Nucleofugality of pentafluorophenolate in various solvents: solvolytic behavior of phenolates

Scientific paper - Original scientific paper

• Author: Mirela Matić
• Author: Nives Bebek
• Author: Bernard Denegri
• Author: Olga Kronja
• Author's institution: University of Zagreb; Faculty of Pharmacy and Biochemistry; (Department of organic chemistry)
• Scientific / art field, discipline and subdiscipline: NATURAL SCIENCES; Chemistry; Organic Chemistry

Abstract (english)

The leaving group ability (nucleofugality) of the pentafluorophenolate anion has been determined from first order solvolytic rate constants (<i>k</i>) of X,Y-substituted benzhydryl pentafluorophenolates measured in a series of solvents, by using the three parameter LFER equation: log <i>k</i> = <i>s</i>_f (<i>E</i>_f + <i>N</i>_f). Comparison with other leaving groups reveals that pentafluorophenolate is a moderate leaving group, whose nucleofugality (<i>N</i>_f value) is between the nucleofugalities of phenyl carbonate and 3,5-dinitrobenzoate leaving groups. However, due to its high reaction constant (<i>s</i>_f = 1.29 in 80 % aq. ethanol), relative reactivities of benzhydryl pentafluorophenolates and corresponding benzhydryl carboxylates vary with the electrofugality of a carbocation formed in the heterolytic step, <i>i.e.</i>, inversion of the reactivity of benzhydryl series with different leaving groups occurs. The plots of Δ^‡<i>G</i>° <i>vs.</i> Δ_r<i>G</i>° for solvolysis of benzhydryl phenolates and carboxylates reveal that phenolates solvolyze over the lower Marcus intrinsic barrier than corresponding carboxylates.
<br><a rel="license" href="http://creativecommons.org/licenses/by/4.0/"><img alt="Creative Commons License" style="border-width:0" src="https://i.creativecommons.org/l/by/4.0/80x15.png" /></a> This work is licensed under a <a rel="license" href="http://creativecommons.org/licenses/by/4.0/">Creative Commons Attribution 4.0 International License</a>.

• Keywords (english): nucleofugality; leaving group; LFER; phenolate; intrinsic barrier; solvolysis
• Language: english
• Publication type: Scientific paper - Original scientific paper
• Publication status: Published
• Peer review: Peer review - international
• Publication version: Published version
• Journal title: Croatica Chemica Acta
• Numbering: vol. 89, no. 3, pp. 355-362
• p-ISSN: 0011-1643
• e-ISSN: 1334-417X
• DOI: https://doi.org/10.5562/cca3040
• URN:NBN: urn:nbn:hr:163:523575
• Publication: 2016
• Document URL: https://hrcak.srce.hr/172243
• Type of resource: Text
• Access conditions: Open access
• Created on: 2020-04-17 13:44:27