Enantioselective hydrogenation of ethyl pyruvate catalysed by cinchonine-modified Pt/Al2O3: Tilted adsorption geometry of cinchonine

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Abstract

The enantioselective hydrogenation of ethyl pyruvate (EtPy) was studied on Pt-alumina catalyst modified by cinchonine (CN) and for comparison by cinchonidine (CD) in toluene and in AcOH. The effects of the modifiers concentration on the reaction rate and the enantioselectivity were examined. Using the Engelhard 4759 catalyst under mild experimental conditions (room temperature, hydrogen pressure 1 bar) in the case of CN (S)-ethyl lactate (EtLt) formed in excess (ee) (in AcOH eemax ∼ 88%; in toluene ee max ∼ 72%). In the case of CD (R)-EtLt formed in excess (in AcOH eemax ∼ 93%; in toluene eemax ∼ 84%). The results of H-D exchange measurements and results of modifier mixtures suggest that the compounds responsible for chiral induction are different intermediates, which structure depends mostly on the acidic or non-acidic nature of the hydrogenation medium. The proposed structure of intermediate responsible for enantioselection is an 1:1 CN- or CD-EtPy surface complex in which the quinoline skeleton of CD approximately parallel on the Pt surface while the quinoline plane of CN being tilted relative to the Pt surface under identical experimental conditions.

Original languageEnglish
Pages (from-to)161-167
Number of pages7
JournalCatalysis Letters
Volume100
Issue number3-4
DOIs
Publication statusPublished - 2005

Fingerprint

pyruvates
Hydrogenation
hydrogenation
Toluene
toluene
lactates
quinoline
Adsorption
adsorption
Geometry
geometry
catalysts
Catalysts
Enantioselectivity
musculoskeletal system
Reaction rates
Aluminum Oxide
induction
reaction kinetics
Alumina

Keywords

  • Chiral hydrogenation
  • Cinchonine
  • Conformation
  • ESI-MS-MS
  • Ethyl pyruvate
  • Intermediate
  • Pt-alumina
  • Solvent effect
  • Tilted adsorption

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Catalysis

Cite this

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title = "Enantioselective hydrogenation of ethyl pyruvate catalysed by cinchonine-modified Pt/Al2O3: Tilted adsorption geometry of cinchonine",
abstract = "The enantioselective hydrogenation of ethyl pyruvate (EtPy) was studied on Pt-alumina catalyst modified by cinchonine (CN) and for comparison by cinchonidine (CD) in toluene and in AcOH. The effects of the modifiers concentration on the reaction rate and the enantioselectivity were examined. Using the Engelhard 4759 catalyst under mild experimental conditions (room temperature, hydrogen pressure 1 bar) in the case of CN (S)-ethyl lactate (EtLt) formed in excess (ee) (in AcOH eemax ∼ 88{\%}; in toluene ee max ∼ 72{\%}). In the case of CD (R)-EtLt formed in excess (in AcOH eemax ∼ 93{\%}; in toluene eemax ∼ 84{\%}). The results of H-D exchange measurements and results of modifier mixtures suggest that the compounds responsible for chiral induction are different intermediates, which structure depends mostly on the acidic or non-acidic nature of the hydrogenation medium. The proposed structure of intermediate responsible for enantioselection is an 1:1 CN- or CD-EtPy surface complex in which the quinoline skeleton of CD approximately parallel on the Pt surface while the quinoline plane of CN being tilted relative to the Pt surface under identical experimental conditions.",
keywords = "Chiral hydrogenation, Cinchonine, Conformation, ESI-MS-MS, Ethyl pyruvate, Intermediate, Pt-alumina, Solvent effect, Tilted adsorption",
author = "M. Bart{\'o}k and M{\'a}ria Sutyinszki and K. Bal{\'a}zsik and G. Sz{\"o}llősi",
year = "2005",
doi = "10.1007/s10562-004-3449-2",
language = "English",
volume = "100",
pages = "161--167",
journal = "Catalysis Letters",
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TY - JOUR

T1 - Enantioselective hydrogenation of ethyl pyruvate catalysed by cinchonine-modified Pt/Al2O3

T2 - Tilted adsorption geometry of cinchonine

AU - Bartók, M.

AU - Sutyinszki, Mária

AU - Balázsik, K.

AU - Szöllősi, G.

PY - 2005

Y1 - 2005

N2 - The enantioselective hydrogenation of ethyl pyruvate (EtPy) was studied on Pt-alumina catalyst modified by cinchonine (CN) and for comparison by cinchonidine (CD) in toluene and in AcOH. The effects of the modifiers concentration on the reaction rate and the enantioselectivity were examined. Using the Engelhard 4759 catalyst under mild experimental conditions (room temperature, hydrogen pressure 1 bar) in the case of CN (S)-ethyl lactate (EtLt) formed in excess (ee) (in AcOH eemax ∼ 88%; in toluene ee max ∼ 72%). In the case of CD (R)-EtLt formed in excess (in AcOH eemax ∼ 93%; in toluene eemax ∼ 84%). The results of H-D exchange measurements and results of modifier mixtures suggest that the compounds responsible for chiral induction are different intermediates, which structure depends mostly on the acidic or non-acidic nature of the hydrogenation medium. The proposed structure of intermediate responsible for enantioselection is an 1:1 CN- or CD-EtPy surface complex in which the quinoline skeleton of CD approximately parallel on the Pt surface while the quinoline plane of CN being tilted relative to the Pt surface under identical experimental conditions.

AB - The enantioselective hydrogenation of ethyl pyruvate (EtPy) was studied on Pt-alumina catalyst modified by cinchonine (CN) and for comparison by cinchonidine (CD) in toluene and in AcOH. The effects of the modifiers concentration on the reaction rate and the enantioselectivity were examined. Using the Engelhard 4759 catalyst under mild experimental conditions (room temperature, hydrogen pressure 1 bar) in the case of CN (S)-ethyl lactate (EtLt) formed in excess (ee) (in AcOH eemax ∼ 88%; in toluene ee max ∼ 72%). In the case of CD (R)-EtLt formed in excess (in AcOH eemax ∼ 93%; in toluene eemax ∼ 84%). The results of H-D exchange measurements and results of modifier mixtures suggest that the compounds responsible for chiral induction are different intermediates, which structure depends mostly on the acidic or non-acidic nature of the hydrogenation medium. The proposed structure of intermediate responsible for enantioselection is an 1:1 CN- or CD-EtPy surface complex in which the quinoline skeleton of CD approximately parallel on the Pt surface while the quinoline plane of CN being tilted relative to the Pt surface under identical experimental conditions.

KW - Chiral hydrogenation

KW - Cinchonine

KW - Conformation

KW - ESI-MS-MS

KW - Ethyl pyruvate

KW - Intermediate

KW - Pt-alumina

KW - Solvent effect

KW - Tilted adsorption

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