In Process Citation

Oxidation of 6-methoxyquinoline with vanadate shows the possibility of initial complex formation between the dioxovanadium(V) ion VO⁺₂ and the ethereal oxygen atom. The opening of the homocycle yields mainly 2-pyridone-3-carboxylic acid. In the case of quinine or mefloquine, the VO⁺₂ ion preferentially forms a pentagonal chelate with the secondary alcohol function. Oxidation of this complex initially produces quinoline-4-carboxylic acids. The acid that results from mefloquine is stable in the reaction solution and this property allows a reproducible consumption of reagent and a quantitative determination of this new antimalarial drug.