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-fluoro3-nitrobenzene by the action of phenols in the presence of potassium carbonate in dimethylformamide at 95-125 degrees C were studied by the competing reaction method. The rate constant ratios k(NO2)/k(F) were correlated with the differences between the corresponding activation parameters (Delta Delta H-double dagger and Delta AS(double dagger)). The greater mobility of the nitro group was found to be determined by the entropy control of the reactivity of arenes. The activation parameters (Delta H-double dagger and Delta S-double dagger) were calculated, and the enthalpy entropy compensation effect was revealed. The reaction mechanism is discussed.