Kinetics and mechanism of the reactions of methyl 2,4,6-trinitrophenyl carbonate with anilines

Abstract

The title reactions in water are subjected to a kinetic investigation. Under excess amine, pseudofirst-order rate coefficients (k obsd ) are obtained. Plots of k obsd against aniline concentration are linear, with k N as the slope. The Brønsted-type plot (log k N vs anilinium pK a ) is linear with slope 0.7, consistent with a concerted mechanism. By comparison of these reactions with others, it is concluded that anilines destabilize the tetrahedral intermediate relative to isobasic pyridines. The change of 2,4-dinitrophenoxide by 2,4,6-trinitrophenoxide as the leaving group of the carbonate destabilizes the tetrahedral intermediate and makes possible a change in mechanism.