ISSN:
0749-1581
Keywords:
1H NMR
;
13C NMR
;
aziridines
;
pyramidal nitrogen inversion
;
inversion rate constant
;
slow exchange spin locking
;
2D exchange spectroscopy
;
Chemistry
;
Analytical Chemistry and Spectroscopy
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
The slow inversion at pyramidal nitrogen in 2,2-dimethylaziridine was investigated by NMR spectroscopy at 304 K using one-dimensional spin locking methods and two-dimensional exchange spectroscopy. The activation free energy was found to be 17.5 kcal mol-1 (73.2 kJ mol-1) at this temperature. This value represents a lower limit for the unimolecular inversion barrier height as autocatalytic and water-catalyzed inversion pathways can in principle also contribute to the observed rate. The spin locking experiments described employ non-selective pulses and are particularly useful for the quantitative study of slow chemical exchange between nuclei of similar resonance frequency where selective magnetization transfer experiments are difficult or impossible.
Additional Material:
5 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/mrc.1260330808
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