JP3087474B2 - Method for producing difluorobromoacetyl fluoride - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a process for producing difluorobromoacetyl fluoride. More specifically, the present invention relates to a method for producing difluorobromoacetyl fluoride which does not use or by-produce 1,2-dibromotetrafluoroethane which is a specific halon.

[0002]

2. Description of the Related Art Difluorobromoacetyl fluoride is a compound useful as an intermediate for the synthesis of various fluorine-containing compounds. For example, it is reacted with hexafluoropropene oxide, then neutralized and thermally decomposed.
Produces perfluoro (2-bromoethyl vinyl ether), which is useful as a raw material for fluororesins.

[0003] As a method for producing such difluorobromoacetyl fluoride, for example, 1,2-dibromotetrafluoroethane, 1-bromo-2-iodotetrafluoroethane,
Fuming sulfuric acid or sulfuric anhydride with an SO ₃ concentration of 50-70% is allowed to act on 1,2-dibromochlorotrifluoroethane, tetrafluoroethylene, etc. to obtain a partial oxide as an intermediate, which is then thermally decomposed Method (JP-A-57-40433-5)
Etc. are known.

However, when 1,2-dibromotetrafluoroethane is used as a starting material, the yield is low and the starting compound itself is specified as a specific halon, so its use is not preferred. When 1-bromo-2-iodotetrafluoroethane is used as a raw material, not only is the reaction system prone to trouble due to iodine precipitation, but also 1,2-dibromotetrafluoroethane is generated as a by-product. From a point of view, its use is not preferred. Further, when 1,2-dibromochlorotrifluoroethane is used as a raw material, ClF ₂ COF or ClF ₂ COCl is by-produced, and since these have close boiling points with BrCF ₂ COF, separation by distillation is difficult. . Furthermore, even when tetrafluoroethylene is used as a raw material, the by-product of 1,2-dibromotetrafluoroethane cannot be avoided.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to use a specific halon of 1,2-dibromotetrafluoroethane without using it or by-producing it during the reaction.
It is an object of the present invention to provide a method for producing difluorobromoacetyl fluoride, which is an object.

[0006]

SUMMARY OF THE INVENTION The object of the present invention is as follows.
General formula Rf [CF ₂ OCF (CF ₃ )] nCF ₂ OCF = CF ₂ [I] (where Rf is a fluorine atom, a lower perfluoroalkyl group or a bromine-substituted lower perfluoroalkyl group,
(n is 0 or 1) by reacting bromine with fuming sulfuric acid or sulfuric anhydride, or Rf [CF ₂ OCF (CF ₃ )] nCF ₂ OCFBrCF ₂ Br [II] (where , Rf is a fluorine atom, a lower perfluoroalkyl group or a brominated lower perfluoroalkyl group,
n is 0 or 1) with fuming sulfuric acid or sulfuric anhydride, and the resulting intermediate is thermally decomposed in an organic solvent in the presence of an alkali metal fluoride to give difluorobromoether. Achieved by producing acetyl fluoride.

The perfluoro compound represented by the above general formula [I]
Vinyl ethers are RfCOF and hexafluoropropene
After reacting with oxide, neutralization and thermal decomposition
Specifically, the following compounds are exemplified.
Can be. CF_ThreeOCF = CF_Two  CF_ThreeCF_TwoCF_TwoOCF = CF_Two  CF_ThreeCF_TwoCF_TwoOCF (CF_Three) CF_TwoOCF = CF_Two  BrCF_TwoCF_TwoOCF (CF_Three) CF_TwoOCF = CF_Two

The reaction using such a perfluorovinyl ether is carried out through the following two steps.

