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A New Preparation Method of High Purity N, N- Dimethylformamide

Dimethylformamide Uses

With the rise of biologic drugs, N, N-dimethylformamide (DMF) acts as a solvent in apis and drug intermediates.

As a result, a large amount of N, N-dimethylformamide, dichloromethane and a small amount of methyl are produced.

 n n dimethylformamide

N, N- dimethylformamide waste liquid, if not recycled, caused environmental pollution, and increase the production costs. In order to recycle the N, n-dimethylformamide, the Dichloromethane, methyl tert-butyl ether and trace drug impurities must be removed.

The traditional process is direct distillation. The impurities are removed and the high purity DMF is produced. However, the recovery rate of the product in the direct distillation process is not high, and the decomposition of N, N-dimethylformamide is high, the quality of recycled products can not meet the requirements of reuse.

N, N- dimethyl formamide Production Process

DMF uses in pharmaceutical

The purpose of the invention is to overcome the inadequacy of the prior art and provide a method for separation, gas stripping by flash evaporation, A method for preparing a vacuum distillation process.

The preparation method of high purity N, N-dimethylformamide is characterized by the following steps:

1. Take N, n-dimethylformamide waste liquid and add acid, acid oxide and acid salt into it. Basic salt or base, base oxides or basic hydroxides; The polarity and pH value of N, N- dimethylformamide were adjusted to control pH value in the range of 6 to 8.

 And react with waste liquid N, N- dimethylformamide organic base and other impurities to form stable salt.

Among them, acid, acid salt, base salt, base including but not limited to sulfuric acid, nitric acid, sodium bisulfate, etc.Sodium chloride, sodium sulfate, potassium chloride and potassium sulfate, sodium hydroxide and potassium hydroxide, sodium carbonate, sodium bicarbonate and other carbonates. ;

2. Feed to the N, n-dimethylformamide obtained in step 1 at a temperature below the boiling point of N,n-dimethylformamide

By flash evaporation, water and low boiling point substances are removed to reduce the decomposition of N, N- dimethylformamide.

3. To the N, n-dimethylformamide obtained by distillation above, preheat to a certain temperature and then heat through to a certain temperature.

Air, carbon dioxide, argon, helium, nitrogen, oxygen and other gases for gas extraction, used to remove water, free amine.

4. Vacuum distillation of N, n-dimethylformamide after stripping; High purity N, N- with purity ≥ 99.9% (wt) was obtained dimethylformamide.

Preferably, in step 1, acid, acid. The volume concentration of alkali salt or strong alkali is 0.5 ~ 2%.

Preferably, in step 2, the temperature of the material entering the flash tank is 60 ~ 150℃, and the vacuum degree of the flash tank is 10mmhg ~500mmhg

Preferably, in step 3, N, N-dimethylformamide preheating temperature 60 ~ 140℃, the temperature of the incoming gas 70 ~ 180℃.

Preferably, it also includes the decompression rectification of N, n-dimethylformamide obtained from the flash treatment in Step 4.

Preferably, vacuum distillation conditions are: vacuum pressure of 5mmHg ~ 300mmHg, bottom temperature of distillation tank of 30 ~ 125.

Temperature of liquid in kettle 25 ~ 122℃, temperature of kettle top 20 ~ 120℃, control reflux ratio of 10∶1 ~ 4∶1.

The invention discloses a high purity preparation from N, n-dimethylformamide (N, n-dimethylformamide) waste liquid

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The Advantages of This N, N- dimethylformamide Preparation Method

N, N- dimethylformamide preparation method, its characteristics are, through flash evaporation, gas extraction method separation, decompression distillation method to

By removing the impurities in the waste liquid N, N- dimethylformamide, high purity N, N- dimethylformamide was obtained.

The invention provides high purity of N, N-dimethylformamide preparation method, through flash evaporation, nitrogen gas extraction, vacuum distillation of a series of processes with low energy consumption reduced N, N-dimethylformamide decomposition in the purification process will contain methylene chloride, methyl tert-butyl ether, hexahydropyridine and other impurities.

N, N- dimethylformamide purity is only 65% – 80% (wt) of N, N-dimethylformamide waste liquor purified to purity ≥99.9% (wt) of high purity N, N-dimethylformamide, realized the recycling of waste liquid N, N-dimethylformamide.

Reduced the pollution degree of N, N- dimethylformamide waste liquid to the environment in the production of pharmaceutical and chemical industry, high material collection, high quality, save the cost of production.

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