Ab initio Study of the Keto-Enol Equilibriumof Malonaldehyde |
| |
Authors: | Vassil B Delchev Georgi S Nikolov |
| |
Institution: | (1) Department of Physical and Theoretical Chemistry, University of Plovdiv, BG-4000 Plovdiv, Bulgaria, BG;(2) Institute of General and Inorganic Chemistry, Bulgarian Academy of Sciences, BG-1113 Sofia, Bulgaria, BG |
| |
Abstract: | Summary. The mechanism of the keto-enol tautomerism of malonaldehyde was studied by ab initio methods using 6-21G** and 6-311G** basis functions at the HF level. Two separate mechanisms were examined: through-space proton transfer in the ω-shaped form
and through-space proton transfer in a sickle-shaped form obtained from the ω form by rotation. The transition state structure
of the ω form is non-planar, whereas that of the sickle form is planar. The sickle form is connected with a 2nd order saddle, indicating that there should exist a lower energy barrier, i.e. that the through-bond mechanism may be preferred. The calculated energy barriers of keto-enol tautomerism for the sickle
form is twice as high as those for the omega form.
Received January 18, 1999. Accepted (revised) August 4, 1999 |
| |
Keywords: | , ,Malonaldehyde, Keto-enol tautomerism, ab initio Calculations, Energy barriers, |
本文献已被 SpringerLink 等数据库收录! |
|