Partial Hydrogenation of Unsaturated Carbonyl Compounds: Toward Ligand-Directed Heterogeneous Catalysis

Schauermann, Swetlana

doi:10.1021/acs.jpclett.8b01782

Cited by 18 publications

(15 citation statements)

References 76 publications

(180 reference statements)

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“…In our recent studies on hydrogenation of the simple carbonyl compounds acetophenone, acrolein, − and isophorone − over Pt and Pd surfaces, we demonstrated that the lateral interaction between neighboring adsorbates can crucially affect their adsorption geometry and chemical transformations. Particularly acetophenone was observed to form dimers on the Pt surface above 136 K, which can either be present as ketone–ketone species or undergo keto–enol tautomerization and form ketone–enol dimers .…”

Section: Introductionmentioning

confidence: 93%

Coverage-Dependent Adsorption Geometry of Acetophenone on Pt(111)

Attia

Schauermann

2019

J. Phys. Chem. C

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A microscopic-level understanding of the interaction of hydrocarbons with transition metal surfaces is an important prerequisite for rational design of new materials with improved catalytic properties. Particularly, their adsorption geometry might critically affect the ability of the surface to activate the selected chemical bonds. In this study, we investigate the interaction of a simple carbonyl compound acetophenone with Pt(111) single crystalline surface as a prototypical system. We apply a combination of molecular beam techniques with infrared reflection−absorption spectroscopy (IRAS) to address the adsorption geometry of acetophenone in a broad coverage range. In particular, we compare the IR spectra recorded for multilayer coverages, reflecting the molecular structure of largely unperturbed molecules, with the spectra obtained at submonolayer coverages, at which the molecular structure of acetophenone is perturbed by the interaction with the underlying metal. The acquired spectroscopic information suggests that two types of acetophenone surface species are formed and coexist on the surface at low temperature. At low coverages, the species S1 are populated, which adopt a flat-lying adsorption geometry with the benzene ring lying parallel to the surface plane. With increasing acetophenone coverage, a second type of the surface species appearsthe species S2exhibiting a more upright orientation with the benzene ring tilted away from the surface. The latter species are more weakly bound to the underlying metal substrate as compared to the flat-lying species S1 as indicated by the temperature dependence of their population on the surface. Additionally, we report a detailed assignment of the vibrational bands in acetophenone based on the comparison of the unperturbed molecular species accumulated in a multilayer with the spectra of gaseous acetophenone theoretically computed with the MP2/aug-cc-pVQZ-level of theory.

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Section: Introductionmentioning

confidence: 93%

Coverage-Dependent Adsorption Geometry of Acetophenone on Pt(111)

Attia

Schauermann

2019

J. Phys. Chem. C

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“…This result is significant because asymmetrically charged hydrogen pairs can influence the mechanism and energetics of reduction reactions. 66…”

Section: Ligand Protonationmentioning

confidence: 99%

Ligand assisted hydrogenation of levulinic acid on Pt(111) from first principles calculations

Gell

Honkala

2022

Catal. Sci. Technol.

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“…不饱和有机化合物的催化加氢反应是化学中应用最广泛的反应之一 [1][2][3][4][5][6][7][8] . 长期以来, 各国的研究者致力于开发不同类型的催化氢化反应体系, 过渡金属催化剂在该领域一直占主导地位, 并已经取得了很多辉煌的成就 [9][10][11][12][13][14][15][16][17] . 直到 2006 年, Stephan 小组 [18] 发现"受阻路易斯酸碱对" (frustrated Lewis pairs, 简称为 FLPs)在 298.15 K 时可以使氢气发生异裂, 其还原形式在 373.15 K 时可释放氢气, 首次实现了非金属催化剂对氢气的可逆活化.…”

Section: 引言unclassified

Mechanism of Silyl Enol Ethers Hydrogenation Catalysed by Frustrated Lewis Pairs: A Theoretical Study

Wang¹,

Wei²,

Duan³

et al. 2021

Acta Chimica Sinica

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Silyl enol ethers have attracted enormous attention as they could serve as a test bed for the development of novel frustrated Lewis pairs (FLPs) catalytic systems. However, the reaction mechanism of hydrogenation catalysed by metal-free FLPs for these compounds to the corresponding secondary alcohols remains elusive to a large extent in previous studies. We thus performed a thorough investigation on the reaction mechanism by density functional theory (DFT). To illustrate the reaction mechanism of FLPs-catalysed hydrogenation for silyl enol ethers, trimethyl((1-phenylvinyl)oxy)silane (Me-TMS) was chosen as the prototype substrate and toluene as the solvent, where the FLPs were generated by ethylbis(perfluorophenyl)borane (Et-B(C6F5)2) and tri-tert-butylphosphine (t-Bu3P). The M06-2X functional in connection with 6-31＋G(d) basis set was used to optimize the structures of related species including in the Gibbs free energy profiles, and the energies were obtained at M06-2X/6-311＋＋G(d,p) level of theory, where the solvent effect was simulated with the integral equation formalism, polarized continuum mode (IEF-PCM) in both calculations. Our results suggest that the FLPs-catalysed hydrogenation of silyl enol ethers in toluene begins with the formation of B-P-FLPs followed by hydrogen activation, proton transfer and hydride transfer to complete the process. It is obvious from the Gibbs free energy profile that the proton transfer is rate-determining step, the formation of B-P-FLPs and proton transfer are endothermal and the hydride transfer is no barrier. This indicates that the amount of H2 and prototype substrate have significant influence on the FLPs-catalysed hydrogenation of silyl enol ethers. A higher temperature (328.15 K) is disadvantageous to hydrogenation reaction catalysed by FLPs but the reaction could be accelerated under higher pressure (4040 kPa). The Gibbs free energy profile calculations for trimethyl((1-phenylprop-1-en-1-yl)oxy)silane (Et-TMS) and tert-butyldimethyl((1-phenylvinyl)oxy)silane (Me-TBS) reveal that substituent group may inhibit the hydride transfer as the absence of a suitable construction for R-H --transfer, where the hydride does not direct to the C ＋ of silyl enol ethers and the distance between C ＋ and hydride is longer. These results would be helpful to design another novel FLPs-catalysed hydrogenation reaction for silyl enol ethers.

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Partial Hydrogenation of Unsaturated Carbonyl Compounds: Toward Ligand-Directed Heterogeneous Catalysis

Cited by 18 publications

References 76 publications

Coverage-Dependent Adsorption Geometry of Acetophenone on Pt(111)

Coverage-Dependent Adsorption Geometry of Acetophenone on Pt(111)

Ligand assisted hydrogenation of levulinic acid on Pt(111) from first principles calculations

Mechanism of Silyl Enol Ethers Hydrogenation Catalysed by Frustrated Lewis Pairs: A Theoretical Study

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