Mechanism of the alkaline hydrolysis of O-ethyl S-(2,4,6-trinitrophenyl) thio- and dithiocarbonates

Abstract

The alkaline hydrolysis of O-ethyl S-(2,4,6-trinitrophenyl) thio- and dithiocarbonates, 1 and 2, respectively, were studied kinetically in 5% dioxane in water, at 25.0 °C, and ionic strength 0.2 mol dm^–3 (KCl). Two kinetic processes, well separated in time, were detected. The fast process involves the formation of a σ-complex by addition of HO^– to one of the unsubstituted positions of the aromatic ring, followed by fast ionisation of this complex. The slow process leads to the formation of a mixture of 2,4,6-trinitrophenoxide and 2,4,6-trinitrobenzenethiolate ions in a 10∶1 ratio, respectively, in the reaction of 2, and to a mixture in a 2∶1 ratio in the reaction of 1, independent of KOH concentration. Although the substrates show different kinetic behaviour with KOH concentration, the results can be discussed on the basis of a common reaction mechanism.