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Swetlana Schauermann - One of the best experts on this subject based on the ideXlab platform.
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keto Enol tautomerization as a first step in hydrogenation of carbonyl compounds
Journal of Physical Chemistry C, 2019Co-Authors: Smadar Attia, Carsten Schröder, Marvin C Schmidt, Jann Weber, Annkatrin Baumann, Swetlana SchauermannAbstract:Keto–Enol tautomerization of carbonyl compounds to their Enol form is theoretically predicted to enable a low-barrier pathway for hydrogenation of normally very stable C═O bond. In the scope of this anticipated mechanism, the reaction can proceed via two consecutive steps, including the formation of Enol followed by an H insertion into the Enolic C═C bond, and exhibits a lower activation barrier than the direct H insertion into the carbonyl group. Here, we present an experimental study on atomistic level details of hydrogenation of a simple carbonyl compound acetophenone over Pt(111) providing experimental evidence that keto–Enol tautomerization plays a crucial role in this reaction. By employing a combination of spectroscopic and imaging techniques, we show that acetophenone forms ketone–Enol dimers, in which the normally unstable form of Enol is stabilized by H-bonding with the carbonyl group of the neighboring acetophenone molecule. These ketone–Enol dimers can attach an H atom to form a reaction inter...
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Keto–Enol Tautomerization as a First Step in Hydrogenation of Carbonyl Compounds
The Journal of Physical Chemistry C, 2019Co-Authors: Smadar Attia, Carsten Schröder, Marvin C Schmidt, Jann Weber, Annkatrin Baumann, Swetlana SchauermannAbstract:Keto–Enol tautomerization of carbonyl compounds to their Enol form is theoretically predicted to enable a low-barrier pathway for hydrogenation of normally very stable C═O bond. In the scope of this anticipated mechanism, the reaction can proceed via two consecutive steps, including the formation of Enol followed by an H insertion into the Enolic C═C bond, and exhibits a lower activation barrier than the direct H insertion into the carbonyl group. Here, we present an experimental study on atomistic level details of hydrogenation of a simple carbonyl compound acetophenone over Pt(111) providing experimental evidence that keto–Enol tautomerization plays a crucial role in this reaction. By employing a combination of spectroscopic and imaging techniques, we show that acetophenone forms ketone–Enol dimers, in which the normally unstable form of Enol is stabilized by H-bonding with the carbonyl group of the neighboring acetophenone molecule. These ketone–Enol dimers can attach an H atom to form a reaction inter...
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Keto–Enol Tautomerization as a First Step in Hydrogenation of Carbonyl Compounds
The Journal of Physical Chemistry, 2019Co-Authors: Smadar Attia, Carsten Schröder, Marvin C Schmidt, Jann Weber, Annkatrin Baumann, Swetlana SchauermannAbstract:Keto–Enol tautomerization of carbonyl compounds to their Enol form is theoretically predicted to enable a low-barrier pathway for hydrogenation of normally very stable C═O bond. In the scope of this anticipated mechanism, the reaction can proceed via two consecutive steps, including the formation of Enol followed by an H insertion into the Enolic C═C bond, and exhibits a lower activation barrier than the direct H insertion into the carbonyl group. Here, we present an experimental study on atomistic level details of hydrogenation of a simple carbonyl compound acetophenone over Pt(111) providing experimental evidence that keto–Enol tautomerization plays a crucial role in this reaction. By employing a combination of spectroscopic and imaging techniques, we show that acetophenone forms ketone–Enol dimers, in which the normally unstable form of Enol is stabilized by H-bonding with the carbonyl group of the neighboring acetophenone molecule. These ketone–Enol dimers can attach an H atom to form a reaction intermediate consisting of a partly hydrogenated acetophenone species and nonhydrogenated acetophenone. Based on the spectroscopic assignment of the reaction intermediate, we conclude that H atom can be attached either to the C═C bond of the Enol part, or to the strongly weakened C═O bond of the ketone part of the ketone–Enol dimer. In both cases, the formation of ketone–Enol dimer species was found to be a crucial step in acetophenone hydrogenation. Observed phenomena provide atomistic level insights into the mechanisms of heterogeneously catalyzed hydrogenation of simple carbonyl compounds and can be employed for purposeful modification of catalysts with functional groups capable of stabilizing the Enol species.
