| Abstract: | A number of 5-aryl-2-acetylthiophenes and 1-(5-aryl-2-thienyl)-3-phenyl-1-propenones were synthesized, and it was shown by means of their IR spectra that the 1-propenones are trans isomers with respect to the orientation of the substituents attached to the double bond and have an s-cis conformation. According to the data from the IR spectra of the H complexes of the investigated compounds with phenol, 5-aryl-2-acetylthiophenes have higher proton-acceptor capacities than acetophenones, 2-acetylthiophenes, and 4-acetyldiphenyl; a similar picture is also noted in a number of 1-propenones and 3-propenones. The transmission factors (  ) obtained by Hammett correlation of the   Oh values for 1,4-phenylene, 2,5-thienylene, and vinylene groupings are identical and are equal to 0.8. It is shown on the basis of a correlation with respect to an equation of the Yukawa-Zuno type that the thiophene ring transmits polar conjugation better than the benzene ring.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1196–1202, September, 1976. |
