CN116969825B

CN116969825B - Purifying method of perfluoro-hexanone

Info

Publication number: CN116969825B
Application number: CN202311235242.4A
Authority: CN
Inventors: 王汉利; 李默韬; 王磊; 张娜; 马慧荣; 王玺
Original assignee: Shandong Huaxia Shenzhou New Material Co Ltd
Current assignee: Shandong Huaxia Shenzhou New Material Co Ltd
Priority date: 2023-09-25
Filing date: 2023-09-25
Publication date: 2023-12-15
Anticipated expiration: 2043-09-25
Also published as: CN116969825A

Abstract

The invention belongs to the technical field of fluorine fine chemical industry, and particularly relates to a method for purifying perfluoro-hexanone, which comprises the following steps: in the presence of a catalyst, the crude product of the perfluorinated hexanone reacts with a nucleophilic reagent at 20-100 ℃, and after the reaction is finished, the mixed product is separated and then rectified to obtain the perfluorinated hexanone, wherein the purity of the perfluorinated hexanone can reach more than 99.9%. The purification method provided by the invention has the advantages of no need of adding solvent, greatly reduced cost and environmental pollution, improved process safety, avoidance of solvent and product separation, solvent recovery treatment and the like, mild reaction conditions, simple operation, low requirements on equipment, low cost, less three wastes, safety, environmental protection and the like, and is suitable for large-scale requirements.

Description

Purifying method of perfluoro-hexanone

Technical Field

The invention belongs to the technical field of fluorine fine chemical industry, and particularly relates to a method for purifying perfluoro-hexanone.

Background

The chemical name of the perfluoro-hexanone (FK-5-1-12) is perfluoro-2-methyl-3-pentanone, which is a fire extinguishing agent for replacing halons and freons, which is proposed by the 3M company of America. The boiling point of the perfluorinated hexanone is 49 ℃, the perfluorinated hexanone is extremely easy to vaporize, no residue is left after release, the atmospheric residence time is short (5 days), the atmospheric ozone layer is not destroyed (ODP=0), the global warming potential value is low (GWP=1), the harm to the environment and human is nearly zero, and the perfluorinated hexanone is a novel clean and green environment-friendly fire extinguishing agent. The perfluoro-hexanone fire extinguishing agent has the comprehensive advantages of high fire extinguishing efficiency, environmental protection, clean, high safety margin, good insulating property, no damage to electronic precision equipment and the like, is accepted by the international fire-fighting community and is widely applied to important places such as aerospace, data centers, libraries, military equipment, subways and the like, is a currently accepted substance capable of replacing hydrofluorocarbon fire extinguishing agents such as heptafluoropropane and the like, has extremely large market demand and has wide market prospect.

At present, various synthetic methods of perfluoro-hexanone exist, and most of the synthetic methods take hexafluoropropylene as a raw material. In the early stage, hexafluoropropylene and hexafluoropropylene oxide are mainly adopted to react under the action of a catalyst; the method for synthesizing the perfluorinated hexanone by taking hexafluoropropylene and acyl halide as raw materials is also invented. In addition, there are several other synthetic methods, such as preparing perfluoro hexanone from potassium perfluorocarboxylate and perfluoro propionyl fluoride at room temperature, and reacting perfluoro carboxylate with perfluoro anhydride to obtain perfluoro hexanone. With the intensive research of the perfluoro-hexanone in China, a safer and more efficient preparation route is explored, and perfluoro-2-methyl-2-pentene (D2) is used as a reaction raw material in all synthetic routes, so that D2 is inevitably introduced into the perfluoro-hexanone, D2 has certain biotoxicity and pungent smell, the purity of the perfluoro-hexanone product is reduced, and the smell and the safety of the perfluoro-hexanone are greatly influenced, so that D2 is removed as much as possible to improve the purity of the perfluoro-hexanone. And D2 and the product of the perfluorinated hexanone are similar in polarity, mutually soluble and quite similar in boiling point, and are difficult to separate and remove by conventional methods such as rectification or extraction.

