The adsorption and reaction of 2-iodoethanol on Ag(111)

Wu, Guan-Wei; Stacchiola, Darı́o; Kaltchev, M.; Tysoe, Wilfred T.

doi:10.1016/s0039-6028(00)00602-6

“…While oxygen influences parallel channels such as ethylene production, and sequential steps such as acetaldehyde oxidation, the energetics and yield of EO are essentially unaffected. This is in contrast to the influence of co-adsorbed iodine observed experimentally in [1,17,18], but is consistent with the DFT results for oxametallacycles on oxygen-containing silver surfaces reported by other groups [21,22], as we noted previously [3].…”

supporting

confidence: 93%

“…A review of some of the earlier results for oxametallacycles synthesized from iodoethanol illustrates this point. Both Wu et al [17] and we [18] have reported TPD results for spectroscopically verified oxametallacycles derived from iodoethanol on Ag(111). The synthesis process deposits a stoichiometric amount of iodine atoms on the surface, and the oxametallacycle intermediates react at 315 K to produce acetaldehyde with high selectivity.…”

mentioning

confidence: 82%

“…' We are aware of five sets of TPD results in the literature ascribed to -CH 2 CH 2 O-oxametallacycles on low index silver surfaces [1-3, 17, 18], including the two cited by Professor Waugh. Four of these include vibrational spectroscopic verification of the assignment [1,2,17,18]. Three involve oxametallacycles synthesized from iodoethanol [1,17,18], including an example from Tysoe and co-workers on Ag(111) [17], and two involve EO ring opening [2,3].…”

mentioning

confidence: 99%

“…Four of these include vibrational spectroscopic verification of the assignment [1,2,17,18]. Three involve oxametallacycles synthesized from iodoethanol [1,17,18], including an example from Tysoe and co-workers on Ag(111) [17], and two involve EO ring opening [2,3]. These examples show (1) that a very rich slate of products including EO, ethanol, acetaldehyde, and c-butyrolactone, can be formed from oxametallacycles on silver; (2) that the product selectivity is strongly dependent on surface structure and the presence of co-adsorbates; and (3) that the temperature range of oxametallacycle reactions (as tracked by TPD peak temperatures) is relatively insensitive to surface structure, co-adsorbates, or oxametallacycle coverage.…”

mentioning

confidence: 99%

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Reply to K. C. Waugh: “Comments on ‘Investigation of Ethylene Oxide on Clean and Oxygen-Covered Ag(110) Surfaces’”

Barteau

¹

2009

Catal Lett

0

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The fall and replacement of scientific paradigms often begins with their inability to explain some seemingly insignificant observation. While it would be the height of hubris to elevate the oxametallacycle mechanism for olefin epoxidation to the level scientific paradigm, nevertheless it has proven remarkably successful at explaining previous observations, producing new experimental and theoretical evidence, and generating successful predictions of new catalysts since direct experimental evidence for the existence of oxametallacycles on silver was produced a decade ago [1]. But is it fundamentally incompatible with the temperature programmed desorption data that we have published for ethylene oxide (EO) on clean [2] and oxygencontaining [3] silver surfaces, as Professor Waugh [4] contends? A brief review of the successes and limitations of this model, and of the possible interpretations of our published results, would appear to be in order.As we noted recently [5], oxametallacycle species were first associated with epoxide formation on silver by Brainard and Madix in 1989 [6]. The first synthesis of a stable oxametallacycle on a silver surface with spectroscopic verification was reported in 1998 [1], and the first example of epoxide formation from an oxametallacycle in 2000 [7]. From a surface science perspective, the last decade has seen the synthesis of different functionalized oxametallacycles on silver via a variety of routes, with spectroscopic verification by vibrational spectroscopies, photoelectron spectroscopies, and X-ray absorption spectroscopies. A rich chemistry of these species has been revealed which includes the production of epoxides in most cases. As an aside, these discoveries have served to stimulate and support the identification of oxametallacycle species on a variety of other surfaces, most recently Si (100) [8].The oxametallacycle mechanism has also led to remarkable advances in our understanding of olefin epoxidation catalysis. It has given form to the ''common intermediate'' in olefin epoxidation and combustion pathways first proposed by Cant and Hall [9]. It has proven central, not only to understanding ethylene epoxidation on silver, but to the epoxidations of butadiene [10] and styrene [11], as well. It has provided a framework for interpretation of some promoter effects on these catalytic processes [12]. It has explained long standing experimental observations from the catalysis literature, including (quantitatively) the deuterium isotope effect on epoxidation selectivity [13]. It has successfully connected theory, surface science, and catalytic reactor experiments for the epoxidations of ethylene, butadiene and styrene [14]. It has led to the successful prediction of new bimetallic catalysts with improved epoxidation selectivity [15], and has provided the basis for extending styrene epoxidation from silver to gold [16].Professor Waugh has suggested that these successes are undermined by the experimental results that we have published [2,3] for TPD experiments following the ring open...