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keto Enol tautomerization as a first step in hydrogenation of carbonyl compounds
The Journal of Physical Chemistry, 2019Co-Authors: Smadar Attia, Carsten Schröder, Marvin C Schmidt, Jann Weber, Annkatrin Baumann, Swetlana SchauermannAbstract:Keto–Enol tautomerization of carbonyl compounds to their Enol form is theoretically predicted to enable a low-barrier pathway for hydrogenation of normally very stable C═O bond. In the scope of this anticipated mechanism, the reaction can proceed via two consecutive steps, including the formation of Enol followed by an H insertion into the Enolic C═C bond, and exhibits a lower activation barrier than the direct H insertion into the carbonyl group. Here, we present an experimental study on atomistic level details of hydrogenation of a simple carbonyl compound acetophenone over Pt(111) providing experimental evidence that keto–Enol tautomerization plays a crucial role in this reaction. By employing a combination of spectroscopic and imaging techniques, we show that acetophenone forms ketone–Enol dimers, in which the normally unstable form of Enol is stabilized by H-bonding with the carbonyl group of the neighboring acetophenone molecule. These ketone–Enol dimers can attach an H atom to form a reaction intermediate consisting of a partly hydrogenated acetophenone species and nonhydrogenated acetophenone. Based on the spectroscopic assignment of the reaction intermediate, we conclude that H atom can be attached either to the C═C bond of the Enol part, or to the strongly weakened C═O bond of the ketone part of the ketone–Enol dimer. In both cases, the formation of ketone–Enol dimer species was found to be a crucial step in acetophenone hydrogenation. Observed phenomena provide atomistic level insights into the mechanisms of heterogeneously catalyzed hydrogenation of simple carbonyl compounds and can be employed for purposeful modification of catalysts with functional groups capable of stabilizing the Enol species.
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Surface-Driven Keto-Enol Tautomerization: Atomistic Insights into Enol Formation and Stabilization Mechanisms.
Angewandte Chemie (International ed. in English), 2018Co-Authors: Smadar Attia, Marvin‐christopher Schmidt, Carsten Schröder, Pascal Pessier, Swetlana SchauermannAbstract:Tautomerisation of simple carbonyl compounds to their Enol counterparts on metal surfaces is envisaged to enable an easier route for hydrogenation of the C=O bond in heterogeneously catalyzed reactions. To understand the mechanisms of Enol formation and stabilization over catalytically active metal surfaces, we performed a mechanistic study on keto-Enol tautomerization of a monocarbonyl compound acetophenon over Pt(111) surface. By employing infrared reflection adsorption spectroscopy in combination with scanning tunneling microscopy, we found that Enol can be formed by building a ketone-Enol dimer, in which one molecule in the Enol form is stabilized through hydrogen bonding to the carbonyl group of the second ketone molecule. Based on the investigations of the co-adsorption behavior of acetophenone and hydrogen, we conclude that keto-Enol tautomerization occurs in the intramolecular process and does not involve hydrogen transfer through the surface hypothesized previously.
Smadar Attia - One of the best experts on this subject based on the ideXlab platform.
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keto Enol tautomerization as a first step in hydrogenation of carbonyl compounds
Journal of Physical Chemistry C, 2019Co-Authors: Smadar Attia, Carsten Schröder, Marvin C Schmidt, Jann Weber, Annkatrin Baumann, Swetlana SchauermannAbstract:Keto–Enol tautomerization of carbonyl compounds to their Enol form is theoretically predicted to enable a low-barrier pathway for hydrogenation of normally very stable C═O bond. In the scope of this anticipated mechanism, the reaction can proceed via two consecutive steps, including the formation of Enol followed by an H insertion into the Enolic C═C bond, and exhibits a lower activation barrier than the direct H insertion into the carbonyl group. Here, we present an experimental study on atomistic level details of hydrogenation of a simple carbonyl compound acetophenone over Pt(111) providing experimental evidence that keto–Enol tautomerization plays a crucial role in this reaction. By employing a combination of spectroscopic and imaging techniques, we show that acetophenone forms ketone–Enol dimers, in which the normally unstable form of Enol is stabilized by H-bonding with the carbonyl group of the neighboring acetophenone molecule. These ketone–Enol dimers can attach an H atom to form a reaction inter...
