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Dual-parameter correlations on rate of dehydration step of a condensation reaction in aqueous solutions of ethanol, propan-2-ol and 2-methylpropan-2-ol
Habibi Yangjeh, A
Dual-parameter correlations on rate of dehydration step of a condensation reaction in aqueous solutions of ethanol, propan-2-ol and 2-methylpropan-2-ol
Habibi Yangjeh, A ; Sharif University of Technology | 2001
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- Type of Document: Article
- DOI: 10.1002/poc.438
- Publisher: 2001
- Abstract:
- The reaction kinetics of the dehydration step of the condensation reaction between phenylhydrazine and benzaldehyde was studied spectrophotometrically in aqueous solutions of ethanol, propan-2-ol and 2-methylpropan-2-ol at pH 11.5 at 25 °C. The apparent second-order rate constants k2app of the reaction increase with mole fraction of water in all the aqueous solutions. Single-parameter correlations of log k2app versus π* (dipolarity/polarizability), α (hydrogen-bond donor acidity) and ETN (normalized polarity parameter) were obtained in all the aqueous solutions. In all cases, the correlations versus ETN and π* are acceptable, but correlations versus α are poor (e.g. in aqueous solutions of ethanol the correlation coefficients are 0.964, 0.967, and 0.751 respectively). The results of dual-parameter correlations of log k2app versus π* and α in all cases represent improvements with regard to the single-parameter models (in aqueous solutions of ethanol r = 0.995; s.e. = 0.038; n = 13). The apparent second-order rate constants of the reaction increase with α, π* and ETN. Increasing the hydrogen-bond donor acidity of the solvent stabilizes the activated complex of the reaction via hydrogen-bond formation with the intermediate. A dual-parameter equation of log k2app versus π* and α was obtained for the combined data set of aqueous solutions (n = 35, r = 0.989, s.e. = 0.062, F2.32 = 719.21), in which π* has the major effect on the reaction rate relative to α. Copyright © 2001 John Wiley & Sons, Ltd
- Keywords:
- Condensation reaction ; Dipolarity/ polarizability ; Dual-parameter correlation ; Hydrogen-bond donor acidity ; Kinetics ; Polarity parameter ; Solvent effect
- Source: Journal of Physical Organic Chemistry ; Volume 14, Issue 12 , 2001 , Pages 884-889 ; 08943230 (ISSN)
- URL: https://onlinelibrary.wiley.com/doi/10.1002/poc.438