Multinuclear NMR Study of Variously Substituted Sulphonamides and Sulphinamides

Article abstract of DOI:10.1002/mrc.1260250302

13C, 15N and 17O NMR chemical shifts, and also ¹J(CH) and ¹J(NH) values, have been determined for variously substituted sulphonamides and some sulphinamides, either neat or in acetone or dimethyl sulphoxide solution.The effect of benzene ring substitutens on the chemical shifts of nitrogen and oxygen nuclei is slight, but N-substitution changes the shielding of both nuclei.Generally, an N-methyl substituent shields an amide nitrogen and an N,Ndimethyl substituent gives further slight shielding.On the other hand, an N-phenyl substituent deshilds the nitrogen strongly, but the deshielding effect of an N,N-diphenyl substituent is markedly smaller.The sulphonyl oxygens are deshilded relative to the sulphinyl oxygens, and N-methyl and N,N-dimethyl substituents shild the oxygen nucleus.The effect of N-phenyl and N,N-diphenyl substituents on the shielding of the oxygen atoms of the sulphonyl group is slight.The direct ¹J(CH) coupling constants are similar, but they are characteristic of different type of sulphur amides.The ¹J(NH) values are of the same order of magnitude for sulphonamides and sulphinamides, but are clearly smaller for N-unsubstituted amides than for N-substituted compounds.KEY WORDS Sulphonamide Sulphinamide Multinuclear NMR