Abstract
Kinetic and equilibrium studies are reported of the reactions of 1,3,5-trinitrobenzene (
TNB
) with a series of
o
-substituted anilines in dimethyl sulfoxide (
DMSO
) in the presence of 1,4-diazabicyclo[2.2.2.]octane (
DABCO
). The
pK
a
values in
DMSO
for the aniline derivatives were measured using the proton-transfer equilibrium with 2,4-dinitrophenol. Kinetic studies are compatible with a two-step process involving initial nucleophilic attack on
TNB
by amine to give a zwitterionic intermediate which may transfer an acidic proton to
DABCO
to yield the anionic product. The results indicate steric hindrance to proton transfer in reactions involving 2,6-disubstituted anilines.