Chinese patent CN102992986a discloses a method for preparing perfluoro-hexanone, i.e. perfluoro-4-methyl-2-pentene (D1) or perfluoro-2-methyl-2-pentene (D2) is used as raw material, and perfluoro-hexanone is prepared by olefin isomerization, olefin epoxidation and epoxide structure rearrangement processes. In order to reduce the content of D2 in the perfluoro-hexanone, a separation and purification step is added in the reaction process, and perfluoro-2-methyl-2-pentene is removed by adopting a method of bromination addition and distillation purification after the intermediate product perfluoro-2, 3-epoxy-2-methylpentane is subjected to fluorine phase water washing and dried by using anhydrous MgSO 4. However, bromine elements are introduced into the bromination addition process to form impurities, and the intermediate product perfluoro-2, 3-epoxy-2-methylpentane needs to be purified. This process not only disrupts the reaction continuity, but also involves multi-step purification and separation, and the boiling point of the product is lower and more volatile, thus resulting in a lower overall yield of perfluorinated hexanone. Patent CN107879912a uses a microchannel reactor to perform continuous epoxidation of olefins, and the continuous reaction product is rapidly removed from the reactor, which shortens the reaction time, but also has the problem of reduced conversion due to short residence time of raw material D2, and removes unreacted D2 during the reaction by rectifying the intermediate product perfluoro-2-methyl-2, 3-pentalene, which can destroy the continuity of the whole reaction, and the multi-step separation and purification operation also leads to reduced yield of perfluorohexanone.

To solve the above problems, patent US6478979B1 proposes an improved method, namely using KMnO ₄ The oxidant removes the dimer under the condition of solvent acetic acid, and the method can effectively remove the dimer in the perfluorinated hexanone. However, potassium permanganate belongs to a strong oxidant, the risk of the reaction process is high, and the potassium permanganate can exert the oxidizing property under the acidic condition, so that the acid value is introduced into the perfluorinated hexanone to cause the acid value to exceed the standard, and the acid removal operation is increased. In addition, the generated solid waste manganese dioxide after the oxidation reaction of potassium permanganate is also difficult to treat.

Disclosure of Invention

The invention provides a perfluoro-hexanone purification method with simple separation method and mild reaction condition, which aims to solve the defects existing in the prior art.

In order to achieve the above purpose, the invention adopts the following technical scheme:

a method for purifying perfluoro hexanone, comprising the steps of:

(1) Mixing a catalyst, a crude product of perfluoro-hexanone and a nucleophilic reagent, reacting, filtering a reaction solution after the reaction is finished, standing and layering; the catalyst is selected from potassium fluoride or cesium fluoride, and the nucleophilic reagent is selected from one or a combination of a plurality of benzyl chloride, benzyl bromide, 3-methylbenzyl bromide, phenol and p-carboxyl phenol;

(2) And (3) collecting the lower liquid in the step (1) for rectification, and obtaining the distillate, namely the pure product of the perfluorinated hexanone.

The catalyst in the step (1) can be one or more selected from sodium fluoride, potassium bifluoride, phosphorus pentafluoride, sulfur tetrafluoride, potassium cyanate, tertiary amine nitrogen oxide and aniline nitrogen oxide.

Preferably, the mass ratio of the crude product of the perfluoro-hexanone to the catalyst in the step (1) is 1:0.001-1, and more preferably 1:0.01-0.04. The content of the perfluoro hexanone in the perfluoro hexanone crude product used in the invention is more than 95 percent. Preferably, the content of the perfluoro-hexanone in the perfluoro-hexanone crude product is 95-98%, the content of perfluoro-2-methyl-2-pentene (D2) is 0.1-1.3%, and the balance is a polar aprotic solvent (such as acetonitrile and the like) and high-boiling impurities.

Preferably, the mass ratio of the nucleophilic reagent to the catalyst in the step (1) is 1:0.05-1, and more preferably 1:0.23-0.5.

