The acidity dependence of orientation in the nitration of quinoline 1-oxide was investigated by using the trifluoromethanesulfonic acid (TFSA)-trifluoroacetic acid (TFA) system and the antimony pentafluoride (SbF 5)-TFSA system. These systems provide a wider range of acidity than that of aqueous sulfuric acid. Comparison of the behavior of quinoline 1-oxide and 1-methoxyquinolinium triflate in acidic and neutral media demonstrated that O- ...