In a 5-l. three-necked flask, fitted with a reflux condenser and stirrer, are placed 2500 ml. of water and 50 g. of α-picoline (0.54 mole) (Note 1). Ninety grams (0.57 mole) of potassium permanganate is added, and the solution is heated on a steam bath until the purple color has practically disappeared (about 1 hour). A second 90-g. portion of permanganate is then introduced, followed by 500 ml. of water, and the heating is continued until the purple color is destroyed (2–2.5 hours). The reaction mixture is allowed to cool slightly, and the precipitated oxides of manganese are filtered and washed well with 1 l. of hot water (Note 2). The filtrate is concentrated under reduced pressure to 150–200 ml., filtered, if necessary, and acidified to Congo red with concentrated hydrochloric acid (65–70 ml., sp. gr. 1.19). This acid solution is then evaporated to dryness under reduced pressure. The solid residue is refluxed for one hour with 250 ml. of 95% ethanol and filtered, and the extraction is repeated with 150 ml. of 95% ethanol. Dry hydrogen chloride is passed into the combined ethanolic filtrates until crystals begin to separate. The solution is then chilled to about 10° in a freezing mixture, the addition of hydrogen chloride being continued until the solution is saturated. The crystals of picolinic acid hydrochloride which separate are filtered and air-dried. The yield is 43–44 g. (50–51%), m.p. 228–230° (Note 3).

This hydrochloride may contain traces of potassium chloride, which can be removed by dissolving the hydrochloride in hot absolute ethanol (50 g. requires 1 l.) and filtering from insoluble material. An equal volume of dry ether is then added to the warm ethanolic solution, and, after cooling, the crystallized product is filtered. The recovery is 40–43 g., m.p. 210–212° (230°) (Note 3) and (Note 4).