Next Article in Journal
Dietary Polyphenols and Periodontitis—A Mini-Review of Literature
Next Article in Special Issue
Kinetic Resolution of Racemic 2-Hydroxyamides Using a Diphenylacetyl Component as an Acyl Source and a Chiral Acyl-Transfer Catalyst
Previous Article in Journal
Zinc (II)-Mediated Selective O-Benzylation of 2-Oxo-1,2-Dihydropyridines Systems
Previous Article in Special Issue
Chiral 2-Aminobenzimidazole as Bifunctional Catalyst in the Asymmetric Electrophilic Amination of Unprotected 3-Substituted Oxindoles
Article Menu
Issue 7 (July) cover image

Export Article

Open AccessArticle
Molecules 2018, 23(7), 1785; https://doi.org/10.3390/molecules23071785

One-Dimensional 13C NMR Is a Simple and Highly Quantitative Method for Enantiodiscrimination

DSM Biotechnology Center, P.O. Box 1, 2600 MA Delft, The Netherlands
*
Author to whom correspondence should be addressed.
Received: 21 June 2018 / Revised: 13 July 2018 / Accepted: 17 July 2018 / Published: 20 July 2018
(This article belongs to the Special Issue Stereogenic Centers)
View Full-Text   |   Download PDF [877 KB, uploaded 20 July 2018]   |  

Abstract

The discrimination of enantiomers of mandelonitrile by means of 1D 13C NMR and with the aid of the chiral solvating agent (S)-(+)-1-(9-anthryl)-2,2,2-trifluoroethanol (TFAE) is presented. 1H NMR fails for this specific compound because proton signals either overlap with the signals of the chiral solvating agent or do not show separation between the (S)-enantiomer and the (R)-enantiomer. The 13C NMR method is validated by preparing artificial mixtures of the (R)-enantiomer and the racemate, and it is shown that with only 4 mg of mandelonitrile a detection limit of the minor enantiomer of 0.5% is obtained, corresponding to an enantiomeric excess value of 99%. Furthermore, the method shows high linearity, and has a small relative standard deviation of only 0.3% for the minor enantiomer when the relative abundance of this enantiomer is 20%. Therefore, the 13C NMR method is highly suitable for quantitative enantiodiscrimination. It is discussed that 13C NMR is preferred over 1H NMR in many situations, not only in molecules with more than one chiral center, resulting in complex mixtures of many stereoisomers, but also in the case of molecules with overlapping multiplets in the 1H NMR spectrum, and in the case of molecules with many quaternary carbon atoms, and therefore less abundant protons. View Full-Text
Keywords: enantiomers; Pirkle’s alcohol; TFAE; qNMR; mandelonitrile; CSA; chirality; chiral solvating agent enantiomers; Pirkle’s alcohol; TFAE; qNMR; mandelonitrile; CSA; chirality; chiral solvating agent
Figures

Graphical abstract

This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. (CC BY 4.0).
SciFeed

Share & Cite This Article

MDPI and ACS Style

Lankhorst, P.P.; van Rijn, J.H.J.; Duchateau, A.L.L. One-Dimensional 13C NMR Is a Simple and Highly Quantitative Method for Enantiodiscrimination. Molecules 2018, 23, 1785.

Show more citation formats Show less citations formats

Note that from the first issue of 2016, MDPI journals use article numbers instead of page numbers. See further details here.

Related Articles

Article Metrics

Article Access Statistics

1

Comments

[Return to top]
Molecules EISSN 1420-3049 Published by MDPI AG, Basel, Switzerland RSS E-Mail Table of Contents Alert
Back to Top