View in EDS

Undergraduate Laboratory Experiment To Determine Absolute Configuration Using Thin-Layer Chromatography.

Saved in:
Bibliographic Details
Title: Undergraduate Laboratory Experiment To Determine Absolute Configuration Using Thin-Layer Chromatography.
Authors: Wagner, Alexander J., Miller, Shawn M., Nguyen, Steven, Ga Young Lee, Rychnovsky, Scott D., Link, Renée D.
Source: Journal of Chemical Education. May2014, Vol. 91 Issue 5, p716-721. 6p.
Subjects: THIN layer chromatography, ALCOHOL research, ENANTIOMERS, ORGANIC chemistry research, CHEMISTRY education in universities & colleges
Abstract: A new undergraduate organic chemistry laboratory experiment has been developed to determine the absolute configuration of enantioen-riched secondary alcohols with the competing enantioselective conversion (CEC) method. The CEC method uses both enantiomers of a chiral kinetic resolution reagent in parallel reactions to identify the fast-reacting reagent and thus the configuration of the alcohol. Students working in pairs are given one of three enantioenriched secondary alcohols with an unknown absolute configuration. They assign the molecular structure using the corresponding ' H NMR spectrum and determine the absolute configuration via the CEC method. The parallel reactions are run at room temperature for 1 h using small quantities of solvent, substrate, and catalyst. Students use thin-layer chromatography (TLC) to analyze the parallel reactions and determine the fast reaction qualitatively. The free program ImageJ is used with a picture of the TLC plate to carry out a quantitative analysis of reaction conversion. Data collected in the spring 2013 laboratory course (n = 1036) show that 93.6% of students determined the absolute configuration of their unknown correctly with just a qualitative analysis of the TLC plate. This experiment provides a platform for discussions of stereochemistry, mechanism, kinetics, energy diagrams, and transition states. [ABSTRACT FROM AUTHOR]
Copyright of Journal of Chemical Education is the property of American Chemical Society and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
Database: Teacher Reference Center
Description
Abstract:A new undergraduate organic chemistry laboratory experiment has been developed to determine the absolute configuration of enantioen-riched secondary alcohols with the competing enantioselective conversion (CEC) method. The CEC method uses both enantiomers of a chiral kinetic resolution reagent in parallel reactions to identify the fast-reacting reagent and thus the configuration of the alcohol. Students working in pairs are given one of three enantioenriched secondary alcohols with an unknown absolute configuration. They assign the molecular structure using the corresponding ' H NMR spectrum and determine the absolute configuration via the CEC method. The parallel reactions are run at room temperature for 1 h using small quantities of solvent, substrate, and catalyst. Students use thin-layer chromatography (TLC) to analyze the parallel reactions and determine the fast reaction qualitatively. The free program ImageJ is used with a picture of the TLC plate to carry out a quantitative analysis of reaction conversion. Data collected in the spring 2013 laboratory course (n = 1036) show that 93.6% of students determined the absolute configuration of their unknown correctly with just a qualitative analysis of the TLC plate. This experiment provides a platform for discussions of stereochemistry, mechanism, kinetics, energy diagrams, and transition states. [ABSTRACT FROM AUTHOR]
ISSN:00219584
DOI:10.1021/ed4004996