Preferably, the reaction temperature in the step (1) is 20-100 ℃, and the reaction time is 1-8 hours; the reaction temperature is 50-80 ℃, the reaction time is 4-6 h, and the reaction pressure is normal pressure.

Preferably, the rectification temperature in the step (2) is 55-80 ℃, the rectification time is 2-12 h, and more preferably, the rectification temperature is 60-70 ℃, and the rectification time is 6-8 h. The reflux ratio is 15.5-16.5, and the more preferable rectification temperature is 65-67 ℃.

The content of D2 in the perfluorinated hexanone pure product obtained in the step (2) is less than 150ppm, preferably less than 100ppm, and most preferably less than or equal to 50ppm.

The boiling point of the perfluoro-hexanone is 49 ℃, the boiling point of the perfluoro-2-methyl-2-pentene is 53-61 ℃, and the perfluoro-2-methyl-2-pentene and the perfluoro-hexanone are difficult to be completely separated by common rectification. The purification method of the invention mainly carries out nucleophilic substitution reaction on the nucleophilic reagent and D2 in the coarse product of the perfluorinated hexanone to generate the dimer derivative, the boiling point of the dimer derivative is 80-150 ℃, and other impurities with higher boiling points in the dimer derivative and the coarse product are removed by rectification, so that the purity of the perfluorinated hexanone is more than 99.9%, and the yield is more than 88%, and the separation and purification method has the advantages of mild reaction conditions, low requirements on equipment, low cost, less three wastes, safety, environmental protection and the like.

The beneficial effects of the invention are that

Compared with the prior art, one or more embodiments provided by the specific embodiments of the present invention have at least the following effects:

1. the invention uses dimer perfluoro-2-methyl-2-pentene (D2) and nucleophilic reagent with specific structure to react to generate dimer derivative to remove D2, then uses rectification to remove dimer derivative and other impurities with higher boiling point, and the purity of the purified perfluoro-hexanone can reach 99.9%. The method can remove D2 in the perfluorinated hexanone product, avoids adding addition, distillation, water washing and other purification methods in the process of preparing the perfluorinated hexanone in the prior art, can simplify the process, and also avoids introducing other impurities in the reaction process to influence the yield.

2. The dimer derivative generated by the reaction can be used as an intermediate of various fluorine-containing surfactants, and a great amount of three wastes generated after the traditional purification method and the acid value exceeding standard caused by the acid value introduced in order to remove D2 in the prior art are avoided.

3. The method can remove low-content (0.1% -0.3%) D2 in the perfluorinated hexanone, and also can remove high-content (more than 0.3%) D2, and the minimum content of D2 in the purified perfluorinated hexanone can be reduced to below 50ppm.

4. The raw materials used in the reaction have low toxicity, no other solvents are needed, the reaction condition is mild, the safety is high, and the purification step is simple.

Drawings

FIG. 1 is a gas chromatogram of the crude perfluorohexanone product of example 1;

FIG. 2 is a gas chromatogram of the purified perfluorohexanone of example 1.

Detailed Description

The present invention will be further illustrated with reference to the following examples, but the present invention is not limited to the following examples. The raw materials used in the following examples or comparative examples are all commercially available unless otherwise specified.

The crude product of the perfluoro-hexanone to be purified in the following examples and comparative examples is prepared by the method described in patent CN107879912a, the intermediate step is not performed for rectification to remove D2, and each batch of reaction is continuously synthesized under the influence of fluctuation of reaction conditions such as temperature, pressure, flow rate, residence time bar, etc., so that the mass fraction of the perfluoro-hexanone in the obtained crude product is 95-98%, the mass fraction of D2 is 0.1-1.3%, and the rest 0.7-4.9% are acetonitrile and high boiling point impurities.

Example 1

A method for purifying perfluoro hexanone, comprising the steps of:

(1) 300g of coarse product of perfluoro-hexanone (D2 content is 0.1%) with the purity of 97.66% and 13g of nucleophilic reagent benzyl chloride, 3g of catalyst CsF are added into a 1000ml three-neck flask with a condensing reflux device, stirred and reacted for 4 hours at the normal pressure and 70-80 ℃, after the reaction is finished, the temperature is cooled to room temperature, filtered, stood for layering, and the upper layer benzyl chloride is recovered.

