A preparation method of
sulfadoxine belongs to the field of
sulfanilamide antimicrobial drug preparation. Cyclization reaction comprises the following steps of: firstly pouring a
sodium methoxide solution into a reactive pan, then successively adding methanamide and methyl ethyl methoxymalonate, keeping warm, recovering
methanol, cooling for
crystallization,
drying by
centrifugation, discharging,and
drying to obtain 5-methoxy-4,6-disodium dihydroxypyrimidine; Chlorination reaction comprises the following steps of: firstly putting
phosphorus oxychloride into a reaction vessel for heating, adding 5-methoxy-4,6-disodium dihydroxypyrimidine into the reaction vessel to react, decompressing and recovering
phosphorus oxychloride until the material is dry, cooling, adding trichloro
ethylene withuniformly stirring, putting into a
hydrolysis pan for hydrolyzation, collecting a trichloro
ethylene layer after standing and delaminating, followed by a
neutralization reaction, controlling pH value, washing, removing a
water layer, recovering trichloro
ethylene, and releasing crystals to obtain 5-methoxy-4,6-dichloropyrimidine. The preparation method provided by the invention can be used to guarantee the product purity, prolong the service life of equipment, avoid the damage to the environment and
human body, reduce emission, and save energy, and accords with foreign
pharmacopoeia standard requirements.