Effect of methyl substituents on the NMR spectra of aromatic protons of some nitrobenzene derivatives

Proton NMR spectra were recorded and analysed for 1-bromo-4-nitrobenzene, 2-bromo-5-nitroluene, 3-bromo-6-nitrotoluene and 2-bromo-5-nitro-p-xylene, as well as for the corresponding compounds having p-CH₃C₆H₄S in place of Br. Chemical shifts and coupling constants generally agree with expected values; however, a deshielding effect of the methyl group on aromatic protons was observed in one case.