(2) And (3) taking the lower layer liquid, rectifying for 8 hours at 65 ℃, wherein the distillate is the perfluorinated hexanone, and the gas phase detection result shows that the D2 content is 50ppm, the perfluorinated hexanone purity is 99.99%, and the yield is 92.3%.

The reaction process is as follows:

。

the gas chromatogram of the crude perfluorohexanone product is shown in FIG. 1, wherein the peak at 7.701min is perfluorohexanone (97.66%), the peak at 7.884min is D2 (0.1%), the peak at 8.821min is high boiling impurities (1.09%), and the peak at 13.165min is acetonitrile (1.15%). The gas chromatogram of the purified perfluoro-hexanone is shown in FIG. 2, in which 7.645min peak is perfluoro-hexanone (99.99%) and 7.805min peak is D2 (50 ppm). It can be seen that the purity of the purified perfluoro-hexanone is improved, the content of D2 is obviously reduced, and both high boiling impurities and acetonitrile are removed. Because the sample injection mode is manual sample injection and has factors such as impurity peak interference, the peak time of each component before and after purification is slightly different, and the sample injection mode belongs to a normal phenomenon.

Example 2

A method for purifying perfluoro hexanone, comprising the steps of:

(1) 300g of coarse product of perfluoro-hexanone (D2 content is 1.24%) with purity of 95.28% is added into a 500ml three-neck flask with a condensing reflux device, 40g of nucleophilic reagent 3-methylbenzyl bromide and 12g of catalyst KF are stirred and reacted for 6 hours at 50-60 ℃ and normal pressure, after the reaction is finished, the temperature is cooled to room temperature, filtered, and the mixture is kept stand for layering, and the upper layer 3-methylbenzyl bromide is recovered.

(2) And (3) taking the lower layer liquid, rectifying for 6 hours at 65 ℃, wherein the distillate is the perfluorinated hexanone, and the gas phase detection result shows that the D2 content is 90ppm, the purity of the perfluorinated hexanone is 99.91%, and the yield is 88.3%.

Example 3

A method for purifying perfluoro hexanone, comprising the steps of:

(1) 300g of perfluoro-hexanone (D2 content is 0.3%) with the purity of 96.53% and 8g of nucleophilic reagent benzyl bromide and 4g of catalyst CsF are added into a 500ml three-neck flask with a condensing reflux device, the mixture is stirred and reacted for 6 hours at 50-60 ℃ under normal pressure, after the reaction is finished, the mixture is cooled to room temperature, filtered, and the mixture is stood for layering, and the upper benzyl bromide is recovered.

(2) And taking the lower layer liquid, rectifying for 7 hours at 66 ℃, wherein the distillate is the perfluorinated hexanone, and the gas phase detection result shows that the D2 content is 92ppm, the perfluorinated hexanone purity is 99.99%, and the yield is 90.5%.

Example 4

A method for purifying perfluoro hexanone, comprising the steps of:

(1) 300g of perfluorohexanone (D2 content is 0.5%) with the purity of 96.2% and 10g of phenol and 5g of catalyst CsF are added into a 1000ml three-neck flask with a condensing reflux device, the mixture is stirred and reacted for 6 hours at the temperature of 70-80 ℃ under normal pressure, after the reaction is finished, the mixture is cooled to room temperature, filtered, and the mixture is stood for layering, so that upper phenol is recovered.

(2) And taking the lower layer liquid, rectifying for 7 hours at 66 ℃, wherein the distillate is the perfluorinated hexanone, and the gas phase detection result shows that the D2 content is 130ppm, the purity of the perfluorinated hexanone is 99.97%, and the yield is 91.1%.

