The infrared absorption spectra of eleven 1-p-tolylthio-3-alkylureas and the corresponding sulfonyl compounds were recorded. Comparison of the thio and sulfonyl derivatives is made with respect to the influence exerted by the S or SO2 group on their respective frequencies due to phenyl and ureido groups. The variations of the absorption positions depend on the electronic nature of each groups. The nature of the alkyl group has relatively little effect on the position of these bands.
