JP2893546B2 - 4-Bromo-3,5,6-trifluorophthalic acid and its preparation, 3-bromo-2,4,5-trifluorobenzoic acid - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a novel compound 4-bromo-3, which is useful as an intermediate material for functional polymer materials, pharmaceuticals, agricultural chemicals and liquid crystal materials.
The present invention relates to 5,6-trifluorophthalic acid and a method for producing the same, and also relates to a method for producing 3-bromo-2,4,5-trifluorobenzoic acid.

[Prior Art] 4-Bromo-3,5,6-trifluorophthalic acid (hereinafter sometimes abbreviated as F ₃ BrPA) of the present invention is referred to as “Chemical A”.
No description is found in “bstract” and the like, and as far as the present inventors know, it is considered a novel substance.

Regarding the method for producing the above-mentioned 3-bromo-2,4,5-trifluorobenzoic acid (hereinafter sometimes abbreviated as F ₃ BrBA),
Several methods are known, e.g.
No. 3 discloses a production method using the following steps.

However, in the method described in the above publication, the production process is extremely long, and the yield from the starting material must be low,
It was not satisfactory as an industrial process.

[Problems to be Solved by the Invention] As described above, the present inventors have found that F ₃ BrPA useful as an intermediate material for functional polymer materials, pharmaceuticals, agricultural chemicals, liquid crystal materials, and the like.
As a result of studying to obtain, when reacting tetrafluorophthalonitrile (hereinafter sometimes abbreviated as F ₄ PN) with a metal bromide such as lithium bromide in an aprotic polar organic solvent such as sulfolane Stopping the reaction when the reaction rate of the F ₄ PN reaches a specific value, or
By adjusting the amount of the metal bromide to F ₄ PN, 4-bromo-3,5,6-trifluorophthalonitrile (hereinafter sometimes abbreviated as F ₃ BrPN) can be efficiently produced. with 4,5-dibromo-3,6-difluoro phthalonitrile found that it is possible to suppress the very small amount of the by-product of (hereinafter sometimes abbreviated as F ₂ Br ₂ PN) and the like, also, the F ₃ A novel compound F ₃ BrPA can be obtained by hydrolyzing BrPN, and further, the F ₃ BrPA
It has been found that F ₃ BrBA can be produced by decarboxylation, and the present invention has been completed.

[Means for Solving the Problem] An object of the present invention is to provide a method for producing 4-bromo-3,5,6-trifluorophthalonitrile.

Further, the present invention is characterized in that a novel compound 4-bromo-3,5,6-trifluorophthalic acid and a method for producing the same, that is, hydrolyzing 4-bromo-3,5,6-trifluorophthalonitrile. An object of the present invention is to provide a method for producing 4-bromo-3,5,6-trifluorophthalic acid.

Further, the present invention provides a method for decarboxylating 4-bromo-3,5,6-trifluorophthalic acid.
It is intended to provide a method for producing 4,5-trifluorobenzoic acid.

 Hereinafter, the present invention will be described in detail.

In the bromination step the present invention First, the F ₃ BRPN efficiently prepared by reacting a metal bromide and F ₄ PN in aprotic polar organic solvents (bromination step).

Examples of the aprotic polar organic solvent used in this step include, for example, dimethyl sulfoxide, diphenyl sulfone, dimethyl sulfone, sulfolane, N, N-dimethylformamide, N, N-dimethylacetamide, N-methylpyrrolidone, acetonitrile, hexamethyl phosphorus Acid triamides, dialkyl ethers of glycolic acid, quinoline and the like can be mentioned. Of these, sulfolane and N, N-dimethylformamide are preferred from the viewpoint of good reactivity when used in the method of the present invention. . Each of these aprotic polar organic solvents, alone,
Alternatively, two or more kinds can be used in combination. Further, the aprotic polar organic solvent may generally contain 10% by weight or less, preferably 5% by weight or less of water.

The amount of the aprotic polar organic solvent used is the starting material F ₄
It is generally 100 to 3000 parts by weight, preferably 200 to 1000 parts by weight, per 100 parts by weight of PN.

As the metal bromide used in this step, for example, lithium bromide, lithium bromide dihydrate, sodium bromide, sodium bromide dihydrate, alkali metal bromide such as potassium bromide or a hydrate thereof And the like. The amount of the metal bromide to be used is generally 0.2 to 20 mol, preferably 0.5 to 10 mol, per 1 mol of the starting material F ₄ PN.

This reaction step can be considered to proceed according to the following reaction formula.

