Preparation method of doxofylline
A technology of doxofylline and theophylline, which is applied in the field of drug synthesis and can solve the problems of unavailable raw materials and high cost
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Embodiment 1
[0037] a. Preparation of bromoacetaldehyde ethylene acetal
[0038] Add 12.414Kg ethylene glycol (200mol) to the reaction tank, slowly add 4.41Kg freshly distilled acetaldehyde (100mol) under stirring conditions and stir at room temperature for 30min, add bromine 15.98Kg (100mol) dropwise, and control the dropping process The temperature is below 10°C. After the dropwise addition, react at 0-10°C for 3 hours, fractionate under reduced pressure, and collect 13.126Kg (78.6mol) of 80-82°C fraction (3.6KPa), which is bromoacetaldehyde ethylene acetal. The yield is 78.6%, and the content is more than 95%.
[0039] b. Preparation of bromoacetaldehyde ethylene acetal
[0040] Add 10.326Kg ethylene glycol (166.37mol) in the reaction tank, slowly add 3.66Kg newly distilled acetaldehyde (83.185mol) under stirring condition and stir at room temperature for 30min, dropwise add bromine 14.622Kg (91.504mol), control The temperature of the dropping process is below 10°C. After the dropwise...
Embodiment 2
[0044] Add theophylline 12.6Kg (69.94mol), 7.85Kg potassium hydroxide (139.88mol), 0.478Kg benzyltriethylammonium chloride (2.10mol) in the reaction tank, add dropwise 14.02Kg bromoacetaldehyde after stirring for 10min Ethylene glycol (83.93mol), temperature controlled in a water bath at 60-70°C, stirred for 6 hours, and monitored by thin-layer chromatography (developing solvent: acetone: dichloromethane = 3:1). After the reaction was finished, the solvent was evaporated to dryness by distillation under reduced pressure, washed 3 times with saturated brine, filtered, and the filter residue was recrystallized with absolute ethanol to obtain 16.69Kg doxofylline (62.74mol), with a yield of 89.7% and a melting point of 143.5- 145°C, the content is above 98.5%.
Embodiment 3
[0046] Add 11.6Kg (64.39mol) of theophylline, 7.3L of absolute ethanol, 3.35Kg of sodium hydroxide (83.71mol) into the reaction tank, stir and reflux for 4 hours, and recover the solvent by distillation under reduced pressure. The obtained theophylline salt is mixed with 722.68ml of PEG-400 , 12.9Kg bromoacetaldehyde ethylene acetal (77.27mol) mixed evenly, water bath temperature control 60 ~ 70 ℃, stirring reaction for 6h, using thin layer chromatography to monitor the end of the reaction (developing agent is acetone: dichloromethane = 3:1 ). After the reaction, wash three times with 1000ml of ice water, filter, and recrystallize the filter residue with water: ethanol=3:1 (v / v) to obtain 15.24Kg doxofylline (57.31mol), with a yield of 89%, and a melting point of 143.5- 145°C, the content is above 98.5%.
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