In the first-stage reaction, bromine is charged into a reaction vessel, fuming sulfuric acid or sulfuric anhydride is added dropwise thereto with stirring, and after continuing stirring, perfluorovinyl ether is added dropwise thereto with stirring. Operation is about 20-50 ℃
Is performed under the following temperature conditions. After completion of the dropwise addition, the mixture is heated to about 20 to 120 ° C. for about 4 to 48 hours. After completion of the reaction, nitrogen gas bubbling is performed, and liquid separation is performed to obtain a lower layer reaction product as an intermediate. Such a first-stage reaction can also be carried out in an autoclave. In this case, the operation of charging bromine and fuming sulfuric acid or sulfuric anhydride in the autoclave, stirring the mixture, and then injecting perfluorovinyl ether into the autoclave, is performed by about one operation.
It is performed under a temperature condition of 0 to 50 ° C. Then to about 20-120 ° C
The intermediate can be obtained by heating for 4 to 48 hours, followed by bubbling with nitrogen gas and liquid separation in the same manner.

[0010] Bromine is used in a ratio of about 0.5 to 2 moles, preferably about 0.8 to 1.5 moles, per mole of perfluorovinyl ether. As the sulfur trioxide to be supplied, fuming sulfuric acid or sulfuric anhydride having an SO ₃ concentration of about 25% or more is used.From the viewpoint of reaction efficiency and handling, the SO ₃ concentration is about 25 to 35% or About 50-70% fuming sulfuric acid or sulfuric anhydride is preferably used. It is used in an amount of about 1 to 5 moles per mole of perfluorovinyl ether, preferably about 1.
It is 1 to 2.2 times mol.

The second-stage reaction is a thermal decomposition reaction. This reaction proceeds by directly pyrolyzing the reaction mixture in the preceding step or by gas phase decomposition in which the reaction mixture is heated to about 200 to 350 ° C. From the viewpoints of properties and reaction efficiency, the reaction is preferably performed in the presence of an alkali metal fluoride. In this reaction, an operation of dropping the obtained intermediate while stirring into a reaction vessel charged with an alkali metal fluoride and an organic solvent is performed under a temperature condition of about 20 to 100 ° C. After completion of the dropwise addition, the intermediate is thermally decomposed by further heating to about 80 to 150 ° C. to obtain difluorobromoacetyl fluoride, which is the target substance, which is purified by distillation to the next step. Raw material.

As the alkali metal fluoride, for example, sodium fluoride, potassium fluoride, cesium fluoride and the like are used, but from the viewpoint of cost, activity and the like, spray-dried powdered potassium fluoride is preferably used. These alkali metal fluorides are used in a ratio of about 0.1 to 10 times mol, preferably about 1.1 to 2.2 times mol, per mol of perfluorovinyl ether. This reaction proceeds even in the absence of a solvent, but it is preferable to use an organic solvent in order to increase the activity of the decomposition catalyst. As the organic solvent, diglyme,
An aprotic polar solvent such as a glyme such as tetraglyme or a sulfur-containing compound such as dimethyl sulfoxide or sulfolane is used, and diglyme is preferably used from the viewpoints of price, handleability and the like.

[0013] Difluorobromoacetyl fluoride, which is a reaction product, collects gas generated during the thermal decomposition reaction from the upper portion of a reflux condenser or the like, and is collected in a trap cooled with dry ice / methanol. Will be collected as In the recovered material, in addition to the target substance, perfluorovinyl ether as the starting compound and the general formula Rf [CF ₂ OCF (C
Perfluoro acid fluoride represented by F ₃ )] nCOF is mixed, and the latter acid fluoride can be a raw material for synthesizing a raw material compound.

Further, a perfluorobromoether represented by the general formula [II] obtained by subjecting a perfluorovinyl ether represented by the general formula [I] to an addition reaction with bromine is used as a starting material for the synthesis of difluorobromoacetyl fluoride. Can also be used. Such compounds include the following. CF ₃ OCFBrCF ₂ Br CF ₃ CF ₂ CF ₂ OCFBrCF ₂ Br CF ₃ CF ₂ CF ₂ OCF (CF ₃ ) CF ₂ OCFBrCF ₂ Br BrCF ₂ CF ₂ OCF (CF ₃ ) CF ₂ OCFBrCF ₂ Br

The reaction using such perfluorobromoether is carried out through the following two steps.

