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A dynamic nuclear magnetic resonance study of nitrogen inversion in N,N'-dimethylimidazolidine

✍ Scribed by Frank A. L. Anet; Issa Yavari

Publisher
John Wiley and Sons
Year
1979
Tongue
English
Weight
268 KB
Volume
12
Category
Article
ISSN
0749-1581

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✦ Synopsis

Abstract

The 251 MHz ^1^H and the natural‐abundance 63.1 MHz ^13^C NMR spectra of N,N'‐dimethylimidazolidine have been measured from −50 to −170°C. Below about −140°C. nitrogen inversion in the compound becomes slow on the NMR time scale and both the ^1^H and the ^13^C spectra indicate that it exists in solution as a mixture of cis and trans conformations having nearly the same energies. The free‐energy barrier (ΔG^≠^) for nitrogen inversion in N,N'‐dimethylimidazolidine is 6.4 kcal mol^−1^, a value which is 1.5 kcal mol^−1^ lower than that for N‐methylpyrrolidine.

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