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Ring inversion process for a series of 3,5‐dialkyl‐1‐oxa‐3,5‐diazacyclohexanes: 1 H DNMR study and semiempirical calculations
Author(s) -
DuBray Cecelia M.,
Gerber Cody L.,
McCulla Ryan D.,
Oakland Angie J.,
Schwartz Keith D.,
Eliason Robert,
Brown Jay H.
Publication year - 2010
Publication title -
journal of physical organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.325
H-Index - 66
eISSN - 1099-1395
pISSN - 0894-3230
DOI - 10.1002/poc.1743
Subject(s) - chemistry , ring flip , reaction rate constant , methylene , inversion (geology) , alkyl , computational chemistry , ring (chemistry) , spectroscopy , proton magnetic resonance , nuclear magnetic resonance , kinetics , organic chemistry , paleontology , physics , quantum mechanics , structural basin , biology
The ring inversion process for a series of 3,5‐dialkyl‐1‐oxa‐3,5‐diazacyclohexanes was studied using proton dynamic nuclear magnetic resonance ( 1 H DNMR) spectroscopy in conjunction with semiempirical calculations. At low temperature, the ring methylene protons decoalesced into two AB spin systems in a 2:1 ratio. Lineshape simulations of the DNMR spectra provided first‐order rate constants for magnetic exchange. The energy barrier for each inversion reaction was calculated from the respective rate constants. In general, as the size of the N ‐alkyl group increased, the barrier to ring inversion decreased. A similar trend was seen in semiempirical calculations that modeled the ring inversion process. Copyright © 2010 John Wiley & Sons, Ltd.