Naslov
Nucleofugality of Pentafluorophenolate in Various Solvents : Solvolytic Behavior of Phenolates

Autori
Matić, Mirela ; Bebek, Nives ; Denegri, Bernard ; Kronja, Olga

Izvornik
Croatica chemica acta (0011-1643) 89 (2016), 3; 355-362

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

Ključne riječi
nucleofugality ; leaving group ; LFER ; phenolate ; intrinsic barrier ; solvolysis

Sažetak
The leaving group ability (nucleofugality) of the pentafluorophenolate anion has been determined from first order solvolytic rate constants (k) of X, Y-substituted benzhydryl pentafluorophenolates measured in a series of solvents, by using the three parameter LFER equation: log k = sf (Ef + Nf). Comparison with other leaving groups reveals that pentafluorophenolate is a moderate leaving group, whose nucleofugality (Nf value) is between the nucleofugalities of phenyl carbonate and 3, 5-dinitrobenzoate leaving groups. However, due to its high reaction constant (sf = 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.e., inversion of the reactivity of benzhydryl series with different leaving groups occurs. The plots of Δ‡G° vs. ΔrG° for solvolysis of benzhydryl phenolates and carboxylates reveal that phenolates solvolyze over the lower Marcus intrinsic barrier than corresponding carboxylates.

Izvorni jezik
Engleski

Znanstvena područja
Kemija

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