The reaction of this step is allowed to proceed efficiently, and the F ₃ BrPN
Suitable methods for preparing, first, is reacted with a metal bromide to F ₄ PN aprotic polar organic solvent, the F ₄ PN response rate 20 to 50% and preferably 25% to 45% reach A method of interrupting the reaction at the time when the reaction is performed can be exemplified.

The above-mentioned reaction rate is obtained by measuring a residual amount of F ₄ PN by gas chromatography (hereinafter, sometimes abbreviated as GC) and collecting a part of the reaction solution at regular intervals from the start of the reaction. It can be obtained by calculation. If the reaction rate is too high above the upper limit, the amount of by-product F ₂ Br ₂ PN is undesirably increased, while if it is too low below the lower limit, the production of the target product F ₃ BrPN is not preferable. Rate is too small,
As will be described later, even if the solution containing the raw material F ₄ PN after the F ₃ BrPN separation is recycled, the productivity of F ₃ BrPN is unfavorably deteriorated.

The amount of metal bromide used in this first method is
In general 0.2 to 2 with respect to the starting material F ₄ PN1 mole as the
0 mol, preferably 0.5 to 10 mol, but it is not easy to separate and recover the metal bromide after the completion of the reaction step.Therefore, when an expensive metal bromide such as lithium bromide is used, the amount used is 0.5 mol. It is particularly preferred that the amount be from .about.1.2 mol.

The reaction temperature in the bromination step of the present invention is generally 50 to
The temperature is 200 ° C., preferably 100-150 ° C., and the reaction time is generally 0.5-20 hours, preferably 1-10 hours.

After completion of the bromination reaction by the first method, the reaction solution usually contains the starting material F ₄ PN, the target product F ₃ BrPN, and a small amount of by-product F ₂ Br ₂ PN. Then, water (the amount of water used is generally 200 to 2000 parts by weight, preferably 300 to 1000 parts by weight, based on 100 parts by weight of the raw material F ₄ PN) is added and mixed, and the resulting crystals are filtered off and dried. rear,
These F ₄ PN, F ₃ BrPN and F ₂ Br ₂ PN
Is separated. The starting material F ₄ PN can be recycled.

The reaction solution was added to water, extracted with a water-insoluble organic solvent, the organic solvent layer was washed with water by a conventional method, concentrated to dryness, and distilled under reduced pressure as described above to obtain F ₄ PN and F ₃ BrPN. and
F ₂ Br ₂ PN can also be separated. Here, “insoluble in water” means that the solubility (weight) in water is 6 or less.

Examples of such a water-insoluble organic solvent include aromatic hydrocarbons such as benzene, toluene, xylene, ethylbenzene, propylbenzene, cumene, butylbenzene and cymene; and halogenated aromatics such as paradichlorobenzene and paradifluorobenzene. Group hydrocarbons; for example,
Propyl ether, dialkyl ethers such as butyl ether; for example, n- hexane, n- C ₈ or more aliphatic, such as heptane hydrocarbons; the like can be exemplified.

Further, as a second preferred method for efficiently proceeding the reaction in this step, when F ₄ PN is reacted with the metal bromide in an aprotic polar organic solvent, the amount of the metal bromide used is reduced to F ₄ PN 1 The method is 0.8 to 2 mol, preferably 0.9 to 1.5 mol, per mol. If the amount is less than the upper limit, it is preferable because by-products such as F ₂ Br ₂ PN can be suppressed to a small amount.If the amount is more than the lower limit, a sufficient reaction rate can be obtained, and a high level of reaction can be obtained. This is preferable because the rate can be maintained. In this method, unlike the first method, it is preferable to carry out the reaction without interrupting the fluorination reaction until F ₄ PN of the starting material substantially disappears.

In this second method, as in the first method, the reaction temperature is generally 50 to 200 ° C, preferably 100 to 150 ° C, and the reaction time is generally 0.5 to 20 hours, preferably 1 to 1 hour.
0 hours.

Since the reaction solution after completion of the bromination reaction by the second method mainly contains the target product F ₃ BrPN and by-product F ₂ Br ₂ PN, this reaction solution is also the same as in the case of the first method. And F ₃ BrPN and F ₂ Br ₂ PN can be separated by distillation under reduced pressure or the like.

Hydrolysis step In the present invention, the F ₃ BrPN obtained by the bromination step
Followed by, for example, 50-90% by weight of an inorganic acid such as, for example, sulfuric acid, hydrochloric acid or hydrobromic acid (preferably sulfuric acid).
By hydrolyzing in an aqueous solution, a novel compound F ₃ BrPA can be produced as shown in the following reaction formula.

