CN108689808B

CN108689808B - Preparation method of chloromethyl hexafluoroisopropyl ether

Info

Publication number: CN108689808B
Application number: CN201810297808.9A
Authority: CN
Inventors: 周庆海
Original assignee: Jiangsu Shengdi Pharmaceutical Co ltd; Jiangsu Hengrui Medicine Co Ltd
Current assignee: Jiangsu Original Drug Research And Development Co ltd; Jiangsu Hengrui Medicine Co Ltd; Shanghai Hengrui Pharmaceutical Co Ltd
Priority date: 2017-04-06
Filing date: 2018-04-04
Publication date: 2021-11-16
Anticipated expiration: 2038-04-04
Also published as: CN108689808A

Abstract

The invention relates to a preparation method of chloromethyl hexafluoroisopropyl ether. Specifically, the invention relates to a preparation method of chloromethyl hexafluoroisopropyl ether, wherein a solvent used in the reaction comprises chloromethyl hexafluoroisopropyl ether. The preparation method introduces the product of the preparation method as a solvent, not only solves the solidification phenomenon generated in a reaction system in the reaction process, but also greatly improves the purity of the product and is beneficial to industrial production.

Description

Preparation method of chloromethyl hexafluoroisopropyl ether

Technical Field

The invention relates to a preparation method of chloromethyl hexafluoroisopropyl ether and a method for preparing sevoflurane by using the same.

Background

Sevoflurane (fluoromethyl-1, 1,1,3,3, 3-hexafluoroisopropyl ether) is a halogenated volatile anesthetic, and is widely used in clinic due to its advantages of rapid onset of action and low side effects. Chloromethyl hexafluoroisopropyl ether is an important intermediate for synthesizing sevoflurane.

US6100434 reports a process for the preparation of chloromethyl hexafluoroisopropyl ether from hexafluoroisopropanol as starting material in the presence of anhydrous aluminum trichloride and trioxymethylene. We find that no solvent is added during the reaction of the method, so that the curing phenomenon exists in a reaction system during the preparation of chloromethyl hexafluoroisopropyl ether, particularly the curing phenomenon is more obvious during the industrial scale-up production process, and the reaction can not even be carried out. Meanwhile, even if the feeding amount is small, the reaction yield is not high although the curing phenomenon is not obvious. In addition, the reaction is easy to generate impurity 2,2' - [ methylene bis (oxy) ] bis- (1, 1,1,3,3, 3-hexafluoropropane) (hereinafter referred to as acetal impurity), and the prepared chloromethyl hexafluoroisopropyl ether product has low purity.

CN101535231A reports a method for preparing chloromethyl hexafluoroisopropyl ether by using hexafluoroisopropanol as a raw material and reacting the hexafluoroisopropyl alcohol with a trioxymethylene equivalent, strong acid and a chlorinating agent.

CN101381289A reports a method for directly synthesizing sevoflurane without purification by using hexafluoroisopropanol, formaldehyde equivalent, strong acid, aluminum trichloride, metal fluoride and the like as raw materials to react to generate chloromethyl hexafluoroisopropyl ether. In the method, concentrated sulfuric acid and other strong acids are introduced as catalysts, and the strong acids are always present in a reaction system because the reaction process is not purified and separated. Therefore, the strong acid is easy to react with polyethylene glycol to generate impurities in the heating process, can also react with metal fluoride to generate highly toxic hydrogen fluoride, and can also act with the product sevoflurane to degrade the sevoflurane, so that the final product contains a large amount of impurities and is not suitable for industrial production.

Although various methods for preparing chloromethyl hexafluoroisopropyl ether are disclosed in the prior art, most of the methods have defects and cannot meet the requirements of industrial production. Therefore, a synthesis process of chloromethyl hexafluoroisopropyl ether, which can prevent the reaction system from solidifying, has less product impurities and can be industrially produced, is urgently needed.

Disclosure of Invention

The invention provides a preparation method of chloromethyl hexafluoroisopropyl ether, which comprises the step of mixing and reacting hexafluoroisopropanol, a chlorination reagent, a methylation reagent and a reaction solvent, wherein the reaction solvent contains chloromethyl hexafluoroisopropyl ether. The weight ratio of chloromethyl hexafluoroisopropyl ether to hexafluoroisopropanol in the reaction solvent is 0.2: 1-1: 1.

