35Cl nuclear quadrupole resonance and infrared studies of hydrogen-bonded adducts of 2-chloro-4-nitrobenzoic acid

Abstract

³⁵ Cl nuclear quadrupole resonance and infrared spectra of solid hydrogen-bonded adducts of 2-chloro-4-nitrobenzoic acid have been studied in relation to the variation of the ΔpK_a value from –2.22 to 9.04. Both methods yield the same critical value of ΔpK_a equal to 3.6–3.7, which corresponds to the lowest value of the position of the centre of gravity of the i.r. protonic vibrational band and the stepwise change of ³⁵Cl n.q.r. frequency.