The 13C n.m.r.
spectra of 17 monosubstituted benzenes, 14 para substituted acetanilides
and ten 4'-nitrophenyl 4-substituted benzoates have been measured in (CD3)2SO
and the chemical shifts have been compared with the infrared carbonyl
stretching frequencies of the substrates (in CCl4), the 1H
n.m.r. chemical shifts of protons close to the reactive site of protonation,
rates of hydrolysis or aminolysis and literature
values of the corresponding basicity constants and
rate constants. The observed substituent chemical shifts are non-additive and
this result has been discussed in terms of the electronic properties of -NHCOCH3
and -COOC6H4NO2. The 13C n.m.r. and
the i.r. data have been treated by single parameter
and dual substituent parameter linear free energy relationships and σR values
of best fit have been identified. Relative resonance and inductive
contributions have been discussed.
