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Elucidating the Mechanism of Ambient-Temperature Aldol Condensation of Acetaldehyde on Ceria.
| Content Provider | Europe PMC |
|---|---|
| Author | Bhasker-Ranganath, Suman Rahman, Md. Saeedur Zhao, Chuanlin Calaza, Florencia Wu, Zili Xu, Ye |
| Copyright Year | 2021 |
| Abstract | Using in situ diffusereflectance infrared Fourier transform spectroscopy(DRIFTS) and density functional theory (DFT) calculations, we conclusivelydemonstrate that acetaldehyde (AcH) undergoes aldol condensation whenflown over ceria octahedral nanoparticles, and the reaction is desorption-limitedat ambient temperature. trans-Crotonaldehyde (CrH)is the predominant product whose coverage builds up on the catalystwith time on stream. The proposed mechanism on CeO2(111)proceeds via AcH enolization (i.e., α C–H bond scission),C–C coupling, and further enolization and dehydroxylation ofthe aldol adduct, 3-hydroxybutanal, to yield trans-CrH. The mechanism with its DFT-calculated parameters is consistentwith reactivity at ambient temperature and with the kinetic behaviorof the aldol condensation of AcH reported on other oxides. The slightlyless stable cis-CrH can be produced by the same mechanismdepending on how the enolate and AcH are positioned with respect toeach other in C–C coupling. All vibrational modes in DRIFTSare identified with AcH or trans-CrH, except fora feature at 1620 cm–1 that is more intense relativeto the other bands on the partially reduced ceria sample than on theoxidized sample. It is identified to be the C=C stretch modeof CH3CHOHCHCHO adsorbed on an oxygen vacancy. It constitutesa deep energy minimum, rendering oxygen vacancies an inactive sitefor CrH formation under given conditions. |
| Related Links | https://europepmc.org/backend/ptpmcrender.fcgi?accid=PMC8294007&blobtype=pdf |
| Journal | ACS Catalysis [ACS Catal] |
| Volume Number | 11 |
| DOI | 10.1021/acscatal.1c01216 |
| PubMed Central reference number | PMC8294007 |
| Issue Number | 14 |
| PubMed reference number | 34306815 |
| e-ISSN | 21555435 |
| Language | English |
| Publisher | American ChemicalSociety |
| Publisher Date | 2021-06-30 |
| Access Restriction | Open |
| Rights License | Permits the broadest form of re-use including for commercial purposes, provided that author attribution and integrity are maintained (https://creativecommons.org/licenses/by/4.0/). © 2021 The Authors. Published by AmericanChemical Society |
| Subject Keyword | aldol condensation CeO2 acetaldehyde crotonaldehyde DRIFTS density functionaltheory reaction mechanism |
| Content Type | Text |
| Resource Type | Article |
| Subject | Chemistry Catalysis |