The chlorinating agent can be aluminum trichloride or phosphorus trichloride. The mol ratio of the chlorination reagent to the hexafluoroisopropanol is 1: 1-1.4: 1.

The methylating agent may be a conventional methylating agent, and may be, for example, one or more of formaldehyde, trioxymethylene, and paraformaldehyde. The molar ratio of the methylating agent to the hexafluoroisopropanol is 1: 1-1.2: 1.

The reaction temperature is not particularly limited, and may be 0 to 35 ℃.

The reaction solvent contains chloromethyl hexafluoroisopropyl ether, which means that chloromethyl hexafluoroisopropyl ether is present in the reaction system as the solvent at the beginning of the reaction. The reaction solvent may also comprise other conventional solvents.

Furthermore, concentrated sulfuric acid is not added in the reaction.

Further, no strong acid is added to the reaction. The strong acid may be one or more of concentrated sulfuric acid, fuming sulfuric acid, concentrated phosphoric acid, and trifluoromethanesulfonic acid.

Further, the process for producing chloromethyl hexafluoroisopropyl ether further comprises a step of separating the chloromethyl hexafluoroisopropyl ether produced.

In another aspect, the invention provides a process for the preparation of sevoflurane, comprising the step of preparing chloromethyl hexafluoroisopropyl ether according to the process described herein.

The method for preparing sevoflurane may further comprise the step of reacting chloromethyl hexafluoroisopropyl ether with fluoride, wherein the reaction may be carried out in the presence or absence of a catalyst, which may be any one or a combination of ethers, polyethers, crown ethers, alcohols, or polyhydroxy compounds, such as ethylene glycol, 18-crown-6, diethylene glycol, triethylene glycol, pentaerythritol, 1, 2, 3-propanetriol, tris (2-hydroxyethyl) amine, and polyhydroxy sugar compounds, which may be mannitol, erythritol, or sorbitol; one or more of pentaerythritol or 1, 2, 3-propanetriol is preferred. The amount of the catalyst can be 3-80% of the weight of chloromethyl hexafluoroisopropyl ether.

The fluoride is selected from metal fluorides such as calcium fluoride, potassium fluoride, sodium fluoride, cesium fluoride or ammonium fluoride or other fluoride salts existing in a solid state under normal conditions, and potassium fluoride is preferred. The molar ratio of chloromethyl hexafluoroisopropyl ether to fluoride is selected from 1:1 to 1: 5.

The reaction of chloromethyl hexafluoroisopropyl ether and fluoride can be carried out in the absence of a solvent or in the presence of a reaction solvent, wherein the reaction solvent can be one or more of polyethylene glycol, sulfolane, N '-dimethylformamide, N' -dimethylacetamide, dimethyl sulfoxide or water, and preferably one or more of polyethylene glycol, sulfolane or water.

In another aspect, the invention provides a process for the preparation of a pharmaceutical product comprising sevoflurane, comprising adding sevoflurane obtained according to the process for the preparation of sevoflurane of the invention to a pharmaceutical container.

In order to be suitable for amplifying industrial production, the preparation method adds the self product as a solvent when preparing chloromethyl hexafluoroisopropyl ether, thereby not only solving the problem of solidification in amplifying production, but also being beneficial to mass transfer and heat transfer in the reaction process and leading the reaction to be easier to carry out; and the existence of other impurities caused by the separation difficulty brought by using other solvents is also avoided. The purity of chloromethyl hexafluoroisopropyl ether finally prepared is greatly improved, the content of acetal impurities is greatly reduced, the purification difficulty of the sevoflurane product prepared subsequently is reduced, and the purity of the prepared sevoflurane meets the medicinal requirement.

Detailed Description

The present invention will be explained in detail with reference to specific examples below, so that those skilled in the art can more fully understand the specific examples of the present invention to illustrate the technical solutions of the present invention, and not to limit the present invention in any way.

Example 1

Adding 310kg of aluminum trichloride and 210kg of solvent chloromethyl hexafluoroisopropyl ether into a 1000L reaction kettle, cooling to-5-0 ℃, dropwise adding 300kg of hexafluoroisopropyl alcohol under stirring, continuously stirring for 0.5 hour after dropwise adding, then adding 56.8kg of paraformaldehyde, and continuously reacting for 17 hours at the reaction temperature of lower than 35 ℃. Cooling to below 0 ℃, dropwise adding 600L of 6mol/L hydrochloric acid, wherein the temperature in the process of dropwise adding the hydrochloric acid is not more than 15 ℃. The organic layer was separated and washed twice with 600L of water to give 352.0kg of chloromethyl hexafluoroisopropyl ether with a GC purity of 99.1% (wherein the acetal impurity content was 0.8%) and a yield of 91.1%.

