Organic Structure Determination Using 2-D NMR Spectroscopy, Second Edition: A Problem-Based Approach
Excerpt on Molecular Dynamics fromOrganic Structure Determination Using 2-D NMR Spectroscopy, 2nd EditionMolecular dynamics covering a wide range of time scales produce an array of effects in NMR spectroscopy. In large molecules, motion in different segments of a molecule may yield measurably distinct relaxation times, thus allowing us to differentiate between signals from different parts of a molecule. Conformational rearrangements can change both the chemical shifts of NMR-active nuclei and the J-couplings observed between various spins. Rapid molecular motions average shifts and/or J-couplings, whereas slower motions may make discovering the underlying mechanistic motions difficult. In many cases, molecular motion and chemical exchange may give broad NMR lines devoid of coupling information.Read full text of this chapter(PDF).Sample Problem 1Problem 15.2 (1S*, 4S*, 10S*)-1-Ethyl-4-(hydroxyethyl)quinolizidine in CDCl3 (Sample 106)(PDF).Sample Courtesy of Shaun Fontaine and Rick DanheiserSample Problem 2Problem 15.6 Brucine in CDCl3 (Sample 113)(PDF).