934-60-1

108-48-5

934-60-1

Step 1: 2,6-dimethylpyridine (10.71 g, 0.1 mol) was dissolved in 500 mL of deionized water, stirred and heated to 60 °C. Subsequently, potassium permanganate (KMnO4, 23.7 g, 0.15 mol) was added in ten portions, with an interval of 30 min between each addition. The temperature was strictly controlled at about 60°C during the reaction, which lasted for 5 h and then stopped. Immediately after completion of the reaction, the insoluble impurities were removed by filtration. The filtrate was adjusted to pH=5 and then extracted with ethyl acetate. The organic phase was collected, concentrated under reduced pressure and finally recrystallized from ethanol to obtain 6-methyl-2-pyridinecarboxylic acid (10.3 g, 75% yield). In this step, the effects of different reaction conditions (e.g., equivalents of KMnO4 of 1, 1.5 and 2, aqueous potassium permanganate solution of different pH, temperature and molar ratio) on the reaction were investigated by orthogonal tests, and the optimal reaction conditions were determined to be neutral aqueous potassium permanganate solution with a dosage of 1.5 equivalents of KMnO4.