A nuclear magnetic resonance study of hindered internal rotation in diethylthiourea

Abstract

Variable-temperature n.m.r. spectra of NN′-diethylthiourea have been recorded in acetone and in chloroform solutions. At low temperature the rotation about the thioamide bonds is slow and different rotational isomers can be detected. Only two of the three possible isomers seem to be present; i.e. the rotamer with two ethyl groups cis and the rotamer with one group cis and the other trans to the thioamide sulphur atom. The third isomer, with the two alkyl groups trans to the sulphur atom, is presumably too sterically hindered to be present in detectable amounts. The effects of solvent and concentration are also discussed.