JPS5959643A - Preparation of perfluoroacyl chloride - Google Patents

Abstract

PURPOSE:To prepare the titled substance useful as a precursor for organic synthesis, safely, in a short time, in high purity and yield, by adding phosphorus oxychloride to a perfluoroalkylcarboxylic acid, and adding N,N-dimethylformamide to the mixture as a catalyst. CONSTITUTION:Phosphorus oxychloride is added as a chlorination agent to a perfluoroalkylcarboxylic acid. N,N-Dimethylformamide is used as a catalyst and is added to the mixture. The components of the mixture are made to react with each other at 0-25 deg.C under atmospheric pressure. The objective compound can be separated by distilling the reaction mixture. The perfluoroalkylcarboxylic acid used as the raw material is preferably an aliphatic carboxylic acid of formula (n is 2-7) (e.g. perfluoropropionic acid). The molar ratios of the (raw material):(phosphorus oxychloride):(N,N-dimethylformamide) are preferably 1: (0.6-0.8):(0.3-0.5), especially 1:(0.6-0.7):(0.4-0.5).

Description

Detailed Description of the Invention The present invention relates to a method for safely producing high-yield, high-purity perfluoroacyl chloride in a short period of time. One of the main uses of perfluoroacyl chloride is as a precursor for organic synthesis. There are bodies, ie, raw materials for the synthesis of other organic compounds.

For example, perfluorodiacyl peroxide is synthesized using perfluoroacyl chloride as a raw material.
In this case, the yield of perfluorodiacyl peroxide is significantly influenced by the purity of the raw material perfluoroacyl chloride. Various methods of producing perfluoroacyl chloride are known as described below, but products produced by any of these methods generally contain unreacted raw materials and reaction by-products and have a high p. ( ) degree is difficult to obtain, and the yield during production was also low. .

Therefore, there has been a strong desire to develop a method for producing high-yield, high-purity perfluoroacyl chloride.

Next, the main conventional manufacturing methods will be described.

First, perfluoroalkyl carboxylic acid and thionyl chloride,
There is a method of producing perfluoroacyl chloride by reacting chlorinating agents such as phosphorus trichloride and phosphorus pentachloride.

For example, in the Journal of the American Chemical Society, Vol. 75, p. 87 (1953), perfluoro-n-capri IJ chloride was recovered by the reaction of perfluoro-n-capric acid with phosphorus pentachloride. rate 58
It is stated that it can be obtained in , also volume 79 of the same magazine,
No. 4159 (1957) describes a method in which phosphorus pentachloride is used to synthesize perfluoroalkylcarboxylic acid yoliperfluoroacyl chloride, and N,N-dimedylaniline is added during distillation.3 However, when phosphorus pentachloride is The method used has a low yield and mainly produces phosphorus oxychloride with a boiling point of 105.8° C. as a by-product. On the other hand, the target compound, such as perfluoro-
The boiling point of n-cabryl chloride is 129-130U/7
44 units Hq, which makes it difficult to obtain high purity through simple distillation alone.Furthermore, since phosphorus pentachloride is a solid, mixing it with raw materials is more troublesome than with liquid chlorinating agents. 1. There is also a method using a Vilsmeier complex, which is disadvantageous for industrial implementation.

It is well known that Vilsmeier complexes are formed when acid amides are reacted with phosgene, thionyl chloride, phosphorus oxychloride, phosphorus pentachloride, etc.

For example, in the case of phosphorus oxychloride, the Journal of
The Chemical So” ET Parkin ■ No. 92
The following reaction is described on page 5 (1975) 1. Chlorination of higher fatty acids (palmitic acid, stearic acid, lauric acid) is a method for synthesizing acyl chloride using this Vilsmeier complex (Oil Chemistry). , Vol. 10, p. 435 (1961)).

In this method, higher fatty acids are placed in a flask, heated to a constant temperature in a hot water bath, N,N-dimethylformamide (hereinafter referred to as DMF) is added, and phosphorus oxychloride is added dropwise.
The reaction continues at a predetermined temperature for a further predetermined period of time. After the reaction is complete, remove the phosphorus compound in the lower layer, and heat the upper layer at 70°C for about 10 minutes.
Diacyl chloride is obtained by degassing with ran IIQ for 1 hour, adding 2% desiccant and suction filtration.In order to produce perfluoroacyl chloride, in the above method, higher fatty acids are It is thought that a similar result can be obtained if a perfluoroalkylcarboxylic acid is used as the substitute.

