13C NMR Spectra of 8-mercaptoquinoline derivatives

Abstract

The additivity of the effect of the increments of the substituents on the 13C chemical shifts in polysubstituted quinolines is demonstrated. In the case of substitution in the pyridine part of quinoline (R = CH3, OCH3, SCH3) the ortho increments are depressed as compared with the increments in benzene derivatives. This is associated with a change in the charge on the ring carbon atom and polarization of the C-H bond because of steric hindrance.