Elimination of nitrile from (E)-2,4,6-trinitrobenzaldehyde O-pivaloyloxime promoted by R2NH in MeCN. Effect of β-aryl group on the nitrile-forming transition-state

Abstract

Nitrile-forming eliminations from (E)-2,4,6-(NO2)3C6H2CH=NOC(O)(CH3)3 promoted by R2NH in MeCN have been studied kinetically. The reactions are second-order and exhibit substantial Hammett ρ and Bronsted β values. The k 2 value for elimination from (E)-2,4,6-trinitrobenzaldehyde O-pivaloyloxime promoted by i-Pr2NH in MeCN falls on a single line in the Hammett plot for different β-aryl substituents, which have been shown to react by the E2 mechanism. This result indicated that the reaction mechanism is not changed by the introduction of the 2,4,6-trinitro substituents, and that the elimination reactions from (E)-benzaldehyde O-pivaloyloximes series proceed by the common E2 mechanism.