阅读说明：本技术 一种普瑞巴林的纯化方法 (Purification method of pregabalin ) 是由 汪有贵 蔡长清 谭俊 朱元勋 颜峰峰 于 2021-10-26 设计创作，主要内容包括：本发明涉及一种普瑞巴林的纯化方法,其包括以下步骤：1)将反应液升温,保温去除杂质；2)向步骤1)中的反应液加酸调节pH值,析晶,离心烘干,得高纯度的普瑞巴林。采用本发明的纯化方法制备得到的普瑞巴林,其产物纯度达到99.8％以上,产物收率90％以上,杂质X及杂质Y含量均≤0.05％,且未检测到相对保留时间为1.3的杂质峰。(The invention relates to a purification method of pregabalin, which comprises the following steps: 1) heating the reaction solution, and keeping the temperature to remove impurities; 2) adding acid into the reaction liquid obtained in the step 1) to adjust the pH value, crystallizing, centrifuging and drying to obtain the high-purity pregabalin. The purity of the pregabalin prepared by the purification method of the invention reaches more than 99.8 percent, the yield of the pregabalin is more than 90 percent, the contents of the impurity X and the impurity Y are both less than or equal to 0.05 percent, and an impurity peak with the relative retention time of 1.3 is not detected.)

1. A purification method of pregabalin, which is characterized by comprising the following steps:

(1) heating the reaction solution, and keeping the temperature to remove impurities;

(2) and (2) adding acid into the reaction liquid obtained in the step (1) to adjust the pH value, crystallizing, centrifuging and drying to obtain pregabalin.

2. The method for purifying pregabalin according to claim 1, wherein the reaction solution in the step (1) is prepared by the following steps:

(a) carrying out oxidation reaction on (R) - (-) -3- (carbamoylmethyl) -5-methylhexanoic acid and an aqueous solution of sodium hypochlorite in an aqueous solution of sodium hydroxide to obtain an oxidation reaction solution;

(b) and (b) adding sodium sulfite into the reaction solution after oxidation in the step (a), and quenching the sodium hypochlorite to obtain the reaction solution.

3. The method for purifying pregabalin according to claim 1, characterized in that in the step (1), the temperature is increased to 40-80 ℃, more preferably to 55-70 ℃.

4. The purification method of pregabalin according to claim 1, characterized in that in the step (1), the holding time is 1-5 h, and more preferably 2-3 h.

5. The method for purifying pregabalin of claim 1, wherein the acid in step (2) is hydrochloric acid, sulfuric acid or phosphoric acid, more preferably hydrochloric acid.

6. The purification method of pregabalin according to claim 1, characterized in that the pH value in step (2) is adjusted to 5-9, more preferably 6-8.

7. The purification method of pregabalin according to claim 2, characterized in that the mass concentration of the sodium hydroxide aqueous solution in the step (a) is 10% to 40%, more preferably 20% to 25%, and the mass concentration of the sodium hypochlorite aqueous solution is 5% to 14%, more preferably 8% to 12%.

8. The process for purifying pregabalin of claim 2, characterized in that the molar ratio of (R) - (-) -3- (carbamoylmethyl) -5-methylhexanoic acid, sodium hypochlorite and sodium hydroxide in step (a) is 1: (0.8-1.2): (2-5).

9. The method for purifying pregabalin of claim 2, wherein the aqueous solution of sodium hypochlorite in the step (a) is added dropwise to the mixed system of (R) - (-) -3- (carbamoylmethyl) -5-methylhexanoic acid and aqueous solution of sodium hydroxide.

10. The method for purifying pregabalin according to claim 2, characterized in that in the step (a), the time of the oxidation reaction is 2 to 20 hours, more preferably 5 to 10 hours, and the temperature of the oxidation reaction is-20 to 30 ℃, more preferably-10 to 30 ℃.

11. The method for purifying pregabalin of claim 2, wherein the molar ratio of the sodium sulfite added to the (R) - (-) -3- (carbamoylmethyl) -5-methylhexanoic acid in step (b) is (0.01-0.50): 1, more preferably (0.02 to 0.15): 1.

Technical Field

The invention relates to the field of pharmaceutical chemicals, and particularly relates to a method for purifying pregabalin.

Background

Pregabalin is a novel gamma-aminobutyric acid (GABA) receptor agonist, can block voltage-dependent calcium channels, reduces the release of neurotransmitters, and is mainly used for treating peripheral neuralgia and adjuvant therapy of partial epilepsy local. Various processes for the preparation of pregabalin are known in the prior art, for example, WO2006121557a1 discloses a simple process for the preparation of pregabalin by the hofmann rearrangement of the compound (R) - (-) -3- (carbamoylmethyl) -5-methylhexanoic acid in the presence of bromine and an alkali metal hydroxide, which uses a large amount of liquid bromine.

