The invention relates to the field of
medicine synthesis, in particular to a synthetic method of
levofloxacin, which comprises the following steps: (1) adding
levofloxacin, N-methyl
piperazine, a
solvent and
potassium fluoride into a reactor, heating to 70-90 DEG C, reacting for 3-6.5 hours, after the reaction is finished, controlling the
internal temperature to be below 120 DEG C, recovering under reduced pressure until no distillate is produced, and then continuously recovering for 0.5 hour until the mixture is dry; and adding water into the filtrate, and carrying out reverse heating, cooling and suction
filtration to obtain the
levofloxacin. According to the synthetic method of levofloxacin provided by the invention, a
solvent is added to filter out a byproduct of generated
potassium bifluoride, and water is directly added into filtrate for
crystallization. In the whole process before
crystallization, no water is introduced, no
hydrogen fluoride is dissociated, equipment
corrosion is avoided, the
pipette shrinkage
reaction conditions are mild, the reaction time is short, no extraction operation is adopted, three wastes and
energy consumption are reduced, the production efficiency is improved, and a
crystallization solvent is the same as a reaction solvent and is convenient to recycle and reuse.