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Keto–Enol Tautomerization as a First Step in Hydrogenation of Carbonyl Compounds
The Journal of Physical Chemistry C, 2019Co-Authors: Smadar Attia, Carsten Schröder, Marvin C Schmidt, Jann Weber, Annkatrin Baumann, Swetlana SchauermannAbstract:Keto–Enol tautomerization of carbonyl compounds to their Enol form is theoretically predicted to enable a low-barrier pathway for hydrogenation of normally very stable C═O bond. In the scope of this anticipated mechanism, the reaction can proceed via two consecutive steps, including the formation of Enol followed by an H insertion into the Enolic C═C bond, and exhibits a lower activation barrier than the direct H insertion into the carbonyl group. Here, we present an experimental study on atomistic level details of hydrogenation of a simple carbonyl compound acetophenone over Pt(111) providing experimental evidence that keto–Enol tautomerization plays a crucial role in this reaction. By employing a combination of spectroscopic and imaging techniques, we show that acetophenone forms ketone–Enol dimers, in which the normally unstable form of Enol is stabilized by H-bonding with the carbonyl group of the neighboring acetophenone molecule. These ketone–Enol dimers can attach an H atom to form a reaction inter...
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Keto–Enol Tautomerization as a First Step in Hydrogenation of Carbonyl Compounds
The Journal of Physical Chemistry, 2019Co-Authors: Smadar Attia, Carsten Schröder, Marvin C Schmidt, Jann Weber, Annkatrin Baumann, Swetlana SchauermannAbstract:Keto–Enol tautomerization of carbonyl compounds to their Enol form is theoretically predicted to enable a low-barrier pathway for hydrogenation of normally very stable C═O bond. In the scope of this anticipated mechanism, the reaction can proceed via two consecutive steps, including the formation of Enol followed by an H insertion into the Enolic C═C bond, and exhibits a lower activation barrier than the direct H insertion into the carbonyl group. Here, we present an experimental study on atomistic level details of hydrogenation of a simple carbonyl compound acetophenone over Pt(111) providing experimental evidence that keto–Enol tautomerization plays a crucial role in this reaction. By employing a combination of spectroscopic and imaging techniques, we show that acetophenone forms ketone–Enol dimers, in which the normally unstable form of Enol is stabilized by H-bonding with the carbonyl group of the neighboring acetophenone molecule. These ketone–Enol dimers can attach an H atom to form a reaction intermediate consisting of a partly hydrogenated acetophenone species and nonhydrogenated acetophenone. Based on the spectroscopic assignment of the reaction intermediate, we conclude that H atom can be attached either to the C═C bond of the Enol part, or to the strongly weakened C═O bond of the ketone part of the ketone–Enol dimer. In both cases, the formation of ketone–Enol dimer species was found to be a crucial step in acetophenone hydrogenation. Observed phenomena provide atomistic level insights into the mechanisms of heterogeneously catalyzed hydrogenation of simple carbonyl compounds and can be employed for purposeful modification of catalysts with functional groups capable of stabilizing the Enol species.
