Is the neutral Knoevenagel reaction initiated by the carbanion formation?
Article first published online: 9 NOV 2010
Copyright © 2010 John Wiley & Sons, Ltd.
Journal of Physical Organic Chemistry
Volume 24, Issue 8, pages 663–671, August 2011
How to Cite
Yamabe, S. and Yamazaki, S. (2011), Is the neutral Knoevenagel reaction initiated by the carbanion formation?. J. Phys. Org. Chem., 24: 663–671. doi: 10.1002/poc.1806
- Issue published online: 14 JUL 2011
- Article first published online: 9 NOV 2010
- Manuscript Accepted: 5 SEP 2010
- Manuscript Revised: 20 AUG 2010
- Manuscript Received: 22 MAY 2010
- density functional calculations;
- hydrogen bonds;
- Knoevenagel reaction;
- reaction mechanisms
The title reactions were studied by means of the density functional theory calculations. A base promoted reaction (called here ‘B’) was traced in a model composed of benzaldehyde, malononitrile, and (H2O)11. A neutral model (‘N’) of Ph-CHO, H2C(CN)2 and (H2O)12 was also examined in line with a reported clean reaction. It was found that the ion pair of HC(CN) and H3O+ is generated at the first step for N. For B, there are five elementary processes, and for N, four ones were obtained. By RB3LY/6-311 + G** SCRF = PCM//RB3LYP/6-31(+)G* energy calculations, the rate determining steps for both B and N reactions are the second proton removal, TS5(B) and TS3(N), respectively. In both B and N, the neutral species Ph(HO)HC-CH(CN)2 is the key intermediate. Copyright © 2010 John Wiley & Sons, Ltd.