CN101910111B discloses a method of using sodium hypochlorite as a substitute for bromine at 50-70 ℃, which can reduce the relative retention time of 1.3 of the impurities mentioned in the patent, but the reaction temperature mentioned in the patent is too high, resulting in a lower reaction yield; meanwhile, the impurity with the relative retention time of 1.3 in partial batches of pregabalin prepared by the method reaches 0.25 percent, the impurity in a particularly preferred scheme also reaches 0.1 percent, and the impurity level difference among different batches is large.

CN106748850A discloses a preparation method of pregabalin, which comprises the steps of reacting (R) - (-) -3- (carbamoylmethyl) -5-methylhexanoic acid with a sodium hypochlorite aqueous solution at low temperature, adding a reducing agent to destroy sodium hypochlorite, finally adding a catalyst, introducing hydrogen to carry out reduction reaction, filtering, adjusting acid of mother liquor, filtering again, and adding a wet product into a mixed solution of isopropanol and water to carry out re-refining to obtain pregabalin. The method adopts the low-temperature reaction of (R) - (-) -3-carbamoylmethyl-5-methylhexanoic acid and sodium hypochlorite aqueous solution, the reaction exists insufficiently or the conversion rate is low under the condition, and the product yield is not ideal; the method also introduces a palladium carbon catalyst for hydrogenation reduction, so that although the contents of impurities X and Y in the pregabalin can be effectively reduced, the introduction of the palladium carbon catalyst is very easy to cause the heavy metal in the pregabalin product to exceed the standard, and meanwhile, certain safety risk exists in the use process of the palladium carbon.

Disclosure of Invention

The invention provides a purification method of pregabalin, which comprises the following steps:

(1) heating the reaction solution, and keeping the temperature to remove impurities;

(2) adding acid into the reaction solution obtained in the step 1) to adjust the pH value, crystallizing, centrifuging and drying to obtain the pregabalin.

As a preferred technical scheme, the reaction solution in the step (1) is prepared by the following method:

(a) carrying out oxidation reaction on (R) - (-) -3- (carbamoylmethyl) -5-methylhexanoic acid and an aqueous solution of sodium hypochlorite in an aqueous solution of sodium hydroxide to obtain an oxidation reaction solution;

(b) and (b) adding sodium sulfite into the reaction solution after oxidation in the step (a), and quenching the sodium hypochlorite to obtain the reaction solution.

Preferably, in the step (1), the temperature for raising the temperature is 40 to 80 ℃, and more preferably 55 to 70 ℃.

Preferably, in the step (1), the heat preservation time is 1-5 h, and more preferably 2-3 h.

Preferably, the acid in step (2) is hydrochloric acid, sulfuric acid or phosphoric acid, and more preferably hydrochloric acid.

Preferably, in the step (2), the pH is adjusted to 5 to 9, and more preferably to 6 to 8.

Preferably, the mass concentration of the aqueous sodium hydroxide solution in the step (a) is 10% to 40%, more preferably 20% to 25%, and the mass concentration of the aqueous sodium hypochlorite solution is 5% to 14%, more preferably 8% to 12%.

Preferably, the molar ratio of (R) - (-) -3- (carbamoylmethyl) -5-methylhexanoic acid, sodium hypochlorite and sodium hydroxide in step (a) is 1: (0.8-1.2): (2-5).

Preferably, the aqueous sodium hypochlorite solution in the step (a) is added dropwise to a mixed system of (R) - (-) -3- (carbamoylmethyl) -5-methylhexanoic acid and aqueous sodium hydroxide solution.

Preferably, in the step (a), the time of the oxidation reaction is 2-20 hours, more preferably 5-10 hours, and the temperature of the oxidation reaction is-20-30 ℃, more preferably-10-30 ℃.

Preferably, in the step (b), the molar ratio of the added sodium sulfite to the (R) - (-) -3- (carbamoylmethyl) -5-methylhexanoic acid is (0.01-0.50): 1, more preferably (0.02 to 0.15): 1.

the purity of the pregabalin prepared by the method is more than 99.8 percent, the yield of the pregabalin is more than 90 percent, the contents of the impurity X and the impurity Y are both less than or equal to 0.05 percent, and an impurity peak with the relative retention time of 1.3 is not detected.

Compared with the prior art, the invention has the following beneficial effects:

(1) the preparation method disclosed by the invention avoids the use of palladium-carbon and hydrogenation reduction operation, reduces the excessive risk of heavy metal residue in the product, simplifies the process operation flow, improves the production efficiency, shortens the production period and is more beneficial to large-scale industrialization.

(2) The preparation method has mild reaction conditions, the whole reaction process is in a controlled state, side reactions caused by spontaneous heat release and temperature rise are avoided, the preparation method does not relate to conditions of high temperature, high pressure, catalysis and the like, the content of impurities in the product is low, and the requirements of medicine application are met.

