High resolution hydrogen resonance spectra of trisubstituted benzenes

Abstract
High resolution hydrogen resonance spectra are given for a number of asymmetrically trisubstituted derivatives of benzene. In some cases the spectra can be analysed as AB2, ABB′ or ABX cases. The ABB′ case, in which the B nuclei have identical chemical shifts but are unequally coupled to A, is discussed and illustrated. The spin-spin coupling constants between protons (a) ortho to one another lie in the range 7 to 9 c/s, (b) meta to one another occur near 2·5 c/s and (c) para to one another are less than 1 c/s.