13C NMR spectra of some 2′-nitromethane-and N-(methylsulphonyl)-2′-nitromethane-sulphonanilides

The 13C chemical shifts in several 2′‐nitromethanesulphonanilides and N‐(methylsulphonyl) ‐ 2′ ‐ nitromethanesulphonanilides are reported. Analysis of the 13C shifts provides an insight into the electronic and steric interactions in these compounds. A comparison of the 2′‐nitromethanesulphonanilides with the corresponding anilines reveals that substitution of a methylsulphonyl group causes an upfield shift of 10–13 pprn for C‐1 while the ortho carbons, C‐2 and C‐6, are deshielded by 4‐6 and 1‐3 ppm, respectively. The unequal shielding of the two ortho carbons is noteworthy. Substitution of a second methylsulphonyl group on nitrogen causes similar changes in the chemical shifts but their magnitude is different. In several compounds the effect of para substituents is not equal at the two ortho or meta carbons.