(3) According to the preparation method, by reasonably adjusting the dosage ratio of the alkali liquor and the acid, after pregabalin is crystallized, the pregabalin can be filtered when being cooled to room temperature (20-30 ℃), and the pregabalin is not required to be filtered when being further cooled to-10 ℃, so that a large amount of energy is saved, and the requirements of energy conservation, emission reduction and environmental protection are met.

Detailed Description

The following examples are intended to illustrate the present invention and should not be construed as limiting the scope thereof.

Example 1

Adding 66g of 25% sodium hydroxide solution into the reaction bottle, and cooling to-20 ℃; adding 20g of (R) - (-) -3- (carbamoylmethyl) -5-methylhexanoic acid, slowly dropwise adding 72g of 10.4% sodium hypochlorite solution, after dropwise adding, slowly heating to 10 ℃, keeping the temperature for reaction for 3 hours, continuously heating to 30 ℃, and reacting for 3 hours; adding 1.0g of sodium sulfite into the reaction solution, stirring for 20 minutes, quenching the rest of sodium hypochlorite, and finishing the reaction; heating the reaction solution to 70 ℃, and preserving the temperature for 2 hours; and cooling the reaction liquid to 45 ℃, dropwise adding 25ml of hydrochloric acid into the reaction bottle, adjusting the pH value to 7.0, cooling to room temperature, filtering and drying to obtain pregabalin, wherein the yield is 91.7%, the purity is 99.8%, the content of the impurity X is 0.04%, the content of the impurity Y is 0.02%, and no impurity peak with the relative retention time of 1.3 is detected.

Example 2

Adding 830g of 20% sodium hydroxide solution into the reaction bottle, and cooling to-15 ℃; adding 200g of (R) - (-) -3- (carbamoylmethyl) -5-methylhexanoic acid, slowly dropwise adding 720g of 10.4% sodium hypochlorite solution, after dropwise adding, slowly heating to 10 ℃, keeping the temperature for reacting for 4 hours, continuously heating to 30 ℃, and reacting for 3 hours; adding 11.0g of sodium sulfite into the reaction solution, stirring for 20 minutes, quenching the rest of sodium hypochlorite, and finishing the reaction; heating the reaction solution to 65 ℃, and preserving the temperature for 2.5 h; and cooling the reaction liquid to 40 ℃, then dropwise adding 265ml of hydrochloric acid into the reaction bottle, adjusting the pH value to 7.1, cooling to room temperature, filtering and drying to obtain pregabalin, wherein the yield is 92.9%, the purity is 99.9%, the content of the impurity X is 0.03%, the content of the impurity Y is 0.02%, and no impurity peak with the relative retention time of 1.3 is detected.

Example 3

Adding 850g of 22% sodium hydroxide solution into the reaction bottle, and cooling to-16 ℃; adding 200g of (R) - (-) -3- (carbamoylmethyl) -5-methylhexanoic acid, slowly dropwise adding 700g of 10.6% sodium hypochlorite solution, after dropwise adding, slowly heating to 10 ℃, keeping the temperature for reaction for 3 hours, continuously heating to 30 ℃, and reacting for 2 hours; adding 10.0g of sodium sulfite into the reaction solution, stirring for 20 minutes, quenching the rest of sodium hypochlorite, and finishing the reaction; heating the reaction solution to 60 ℃, and preserving the temperature for 3 hours; and cooling the reaction liquid to 50 ℃, dropwise adding 280ml of hydrochloric acid into the reaction bottle, adjusting the pH value to 7.0, cooling to room temperature, filtering and drying to obtain pregabalin, wherein the yield is 92.3%, the purity is 99.8%, the content of the impurity X is 0.04%, the content of the impurity Y is 0.02%, and no impurity peak with the relative retention time of 1.3 is detected.

Example 4

Adding 420kg of 20% sodium hydroxide solution into the reaction kettle, and cooling to-18 ℃; adding 100kg of (R) - (-) -3- (carbamoylmethyl) -5-methylhexanoic acid, slowly dropwise adding 350g of 10.4% sodium hypochlorite solution, after dropwise adding, slowly heating to 10 ℃, keeping the temperature for reaction for 3 hours, continuously heating to 30 ℃, and reacting for 2 hours; adding 14kg of sodium sulfite into the reaction solution, stirring for 30 minutes, quenching the rest of sodium hypochlorite, and finishing the reaction; heating the reaction solution to 70 ℃, and preserving the temperature for 3 hours; and cooling the reaction liquid to 50 ℃, dropwise adding 140L of hydrochloric acid into the reaction bottle, adjusting the pH to 7.0, cooling to room temperature, filtering and drying to obtain pregabalin, wherein the yield is 93.7%, the purity is 99.9%, the content of the impurity X is 0.05%, the content of the impurity Y is 0.02%, and no impurity peak with the relative retention time of 1.3 is detected.