The reaction process is as follows:

。

example 5

A method for purifying perfluoro hexanone, comprising the steps of:

(1) 300g of 97% pure perfluoro-hexanone (D2 content 0.4%) and 12g of nucleophilic reagent p-carboxyphenol, 6g of catalyst KF are added into a 500ml three-neck flask with a condensing reflux device, stirred and reacted for 6h at 50-60 ℃ under normal pressure, cooled to room temperature after the reaction is finished, filtered, and stood for layering.

(2) And taking the lower layer liquid, rectifying for 7 hours at 66 ℃, wherein the distillate is the perfluorinated hexanone, and the gas phase detection result shows that the D2 residue is 150ppm, the purity of the perfluorinated hexanone is 99.98%, and the yield is 91.1%.

Comparative example 1

A method for purifying perfluoro hexanone, comprising the steps of:

(1) 300g of perfluorinated hexanone with the purity of 96.2 percent (D2 content is 0.5 percent), 12g of m-carboxyphenol and 6g of KF are added into a 500ml three-neck flask with a condensing reflux device, stirred and reacted for 6 hours at 70-80 ℃ and normal pressure, cooled to room temperature after the reaction is finished, filtered, stood for layering, and the upper-layer carboxyphenol is recovered.

(2) And (3) taking the lower layer liquid, rectifying for 7 hours at 67 ℃, wherein the distillate is the perfluorinated hexanone, and the gas phase detection result shows that the D2 residue is 5000ppm, the purity of the perfluorinated hexanone is 99.5%, and the yield is 90.9%.

Comparative example 2

A method for purifying perfluoro hexanone, comprising the steps of: 300g of perfluorohexanone with the purity of 96.2 percent (D2 content of 0.5 percent), 3g of diethanolamine and 150mL of acetonitrile are added into a 500mL three-neck flask with a condensing reflux device, stirring is started, the reaction temperature is controlled to be 30 ℃ for 3h, after the reaction is finished, standing and layering are carried out, the lower liquid is taken to be added into 195mL of water for stirring and washing, so as to obtain the perfluorohexanone, after rectification for 7h at 67 ℃, the gas phase detection result shows that the D2 residue is 1200ppm, the purity of the perfluorohexanone is 99.88 percent, and the yield is 80 percent.

Claims

1. A method for purifying perfluoro-hexanone, comprising the steps of:

(1) Mixing a catalyst, a crude product of perfluoro-hexanone and a nucleophilic reagent, reacting, filtering a reaction solution after the reaction is finished, standing and layering; the catalyst is potassium fluoride or cesium fluoride, and the nucleophile is selected from one or a combination of a plurality of benzyl chloride, benzyl bromide and 3-methylbenzyl bromide;

2. The purification method according to claim 1, wherein the mass ratio of the crude product of the perfluorinated hexanone to the catalyst in the step (1) is 1:0.001-1; the mass ratio of the nucleophilic reagent to the catalyst is 1:0.05-1.

3. The purification method according to claim 2, wherein the mass ratio of the crude product of the perfluorinated hexanone to the catalyst in the step (1) is 1:0.01-0.04; the mass ratio of the nucleophilic reagent to the catalyst is 1:0.23-0.5.

4. The purification method according to claim 1, wherein the reaction temperature in step (1) is 20 to 100 ℃ and the reaction time is 1 to 8 hours.

5. The purification method according to claim 4, wherein the reaction temperature in step (1) is 50 to 80 ℃ and the reaction time is 4 to 6 hours.

6. The purification method according to claim 1, wherein the rectification temperature in step (2) is 55-80 ℃ and the rectification time is 2-12 hours.

7. The purification method according to claim 6, wherein the rectification temperature in step (2) is 60-70 ℃ and the rectification time is 6-8 hours.

8. The purification method according to claim 1, wherein the rectification temperature in step (2) is 65-67 ℃.

9. The purification process according to claim 1, wherein the pure product of perfluoro hexanone obtained in step (2) has a D2 content of less than 150ppm.

10. The purification method according to claim 1, wherein the content of D2 in the pure product of the perfluoro hexanone obtained in the step (2) is 50ppm or less.