Spectra of sulphonyl derivatives. IV. Sulphonic esters

Abstract

The symmetric and asymmetric SO₂ stretching frequencies (1190, 1365 cm^-1) and the SO₂ deformation frequency (565 cm^-1) in esters of arylsulphonic acids are similar to those for sulphonyl chlorides. A frequency of about 800 cm^-1 can be correlated with the presence of the SO₂.OR group and is probably the S-OR bond stretching vibration. The corresponding frequencies in methyl methane sulphonate are slightly lower. A doubling of some frequencies is attributed to the occurrence of rotational isomerism in the sulphonic ester group. The frequency noted by Ham and Hambly (1953b) and suggested as characteristic of aromatic sulphonyl derivatives corresponds to a very constant vibration 1098-1099 cm^-1 in the aromatic esters studied.