Ultraviolet and infrared absorption spectra of 2-thiophenesulfonamides

The uv and ir absorption spectra of thirty-one 2-thiophenesulfomides have been investigated. The uv spectroscopic data are discussed in relation to the absorption of some parent compounds and the spectral changes are correlated with substituent effects. The ir stretching frequencies of NH bond are reported. In KBr discs, only one NH stretching absorption band, due to associated sulfonamide, is observed. In CCl4 solutions, however, two bands, due to free and associated NH group, are present. A good correlation is found between the Hammett substituent constants and the NH frequencies. Also, the ir stretching of SO, CS and SN bonds is briefly discussed.