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keto Enol tautomerization as a first step in hydrogenation of carbonyl compounds
The Journal of Physical Chemistry, 2019Co-Authors: Smadar Attia, Carsten Schröder, Marvin C Schmidt, Jann Weber, Annkatrin Baumann, Swetlana SchauermannAbstract:Keto–Enol tautomerization of carbonyl compounds to their Enol form is theoretically predicted to enable a low-barrier pathway for hydrogenation of normally very stable C═O bond. In the scope of this anticipated mechanism, the reaction can proceed via two consecutive steps, including the formation of Enol followed by an H insertion into the Enolic C═C bond, and exhibits a lower activation barrier than the direct H insertion into the carbonyl group. Here, we present an experimental study on atomistic level details of hydrogenation of a simple carbonyl compound acetophenone over Pt(111) providing experimental evidence that keto–Enol tautomerization plays a crucial role in this reaction. By employing a combination of spectroscopic and imaging techniques, we show that acetophenone forms ketone–Enol dimers, in which the normally unstable form of Enol is stabilized by H-bonding with the carbonyl group of the neighboring acetophenone molecule. These ketone–Enol dimers can attach an H atom to form a reaction intermediate consisting of a partly hydrogenated acetophenone species and nonhydrogenated acetophenone. Based on the spectroscopic assignment of the reaction intermediate, we conclude that H atom can be attached either to the C═C bond of the Enol part, or to the strongly weakened C═O bond of the ketone part of the ketone–Enol dimer. In both cases, the formation of ketone–Enol dimer species was found to be a crucial step in acetophenone hydrogenation. Observed phenomena provide atomistic level insights into the mechanisms of heterogeneously catalyzed hydrogenation of simple carbonyl compounds and can be employed for purposeful modification of catalysts with functional groups capable of stabilizing the Enol species.
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Surface-Driven Keto-Enol Tautomerization: Atomistic Insights into Enol Formation and Stabilization Mechanisms.
Angewandte Chemie (International ed. in English), 2018Co-Authors: Smadar Attia, Marvin‐christopher Schmidt, Carsten Schröder, Pascal Pessier, Swetlana SchauermannAbstract:Tautomerisation of simple carbonyl compounds to their Enol counterparts on metal surfaces is envisaged to enable an easier route for hydrogenation of the C=O bond in heterogeneously catalyzed reactions. To understand the mechanisms of Enol formation and stabilization over catalytically active metal surfaces, we performed a mechanistic study on keto-Enol tautomerization of a monocarbonyl compound acetophenon over Pt(111) surface. By employing infrared reflection adsorption spectroscopy in combination with scanning tunneling microscopy, we found that Enol can be formed by building a ketone-Enol dimer, in which one molecule in the Enol form is stabilized through hydrogen bonding to the carbonyl group of the second ketone molecule. Based on the investigations of the co-adsorption behavior of acetophenone and hydrogen, we conclude that keto-Enol tautomerization occurs in the intramolecular process and does not involve hydrogen transfer through the surface hypothesized previously.
Masako Nakagawa - One of the best experts on this subject based on the ideXlab platform.
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Synthesis of substituted 1,2-dihydroquinolines and quinolines using ene–ene metathesis and ene–Enol ether metathesis
Tetrahedron Letters, 2001Co-Authors: Mitsuhiro Arisawa, Chumpol Theeraladanon, Atsushi Nishida, Masako NakagawaAbstract:Abstract We describe a novel and convenient method for quinoline synthesis using ring-closing olefin metathesis (RCM), ene–ene metathesis, and ene–Enol ether metathesis. We also report the first example of Enol silyl ether–ene metathesis to produce cyclic Enol silyl ether. Using this method, versatile substituted quinoline derivatives were readily prepared in excellent yield from anthranilic acid derivatives.
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synthesis of substituted 1 2 dihydroquinolines and quinolines using ene ene metathesis and ene Enol ether metathesis
Tetrahedron Letters, 2001Co-Authors: Mitsuhiro Arisawa, Chumpol Theeraladanon, Atsushi Nishida, Masako NakagawaAbstract:Abstract We describe a novel and convenient method for quinoline synthesis using ring-closing olefin metathesis (RCM), ene–ene metathesis, and ene–Enol ether metathesis. We also report the first example of Enol silyl ether–ene metathesis to produce cyclic Enol silyl ether. Using this method, versatile substituted quinoline derivatives were readily prepared in excellent yield from anthranilic acid derivatives.
Robert A. Reamer - One of the best experts on this subject based on the ideXlab platform.
