Refining method of metformin hydrochloride
A technology of metformin hydrochloride and refined products, applied in chemical instruments and methods, preparation of organic compounds, organic chemistry, etc., can solve the problems of product purity and impurity content that are difficult to meet requirements, purity cannot meet requirements, and environmental pollution is large. Simple and easy to control, less pollution, easy to deal with
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[0042] The embodiment of the present invention relates to a method for preparing metformin hydrochloride, through refining the crude metformin hydrochloride, the key impurity dicyandiamide can be completely removed. Specifically, at least the following steps are included:
[0043] (1) adopt solvent method to prepare metformin hydrochloride crude product;
[0044] (2) Add absolute ethanol I to the crude metformin hydrochloride, raise the temperature until reflux occurs, the reflux temperature is 60-78°C, add water dropwise under the reflux state, that is, the system temperature in the process of adding water is not lower than the reflux temperature, and the system dissolves After clearing, add absolute ethanol II dropwise, and the state of dissolving is clear and translucent without crystals visible to the naked eye, and maintains a reflux state during the dissolving and adding process, that is, the system temperature is not lower than the reflux temperature. Suction filtratio...
Embodiment 1
[0071] (1) the preparation of metformin hydrochloride crude product:
[0072] Add 672g of dicyandiamide, 825g of dimethylamine hydrochloride, and 2515g of cyclohexanol into a 1L three-necked flask, and place it in an oil bath environment. When the temperature rises to 86°C, the solids of the system begin to dissolve, and when the temperature continues to rise to 114°C, the system completely dissolves. Clear, slightly green and transparent, when the temperature rises to 140°C ~ 145°C, the color turns brown, and the reaction is kept at 140°C ~ 145°C for 4 hours. It is observed that crystals precipitate out of the system when the reaction is carried out for about 1 hour, and the addition reaction product Generate gradually. When the heat preservation is over, lower the temperature to 100°C, hold at 100°C for 3 hours, and then filter with suction. The filter cake is soaked twice in absolute ethanol with 2 times the weight of dicyandiamide, and then put into a blast drying oven, an...
Embodiment 2
[0081] Compared with Example 1, the only difference is that the amount of purified water added is 816g.
[0082] The parameters of the metformin hydrochloride refined product finished product that obtains are as shown in table 2.
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