Thermal reactions of 2-iodoethanol on Cu(100)

Liao, Yung Hsuan; Chen, Chia Yuan; Fu, Tao Wei; Wang, Ching Yung; Fan, Liang Jen; Yang, Yaw Wen; Lin, Ja‐Chen

doi:10.1016/j.susc.2005.10.059

Cited by 5 publications

(13 citation statements)

References 17 publications

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“…Similar reaction products have been reported in previous studies of 2-iodoethanol on Ag(111), 7 Ag(110), 8 Ni(100), 9 Cu(100), 10 and Rh(111). 11 Figure 2 shows the effect of varying 2-iodoethanol exposure sizes on carbon monoxide, hydrogen, ethanol, 2-iodoethanol, acetaldehyde, and ethylene desorption rates.…”

Section: ■ Resultssupporting

confidence: 87%

“…The strong C−C stretch, C−O stretch, and C−C−O deformation modes at 1015 cm −1 indicate that the molecular backbone remains intact upon adsorption, in agreement with previous studies on Ag(111) 7 and Cu(100). 10 The CH 2 rocking, wagging, and bending modes at 800, 1260, and 1390 cm −1 suggest that the C−H bonds are also intact. However, noticeably absent on Pd(111) are the modes associated with the C−I bond.…”

Section: ■ Resultsmentioning

confidence: 99%

“…15,16 The surface chemistry of 2-iodoethanol has been studied on Ag(111), 7 Ag(110), 8 Ni(100), 9 Rh(111), 11 and Cu(100). 10 On all of the surfaces 2-iodoethanol undergoes C−I scission at low temperatures, forming 2-hydroxyethyl (−CH 2 CH 2 OH). On Ag(111), 7 the hydroxyethyl species reacts at 255 K to form ethylene, acetaldehyde, and a surface oxametallacycle (−CH 2 CH 2 O−).…”

Section: ■ Introductionmentioning

confidence: 99%

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Surface Chemistry of 2-Iodoethanol on Pd(111): Orientation of Surface-Bound Alcohol Controls Selectivity

2012

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Temperature-programmed desorption (TPD), high-resolution electron energy loss spectroscopy (HREELS), and density functional theory (DFT) were used to investigate the thermal surface chemistry of 2-iodoethanol (ICH 2 CH 2 OH) on Pd(111). 2-Iodoethanol undergoes C−I scission upon adsorption at low temperatures, resulting in 2-hydroxyethyl (−CH 2 CH 2 OH) formation. At low coverage, this intermediate decomposes to form carbon monoxide and hydrogen during TPD. At higher coverage, hydroxyethyl reacts to produce ethanol, ethylene, water, 2-iodoethanol, and acetaldehyde, with nearly complete suppression of the decarbonylation pathway. DFT and HREELS results indicate that the coverage dependence of the reaction pathways is correlated with a change in the adsorption geometry of hydroxyethyl. At low coverage the C−O bond lies parallel to the surface, while at higher coverage it is shifted into a perpendicular position. Adsorbed iodine is observed to play a significant role in blocking sites and favoring the upright adsorption geometry. These results have important implications for the use of catalyst modifiers in controlling selectivity in reactions of functional alcohols.

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Section: ■ Resultssupporting

confidence: 87%

Section: ■ Resultsmentioning

confidence: 99%

Section: ■ Introductionmentioning

confidence: 99%

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Surface Chemistry of 2-Iodoethanol on Pd(111): Orientation of Surface-Bound Alcohol Controls Selectivity

2012

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“…On the other hand, the O 1s binding energy for the carboxylate group appears at ∼531.5 eV. In the 400 K spectrum of Figure , the I 4d signals of 49.7 eV (I 4d 5/2 ) and 51.5 eV (I 4d 3/2 ) are due to adsorbed I . In the 230 K spectrum, the photoelectrons of O 1s and I 4d are peaked at almost the same binding energies as those observed at 400 K, indicating the presence of carboxylate groups and I atoms on the surface.…”

