Study of the properties and structure of 6-substituted 2-thionolepidines

It has been shown that 2-thioquinolones are weaker conjugate acids and bases than 4-thioquinolones [1]. The UV spectra of solutions and the IR spectra of crystalline 6-substituted 2-thionolepidines confirm the predominance of the thione structure. It was found that 2-thioquinolones exist in the form of a dipolar ion. In contrast to 2-thiopyridones, 2-thioquinolones form derivatives of only the thiol form with methyl iodide, diazomethane, and acrylonitrile. The pK_a (–H)⁺ values are correlated with the J constants.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 521–524, April, 1973.