13C NMR spectra of 5-substituted 8-mercaptoquinolines
The increments of the substituents were determined from the 13C NMR spectra of 5-substituted quinolines. It is shown that the increments correlate with those in benzenes, as well as with the Swain-Lupton constants. The 13C chemical shifts of some 5-substituted 8-mercapto-, 8-(methylthio)-, and 8-hydroxyquinolines were investigated. Their values are in satisfactory agreement with the additive contribution. of the increments of the substituents. The deviations from additivity are associated with the steric hindrance to interaction of the substituents with the ring.