13C NMR spectra of protonated S-methylquinolines

The signals in the¹³C NMR spectra of protonated 2-, 3-, 4-, 5-, 6-, and 8-S-methylquinolines in solution in 6 N DCl were assigned. The changes in the¹³C chemical shifts relative to the neutral molecules were compared with the results of calculations within the CNDO/2 approximation. It is shown that when the molecules are protonated, the shift of the¹³C signals is due to changes in the charges and the paramagnetic components of shielding of the nuclei.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 663–665, May, 1980.