Tautomerism of a series of substituted 9-acridinethiones

Application of mass spectrometry for the analysis of organic tautomeric compounds

“…In the gas phase and in crystalline state, these compounds exist as thione tautomers (IR and UV data). However, structures 35 and 36 could be formed in solution, depending on solvent polarity (Kurapov, Martynovskii, & Klyuev, 1984). The thione tautomers of mercaptobenzothiazoles also prevail in the gas phase (Chikishev, Klyuev, & Vantberg, 1975;Ogyra, Sigimoto, & Itoh, 1970).…”

“…Annelation of heterocyclic rings shifts the equilibrium towards the formation of thione structures. Mass spectra of substituted 9-mercaptoacridines 35 indicate that these compounds are mainly acridinthiones 36 (Scheme 17) (Kurapov, Martynovskii, & Klyuev, 1984;1984).…”