying Tertiary Amines as a Catalyst Inside Microflow Reactors Used forKnoevenagelReactions

et al. 2020

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A novel application is described for utilizing hydrogel dots as organocatalyst carriers inside microfluidic reactors. Tertiary amines were covalently immobilized in the hydrogel dots. Due to the diffusion of reactants within the swollen hydrogel dots, the accessible amount of catalysts inside a microfluidic reactor chamber can be increased compared to the accessible amount of surface‐bound catalysts. To perform fast Knoevenagel reactions, important flow parameters had to be validated to optimize the reactor performance while keeping the dimensions of the reactor chamber constant; e.g. the height of the hydrogel dots had to be adjusted to the invariable dimensions of the reactor chamber, or an adjustment of organocatalysts in the hydrogel dots had to be validated to achieve the highest conversion rate during a certain residence time. To characterize the conversion, nuclear magnetic resonance (NMR) and UV/Vis‐spectroscopy were utilized as an offline and online method, respectively. With suitable hydrogel dots, the influence of different flow parameters (e.g., operating flow rate and reactant concentration) on the selected model reactions in the microfluidic reactor was investigated. Finally, a variety of reactants were screened with the optimized flow parameters. With these results, the turnover frequency was determined for the Knoevenagel reactions in a microfluidic reactor, and the results were compared with published data that were determined by other synthetic approaches.

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Azlactone-functionalized smart block copolymers for organocatalyst immobilization

Cited by 10 publications

References 61 publications

Micellar Organocatalysis Using Smart Polymer Supports: Influence of Thermoresponsive Self-Assembly on Catalytic Activity

Micellar Organocatalysis Using Smart Polymer Supports: Influence of Thermoresponsive Self-Assembly on Catalytic Activity

Recent Advances in the Synthesis and Application of Polymer Compartments for Catalysis

Novel Application of Polymer Networks Carrying Tertiary Amines as a Catalyst Inside Microflow Reactors Used forKnoevenagelReactions

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