The reaction temperature is generally about 100 to 180 ° C.

The resulting F ₃ BrPA is isolated according to any known method,
It can be purified. For example, a method of adding a water-insoluble organic solvent in the bromination step to a reaction solution cooled after the completion of the hydrolysis reaction, extracting an organic solvent layer, and drying the resulting solution can be employed.

When F ₃ BrPA is subsequently decarboxylated to obtain F ₃ BrBA, a non-water-soluble nitrogen-containing organic base having no NH bond used in a decarboxylation step described below, Alternatively, using a water-insoluble aprotic polar organic solvent or non-polar organic solvent, extracting the product F ₃ BrPA obtained in the hydrolysis step, without isolating the F ₃ BrPA , Using the extract as it is, or adding another solvent and / or a catalyst described below to this as needed,
By performing the following decarboxylation step, the desired product F ₃ BrBA can be produced.

In the decarboxylation step the present invention, furthermore, F ₃ by the F ₃ BrPA obtained in the hydrolysis step by heating at a temperature range of 80 to 250 ° C. in a solvent decarboxylated as the following reaction scheme BrBA is easily manufactured.

The above-mentioned solvent is one which does not cause an undesired side reaction in the decarboxylation step between the starting material F ₃ BrPA of this step, the reaction product F ₃ BrBA and the catalyst used as required. I just need. As such a solvent, water, a nonprototonic polar organic solvent, a nitrogen-containing organic base having no NH bond, and a mixture thereof can be suitably used.

The “polar organic solvent” in this specification refers to a neutral organic compound having a permanent dipole moment of 2D (Debye) or more in the molecule.

Examples of the aprotic organic solvent include, for example, dimethyl sulfoxide, diphenyl sulfone, dimethyl sulfone, tetramethylene sulfone (sulfolane), dimethylformamide, dimethylacetamide, N-methylpyrrolidone, acetonitrile, hexamethylphosphoric triamide, benzonitrile, Examples include nitrobenzene, dialkyl ethers of glycolic acid, and quinoline.

Among these, examples of the water-soluble aprotic polar organic solvent include dimethyl sulfoxide, dimethyl sulfone, tetramethylene sulfone (sulfolane), dimethylformamide, dimethylacetamide, N-methylpyrrolidone, acetonitrile, hexamethylphosphoric triamide, and glycol. Examples include dialkyl ethers of acids [eg, diethylene glycol dimethyl ether (diglyme), triethylene glycol dimethyl ether (triglyme), tetraethylene glycol dimethyl ether (tetraglyme)], quinoline, and the like. Examples of the water-insoluble aprotic polar organic solvent include benzonitrile, nitrobenzene, and the like.

The nitrogen-containing organic solvent-free base having no NH bond which can be used in the decarboxylation step of the present invention, and may be abbreviated as an aprotic organic base. And a tertiary amine represented by

Preferred among such tertiary amines are trialkylamines (e.g., trimethylamine, triethylamine, tripropylamine, tributylamine, trioctylamine, trilaurylamine, tristearylamine, dimethylethylamine, methyldiethylamine, dii-propylamine). Ethylamine), trialkenylamine, dialkylarylamine (eg, dimethylaniline, diethylaniline), alkyldiarylamine (eg, diphenylmethylamine, diphenylethylamine), triarylamine (eg, triphenylamine), dialkylcycloalkylamine (eg, Dimethylcyclohexylamine), N-alkyl-substituted saturated nitrogen heterocyclic compounds (eg, N-methylpyrrolidine,
N-methylmorpholine, N-methylpiperidine) or quinuclidine.

Examples of other aprotic organic bases that can be used in the decarboxylation step include those of the general formula Can be mentioned.

Such diamines include, for example, N, N'-tetraalkylalkylenediamines (e.g., N, N'-tetramethylmethylenediamine, N, N'-tetramethylethylenediamine, N, N'-tetramethyltrimethylene Diamine), N, N'-tetraalkylarylenediamine (e.g., N, N'-tetramethylphenylenediamine), or cyclic diamine (e.g., triethylenediamine, N, N'-dimethylpiperidine).

Examples of further aprotic organic bases that can be used in the decarboxylation step include compounds of the general formula Amidine represented by

Examples of such amidines include, for example, trialkylamidines or bicyclic amidines (eg, diazabicycloundecene, diazabicyclononene).

