1. Into salt. Weigh 30g crude heparin sodium and add proper amount of purified water to dissolve it to obtain heparin sodium solution. Benzalkonium chloride solution was obtained by weighing 75g benzalkonium chloride and adding purified water to dissolve it. Slowly add benzalkonium chloride solution to heparin sodium solution, stir while adding, stir well, and let stand for 2 hours. After centrifuge operation, the solid obtained from centrifuge was washed with purified water. Finally, the obtained heparin benzyl chloride was dried in vacuum to obtain heparin benzyl chloride.
2. Esterification. To the heparin benzyl ammonium chloride to add 5 times the volume of methylene chloride, stir to dissolve to join heparin benzyl again after 1 times the volume of benzyl chloride ammonium chloride, maintain temperature 35 ℃, mixing reaction for 24 hours, end of the reaction to join heparin benzyl line 6 times the volume of 10% ammonium chloride sodium acetate methanol solution, stirring for 10 minutes, let stand for 4 hours, the precipitation filtration, precipitation will be filtered repeatedly with methanol washing twice raw heparin benzyl ester is wet. Add 8% sodium chloride solution of 3 times the weight and volume of benzyl heparin to the wet crude heparin, stir until it is completely dissolved, then add methanol of 4 times the volume of sodium chloride solution, continue to stir for 10 minutes, let stand for 2 hours, filter and repeat this operation for 3 times to obtain the wet heparin benzyl ester. The heparin benzyl ester can be obtained by vacuum drying.
3. The depolymerization. The heparin benzyl ester was added with purified water of 20 times its weight, dissolved with stirring and heated to 60℃. Weigh and dissolve 10% of heparin benzyl ester with purified water, then slowly add heparin benzyl ester solution, maintain temperature 60℃, stir for 2 hours, then adjust solution pH6.0~6.5 with appropriate amount of hydrochloric acid, cool the solution to room temperature, depolymerize. Add proper amount of sodium chloride into the depolymerization solution, make its concentration 10%, stir until it is completely dissolved, then add methanol of 60 times the volume of heparin benzyl ester in the state of agitation, stir evenly and leave for 5 hours, then separate the supernatant to obtain enoxaparin sodium wet crude product.
4. Oxidation alcohol precipitation. Add purified water of 3 times its weight and volume to enoxaparin sodium wet crude product, stir until completely dissolved, add purified water to make solution concentration of 20%. Then add 1% sodium chloride in the solution volume, stir it, heat up to 35℃, and adjust the pH of the solution to 9.5~10.0 with sodium hydroxide. The oxidized solution was obtained by adding 1% hydrogen peroxide of solution volume (30% concentration) and maintaining the temperature and pH for 8 hours. The oxidized liquid was filtered by 0.45mu filter core, pH6.0~6.5 was mixed with hydrochloric acid, methanol 5 times the volume of the filtrate was added, stirred evenly, stood for 5 hours, and the supernatant was separated, then enoxparin sodium oxidized alcohol was obtained.
5. Sterilize and filter. Add proper amount of purified water to the oxidized alcohol, make its concentration 25%, stir until completely dissolved, then filter the solution through the filter core. After drying the filtrate by freeze-drying machine, crushing and mixing, enoxaparin sodium can be obtained.