Michelle J. O'Mahony
Substituent effects on the dehydration of arene hydrates in aqueous solution
O'Mahony, Michelle J.; More O'Ferrall, R.A.; Boyd, D.R.; Lam, C.M.; O'Donoghue, A.C.
Authors
R.A. More O'Ferrall
D.R. Boyd
C.M. Lam
Professor Ann O'Donoghue annmarie.odonoghue@durham.ac.uk
Professor
Abstract
Rate constants have been determined by UV spectrophotometry at 25 °C for the acid-catalyzed dehydration of different types of monocyclic arene hydrates including those substituted at the 1-, 2- or 3-positions. General acid catalysis was not observed, and linear plots of pseudo-first-order rate constants for dehydration against hydronium concentration were obtained. A Hammett plot of the second-order rate constants for acid-catalyzed dehydration, kH (M−1s−1), of unsubstituted- (8a), 3-substituted (8b, 8c, 8d, 8e) and 1-substituted-benzene hydrates (14f and 14h) shows an excellent correlation with σ+ values and yields a large negative ρ-value of –6.5. The results are consistent with rate-determining formation of a benzenium ion in which direct mesomeric interaction with the substituent occurs, presumably permitted by the coplanar arrangement of the diene and carbocation centre in the intermediate. Data points for 2-substituted arene hydrates (13f, 13g, 13h, 13i) deviate negatively from the Hammett plot as direct mesomeric interaction with the substituent is not possible in the corresponding benzenium intermediates.
Citation
O'Mahony, M. J., More O'Ferrall, R., Boyd, D., Lam, C., & O'Donoghue, A. (2013). Substituent effects on the dehydration of arene hydrates in aqueous solution. Journal of Physical Organic Chemistry, 26(12), 989-996. https://doi.org/10.1002/poc.3174
Journal Article Type | Article |
---|---|
Acceptance Date | Jun 18, 2013 |
Publication Date | Dec 1, 2013 |
Deposit Date | Oct 11, 2013 |
Publicly Available Date | Mar 29, 2024 |
Journal | Journal of Physical Organic Chemistry |
Print ISSN | 0894-3230 |
Electronic ISSN | 1099-1395 |
Publisher | Wiley |
Peer Reviewed | Peer Reviewed |
Volume | 26 |
Issue | 12 |
Pages | 989-996 |
DOI | https://doi.org/10.1002/poc.3174 |
Keywords | Arene hydrates, Dehydration, Substituent effects. |
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Copyright Statement
This is the accepted version of the following article: O'Mahony M. J., More O'Ferrall R. A., Boyd D. R., Lam C. M. and O'Donoghue A. C. (2013), Substituent effects on the dehydration of arene hydrates in aqueous solution, Journal of Physical Organic Chemistry, 26(12): 989-996, which has been published in final form at http://dx.doi.org/10.1002/poc.3174. This article may be used for non-commercial purposes in accordance With Wiley Terms and Conditions for self-archiving.
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