The various solvents can be used alone or in combination with each other. For example, the aprotic organic base and water, the aprotic organic base and aprotic polar organic solvent, or water and aprotic polar organic solvent can be used in combination.

Further, as the solvent used in the decarboxylation step, an organic solvent other than the above can be used in combination, if necessary.

Among such organic solvents, preferred are, for example,
Non-polar organic solvents can be mentioned. Here, the “non-polar organic solvent” refers to a neutral organic compound having a permanent dipole moment in a molecule of less than 2D.

Such a non-polar organic solvent is preferably an organic compound having a boiling point of 80 to 300 ° C., for example, a C ₄ or more aliphatic alcohol such as butanol, hexanol, and cyclohexanol; for example, propyl ether, butyl ether and the like. of dialkyl ethers at least one of the alkyl group is C ₃ or more; for example, aromatic hydrocarbons such as benzene, toluene, xylene, mesitylene, ethylbenzene, propylbenzene, cumene, butylbenzene, cymene and the like; for example, para-dichlorobenzene , halogen-substituted aromatic hydrocarbons such as para-difluorobenzene; for example, heptane, C ₇ or more aliphatic hydrocarbons such as octane; for example, 1,2-dichloroethane, 1,1,2,2-tetrachloroethane, etc. Halogen-substituted aliphatic hydrocarbons;

Among these non-polar organic solvents, it is preferable to use hydrocarbon solvents such as aromatic hydrocarbons, halogen-substituted aromatic hydrocarbons, aliphatic hydrocarbons, and halogen-substituted aliphatic hydrocarbons. The use of aromatic hydrocarbons which are not substituted by atoms is particularly preferred.

The decarboxylation step can optionally be performed in the presence of a catalyst. The catalyst may be appropriately selected from those known in this type of decarboxylation reaction according to the type of solvent used.

Catalysts that can be used in the reaction in an aqueous solvent include, for example, ammonia hydroxide, carbonate, sulfate,
Organic acid salts or fluorides; alkali metal hydroxides, carbonates, bicarbonates, sulfates; organic acid salts or fluorides; alkaline earth metal oxides, hydroxides, carbonates, sulfates;
Organic acid salts or fluorides; sulfates such as organic salts, organic acid salts or fluorides; and the like.

As the hydroxide, carbonate, sulfate, organic acid salt or fluoride of ammonia, for example, ammonia water, ammonium carbonate, ammonium sulfate, ammonium fluoride,
Or a salt of the reaction raw material or product with ammonia,
That is, ammonium 4-bromo-3,5,6-trifluorophthalate and ammonium 3-bromo-2,4,5-trifluorobenzoate can be exemplified.

As the hydroxide, carbonate, bicarbonate, sulfate, organic acid salt or fluoride of an alkali metal, for example, sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium bicarbonate, potassium bicarbonate, Examples include sodium sulfate, potassium sulfate, rubidium sulfate, cesium sulfate, sodium fluoride, potassium fluoride, or a salt of a reaction raw material or product with an alkali metal (eg, sodium, potassium, rubidium or cesium) hydroxide. .

Oxides, hydroxides, carbonates, sulfates, organic acid salts or fluorides of alkaline earth metals; sulfates, organic acid salts or fluorides of organic bases include, for example, magnesium oxide, calcium oxide, oxide oxide Oronium, barium oxide, magnesium hydroxide, calcium hydroxide, strontium hydroxide, barium hydroxide, magnesium carbonate,
Calcium carbonate, barium carbonate, magnesium sulfate, calcium sulfate, strontium sulfate, calcium fluoride, or a salt of a reaction raw material or product and an alkaline earth metal (eg, magnesium, calcium, strontium or barium) with a hydroxide Can be illustrated.

Examples of the organic base sulfate, organic acid salt or fluoride include, for example, pyridine sulfate, quinoline sulfate, or the above-mentioned aprotic organic base sulfate, fluoride,
A salt with the reaction raw material F ₃ BrPA or a salt with the product F ₃ BrBA can be exemplified.

Next, examples of the catalyst used in the solvent containing the aprotic polar organic solvent include the above-mentioned inorganic bases such as hydroxides, carbonates and bicarbonates of alkali metals.

Furthermore, in the solvent containing the aprotic organic base, the aprotic organic base itself has a catalytic action, and the aprotic organic base and the aprotic organic base are optionally contained in the reaction raw material solution. Salts with sulfuric acid and salts with organic acids, which are reaction raw materials or products, also have a catalytic action, so that it is not always necessary to separately add a catalyst.