However, when a perfluoroalkylcarboxylic acid is used instead of a higher fatty acid and DMF is added dropwise to it at room temperature, because the perfluoroalkylcarboxylic acid is a strong acid, an acid-base reaction produces white smoke and reacts exothermically. death,
White smoke (main components are perfluoroalkyl carboxylic acid and D
Since MF) flows into the distillation receiver, there were problems such as a decrease in purity. In order to suppress the generation of white smoke and heat generation, the perfluoroalkyl carboxylic acid must be cooled to below 0°C and DMF must be added dropwise over a long period of time. It wasn't the method.

As a result of intensive research to improve the drawbacks of these conventional production methods, the present inventors first added and mixed phosphorus oxychloride into perfluoroalkyl carboxylic acid, and then added DMF as a catalyst. They have discovered that highly pure perfluoroacyl chloride can be produced safely, in a short period of time, and in high yield, and have completed the present invention.

That is, the present invention is a process for producing perfluoroacyl chloride, which is characterized in that after pre-mixing perfluoroalkyl carboxylic acid and phosphorus oxychloride, N,N-dimethylformamide is further mixed as a catalyst, and then the mixture is distilled. Regarding the method.

The raw material Berfur]roalkylcarboxylic acid used in the present invention is preferably one represented by the following general formula.

F (CF2)7LCO2H (7+-2~7) When n≧8, it is a solid and mixing operation becomes easy, and also? L=
= 1, the product is a gas at 0°C 1ν, so it is easy to handle.1.Specific examples of the perfluoroargylcarboxylic acid represented by the above general formula include perfluoropropionic acid, perfluoro-n-acetic acid, perfluoro-nMe, perfluoro-''-cafo7 acid,
perfluoro-n-enantylic acid, perfluoro-n-
Caprylic acid, etc. can be shown.

Further, the chlorinating agent used in the present invention must be phosphorus oxychloride, and if phosphorus trichloride or phosphorus pentachloride is used instead of phosphorus oxychloride, the yield and purity of perfluoroacyl chloride will decrease.

Unfortunately, when thionyl chloride is used, the yield of perfluoroacyl chloride is low, and 111. 1. Phosphorus oxychloride and D for perfluoroargyl carboxylic acid in the present invention are industrially disadvantageous because sulfuric acid gas is produced as a by-product.
The molar ratio of MF is 1:0.6 to 0,8:0.3 to 0
, 5 is preferred, more preferably 1:O06 to 0.7
: 0.4 to 0.5. If the molar ratio of phosphorus oxychloride exceeds 0.8, the pure amount of perfluoroacyl chloride in the product will tend to decrease, while if it is less than 0.6, the reaction rate will tend to decrease. The molar ratio of DMF is also the same as the molar ratio of phosphorus chloride (3, which tends to be Ace).
The reaction in the present invention can be carried out at a reaction eddy current of 0 to 25°C and a reaction pressure of atmospheric pressure1.If the reaction temperature is low, the reaction will be impractical, and if it is high, the reaction will be rapid. It is unsafe because the raw materials are mixed into the product, and the purity and yield of perfluoroacyl chloride are reduced1.Also, when the pressure is high, it is not easy to charge the raw materials. It is also industrially disadvantageous from the standpoint of distillation operations.

In the method of the present invention, it is not necessary to particularly cool the perfluoroalkyl carboxylic acid or to add phosphorus oxychloride to the carboxylic acid for a certain period of time. Even if it is added dropwise for a few minutes, the generation of white smoke and heat generation are suppressed, and the chlorination reaction after adding DMF is fast, so there is no need to continue the reaction at a predetermined temperature for a certain period of time as in known methods, and DMF is added dropwise. The desired perfluoroacyl chloride can be easily obtained by simple distillation (or vacuum distillation) immediately after the completion of the reaction, eliminating the need for precision distillation7. It is much easier to operate than the conventional method using chlorinating agents. In addition, it has less irritating odor than liquid phosphorus trichloride, etc., so it is very easy to handle.1 The perfluoroacyl chloride produced as described above is highly pure, making it useful as a precursor for organic synthesis. .

It is particularly useful as a catalyst for the polymerization of fluoroolefins and as a raw material for fluorine-based beluoside, which has recently attracted attention.

The present invention will be specifically explained below with reference to Examples, Comparative Examples, and Reference Examples. Perfluoro-71-butyric acid 521.1r (
Add 1,50 mol) and stir 4 phosphorus oxychloride
61°3r (1.05 mol) was added over 2 minutes at room temperature. No heat generation was observed at that time 1, DM after addition, F
55. Oy (0,75-El) was added dropwise over 5 minutes at 5°C. At that time, almost no white smoke or heat generation was observed. After the dropwise addition was completed, the temperature of the bath for heating the flask was raised to 50°C, and simple distillation was carried out. The obtained product is a colorless liquid with a boiling point of 36-37°C, and the yield is 3.
The yield was 37.7F (yield: 96.8F). The purity of the product was determined by gas chromatography and found to be 99.
．． Furthermore, the product t↓infrared absorption spectrum showed carbonyl absorption at 1790 crn-''.From the boiling point and infrared absorption spectrum, the obtained product was perfluoro-n-butyl. It was confirmed that it was lyl chloride.