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asymmetric synthesis of cyclic hydroxy ketones derived from Enol ethers via sharpless asymmetric dihydroxylation a study in the correlation of the Enol ether chain length and enantioselectivity
Journal of Organic Chemistry, 2003Co-Authors: Benjamin Marcune, Sandor Karady, Lisa Dimichele, Mirlinda Biba, Paul J. Reider, Ross A. Miller, Robert A. ReamerAbstract:The Sharpless asymmetric dihydroxylation reaction of Enol ethers derived from their corresponding cyclic ketones, gave α-hydroxyketones with high enantioselectivity. The enantiomeric excess was found to be proportional to the length of the unbranched Enol ether chain with a maximum ee for the pentyl Enol ether. An efficient synthesis of α-hydroxy chromanone in >90% ee was demonstrated using this method.
Carsten Schröder - One of the best experts on this subject based on the ideXlab platform.
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keto Enol tautomerization as a first step in hydrogenation of carbonyl compounds
Journal of Physical Chemistry C, 2019Co-Authors: Smadar Attia, Carsten Schröder, Marvin C Schmidt, Jann Weber, Annkatrin Baumann, Swetlana SchauermannAbstract:Keto–Enol tautomerization of carbonyl compounds to their Enol form is theoretically predicted to enable a low-barrier pathway for hydrogenation of normally very stable C═O bond. In the scope of this anticipated mechanism, the reaction can proceed via two consecutive steps, including the formation of Enol followed by an H insertion into the Enolic C═C bond, and exhibits a lower activation barrier than the direct H insertion into the carbonyl group. Here, we present an experimental study on atomistic level details of hydrogenation of a simple carbonyl compound acetophenone over Pt(111) providing experimental evidence that keto–Enol tautomerization plays a crucial role in this reaction. By employing a combination of spectroscopic and imaging techniques, we show that acetophenone forms ketone–Enol dimers, in which the normally unstable form of Enol is stabilized by H-bonding with the carbonyl group of the neighboring acetophenone molecule. These ketone–Enol dimers can attach an H atom to form a reaction inter...
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Keto–Enol Tautomerization as a First Step in Hydrogenation of Carbonyl Compounds
The Journal of Physical Chemistry C, 2019Co-Authors: Smadar Attia, Carsten Schröder, Marvin C Schmidt, Jann Weber, Annkatrin Baumann, Swetlana SchauermannAbstract:Keto–Enol tautomerization of carbonyl compounds to their Enol form is theoretically predicted to enable a low-barrier pathway for hydrogenation of normally very stable C═O bond. In the scope of this anticipated mechanism, the reaction can proceed via two consecutive steps, including the formation of Enol followed by an H insertion into the Enolic C═C bond, and exhibits a lower activation barrier than the direct H insertion into the carbonyl group. Here, we present an experimental study on atomistic level details of hydrogenation of a simple carbonyl compound acetophenone over Pt(111) providing experimental evidence that keto–Enol tautomerization plays a crucial role in this reaction. By employing a combination of spectroscopic and imaging techniques, we show that acetophenone forms ketone–Enol dimers, in which the normally unstable form of Enol is stabilized by H-bonding with the carbonyl group of the neighboring acetophenone molecule. These ketone–Enol dimers can attach an H atom to form a reaction inter...
