Original scientific paper

https://doi.org/10.5562/cca2179

The Reactivity of Benzoates in Mixtures of Water and Aprotic Solvents

Mirela Matić ; Faculty of Pharmacy and Biochemistry, University of Zagreb, Ante Kovačića 1, HR-10000 Zagreb, Croatia
Bernard Denegri orcid.org/0000-0001-6335-6723 ; Faculty of Pharmacy and Biochemistry, University of Zagreb, Ante Kovačića 1, HR-10000 Zagreb, Croatia
Olga Kronja ; Faculty of Pharmacy and Biochemistry, University of Zagreb, Ante Kovačića 1, HR-10000 Zagreb, Croatia

Abstract

Nucleofugalities of pentafluorobenzoate (PFB), 2,4,6-trifluorobenzoate (TFB), 2-nitrobenzoate,
and 3,5-dinitrobenzoate (DNB) leaving groups have been derived from the solvolysis rate constants of the
corresponding X,Y-substituted Z-benzhydryl benzoates in 60 % and 80 % aqueous acetonitrile and 60 %
aqueous acetone, by applying the LFER equation: log k = f s (Ef + Nf). The experimental barriers (ΔG‡
exp) for
solvolyses of 13 dianisylmethyl Z-substituted benzoates in these solvents correlate very well with the ΔH‡
calc
of the model epoxy ring formation (calculated earlier by the B3LYP-PCM quantum-chemical method). Using
the ΔG‡
exp vs. ΔH‡
calc correlation, and taking f s based on similarity, the nucleofugality parameters for about
70 benzoates have been determined in 60 % and 80 % aqueous acetonitrile and 60 % aqueous acetone.
Z-Substituents on the phenyl ring have larger impact on the solvolytic reactivity in the less polar solvent than
in the more polar solvent due to the more carbocation-like transition state. (doi: 10.5562/cca2179)

Keywords

nucleofugality; reactivity; substituted benzoate; aprotic solvent

Hrčak ID:

94471

URI

https://hrcak.srce.hr/94471

Publication date:

17.12.2012.

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