In the decarboxylation step of the present invention, the heating conditions, the quantitative ratio of the reaction raw material and the solvent, and the like can be easily set according to the type of the catalyst used and the type of the catalyst used in some cases.

For example, when decarboxylation is performed in an aprotic polar organic solvent, the reaction temperature is 80 to 200 ° C, preferably 90 to 180 ° C.
C., particularly preferably at 105 to 140.degree. C., for 0.5 to 3 hours, preferably about 1 hour, under atmospheric pressure. The amount of the catalyst is in the range of 0.05 to 0.75 mol, preferably 0.2 to 0.5 mol, per mol of the reaction raw material.

When decarboxylation is carried out in the presence of an aprotic organic base solvent, the reaction temperature is 100 to 200 ° C., preferably 120 to 180 ° C., for 0.5 to 50 hours, preferably about 0.5 to 5 hours. Heat treatment is preferably performed under atmospheric pressure. When the reaction is carried out in the co-presence of a non-polar organic solvent, generally 0.1 to 3 mol of an organic base (preferably 0.3 to 2 mol, more preferably more than 0.75 to 1.5 mol from the viewpoint of reaction rate) per mol of the reaction raw material. ) And 0.2 to 10 moles (preferably 0.5
５5 mol). When a nonpolar organic solvent is not used, preferably 0.5 to 10
The organic base is used in an amount of from 0.5 to 5 mol, more preferably from 0.5 to 5 mol.

Further, when decarboxylation is carried out in an aqueous solvent, the reaction temperature is 80 to 250 ° C, preferably 100 to 220 ° C, particularly preferably 130 to 180 ° C for 2 to 40 hours, preferably about 5 to 30 hours,
The heat treatment is carried out at a pH of 0.7 to 2.2, preferably 1.2 to 2.0, under vacuum to about 15 atm, preferably 1 to 10 atm. The amount of the aqueous solvent used is 0.1 mol per mol of the reaction raw material.
２2 mol, preferably 0.2-1 mol. The amount of the catalyst used varies depending on the type of the catalyst. For each mole of the reaction raw material, ammonia, an alkali metal, an alkaline earth metal, or a sulfate or fluoride of an organic base is used.
0.01-3 mol, preferably 0.05-1 mol; for organic bases
0.01 to 1.2 moles, preferably 0.1 to 0.9 moles; 0.1 for hydroxides, carbonates or organic acid salts of ammonia and oxides, hydroxides, carbonates or organic acid salts of alkaline earth metals.
01 to 0.4 mol, preferably 0.05 to 0.25 mol; 0.002 to 0.1 for alkali metal hydroxide, carbonate or organic acid salt
Mole, preferably 0.005 to 0.05 mole.

The obtained target product F ₃ BrBA can be isolated and purified according to any known method. For example, when using a water-insoluble solvent such as a water-insoluble aprotic organic base, a water-insoluble aprotic polar organic solvent, and a water-insoluble non-polar organic solvent, the mixture was cooled after the decarboxylation reaction was completed. To the reaction solution, an aqueous solution of an alkaline compound such as an aqueous solution of sodium hydroxide was added and stirred, and the aqueous layer was separated by liquid separation. Can be adopted by filtering and drying.

As described above, the product F ₃ in the hydrolysis step
Without isolating BrPA, the F ₃ BrPA was extracted using a water-insoluble aprotic organic base, a water-insoluble aprotic polar organic solvent, and a water-insoluble non-polar organic solvent. If necessary, a water-insoluble or water-soluble aprotic organic base, an aprotic polar organic solvent, a non-polar organic solvent, and / or a catalyst described above may be added to continuously carry out the decarboxylation step. it can.

Such water-insoluble aprotic organic bases include:
For example, tertiary amines such as trialkylamines (each alkyl group having 2 or more carbon atoms), dialkylarylamines, alkyldiarylamines, triarylamines, dialkylcycloalkylamines; N, N'-tetraalkylarylene Examples of the non-water-soluble aprotic polar organic solvent include benzonitrile and nitrobenzene. Examples of the non-water-soluble non-polar organic solvent include benzene and toluene.
Xylene, mesitylene, ethylbenzene, propylbenzene, cumene, butylbenzene, aromatic hydrocarbons such as cymene; for example, para-dichlorobenzene, halogenated aromatic hydrocarbons such as para-difluorobenzene or the like; for example, heptane, octane C ₇ Examples of the above aliphatic hydrocarbons; for example, dialkyl ethers such as propyl ether and butyl ether;

Examples Hereinafter, the present invention will be described in more detail with reference to Examples, Comparative Examples, and Reference Examples.

