Structure and reaction pathways of methyl lactate on Pd(111)

Burkholder, Luke

doi:10.1016/j.susc.2009.07.008

Cited by 8 publications

(5 citation statements)

References 51 publications

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“…Two keto forms of methyl pyruvate have been previously identified on Pd(111) by infrared spectroscopy: a flat-lying species present at lower coverages, which converts to a second, perpendicular form due to surface crowding as the surface coverage increases. 6,59 The assignment to these species was confirmed using DFT, 43 and the calculated heats of adsorption agreed well with the measured desorption activations energies. Therefore, at first sight this would suggest that the two structures measured by STM (Figures 1 and 2) should correspond to the flat-lying and upright geometries of the keto form of methyl pyruvate.…”

Section: ■ Resultssupporting

confidence: 65%

Identifying Molecular Species on Surfaces by Scanning Tunneling Microscopy: Methyl Pyruvate on Pd(111)

et al. 2013

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The structures of low coverages of methyl pyruvate on a Pd(111) surface at 120 K were studied using scanning tunneling microscopy in ultrahigh vacuum. The experimentally observed images were assigned to adsorbate structures using a combination of density functional theory calculations and by simulating the images using the Bardeen method. Two forms of methyl pyruvate were identified. The first, previously found using reflection–absorption infrared spectroscopy, was a flat-lying, keto form of cis-methyl pyruvate. It was characterized by elongated, two-lobed images with the long axes of the images oriented at ∼0 and ∼30° to the close-packed directions. The structure was simulated using clean, CO- and methyl-functionalized gold tips, and the simulated images agreed well with those found experimentally. The simulated structures were not strongly dependent on the tip structure or tip bias. This approach was used to identify the nature of the second species as the enol form of cis-methyl pyruvate with the carbonyl groups located over atop and bridge sites. Again, the orientation of the image with respect to the underlying Pd(111) lattice as well as the calculated image shape agreed well with the experimental images.

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Section: ■ Resultssupporting

confidence: 65%

Identifying Molecular Species on Surfaces by Scanning Tunneling Microscopy: Methyl Pyruvate on Pd(111)

et al. 2013

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“…The sharp feature at 1755 cm -1 is assigned to a C O stretching mode, and the broad features at ~1450 and ~1370 cm -1 to asymmetric and symmetric methyl bending modes, respectively. 19 The intense peak at ~1228 cm -1 is due to an asymmetric COC ester group stretching vibration and the feature at 1134 cm -1 is assigned to a methyl rocking mode. The smaller peaks at ~1053 and ~984 cm -1 are assigned to C-C and C-O modes, respectively.…”

Section: Resultsmentioning

confidence: 99%

Double metal cyanide catalysts bearing lactate esters as eco-friendly complexing agents for the synthesis of highly pure polyols

et al. 2011

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A green way of synthesizing double metal cyanide (DMC) catalysts for the ring opening polymerization of propylene oxide has been developed by using environmentally friendly and nontoxic lactate esters as complexing agents (CAs). The total amount of CA consumed in the catalyst preparation procedure can also be greatly reduced by combining with co-complexing agents bearing polyether backbones. The DMC catalysts produce highly pure polymers in high activity, enough to avoid labor, energy, and time-consuming catalyst removal procedures.

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“…First, a chiral alcohol product reacting back to a prochiral ketone re-enters the catalytic process and has a probability to undergo hydrogenation at nonmodified racemic sites, thereby lowering both the enantiomeric excess and the conversion. The conversion of methyl lactate to chemisorbed methyl pyruvate on Pd(111) has been recently reported . Second, self-assembled enol structures could compete with the formation of 1:1 α-ketoester-modifier complexes.…”

Section: Discussionmentioning

confidence: 99%

Two-Dimensional Self-Assembly and Catalytic Function: Conversion of Chiral Alcohols into Self-Assembled Enols on Pt(111)

et al. 2009

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The chemical transformation and subsequent self-assembly of chiral alcohols on platinum was studied using three different pairs of prochiral ketones and their alcohol products. The ketones were chosen because they represent three different types of substrates in the asymmetric hydrogenation on chirally modified platinum catalysts. Scanning tunneling microscopy and high-resolution electron energy loss vibrational spectroscopy data were combined to show that methyl lactate transforms into the enol tautomer of methyl pyruvate on Pt(111) at room temperature. Specifically, the chiral alcohol undergoes dehydrogenation leading to the same adsorbed enol assemblies that are formed directly through the adsorption of the prochiral α-ketoester. Similarly, 1-phenylethanol transforms into assemblies of the enol tautomer of acetophenone. The interrelationship between surface reactivity and self-assembly was further explored by studying the oxidation of 1-phenyl-2,2,2-trifluoroethanol to form CH···O bonded 2,2,2-trifluoroacetophenone assemblies. In terms of catalytic function, these self-assembly processes provide insight on the optimization of the asymmetric hydrogenation of activated ketones on chirally modified platinum catalysts.

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Structure and reaction pathways of methyl lactate on Pd(111)

Cited by 8 publications

References 51 publications

Identifying Molecular Species on Surfaces by Scanning Tunneling Microscopy: Methyl Pyruvate on Pd(111)

Identifying Molecular Species on Surfaces by Scanning Tunneling Microscopy: Methyl Pyruvate on Pd(111)

Double metal cyanide catalysts bearing lactate esters as eco-friendly complexing agents for the synthesis of highly pure polyols

Two-Dimensional Self-Assembly and Catalytic Function: Conversion of Chiral Alcohols into Self-Assembled Enols on Pt(111)

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