6-Hydroxy-2-quinolinecarboxylic acid

75433-99-7

75434-18-3

6-Methoxyquinoline-2-carboxylic acid (4 g, 0.019 mol) was used as starting material and suspended in 48% aqueous hydrobromic acid (80 ml). The reaction mixture was heated to reflux at 125°C overnight. Upon completion of the reaction, the mixture was cooled to 0 °C and the pH was adjusted to 6-7 by slow addition of aqueous ammonium hydroxide. subsequently, dilute hydrochloric acid was added dropwise until the pH reached 3-4, at which point the target product, 6-hydroxy-2-quinolinecarboxylic acid, precipitated as a solid. The precipitate was collected by filtration, washed thoroughly with deionized water, and finally dried in a vacuum drying oven to give 3.5 g of the product in the form of a yellow solid (0.0185 mol, 97% yield). The molecular weight of the product was confirmed to be 190.1 (M+H)+ by mass spectrometry.