In the first-stage reaction, perfluorobromoether is charged into a reaction vessel, fuming sulfuric acid or sulfuric anhydride is added dropwise thereto with stirring, and the stirring is continued at about 20 to 50 ° C. Is performed under the following temperature conditions. After completion of the dropwise addition, the mixture is heated to about 20 to 120 ° C. for about 4 to 48 hours. After completion of the reaction, the same treatment as in the case of using perfluorovinyl ether is performed to obtain an intermediate. The amount of fuming sulfuric acid or sulfuric anhydride used in this reaction is the same as described above.

The second stage reaction and product recovery are also
The procedure is the same as with fluorovinyl ether.
You. The collected product contains the target product, difluorobromoacetate.
In addition to tylfluoride, the following compounds are mixed
Therefore, by distillation and purification, the raw material for the next process
Becomes Rf [CF_TwoOCF (CF_Three)] nCF_TwoOCF = CF_Two  Rf [CF_TwoOCF (CF_Three)] nCOF

[0018]

According to the method of the present invention, the specific halon is used.
Difluorobromoacetyl fluoride can be obtained in good yield without using 1,2-dibromotetrafluoroethane and without by-producing it during the reaction.

The general formula Rf [CF ₂ OCF, which is a by-product of the reaction,
(CF ₃ )] nCOF can be reused as a raw material for synthesizing perfluorovinyl ether or perfluorobromoether as a raw material compound.

[0020]

Next, the present invention will be described with reference to examples.

Example 1 Bromine was placed in a 500 ml round bottom flask equipped with a stirrer, thermometer, reflux condenser, dropping funnel and gas inlet tube.
0 g, and then 30 g while stirring 320 g of 25% fuming sulfuric acid.
The mixture was added dropwise at 1 ° C. over 1 hour, and the mixture was further stirred for 2 hours after completion of the addition.

Thereafter, 133.0 g of perfluoro (propyl vinyl ether) was added dropwise thereto over 2 hours with stirring, and after completion of the addition, stirring was continued for another 24 hours while heating at 100 ° C. After completion of the reaction, the flask was cooled and nitrogen gas bubbling was performed. Thereafter, the contents of the flask were transferred to a separating funnel, and 158.2 g of a lower layer reaction product (intermediate) was taken out.

A round bottom flask equipped with a stirrer, a thermometer, a reflux condenser and a dropping funnel was charged with 24.4 g of spray-dried powdered potassium fluoride and 150 g of diglyme. It was dropped over time. After completion of the dropwise addition, stirring was continued for another 4 hours while heating to 110 ° C. to perform thermal decomposition.

The gas generated during this period was extracted from the upper part of the reflux condenser, and collected in a trap cooled with dry ice / methanol. After collecting this collected material, 4
0.6 g, which was analyzed by gas chromatography to find that the target substance, difluorobromoacetyl fluoride, was contained at 28.5%, and that the combined yield of all the steps (excluding the recovered starting compound; the same applies hereinafter) Was 24.3%.

The recovered material also contains 32.5% of perfluoropropionic acid fluoride and 13.8% of perfluoro (propyl vinyl ether) as a starting compound, and the specific halon, BrCF ₂ CF ₂ Br, Not detected.

Example 2 In Example 1, 60% fuming sulfuric acid was used instead of 25% fuming sulfuric acid.
Use 100g, and the reaction conditions are 100 ° C, 24 hours to 60 ° C, 8
The time was changed to give 172.5 g of the intermediate. 85.2g of this
The same thermal decomposition as in Example 1 was performed using the intermediate
g of recovery was obtained.

The recovered product contained 35.5% of the desired product (yield 4%).
2.7%), 39.5% perfluoropropionic acid fluoride,
Each of the starting compounds contained 6.0%, and the specific halon, BrCF ₂ CF ₂ Br, was not detected.

Example 3 In Example 1, 48 g of sulfuric anhydride was used instead of 25% fuming sulfuric acid.
And the reaction conditions were changed from 100 ° C. for 24 hours to 30 ° C. for 4 hours to obtain 181.5 g of an intermediate. Using 85.2 g of the intermediate, pyrolysis was carried out in the same manner as in Example 1 to obtain 51.6 g of a recovered product.

