Chemical Properties
Pale Yellow Solid
Uses
Pantoprazole EP Impurity C. Pantoprazole USP Related Compound C.
General Description
5-(Difluoromethoxy)-2-mercapto-1
H-benzimidazole may be used in the synthesis of pantoprazole, a drug for treating gastroesophageal reflux disease and gastrointestinal disorders.
Synthesis
In a four-necked flask equipped with a mechanical stirrer, a reflux condenser and a thermometer, the alkaline solution was prepared: 6.6 g of sodium carbonate was dissolved in 20 g of tap water, stirred until completely dissolved, cooled slightly, and then 34.8 g of 4-(difluoromethoxy)benzene-1,2-diamine was added, stirring was continued for 20 minutes. The reaction mixture was heated to 30°C and 20 g of carbon disulfide was slowly added dropwise, controlling the dropwise temperature at 25-35°C. After the dropwise addition was completed, the temperature was raised to 30-40°C and the condensation reaction was maintained at this temperature for 6 hours. Subsequently, continue heating to 60-70°C and maintain this temperature for cyclization for 6 hours. After the reaction was completed, activated carbon was added for decolorization. The pH of the filtrate was adjusted to 5-6 with sulfuric acid, and after filtration, washing and drying, 33.2 g of 5-difluoromethoxy-2-mercapto-1H-benzimidazole was obtained in 95.4% yield (based on 4-(difluoromethoxy)benzene-1,2-diamine).
References
[1] Patent: CN103539746, 2016, B. Location in patent: Paragraph 0037; 0038
[2] Advanced Synthesis and Catalysis, 2018, vol. 360, # 21, p. 4161 - 4167
