Spectroscopic Study of the Conformation of 2-Anilino-2-ethoxy-3-oxothiobutyric Acid Anilides

摘要

An NMR study of hte equilibrium mixture of two conformers of 2-anilino-2-ethoxy-3-oxothiobutyric acid anilides 3 allows to estimate their population ratio in solvents of increasing polarity. X-Ray analysis as well as IR spetroscopy confirmed that the conformer present in thesolid state is stabilized by two hydrogen bonds. The structural basis of the second conformer observed in solution is the 1,4-type S...O interaction between thesulfur of the thioanilide moiety and the oxygen of the ethoxy group with a distance of 20878 A.