The recovered product contained 37.8% of the desired product (yield 4%).
7.0%), 40.2% of perfluoropropionic acid fluoride,
The starting compound was contained in 2.7%, and the specific halon, BrCF ₂ CF ₂ Br, was not detected.

Example 4 In Example 2, the starting compound was prepared from perfluoro (propyl vinyl ether), and by-product perfluoro (propoxypropyl vinyl ether) at the time of its production was used.
Change to 0 g to give 203.5 g of the intermediate. Using 118.4 g of the intermediate, pyrolysis was carried out in the same manner as in Example 1, and 49.7 g of the intermediate was obtained.
Was obtained.

The recovered product contained 45.2% of the desired product (yield 4
3.6%), 26.0% of perfluoro (propyl vinyl ether) which can be a raw material of perfluoro (propyl vinyl ether) and 1.4% of raw material compounds are contained, respectively, and the specific halon, BrCF ₂ CF ₂ Br, is detected. Did not.

Example 5 In Example 2, the starting compound was changed from perfluoro (propyl vinyl ether) to 221.5 g of perfluoro (bromoethoxypropyl vinyl ether) to obtain 182.2 g of an intermediate. Using 120.6 g of the intermediate, the same thermal decomposition as in Example 1 was performed to obtain 47.1 g of a recovered product.

The recovered product contained 51.0% of the desired product (yield 4%).
1.0%), perfluoro that can be a raw material for this raw material compound
(Bromoethoxypropionic acid fluoride) at 19.2% and the starting compound at 1.6%, respectively, and the specific halon, BrCF ₂ CF ₂ Br, was not detected.

Example 6 500 ml capacity equipped with a stirrer, thermometer and gas inlet tube
The pressure in the autoclave was reduced, and 84.0 g of bromine and 100 g of 60% fuming sulfuric acid were sequentially charged therein, followed by stirring at 30 ° C. for 2 hours. Then, perfluoro (methyl vinyl ether) 83.0
g was injected over 2 hours, and stirring was continued while heating to 100 ° C. for an additional 24 hours after injection to perform thermal decomposition.

After the completion of the reaction, the autoclave was cooled and nitrogen was bubbled, and then the contents in the autoclave were transferred to a separating funnel, and 134.9 g of a lower layer reaction product (intermediate) was taken out. Using 65.2 g of the intermediate, pyrolysis was carried out in the same manner as in Example 1 to obtain 28.3 g of a recovered product.

The recovered product contained 54.3% of the desired product (yield 3%).
6.0%), 5.2% carbonyl fluoride and 10.
7% each, which is a specific halon, BrCF ₂ CF ₂ Br
Was not detected.

EXAMPLE 7 213.0 g of perfluoro (propyl-1,2-dibromoethyl ether) was placed in a 500 ml round bottom flask equipped with a stirrer, thermometer, reflux condenser, dropping funnel and gas inlet tube. Then, 320 g of 25% fuming sulfuric acid was added dropwise at 30 ° C. over 1 hour with stirring, and the mixture was further stirred for 2 hours after completion of the addition.
Thereafter, stirring was continued for another 24 hours while heating to 100 ° C.

Then, in the same manner as in Example 1, nitrogen gas bubbling, liquid separation (intermediate 162.8 g), reaction with potassium fluoride in diglyme using intermediate 85.2 g, and thermal decomposition were carried out. g collected matter was collected. The recovered material contains 32.4% (yield 33.0%) of the target substance, 36.2% of perfluoropropionic acid fluoride, and 11.4% of perfluoro (propyl vinyl ether), and the specific halon, BrCF ₂ CF ₂ Br
Was not detected.

Example 8 In Example 7, 60% fuming sulfuric acid was used instead of 25% fuming sulfuric acid.
Use 100g, and the reaction conditions are 100 ° C, 24 hours to 60 ° C, 8
The time was changed to give 180.4 g of the intermediate. 85.2g of this
The same thermal decomposition as in Example 7 was performed using the intermediate
g of recovery was obtained.

