Lichter, Robert L. and Roberts, John D. (1972) Nitrogen-15 Magnetic Resonance Spectroscopy. XIV. Natural-Abundance Nitrogen-15 Chemical Shifts of Amines. Journal of the American Chemical Society, 94 (7). pp. 2495-2500. ISSN 0002-7863. doi:10.1021/ja00762a050. https://resolver.caltech.edu/CaltechAUTHORS:20151009-133526915
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Abstract
It has been found possible to measure the shifts of a variety of amines to an accuracy of 0.2 ppm with the isotope at its natural-abundance level. Successful observation of these resonances with our existing equipment is dependent on a favorable nuclear Overhauser effect arising from irradiation of the protons. Chemical exchange of protons directly bound to the amine nitrogen can reduce the signal intensity sufficiently to make detection of the ^(15)N resonance difficult or impossible. The ^(15)N shifts generally correlate linearly with the ^(13)C shifts of alkanes derived by replacing the amine nitrogen with an appropriately substituted carbon. Detailed examination leads to deshielding α and β substituent shift parameters, a shielding y effect, and possible deshielding associated with hydrogen bonding. Effects of constraints in geometrically rigid systems as well as incorporation of the nitrogen into six-, five-, and three-membered rings are discussed and compared with corresponding ^(13)C shifts. Parallel trends were found for all cases. Natural-abundance ^(15)N spectroscopy is thus a practicable, if far from routine, means of structural analysis.
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Additional Information: | © 1971 American Chemical Society. Received May 26, 1971. Supported by the Public Health Service, Research Grant No. GM-11072-07 from the Division of General Medical Sciences. | |||||||||
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Issue or Number: | 7 | |||||||||
DOI: | 10.1021/ja00762a050 | |||||||||
Record Number: | CaltechAUTHORS:20151009-133526915 | |||||||||
Persistent URL: | https://resolver.caltech.edu/CaltechAUTHORS:20151009-133526915 | |||||||||
Official Citation: | Nitrogen-15 magnetic resonance spectroscopy. XIV. Natural-abundance nitrogen-15 chemical shifts of amines Robert L. Lichter and John D. Roberts Journal of the American Chemical Society 1972 94 (7), 2495-2500 DOI: 10.1021/ja00762a050 | |||||||||
Usage Policy: | No commercial reproduction, distribution, display or performance rights in this work are provided. | |||||||||
ID Code: | 60958 | |||||||||
Collection: | CaltechAUTHORS | |||||||||
Deposited By: | Ruth Sustaita | |||||||||
Deposited On: | 15 Oct 2015 22:21 | |||||||||
Last Modified: | 10 Nov 2021 22:42 |
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