The stabilities of Meisenheimer complexes. Part XIII. Kinetic and equilibrium data for spiro-complex formation from 1-(2-mercaptoethylthio)- and 1-(2-hydroxyethylthio)-2,4,6-trinitrobenzene in water

Abstract

Cyclisation of 1-(2-mercaptoethylthio)-2,4,6-trinitrobenzene occurs in water to give a spiro complex (III), of high thermodynamic stability. Opening of the dithiolan ring of (III) is catalysed by mercury(II) ions but not by acids. In the presence of aqueous base cyclisation of 1-(2-hydroxyethylthio)-2,4,6-trinitrobenzene to the spiro complex (IV) is followed by irreversible decomposition to ethylene sulphide and picrate ions. Kinetic and equilibrium data for the formation of (III) and (IV) are reported and are compared with those for the analogous dioxolan, complex (V).