Example 2 Perfluoro-n- Buji +)
Lucuro 17do was manufactured. There was almost no generation of white smoke or heat generation during the addition of phosphorus oxychloride 1, yield of ili distillation distillation product was 301.7f, yield rj', 8
6.5, and the boiling point was 35-67°C. Example 1
Using the same method as above, it was confirmed that the purity of the product was 99.2% and that the product was perfluoro-n-butyryl chloride.

Example 3 The amount of phosphorus oxychloride was 161.5f (1.05 mol)
t, 1 except that it was changed from to 126.52 (0.85 mol)
．． Perfluoro-n-butyryl chloride was produced in exactly the same manner as in Example 1. There was almost no generation of white smoke or heat generation during the addition of phosphorus oxychloride.

The yield of the product was 305.6f, the yield was 87.6%, and the boiling point was 34-56°C. Using the same method as in Example 1, it was confirmed that the product had a purity of 99.5% and was perfluoro-n-butyryl chloride.

Example 4 Example 1 except that perfluoro-n-butyric acid was changed to perfluoro-n-caproic acid 471.1F (1,50 mol) and the temperature during distillation was changed from 50°C to 100°C.
Perfluoro-n-cabroyl chloride was produced in the same manner as above. There was almost no generation of white smoke or heat generation during the addition of phosphorus oxychloride. The yield of product was 494.
It was a colorless liquid with a boiling point of 84-85°C. The purity of the product was determined by the same method as in Example 1, and it was found to be 99.5.1. The infrared absorption spectrum showed carbonyl absorption at 1795 an-''. From the spectrum,
The obtained product was confirmed to be perfluoro-n-cabroyl chloride.1. Example 5 A 100me flask equipped with a mechanical stirrer, a thermometer, a dropping funnel, and a distillation condenser was equipped with an exhaust port and an aspirator. Connect it through the manometer, perfluoro
41.41 (0.10 mol) of n-cagrilic acid was put thereinto, and 10.7 f (0.07 mol) of phosphorus oxychloride was added thereto under stirring over 1 minute at room temperature.

After the addition, 5.7 t (0.05 mol) of DMF was added dropwise at room temperature over 2 minutes. At that time, there was no generation of white smoke or heat generation. After the dropwise addition was completed, the temperature of the bath for heating the flask was raised to 50°C, and vacuum distillation was performed. Yield 44゜5
A colorless liquid of f (yield 99.9%) was obtained. The boiling point of the product was 36-b. The purity of the product was determined in the same manner as in Example 1 and was found to be 97.1%. In addition, carbonyl absorption was observed in 1810Crn-1 in the infrared absorption spectrum, and from the above boiling point value, the product was confirmed to be perfluoro-n.
- It was confirmed that it was caprylyl chloride.

Comparative Example 1 In a 500 ml flask equipped with the same equipment as used in Example 1, 56.2 f (0,17 mol) of phosphorus pentachloride in solid form and 52,2 f (0,17 mol) of phosphorus oxychloride as solvent were added.
21 mol)'f was added. While stirring, 52.1f (0.15 mol) of perfluorinated butyric acid was added dropwise at room temperature over 60 minutes. After the dropwise addition was completed, the temperature of the reaction tank was raised to 70°C and simple distillation was performed. The product yield was 25.62 (yield 71.
It was a colorless liquid with a boiling point of 35-36°C. Using the same method as in Example 1, the purity of the product was 92. o%
It was confirmed that the product was perfluoro-louptyryl chloride.

Comparative Example 2 A flask equipped with the same equipment as used in Example 1 was charged with 94.8 F (0.69 mol) of phosphorus trichloride. Perfluoro-n-E acid 289.02 (1,3
5 mol)'IC-dropwise, then DMF 9.9y (
0.14 mol) was added dropwise over 50 minutes at room temperature. After the dropwise addition was completed, the temperature of the bath for heating the flask was raised to 57° C. and simple distillation was performed. The product has a yield of 200. Of
3 was a colorless liquid (yield 65.7%) and the boiling point of the product was 54-65°C. Using the same method as in Example 1, it was confirmed that the purity of the product was 87.3q6 and that the product was perfluoro-'TL-butyryl chloride.

