Correlation of reaction rates with acidity functions in strongly basic media. Part III. The effect of temperature and leaving group for aromatic Sn2 reactions

Abstract

The rates of the S_N2 reactions of aqueous sodium hydroxide with 1-chloro-2,4-dinitrobenzene and 2,4-dinitrophenetole at 25° and 2,4-dinitroanisole at four other temperatures have been measured. A unique J_ acidity function is defined by results for the three substrates at 25°. For 2,4-dinitroanisole the rate of change of J_ with sodium hydroxide concentration was independent of temperature. The results are discussed in terms of solvation-model explanations of acidity function behaviour. An extension of an equation for the calculation of ionic activity coefficients to the fitting of acidity functions for concentrated acid solutions is also applicable to the J_ function for aqueous sodium hydroxide.