Esquivel Merino, Maria Dolores

Lauwaert, Jeroen

Ouwehand, Judith

Thybaut, Joris

Van Der Voort, Pascal

English

Ghent University Academic Bibliography

ONHCOOHAmino Acid functionalized Periodic Mesoporous Organosilicasas Bifunctional CatalystsJudith Ouwehanda, Dolores Esquivela, Jeroen Lauwaertb, Joris Thybautb, Pascal Van Der VoortaaCenter for Ordered Materials, Organometallics and Catalysis (COMOC), Universiteit GentbLaboratory for Chemical Technology (LCT), Universiteit GentPeriodic Mesoporous Organosilicas, commonly known as PMOs, are a class of hybrid mesoporous materials. The materials are formed by the hydrolysis and condensation of anorganobissilane precursor of the form (R’O)3Si-R-Si(OR’)3 around a structure directing agent. In this study, two PMOs which were developed in COMOC, namely an E-ethene-PMO [1] and a thiol-PMO [2], are functionalized with amino acids via a thiol-ene click reaction. The bifunctional acid-base catalysts obtained this way are tested in an aldolcondensation reaction.(EtO)3SiSi(OEt)31) P123, KCl, H2O, (BuOH or KCl)2) Acetone or HCl, EtOHPMO Synthesis+ +Thiol-ene ClickComparison of cysteine and prolineReusabilityAldol reaction of p-nitrobenzaldehyde and acetoneIntroductionSynthesis CharacterizationCatalysisConclusionsBifunctional CatalystsProline PMO: 1.15 mmol/gCysteine PMO: 0.53 mmol/g Elemental AnalysisBoth bifunctional catalysts were found to be active in the aldol reaction of acetone andnitrobenzaldehyde. The first catalytic tests showed that the cysteine functionalized PMO was more active than the proline functionalized PMO and also showed good reusability. Later studies revealed that the loading of the amino acid has a big influence and possibly the prolinePMO was less active due to a higher loading.In the future, the enantioselective properties of the catalysts will also be investigated.[1] C. Vercaemst, M. Ide, B. Allaert, N. Ledoux, F. Verpoort, P. Van Der Voort, Chem Commun 2007, 2261-2263.[2] D. Esquivel, O. van den Berg, F.J. Romero-Salguero, F. Du Prez, P. Van Der Voort, Chem Commun 2013, 49, 2344-2346.Website: http://www.comoc.ugent.be Email: Judith.Ouwehand@UGent.beWhen cysteine PMOswith differnt loadings arecompared, we see that the lower loading gives thehighest conversion.At high loadings, we think that H-bondingoccurs, which deactivatesthe catalyst.XRDDRIFTSDRIFTSCHC=OCH2Si-OH CHC=ONH(100)(110) (200)ONOO+OOHNOOONitrogen sorptionComparison of different loadingsCysteine PMO Proline PMO

Amino acid functionalized periodic mesoporous organosilicas as bifunctional catalysts

https://biblio.ugent.be/publication/5875150/file/5875155.pdf

Amino acid functionalized periodic mesoporous organosilicas as bifunctional catalysts

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