Results 151 to 160 of about 33,103 (197)

Optical purity, enantiomeric excess and the Horeau effect

Organic & Biomolecular Chemistry, 2020
Optical purity (op) and enantiomeric excess (ee) become equal when either heterochiral dimerization constant is twice that of homochiral dimerization constant or specific rotations of monomer and dimer are equal.
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Asymmetric Synthesis. Kinetic Amplification of Enantiomeric Excess

Comments on Inorganic Chemistry, 1987
Abstract The efficiency of an asymmetric synthetic reaction is measured by what is called the enantiomeric excess (e.e.). It is commonly assumed that this is a unique quantity for a given asymmetric reaction under specified conditions. The purpose of this Comment is to show that this is not necessxily so, and that, under certain circumstances, e.e.
Steven Bergens, B. Bosnich
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ChemInform Abstract: Rapid Enantiomeric Excess Determination

ChemInform, 2013
AbstractReview: 29 refs.
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Recent Advances in the Measurement of Enantiomeric Excesses

Advanced Synthesis & Catalysis, 2002
The elaboration of an ever increasing number of chiral catalysts or reagents demands fast and sensitive methods to measure enantiomeric excesses of the products. This review discusses the various ways to solve these problems. Mass spectrom- etry, chromatographic or chiroptical methodologies, fluorescence, liquid crystals, enzymatic methods, and ...
Masaki Tsukamoto, Henri B. Kagan
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Rapid Determination of Enantiomeric Excess Using Infrared Thermography

Organic Process Research & Development, 2002
Infrared thermography (IRT) is presented as a novel technique to screen a potentially large number of asymmetric catalysts or substrates in a high-throughput fashion.
Nicolas Millot, Phil Borman, Mike S. Anson, Ian B. Campbell, Simon J. F. Macdonald, Mahmoud Mahmoudian   +5 more
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Determination of enantiomeric excess using Raman optical activity

Journal of Raman Spectroscopy, 1995
AbstractA simple method for the determination of enantiomeric excess is described. It is based on depolarized Raman optical activity (ROA) measurements in right‐angle scattering employing the incident ciruclar polarization (ICP) modulation approach. The accuracy of this method was assessed utilizing α‐pinene as a chiral test compound. The four α‐pinene
Lutz Hecht, Anthony L. Phillips, Laurence D. Barron   +2 more
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Direct 1H NMR determination of the enantiomeric excess of carnitine

The Analyst, 1988
The enantiomeric purity of carnitine may be determined without any derivatisation of the molecule. Preparations of aqueous mixtures containing stereochemically pure L-malic acid, carnitine and europium trichloride lead to the formation of a complex in which the trimethylammonium groups of D- and L-carnitine are diastereotopic.
J, Bounoure, J, Souppe
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Determination of Enantiomeric Excess via ³¹P‐NMR

Chirality
ABSTRACT31P is a very attractive nucleus for nuclear magnetic resonance (NMR) analysis because of the large chemical dispersion and the simplicity of the spectra when compared with other nuclei (other than 19F). The ability to rapidly and quantitatively assay for enantiomeric excess (ee) measurements of alcohols, amines, thiols, and other chiral ...
Ellis Guernsey, Jean‐Luc Montchamp
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Rapid determination of enantiomeric excess: a focus on optical approaches

Chem. Soc. Rev., 2012
High-throughput screening (HTS) methods are becoming increasingly essential in discovering chiral catalysts or auxiliaries for asymmetric transformations due to the advent of parallel synthesis and combinatorial chemistry. Both parallel synthesis and combinatorial chemistry can lead to the exploration of a range of structural candidates and reaction ...
Diana, Leung, Sung Ok, Kang, Eric V, Anslyn   +2 more
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Diporphyrin tweezer for multichannel spectroscopic analysis of enantiomeric excess

Frontiers of Chemical Science and Engineering, 2020
Chiral 1,1’-binaphthyl-linked diporphyrin ‘tweezers’ (R)-1/(S)-1 and the corresponding zinc(II) complexes (R)-2/(S)-2 were prepared as chiral host molecules, and their utility for chiral analyses (especially enantiomeric excess (ee) determinations) were evaluated. Tris(1-n-dodecyl)porphyrins were used for the first time as the interacting units.
Daniel T. Payne, Mandeep K. Chahal, Václav Březina, Whitney A. Webre, Katsuhiko Ariga, Francis D’Souza, Jan Labuta, Jonathan P. Hill   +7 more
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