Section: Resultsmentioning

confidence: 73%

Reaction Pathways of 2-Iodoacetic Acid on Cu(100): Coverage-Dependent Competition between C−I Bond Scission and COOH Deprotonation and Identification of Surface Intermediates

Lin

Liao

et al. 2010

Langmuir

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The chemistry of 2-iodoacetic acid on Cu(100) has been studied by a combination of reflection-absorption infrared spectroscopy (RAIRS), X-ray photoelectron spectroscopy (XPS), temperature-programmed reaction/desorption (TPR/D), and theoretical calculations based on density functional theory for the optimized intermediate structures. In the thermal decomposition of ICH(2)COOH on Cu(100) with a coverage less than a half monolayer, three surface intermediates, CH(2)COO, CH(3)COO, and CCOH, are generated and characterized spectroscopically. Based on their different thermal stabilities, the reaction pathways of ICH(2)COOH on Cu(100) at temperatures higher than 230 K are established to be ICH(2)COOH --> CH(2)COO + H + I, CH(2)COO + H --> CH(3)COO, and CH(3)COO --> CCOH. Theoretical calculations suggest that the surface CH(2)COO has the skeletal plane, with delocalized pi electrons, approximately parallel to the surface. The calculated Mulliken charges agree with the detected binding energies for the two carbon atoms in CH(2)COO on Cu(100). The CCOH derived from CH(3)COO decomposition has a CC stretching frequency at 2025 cm(-1), reflecting its triple-bond character which is consistent with the calculated CCOH structure on Cu(100). Theoretically, CCOH at the bridge and hollow sites has a similar stability and is adsorbed with the molecular axis approximately perpendicular to the surface. The TPR/D study has shown the evolution of the products of H(2), CH(4), H(2)O, CO, CO(2), CH(2)CO, and CH(3)COOH from CH(3)COO decomposition between 500 and 600 K and the formation of H(2) and CO from CCOH between 600 and 700 K. However, at a coverage near one monolayer, the major species formed at 230 and 320 K are proposed to be ICH(2)COO and CH(3)COO. CH(3)COO becomes the only species present on the surface at 400 K. That is, there are two reaction pathways of ICH(2)COOH --> ICH(2)COO + H and ICH(2)COO + H --> CH(3)COO + I (possibly via CH(2)COO), which are different from those observed at lower coverages. Because the C-I bond dissociation of iodoethane on copper single crystal surfaces occurs at approximately 120 K and that the deprotonation of CH(3)COOH on Cu(100) occurs at approximately 220 K, the preferential COOH dehydrogenation of monolayer ICH(2)COOH is an interesting result, possibly due to electronic and/or steric effects.

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“…Investigations of oxygenated hydrocarbon fragments on metal catalysts have attracted attention in the development of biomass conversion, involving bifunctional alcohols and olefin epoxidation. − Oxametallacycles have been proposed to be important surface intermediates in the oxidation of alkenes and hydrogenlysis of epoxides . Haloalcohols were often used as precursors to produce hydrocarbon fragments or oxametallacycles on well-defined metal surfaces. , For −CH 2 CH 2 O–, the reported systems included 2-haloethanols on Ag(100), Ag(111), Rh(111),Pd(111), Ni(100), Ni(111), and Cu(100). − The studies for ICH 2 CH 2 OH on Ag(110) and Ni(100), ClCH 2 CH 2 OH on Ni(111), and BrCH 2 CH 2 OH on Cu(100) made contributions to delineating the adsorption structure and diversified reaction pathways of −CH 2 CH 2 O– intermediate on the model surfaces with different catalytic reactivities. ,,− Besides, because of the competition in the bifunctional (C–X (carbon–halogen) and C–O–H) reactions, other surface intermediates, such as −CH 2 CH 2 OH and/or −OCH 2 CH 2 X, have been generated that further enrich the surface chemistry of 2-haloethanols. On Ag(111), −CH 2 CH 2 O– decomposes at 320 K to evolve acetaldehyde .…”