Comparative Example 6 Perfluoro-T-
Butyric acid 321.1? (1,50 mol) was added to a flask and heated to -1°C under stirring with DMF 55. Of (0.75 mol) was added dropwise over 20 minutes. At that time, white smoke emitted/:1-
The white smoke flowed into the distillation vessel, and no further heat generation was observed, and the temperature rose to 20°C. I) After dropping MF', 161.59 (1.05 mol) of phosphorus oxychloride was added dropwise at room temperature for 15 minutes.
℃ rose. The generated white smoke liquefied in the receiver, so the distillation receiver was changed, the temperature of the bath for heating the flask was raised to 50C, and simple distillation was performed.

The yield of product was 317.4'r (yield 91.0t).

The boiling point of the product was 35-36°C1, Example 1
Using the same method as above, it was confirmed that the purity of the product was 95.2% and that the product was perfluoro-n-butyryA chloride.

Reference Example [Synthesis of bis[perfluoro-n-7”] peroxide] 5001 equipped with a mechanical stirrer, a thermometer and a dropping funnel
Sodium hydroxide 8.8f (0,22
mol)'f, add 165°01 of water and dissolve, add 8.22% of common salt, 7.52% of hydrogen peroxide (7.52%)
, 11 mol) was added, and under stirring 1,1.2-) Licro 1
After adding '-1,2,2-trifluoroethane 1422, the reaction solution was cooled to -5°C. After cooling, perfluoro-n-butyryl chloride so,4y (0.13 mol) with a purity of 99.6% obtained as in Example 1 and 1.1
．． 2-) Lichloro-4,2,2-)lifluoroethane 5
A mixed solution with 6f was added dropwise at a temperature of -2 to -5°C.

Aged for 60 minutes, washed with water, and dried with magnesium sulfate.
Bis(perfluoro-n-butyryl) peroxide was obtained with a yield of 67.5% and a purity of 9.7%.1, Reference Example 2 [Synthesis of bis(perfluoro-n,-butyryl)peroxide] Perfluoro-71,- Butyrylchlor 1,1 Tora Ratio M
Perfluoro-η- with a purity of 87.5% obtained from Example 2
Treatment 1. was carried out in the same manner as in Example 1 except that butyryl chloride 54.6 Y (11,13'1-l) was used. -te,bis(perfluoro-n-butyryl)peroxidora was synthesized, yield 3f: 181.6, yield 21.6%, purity 6.3%.

Reference Example 3 Synthesis of rbis(perfluoro-jt-7'thyl)peroxide] Sodium hydroxide was mixed with sodium carbonate 13.9SF (0,
13 mol) and further added 50% hydrogen peroxide solution to 8.9 mol.
Bis(perfluoro-η-butyryl) peroxide was synthesized in the same manner as in Reference Example 1 except that f (0.13 mol) was changed, yield 195°2f, yield 7.
The purity was 10.7%. Nao beach examples 1-6
The yield was 1 for perfluoro-η-butyryl chloride, Comparative Example 1 used solid phosphorus pentachloride as the chlorinating agent, Comparative Example 2 used phosphorus trichloride, and Comparative Example 5 used solid phosphorus pentachloride as the chlorinating agent. (I) When MF was added to perfluoro-r-butyric acid prior to phosphorus oxychloride, in both cases the yield of the product was significantly lower than in the examples.

Also, as a reference example, when bis(berflumelo-n-butyryl) peroxide is synthesized using Babe/L, fluoro-n,-butyryl chloride as a raw material, it is shown that the purity of the raw material has an effect on the yield of the synthesized product. It is something. That is, pure 1α9
Purity was 87.3% compared to Reference Example 1 using 9.6% raw material.
In Reference Example 2.6 using % of raw materials, the yield of synthesized bis(perfluoro-n-butyryl) peroxide was low.

Claims (3)

[Claims] (1) After pre-mixing perfluoroalkylcarboxylic acid and phosphorus oxychloride, N and N as catalysts are added.
A method for producing perfluoroacyl chloride, which comprises mixing and reacting N-dimegolformamide and then distilling the mixture; (2) Perfluoroalkylcarboxylic acid (general formula F)
The method for producing perfluoroacyl chloride according to claim 1, which is an aliphatic carboxylic acid represented by (CF2)ncO2H (n=2-7). (3) The molar ratio of perfluoroalkylcarboxylic acid, phosphorus oxychloride and N,N-dimethylforno,amide is 1:0.6~0.8:0.3~0.5f
lr>rrClaim 1. Method for producing perfluoroacyl chloride according to claim 2.1.