Method for preparing 3-methylquinoline

The invention relates to a method for preparing 3-methylquinoline, in particular to a method for preparing 3-methylquinoline serving as an argatroban intermediate. The method comprises the following steps of: adding 2-chloro-3-methylquinoline into an ethanol aqueous solution of sodium acetate, stirring, and adding 5 percent palladium carbon; and introducing nitrogen for ventilation, introducing hydrogen for ventilation, stirring, reacting at the temperature of between 50 and 55 DEG C until the hydrogen is not absorbed, ventilating, filtering out the palladium carbon, evaporating ethanol, adding chloroform into residues, washing by using a 10 percent sodium bicarbonate solution until a water layer is neutral, washing, distilling residue paste in vacuum, and collecting fractions at the temperature of between 120 and 135 DEG C under the pressure of 5mmHg. The originally used glacial acetic acid serving as a solvent is changed into ethanol-water, and the use times of the palladium carbon during production is grea