Section: Introductionmentioning

confidence: 99%

Comparison of the Chemistry of ClCH₂CH(CH₃)OH and ClCH₂CH₂CH₂OH on Cu(100) and O/Cu(100)

Yang

Chen

et al. 2016

J. Phys. Chem. C

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Thermal reactions of bifunctional 1-chloro-2-propanol and 3-chloro-1-propanol on Cu(100) and oxygen-precovered Cu(100) are presented in this article. X-ray photoelectron spectroscopy, reflection–absorption infrared spectroscopy and temperature-programmed reaction/desorption have been employed to investigate the decomposition process of 1-chloro-2-propanol on Cu(100). The competitive dissociation of the functional C–Cl and CO–H at 265 K results in the formation of ClCH2CH(CH3)O– and −CH2CH(CH3)O– surface intermediates at a 2:1 concentration ratio. This ratio decreases to ∼0.6:1 at 300 K. The −CH2CH(CH3)O– oxametallacycle is theoretically predicted to be bonded on the Cu(100) surface, with both the O and CH2 at bridge sites. This surface intermediate decomposes mainly at 300 K producing CH3C(O)CH3 and CH3CHCH2 in addition to H2 and CO. Preadsorbed oxygen atoms can stabilize the oxametallacycle and increases its reaction temperature to ∼350 K. Moreover, propene formation is promoted relative to acetone. In the reaction of 3-chloro-1-propanol on Cu(100), a low-temperature (159 K) formation channel of ClCH2CHCH2 is observed. Other products presumably from −CH2CH2CH2O– reaction, including CH2CHCHO, CH3CH2CHO, C2H4, CO, and H2, evolve at a temperature higher than ∼300 K. No propene from C–O dissociation is formed. Preadsorption of oxygen causes the evolution of these products to be shifted to ∼400 K, with additional CH3CH2CH2OH and a small amount of CH3CHCH2. The theoretical calculation indicates that −CH2CH2CH2O– is bonded via the 3CH2 and O at atop and bridge sites, respectively, and has an energy slightly higher than that of −CH2CH(CH3)O–, by 3.4 kcal·mol–1.

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Thermal reactions of 2-iodoethanol on Cu(100)

Cited by 5 publications

References 17 publications

Surface Chemistry of 2-Iodoethanol on Pd(111): Orientation of Surface-Bound Alcohol Controls Selectivity

Surface Chemistry of 2-Iodoethanol on Pd(111): Orientation of Surface-Bound Alcohol Controls Selectivity

Reaction Pathways of 2-Iodoacetic Acid on Cu(100): Coverage-Dependent Competition between C−I Bond Scission and COOH Deprotonation and Identification of Surface Intermediates

Comparison of the Chemistry of ClCH₂CH(CH₃)OH and ClCH₂CH₂CH₂OH on Cu(100) and O/Cu(100)

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Thermal reactions of 2-iodoethanol on Cu(100)

Cited by 5 publications

References 17 publications

Surface Chemistry of 2-Iodoethanol on Pd(111): Orientation of Surface-Bound Alcohol Controls Selectivity

Surface Chemistry of 2-Iodoethanol on Pd(111): Orientation of Surface-Bound Alcohol Controls Selectivity

Reaction Pathways of 2-Iodoacetic Acid on Cu(100): Coverage-Dependent Competition between C−I Bond Scission and COOH Deprotonation and Identification of Surface Intermediates

Comparison of the Chemistry of ClCH2CH(CH3)OH and ClCH2CH2CH2OH on Cu(100) and O/Cu(100)

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Comparison of the Chemistry of ClCH₂CH(CH₃)OH and ClCH₂CH₂CH₂OH on Cu(100) and O/Cu(100)