Example 2

In a 1000L reactor, 450kg of sulfolane, 105kg of potassium fluoride and 30kg of pentaerythritol were charged, and 140kg of chloromethyl hexafluoroisopropyl ether and 25kg of purified water were further charged. Heating, reacting for 10 hours at 97-102 ℃, cooling, adding 150kg of purified water, distilling to obtain 105.0kg of crude sevoflurane, and rectifying to obtain 64.0kg of finished sevoflurane product with the GC purity of 99.991%.

Example 3: according to the method of US6100434

Adding 50kg of aluminum trichloride into a 200L reaction kettle, cooling to-5-0 ℃, dropwise adding 63kg of hexafluoroisopropanol under stirring, continuously stirring for 0.5 hour after dropwise adding, then adding 12kg of paraformaldehyde, and continuously reacting for 17 hours at the reaction temperature of lower than 35 ℃. Cooling to below 0 ℃, dripping 100L of 6mol/L hydrochloric acid (solidification phenomenon exists in the process), wherein the temperature is not more than 15 ℃ in the dripping process. The lower organic layer was washed twice with 100L of water to give 69.9kg of a chloride having a GC purity of 87.0% (wherein the acetal impurity content was 12%) and a yield of 86.1%.

Since the invention has been described in terms of specific embodiments thereof, certain modifications and equivalent variations will be apparent to those skilled in the art and are intended to be included within the scope of the invention.

Claims

1. A preparation method of chloromethyl hexafluoroisopropyl ether comprises the step of mixing and reacting hexafluoroisopropyl alcohol, a chlorination reagent, a methylation reagent and a reaction solvent, wherein the chlorination reagent is selected from aluminum trichloride or phosphorus trichloride, the methylation reagent is selected from one or more of formaldehyde, trioxymethylene and paraformaldehyde, and the reaction solvent contains chloromethyl hexafluoroisopropyl ether.

2. The method according to claim 1, wherein the weight ratio of chloromethyl hexafluoroisopropyl ether to hexafluoroisopropyl alcohol in the reaction solvent is 0.2:1 to 1: 1.

3. The method according to claim 1, wherein the molar ratio of the chlorinating agent to hexafluoroisopropanol is 1:1 to 1.4: 1.

4. The method according to claim 1, wherein the molar ratio of the methylating agent to hexafluoroisopropanol is 1:1 to 1.2: 1.

5. The method according to claim 1, wherein concentrated sulfuric acid is not added in the reaction.

6. The method according to claim 1, wherein no strong acid is added to the reaction.

7. The process according to claim 1, further comprising a step of isolating chloromethyl hexafluoroisopropyl ether formed.

8. A process for the preparation of sevoflurane comprising the step of preparing chloromethyl hexafluoroisopropyl ether according to the process of any one of claims 1 to 7.

9. The method of claim 8, further comprising the step of reacting chloromethyl hexafluoroisopropyl ether with fluoride.

10. The method of claim 9, wherein the reaction is carried out in the presence of a catalyst selected from one or more of ethylene glycol, 18-crown-6, diethylene glycol, triethylene glycol, pentaerythritol, 1, 2, 3-propanetriol, tris (2-hydroxyethyl) amine, mannitol, erythritol or sorbitol.

11. The method according to claim 10, wherein the catalyst is selected from one or more of pentaerythritol and 1, 2, 3-propanetriol.

12. The method of claim 9, wherein the reaction is carried out in the presence of a solvent selected from one or more of polyethylene glycol, sulfolane, N '-dimethylformamide, N' -dimethylacetamide, dimethylsulfoxide, or water.

13. The method of claim 12, wherein the solvent is selected from one or more of polyethylene glycol, sulfolane, and water.

14. The method of claim 9, wherein said fluoride is selected from the group consisting of calcium fluoride, potassium fluoride, sodium fluoride, cesium fluoride and ammonium fluoride.

15. The method of claim 14, wherein the fluoride compound is potassium fluoride.