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Research Article
Is the neutral Knoevenagel reaction initiated by the carbanion formation?
Article first published online: 9 NOV 2010
DOI: 10.1002/poc.1806
Copyright © 2010 John Wiley & Sons, Ltd.
Additional Information
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
Publication History
- 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
Keywords:
- aldehydes;
- density functional calculations;
- hydrogen bonds;
- Knoevenagel reaction;
- reaction mechanisms
Abstract
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.