NMR of terminal oxygen. 6—17O NMR of the S-O ‘double bond’: Derivatives of arylsulphinic and arylsulphonic acids

Abstract

The ¹⁷O NMR spectra of terminal oxygen atoms in esters, anions and amides of substituted arenesulphinic acids and in esters and amides of substituted arenesulphonic acids were measured. The signals of the terminal O appear close to those of the bridge O. Compared with carbonyl O, terminal SO shows (a) a lower sensitivity to the electronic influences of geminal groups, (b) only a low sensitivity to arene ring substituents and (c) small solvent effects. The difference between C‐ and S‐bound O is discussed in terms of π‐bond character. Dy³⁺ complexation occurs with the terminal O in methyl arenesulphinates.