MU Chemistry 416 FS97

Articles of 1D-NMR


Acetone and Ethyl Acetate in Commercial Nail Polish Removers: A Quantitative NMR Experiment Using an Internal Standard. D. W. Clarke J. Chem. Educ. 1997, 74, 1464-1465.
A simple and attractive experiment is described to demonstrate quantitative analysis via NMR.

Following Glycolysis Using 13C NMR - An Experiment Adaptable to Different Undergraduate Levels. T. L. Mega, C. B. Carlson, D. A. Cleary J. Chem. Educ. 1997, 74, 1474-1476.
A simple and attractive experiment is described to demonstrate quantitative kinetic analysis via 13C-NMR. The 1-position of glucose is labelled and the decrease of the peak corresponding to the alpha-C is monitored. During glycolysis, new peaks appear for ethanol and glycerol.

1H NMR Analysis of Mixtures Using Internal Standards J. Peterson J. Chem. Educ. 1992, 69, 843-845.
An illustration of the principles of quantitative NMR analysis. Figures A and B show that indeed the peak intensity is proportional to the solute concentration and how such calibration curves can then be used in quantitative analysis.

The Esterification of Trifluoroacetic Acid - A Variable Temperature NMR Kinetics Study T. N. Gallaher, D. A. Gaul, and S. Schreiner J. Chem. Educ. 1996, 73, 465-467.
A short article that demonstrates how variable temperature NMR kinetics can be used to determine the rates of reaction of slow organic reactions.

Structure Determination Using 19F NMR - A Simple Fluorination Experiment of Cinnamyl Alcohol D. J. deMendonca, C. A. Digits, E. W. Navin, T. C. Sanders, G. B. Hammond J. Chem. Educ. 1995, 72, 736-739.
Take a look at the H NMR spectrum of the mixture of 3-fluoro-1-phenyl-propene and 3-fluoro-3-phenyl-propene. The spectrum is exceedingly complicated due to the coupling between H and F. On the other hand, the F NMR is easy to interpret (make sure you understand what you see in Figures 3 - 5). Realize why that is so: The coupling J(H,F) constants are very small when compared to the energy range of the F chemical shift scale. "It is always better to look at the nucleus that has a wider chemical shift range."

The Chiral S-N Axis in Sulfenamides: Enantiomeric Resolution, Direct Demonstration of Optical Activity, and Kinetics of Interconversion. Merav Ben-David Blanca, Eric Maimon, and Daniel Lost Angew. Chem. Int. Ed. Engl. 1997, 36, 2216-2219.
An excellent article for the demonstration of the use of an selective inversion revovery H-NMR to determine the activation barrier for an internal rotation. Make sure you understand the NMR spectrum of 6. The fact that there are enantiomers due to the hindered rotation about the N-S bond makes the two methyl groups of the iso-propyl group diasterotopic. These methyl groups show up as a doublet of doublets (large J due to CH, small J due to chiral environment). The relaxation after the selective inversion of one of these doublets depend on the magnetization transfer and the rate constant for enantiomerization.

Noncovalent Assembly of Functional Groups on Calix[4]arene Molecular Boxes P. Timmerman, R. H. Vreekamp, R. Hulst, W. Verboom, D. N. Reinhoudt, K. Rissanen, K. A. Udachin, and J. Ripmeester Chem. Eur. J. 1997, 3, 1283-1832.
Calix[4]arenes are synthesized with two melamine attached to the upper rim. Melamine is a 6-membered 1,3,5-trinitrogen heterocycle with amino groups in the 2,4,6 positions. These amino groups allow for H-bonding with two 5,5-diethylbarbituric acid (DEB) molecules. It is found that box like aggregates are formed of the type X3(DEB)6. The trimerization of the X1(DEB)2 is facilitated by H-bonding as well. Why are we interested in this? Because this paper presents a nice illustration of the fact that NMR line shapes reflect the stability of H-bonds. Read the article and make sure to understand Figures 2 (the sharp peaks >12 ppm for the 1:2 complex) and 6 (the solvent dependency of the box like assembly).