Name
Title | ||
|---|---|---|
A theoretical study on keto-enol tautomerization involving simple carbonyl derivatives |
Abstract | ||
|---|---|---|
The relative stabilities of the keto and enol forms [Delta E(0) (enol-keto)] and the energy barriers to enolization of the keto forms [Delta E(not equal) (transition state-keto)] for CH(3)COR (R=CH3, H, F, and CN) and CH3CHY (Y=CH2, NH, and S) are investigated theoretically by Hartree-Fock and Moller-Plesset second-order calculations with 6-31G** basis sets. Specific and bulk solvent effects are considered by incorporating one water molecule and applying the self-consistent reaction field (SCRF) method to the reaction system, respectively. The Delta E(MP2)(0) values are all positive, in agreement with the lower stability of Me enol form in the gas phase as well as in solution. In contrast to a relatively small effect of specific as well as bulk solvation on a Delta E(0), there is a large lowering of Delta E(not equal) (by ca. 30 kcal/mol) when solvent effects are accounted for. In general, both Delta E(0) and Delta E(not equal) are depressed in solution and hence enolization is favored thermodynamically as well as kinetically. The keto form is strongly stabilized by a pi donor, whereas the enol isomer is stabilized by a pi as well as a sigma-acceptor substituent, R. As a result, substituent R=F is the most unfavorable whereas R=CN is the most favorable for the enolization. The water catalyzed enolization in the neutral water proceeds concertedly, but carbon deprotonation is more important than carbonyl-oxygen protonation by water in the rate determining step. (C) 1997 by John Wiley & Sons, Inc. |
Year | DOI | Venue |
|---|---|---|
1997 | 10.1002/(SICI)1096-987X(19970115)18:1<56::AID-JCC6>3.0.CO;2-Z | JOURNAL OF COMPUTATIONAL CHEMISTRY |
Field | DocType | Volume |
Organic chemistry,Computational chemistry,Chemistry,Keto–enol tautomerism | Journal | 18 |
Issue | ISSN | Citations |
1 | 0192-8651 | 0 |
PageRank | References | Authors |
0.34 | 0 | 5 |
Name | Order | Citations | PageRank |
|---|---|---|---|
| Doyoung Lee | 1 | 0 | 0.34 |
| Chang Kon Kim | 2 | 2 | 2.75 |
| Bon-su Lee | 3 | 2 | 1.74 |
| Ikchoon Lee | 4 | 0 | 1.35 |
| Byung Choon Lee | 5 | 0 | 0.34 |