The invention discloses a preparation method of
albendazole, which comprises the following steps of: dissolving 4-propylthio-o-phenylenediamine in
methanol, cooling, keeping the temperature at 0-5 DEGC, slowly dropwise adding
cyanogen chloride for reaction under the condition of uniform stirring, and regulating and keeping the pH value at 4-5 in the process; heating to 35-45 DEG C after dropwiseadding is finished, carrying out heat preservation for 1-2 hours, then carrying out atmospheric
distillation to recover
methanol to obtain a
solid-liquid mixed
aqueous solution, and carrying out cooling, filtering and
drying to obtain 6-propylthio-2-amino-1-
hydrogen-benzo [d]
imidazole; adding the obtained product into
methanol, stirring, cooling, maintaining the temperature at 5-10 DEG C, slowlydropwise adding
methyl chloroformate, and adjusting and maintaining the pH value at 6-7; after dropwise adding is finished, heating to 35-45 DEG C, keeping the temperature for 1-2 hours, distilling atnormal pressure to recover methanol, cooling to 15-20 DEG C, and performing filtering and
drying to obtain an
albendazole product. The method has the advantages of mild
process conditions, low cost of used raw materials,
water saving, strong reaction activity, good selectivity, high product yield and good product quality.