Reactions in strongly basic media. Part 7. Correlation of the rates of alkaline hydrolysis of 2-substituted 3- and 5-nitropyridines, 4-nitropyridine N-oxide, and 2- and 4-substituted pyridine methiodides in aqueous dimethyl sulphoxide with an acidity function

Abstract

The rate coefficients for the alkaline hydrolysis of a series of 2-substituted 3- and 5-nitropyridines, 4-nitropyridine N-oxide, and 2- and 4-substituted pyridine methiodides in aqueous dimethyl sulphoxide have been measured at 30.0 °C. The halogenonitropyridines react by ring fission, whereas all the other substrates react by substitution. The rates have been correlated with an acidity function for the medium and the slopes of the linear relations are discussed. The observation of Meisenheimer intermediates, and its lack, is related to the structures of the substrates.