The recovered product contained 37.9% of the desired product (yield 4%).
9.3%), 41.7% perfluoropropionic acid fluoride,
4.4% of perfluoro (propyl vinyl ether) was contained, and the specific halon, BrCF ₂ CF ₂ Br, was not detected.

Example 9 In Example 7, 48 g of sulfuric anhydride was used instead of 25% fuming sulfuric acid.
And the reaction conditions were changed from 100 ° C. for 24 hours to 30 ° C. for 4 hours to obtain 177.6 g of an intermediate. Using 85.2 g of the intermediate, the same thermal decomposition as in Example 7 was performed to obtain 52.8 g of a recovered product.

The recovered product contained 39.1% of the desired product (yield: 49.1%).
8.6%), 42.5% perfluoropropionate fluoride,
1.9% of perfluoro (propyl vinyl ether) was contained, and the specific halon, BrCF ₂ CF ₂ Br, was not detected.

Example 10 In Example 8, the starting compound was converted from perfluoro (propyl-1,2-dibromoethyl ether) to perfluoro (propoxypropyl-1,2,
-Dibromoethyl ether) was changed to 296.0 g to obtain 227.6 g of an intermediate. Example 7 was performed using 118.4 g of the intermediate.
The same thermal decomposition was performed to obtain 52.8 g of a recovered product.

The recovered product contained 39.1% of the desired product (yield 4%).
4.8%), 35.0% of perfluoro (propoxypropionic acid fluoride) and 2.9% of perfluoro (propoxypropylvinyl ether), respectively, and the specific halon, BrCF ₂ CF ₂ Br, was not detected.

Example 11 In Example 8, the starting compound was changed from perfluoro (propyl-1,2-dibromoethyl ether) to perfluoro
(2-Bromoethoxypropyl-1,2-dibromoethyl ether) was changed to 301.5 g to obtain 180.4 g of an intermediate. The same thermal decomposition as in Example 7 was carried out using 120.6 g of the intermediate to obtain 43.5 g of a recovered product.

The recovered product contained 54.7% of the desired product (yield 4%).
0.3%), perfluoro (bromoethyl vinyl ether) raw material perfluoro (bromoethoxypropionic acid fluoride) 22.4%, perfluoro (bromoethoxypropyl vinyl ether) contains 1.4% each,
The specific halon, BrCF ₂ CF ₂ Br, was not detected.

Example 12 In Example 8, the starting compound was changed from perfluoro (propyl-1,2-dibromoethyl ether) to perfluoro
(Methyl-1,2-dibromoethyl ether) was changed to 163.0 g to obtain 125.0 g of an intermediate. Using 65.2 g of the intermediate, pyrolysis was carried out in the same manner as in Example 7 to obtain 31.6 g of a recovered product.

In this recovered product, the target substance was 59.3% (yield: 49.3%).
0.6%), carbonyl fluoride 6.4%, and perfluoro (methyl vinyl ether) 11.1%, respectively, and the specific halon, BrCF ₂ CF ₂ Br, was not detected.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) C07C 51/58 C07C 51/62 C07C 53/48

Claims (2)

(57) [Claims] 1. The general formula Rf [CF ₂ OCF (CF ₃ )] nCF ₂ OCF = CF
₂ (where Rf is a fluorine atom, a lower perfluoroalkyl group or a bromine-substituted lower perfluoroalkyl group, and n is 0 or 1), to the perfluorovinyl ether represented by bromine and fuming sulfuric acid or sulfuric anhydride. And subjecting the resulting intermediate to thermal decomposition in an organic solvent in the presence of an alkali metal fluoride, a process for producing difluorobromoacetyl fluoride. 2. The general formula Rf [CF ₂ OCF (CF ₃ )] nCF ₂ OCFBrCF ₂ Br
(Where Rf is a fluorine atom, a lower perfluoroalkyl group or a bromine-substituted lower perfluoroalkyl group,
(n is 0 or 1) perfluorobromoether represented by fuming sulfuric acid or sulfuric anhydride, and the resulting intermediate is thermally decomposed in an organic solvent in the presence of an alkali metal fluoride. A method for producing difluorobromoacetyl fluoride.