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“…The aldehyde has been proposed as the gateway species to combustion products [21]. Stable, spectroscopically verified oxametallacycles have been synthesized from 2-iodo-ethanol on Ag(110) [22] and Ag(111) [6,23], ethylene oxide on Ag(111) [3], epoxybutene on Ag(110) [5] and Ag(111) [8], and styrene oxide on Ag(110) [24] and Ag(111) [9].…”

Section: Introductionmentioning

confidence: 99%

Investigation of Ethylene Oxide on Clean and Oxygen-Covered Ag(110) Surfaces

Lukaski

¹

,

Barteau

²

2008

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Temperature-programmed desorption (TPD) and Density Functional Theory (DFT) were used to investigate the reactions of oxametallacycles derived from ethylene oxide on clean and oxygen-covered Ag (110) surfaces. Ethylene oxide ring-opens following adsorption at 250 K on both clean and O-covered Ag(110) to form a stable oxametallacycle. On the clean Ag(110) surface, the oxametallacycle reacts to reform the parent epoxide at 280 K during TPD, while the aldehyde isomer, acetaldehyde, is observed at higher oxametallacycle coverages. In the presence of coadsorbed oxygen atoms, a portion of the oxametallacycles dissociate to release ethylene. However, of those that react to form oxygen-containing products, the fraction forming ethylene oxide is similar to that on the clean surface. The acetaldehyde product of oxametallacycle reactions combusts via formation of acetate species; the acetates react to form CO 2 at temperatures as low as 360 K on the O-covered surface. No evidence was observed for other combustion channels. This work provides experimental evidence for the connection of oxametallacycles to combustion via acetaldehyde formation as well as to ringclosure to form ethylene oxide.

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Electrochemistry of Silver

Orlik

¹

,

Galus

²

2006

Encyclopedia of Electrochemistry

1

0

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The sections in this article are Properties of Ag Electrodes Polycrystalline Ag Electrodes Preparation Surface and Double‐layer Properties Single‐crystal Ag Electrodes Preparation Surface and Double‐layer Properties Surface Dynamics Affinity of Water and Nonaqueous Solvent Molecules to Ag Surfaces Adsorption of Inorganic Species on Ag Electrodes Halide Ions pc ‐ Ag Electrodes Single‐crystal Ag Electrodes Pseudohalide Oxygen and its Compounds Sulfur Compounds Inorganic Carbon Compounds Fullerenes Other Inorganic Compounds Metalocenes Adsorption of Organic Species on Ag Electrodes Hydrocarbons Pyridine and Other Nitrogen Compounds Carboxylic Acids Alcohols Sulfur Compounds Thiourea ( TU ) Alkanethiols and Self‐assembled Monolayers Biochemically Important Compounds Adsorption on Modified Ag Electrodes Other Organic Compounds Electrode Processes with Participation of Silver Electrodes Reactions Involving Oxidation of Ag Surface Oxygen and its Compounds Sulfur Compounds Carbon Compounds Electrode Reactions of Selected Organic Compounds, Adsorbed on Ag Electrodes Biochemically Important Species Underpotential Deposition Processes Ag UPD on Ag Ag UPD on Au and Pt Pb Tl Ni Chalcogenides Other Elements and Compounds Electrodeposition and Electrodissolution Processes of Ag Electrodeposition Processes Electrodissolution Processes Silver Compounds at the Oxidation States Higher Than I

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The adsorption and reaction of 2-iodoethanol on Ag(111)

Cited by 50 publications

References 21 publications

Reply to K. C. Waugh: “Comments on ‘Investigation of Ethylene Oxide on Clean and Oxygen-Covered Ag(110) Surfaces’”

Reply to K. C. Waugh: “Comments on ‘Investigation of Ethylene Oxide on Clean and Oxygen-Covered Ag(110) Surfaces’”

Investigation of Ethylene Oxide on Clean and Oxygen-Covered Ag(110) Surfaces

Electrochemistry of Silver

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