Resolution of Racemic <i>N</i>‐Benzyl α‐Amino Acids by Liquid‐Liquid Extraction: A Practical Method Using a Lipophilic Chiral Cobalt(III) Salen Complex and Mechanistic Studies

Dżygiel, Paweł; Reeve, Toby B.; Piarulli, Umberto; Krupička, Martin; Tvaroŝka, Igor; Gennari, Cesare

doi:10.1002/ejoc.200701101

Cited by 41 publications

(25 citation statements)

References 67 publications

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“…[47][48][49][50][51] The details for OER catalyst film preparation can be found in the experimental section. The as-prepared catalyst films were named Similar CV scans can be observed for complex 2, as shown in Figure S1.…”

Section: Resultsmentioning

confidence: 99%

Cobalt–Salen Complexes as Catalyst Precursors for Electrocatalytic Water Oxidation at Low Overpotential

et al. 2015

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Water oxidation is an important half-reaction to achieve overall water splitting. In this present study, we show that a series of molecular cobalt-salen complexes can serve as catalyst precursors to form nanostructured and amorphous cobalt-based thin films during electrodeposition, which can catalyze the water oxidation reaction at low overpotentials. Cyclic voltammetry and bulk electrolysis using the cobalt-based film electrodes demonstrated obvious catalytic currents in 0.1 M KBi solution at pH 9.2. The onset catalytic potentials of the catalyst films are at ~0.84 V (vs. Ag/AgCl) with a film made by electrodeposition of cobalt-salen complex 2 on FTO and at ~0.85 V for complex 4. Oxygen gas bubbles were clearly see on the FTO electrode when the applied potential was above the onset potential. The Tafel plots using a catalyst film made of complex 4 showed that appreciable catalytic current was observed starting at η = 0.26 V for the film (a current density of 0.1 mA/cm 2 required η = 290 mV), accompanied by a Faradic efficiency > 93% at 1.2 V.The catalyst film was further characterized by scanning electron microscopy (SEM), energy-dispersive X-ray analysis (EDX), and X-ray photoelectron spectroscopy (XPS).

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Section: Resultsmentioning

confidence: 99%

Cobalt–Salen Complexes as Catalyst Precursors for Electrocatalytic Water Oxidation at Low Overpotential

et al. 2015

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“…However, these techniques are highly complex and often need very demanding reaction conditions. As a result, there are ongoing efforts to develop more economically attractive chiral separation methods to obtain enantiopure compounds …”

Section: Methodsmentioning

confidence: 99%

“…As a result, there are ongoing efforts to develop more economically attractive chiral separation methods to obtain enantiopure compounds. 2,3 Enantioselective liquid-liquid extraction is relatively new, which represents a potentially attractive technique for chiral separation. 4 Currently, the most commonly used extractants for enantioselective liquid-liquid extraction are crown ethers, metal complexes, and metalloids, 4 tartaric acid esters, 5 dibenzoyl tartaric acid (DBTA), 6 and some amino acids like proline and hydroxyproline.…”

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confidence: 99%

Enantioselective Liquid–Liquid Extraction of Zopiclone With Mandelic Acid Ester Derivatives

Peng

Zuo

et al. 2013

Chirality

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Enantioselective liquid-liquid extraction of zopiclone was conducted by employing a series of (R)-mandelic acid esters as chiral extractants. The effects of concentration of extractant, concentration of zopiclone, type of organic solvent, pH value, and temperature on the extraction efficiency were investigated. (R)-o-chloromandelic acid propyl ester was demonstrated to be an efficient chiral extractant for zopiclone resolution with a maximum enantioselectivity of 1.6.

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“…[55] untersucht. Vor kurzem wurden erfolgreiche Versuche beschrieben, die die Effekte zweier Carrier kombinieren.…”

Section: Angewandte Chemieunclassified

Verfahren zur Enantiomerentrennung

Lorenz

Seidel‐Morgenstern

2014

Angewandte Chemie

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Die Verfügbarkeit reiner Enantiomere ist von steigender Bedeutung für die pharmazeutische Industrie sowie auch für die Agrochemie und Biotechnologie. Generell gibt es zwei konkurrierende Ansätze zur Gewinnung von reinen Enantiomeren. Der “chirale” Ansatz basiert auf der Entwicklung einer asymmetrischen Synthese, die selektiv eines der Enantiomere liefert. Der “racemische” Ansatz basiert auf der Trennung eines Gemischs der beiden Enantiomere, wobei hier in den letzten Jahren bemerkenswerte Fortschritte erzielt werden konnten. Dieser Aufsatz fokussiert insbesondere auf enantioselektive Kristallisationsprozesse und präparative Chromatographie, einschließlich hybrider Trennprozesse und der zusätzlichen Integration von Racemisierungsschritten. Zur Illustration dienen mehrere in unserem Arbeitskreis untersuchte Trennungen.

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Resolution of Racemic N‐Benzyl α‐Amino Acids by Liquid‐Liquid Extraction: A Practical Method Using a Lipophilic Chiral Cobalt(III) Salen Complex and Mechanistic Studies

Cited by 41 publications

References 67 publications

Cobalt–Salen Complexes as Catalyst Precursors for Electrocatalytic Water Oxidation at Low Overpotential

Cobalt–Salen Complexes as Catalyst Precursors for Electrocatalytic Water Oxidation at Low Overpotential

Enantioselective Liquid–Liquid Extraction of Zopiclone With Mandelic Acid Ester Derivatives

Verfahren zur Enantiomerentrennung

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