METHOD FOR PREPARATION OF SULFADIMEZINE (VARIANTS) Russian patent published in 2018 - IPC C07D239/69 

FIELD: medicine; pharmaceuticals.

SUBSTANCE: invention relates to improved versions of a process for preparation of sulfadimezine which allow preparation of pharmacopeinically pure sulfadimezine with a yield of the finished product from 93.6 to 94.2 %. One of the variants of the method is that the method is carried out as follows: water is charged into the reactor, technical sulfadimezin, activated carbon, the reaction mixture is heated to a temperature of 85 ± 5 °C, then 46 % solution of sodium hydroxide is added, adjust the pH from 9.0 to 10.5; the reaction mixture is stirred for 10–20 minutes. Reaction mixture was then filtered through a different filter, crystallized and heated to a temperature of 84 ± 5 °C. Thereafter, orthophosphoric acid, sodium hydrogen sulfite and 20 % acetic acid are charged into the reaction mixture, pH is adjusted to 6.0–7.0, then the reaction mass is cooled to a temperature of 18 ± 5 °C, filtered, washed with purified water, then dried at 110 ± 7 °C to a moisture content of not more than 0.5 %. Another method for producing sulfadimezine is to carry out the process as follows: Absolute isopropyl alcohol is charged to the reactor, technical sulfadimezin, activated carbon, the reaction mixture is heated to a temperature of 52 ± 5 °C, then mixed for 10–20 minutes. Reaction mixture is then filtered through a different filter, crystallized and cooled to a temperature of 32 ± 5 °C for 2–3 hours. After that, the reaction mixture is cooled to a temperature of 18 ± 5 °C, the reaction mixture was filtered, washed with isopropyl alcohol absolute, then dried at 110 ± 7 °C to a moisture content of not more than 0.5 %.

EFFECT: improved variants of the method for preparation of sulfadimezine allow preparation of pharmacopeinically pure sulfadimezine.

2 cl, 4 ex