Mechanism of replacement of the nitro group and fluorine atom in meta-substituted nitrobenzenes by phenols in the presence of potassium carbonate
The relative mobilities of the nitro group and fluorine atom in 1,3-dinitrobenzene and 1-fluoro-3-nitrobenzene by the action of phenols in the presence of potassium carbonate in dimethylformamide at 95-125°C were studied by the competing reaction method. The rate constant ratios k(NO 2)/k(F) were correlated with the differences between the corresponding activation parameters (ΔΔH≠ and ΔΔS≠). The greater mobility of the nitro group was found to be determined by the entropy control of the reactivity of arenes. The activation parameters (ΔH≠ and ΔS≠) were calculated, and the enthalpy-entropy compensation effect was revealed. The reaction mechanism is discussed.