The rates and equilibria of some reactions of trinitrotoluene and related substances from —80 to +20°C

Abstract

Rates and equilibria between —78*5 and + 20°C have been investigated for the colourproducing reaction between ethoxideion and 2:4:6 -trinitrotoluene, and the related reactions with trinitrobenzene, trinitroaniline and similar substances. With trinitrobenzene the reaction is presumably an addition; with trinitrotoluene it appears to be a proton transfer producing a colouredanion. The observed variations in reaction rate, in the parameters A and E of the Arrhenius equations, and in the equilibrium constant are interpreted in terms of changes of solvation due to delocalization of charge in the transition state. No deviations from the Arrhenius equation have been observed. Comparison of the kinetics of proton transfer with those of addition suggests that the rate of the ethoxide-trinitrotoluene reaction may be controlled not by the proton transfer alone but also by accompanying changes such as the movements of solvent molecules. The rates of the reactions between the anion of trinitrotoluene and various weak acids have been measured at — 78.5 and at +20° C, and found to exhibit a relation of the Brønsted type between rates and acid strengths.