Dynamic 1H NMR study of the barrier to rotation about the C-N bond in primary carbamates and its solvent dependence

Ali Reza Modarresi-Alam; Parisa Najafi; Mohsen Rostamizadeh; Hossein Keykha; Hamid-Reza Bijanzadeh; Erich Kleinpeter

doi:10.1021/jo061301f

Dynamic 1H NMR study of the barrier to rotation about the C-N bond in primary carbamates and its solvent dependence

J Org Chem. 2007 Mar 16;72(6):2208-11. doi: 10.1021/jo061301f. Epub 2007 Feb 20.

Authors

Ali Reza Modarresi-Alam¹, Parisa Najafi, Mohsen Rostamizadeh, Hossein Keykha, Hamid-Reza Bijanzadeh, Erich Kleinpeter

Affiliation

¹ Department of Chemistry, University of Sistan & Baluchestan, Zahedan, Iran. modaresi@hamoon.usb.ac.ir

PMID: 17309303
DOI: 10.1021/jo061301f

Abstract

The dynamic 1H NMR study of some primary carbamates in the solvents CDCl3 and CD3COCD3 between 183 and 298 K is reported. The free energies of activation, thus obtained (12.4 to 14.3 kcal mol-1), were attributed to the conformational isomerization about the N-C bond. These barriers to rotation show solvent dependence in contrast to the tertiary analogues and are lower in free energy by ca. 2-3 kcal mol-1.