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Keto–Enol Tautomerization as a First Step in Hydrogenation of Carbonyl Compounds
The Journal of Physical Chemistry, 2019Co-Authors: Smadar Attia, Carsten Schröder, Marvin C Schmidt, Jann Weber, Annkatrin Baumann, Swetlana SchauermannAbstract:Keto–Enol tautomerization of carbonyl compounds to their Enol form is theoretically predicted to enable a low-barrier pathway for hydrogenation of normally very stable C═O bond. In the scope of this anticipated mechanism, the reaction can proceed via two consecutive steps, including the formation of Enol followed by an H insertion into the Enolic C═C bond, and exhibits a lower activation barrier than the direct H insertion into the carbonyl group. Here, we present an experimental study on atomistic level details of hydrogenation of a simple carbonyl compound acetophenone over Pt(111) providing experimental evidence that keto–Enol tautomerization plays a crucial role in this reaction. By employing a combination of spectroscopic and imaging techniques, we show that acetophenone forms ketone–Enol dimers, in which the normally unstable form of Enol is stabilized by H-bonding with the carbonyl group of the neighboring acetophenone molecule. These ketone–Enol dimers can attach an H atom to form a reaction intermediate consisting of a partly hydrogenated acetophenone species and nonhydrogenated acetophenone. Based on the spectroscopic assignment of the reaction intermediate, we conclude that H atom can be attached either to the C═C bond of the Enol part, or to the strongly weakened C═O bond of the ketone part of the ketone–Enol dimer. In both cases, the formation of ketone–Enol dimer species was found to be a crucial step in acetophenone hydrogenation. Observed phenomena provide atomistic level insights into the mechanisms of heterogeneously catalyzed hydrogenation of simple carbonyl compounds and can be employed for purposeful modification of catalysts with functional groups capable of stabilizing the Enol species.
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keto Enol tautomerization as a first step in hydrogenation of carbonyl compounds
The Journal of Physical Chemistry, 2019Co-Authors: Smadar Attia, Carsten Schröder, Marvin C Schmidt, Jann Weber, Annkatrin Baumann, Swetlana SchauermannAbstract:Keto–Enol tautomerization of carbonyl compounds to their Enol form is theoretically predicted to enable a low-barrier pathway for hydrogenation of normally very stable C═O bond. In the scope of this anticipated mechanism, the reaction can proceed via two consecutive steps, including the formation of Enol followed by an H insertion into the Enolic C═C bond, and exhibits a lower activation barrier than the direct H insertion into the carbonyl group. Here, we present an experimental study on atomistic level details of hydrogenation of a simple carbonyl compound acetophenone over Pt(111) providing experimental evidence that keto–Enol tautomerization plays a crucial role in this reaction. By employing a combination of spectroscopic and imaging techniques, we show that acetophenone forms ketone–Enol dimers, in which the normally unstable form of Enol is stabilized by H-bonding with the carbonyl group of the neighboring acetophenone molecule. These ketone–Enol dimers can attach an H atom to form a reaction intermediate consisting of a partly hydrogenated acetophenone species and nonhydrogenated acetophenone. Based on the spectroscopic assignment of the reaction intermediate, we conclude that H atom can be attached either to the C═C bond of the Enol part, or to the strongly weakened C═O bond of the ketone part of the ketone–Enol dimer. In both cases, the formation of ketone–Enol dimer species was found to be a crucial step in acetophenone hydrogenation. Observed phenomena provide atomistic level insights into the mechanisms of heterogeneously catalyzed hydrogenation of simple carbonyl compounds and can be employed for purposeful modification of catalysts with functional groups capable of stabilizing the Enol species.
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Surface-Driven Keto-Enol Tautomerization: Atomistic Insights into Enol Formation and Stabilization Mechanisms.
Angewandte Chemie (International ed. in English), 2018Co-Authors: Smadar Attia, Marvin‐christopher Schmidt, Carsten Schröder, Pascal Pessier, Swetlana SchauermannAbstract:Tautomerisation of simple carbonyl compounds to their Enol counterparts on metal surfaces is envisaged to enable an easier route for hydrogenation of the C=O bond in heterogeneously catalyzed reactions. To understand the mechanisms of Enol formation and stabilization over catalytically active metal surfaces, we performed a mechanistic study on keto-Enol tautomerization of a monocarbonyl compound acetophenon over Pt(111) surface. By employing infrared reflection adsorption spectroscopy in combination with scanning tunneling microscopy, we found that Enol can be formed by building a ketone-Enol dimer, in which one molecule in the Enol form is stabilized through hydrogen bonding to the carbonyl group of the second ketone molecule. Based on the investigations of the co-adsorption behavior of acetophenone and hydrogen, we conclude that keto-Enol tautomerization occurs in the intramolecular process and does not involve hydrogen transfer through the surface hypothesized previously.
