Modulations in restricted amide rotation by steric induced conformational trapping |
| |
Authors: | Krishnan V V Thompson William B Maitra Kalyani Maitra Santanu |
| |
Institution: | Department of Chemistry, California State University, Fresno CA 93740. |
| |
Abstract: | The rotation around the amide bond in N,N-diethyl-m-toluamide (m-DEET) has been studied extensively and often used in laboratory instructions to demonstrate the phenomenon of chemical exchange. Herein, we show that a simple modification to N,N-diethyl-o-toluamide (o-DEET) significantly alters the dynamics of the restricted rotation around the amide bond due to steric interactions between the ring methyl group and the two N-ethyl groups. This alters the classic two-site exchange due to restricted rotation around the amide bond, to a three-site exchange, with the third conformation trapped at a higher-energy state compared to the other two. This often overlooked phenomenon is elucidated using variable-temperature NMR, two-dimensional exchange spectroscopy and molecular modeling studies. |
| |
Keywords: | |
本文献已被 PubMed 等数据库收录! |
|