Production Example 1 100 ml of 4 equipped with a stirrer, thermometer and reflux condenser
In a flask with tetrafluorophthalonitrile (F ₄ PN)
50g (purity about 98% by weight, about 0.245 mol), lithium bromide 1
7.2 g (purity about 99% by weight, about 0.196 mol) and sulfolane 1
50 g was charged and reacted at about 110 ° C. Every 30 minutes after the start of the reaction, the residual amount of F ₄ PN in the reaction solution was measured by gas chromatography (GC), and the reaction rate of F ₄ PN was calculated. After 3 hours the reaction, F ₄ PN residual amount 5 response rate with respect to 45% [material F ₄ PN
5.0%, target product 4-bromo-3,5,6-trifluorophthalonitrile (F ₃ BrPN) 44.0% and by-product 4,5-dibromo-3,5,6-trifluorophthalonitrile (F ₂ Br ₂ PN) 1.
0%], the reaction was interrupted, and the reaction solution was brought to room temperature (20%).
C.) and then the reaction was added to about 300 ml of distilled water and mixed. The generated crystals were separated by suction filtration and dried, and the resulting crystals were fractionated under a reduced pressure of about 25 Torr to obtain 26.0 g of the desired product F ₃ BrPN (purity: 98.4% by weight, yield: about 40%).
And 25.0 g of starting material F ₄ PN (purity 98.0% by weight, raw material recovery rate 50%) was obtained. The physical properties of the obtained F ₃ BrPN are as follows.

Melting point: 114-115 ° C Mass spectrum (EI): m / z = 260 ¹⁹ F-NMR: (CDCl ₃ solvent, CF ₃ COOH internal standard, ¹ H-decoupling) (ppm) δ = −23.6 (1F, d) −d, J = 6.10Hz, 10.99Hz) −3
7.9 (1F, d-d, J = 6.10 Hz, 21.97 Hz)-53.6 (1F, d-d,
J = 10.99Hz, 21.97Hz) Production Example 2 In Production Example 1, the amount of lithium bromide used was changed to 25.8 g.
(Purity: about 99% by weight, about 0.294 mol), and the reaction was carried out in the same manner except that the reaction was carried out for 7 hours without measuring the remaining amount of F ₄ PN in the reaction solution by GC. The obtained reaction solution was analyzed by GC. As a result, the target product F ₃ BrPN 82% and by-products
It contained 14% of F ₂ Br ₂ PN. Thereafter, by treating in the same manner as in Example 1, 48.7 g of the desired product F ₃ BrPN (purity of about 98.5
%, About 75% yield) and by-products ₂ Br _{2 PN9.6g} (purity about 9
8.5% by weight, yield about 12%).

Example 1 In a device similar to that of Production Example 1, 50 g of F ₃ BrPN (about 98% by weight, about 0.245 mol) and 73.6 g of a 75% by weight aqueous sulfuric acid solution (0.
563 mol) and subjected to a hydrolysis reaction at about 150 ° C. for 2 hours. After the completion of the reaction, add 100 g of distilled water to the reaction solution, and add
° C), then extract twice with 50 g of ether, and dry the extract to obtain 56.8 g of F ₃ BrPA (purity 9%).
8.0% by weight, yield 99.1% based on F ₃ BrPN). Physical properties of the obtained F ₃ BrPA were as follows.

Melting point: 160-161 ° C Mass spectrum (EI): m / z = 298 ¹⁹ F-NMR: (CDCl ₃ solvent, CF ₃ COOH internal standard, ¹ H-decoupling) (ppm) δ = −33.3 (1F, d) −d, J = 2.44Hz, 13.43Hz) −4
6.5 (1F, d−d, J = 2.44Hz, 21.97Hz) −63.8 (1F, d−d,
J = 13.43Hz, 21.97Hz) in the same apparatus as in Example 2 Production Example 1, F ₃ BrPA50g (purity about 98%, about 0.164 mol) and tri n- octylamine 58g
(0.164 mol) and subjected to a decarboxylation reaction at about 130 ° C. for 1 hour. After completion of the reaction, the reaction solution is cooled to room temperature (20 ° C),
Next, 78.7 g (0.197 mol) of a 10% by weight aqueous sodium hydroxide solution was added and mixed well with stirring, followed by liquid separation to take out an aqueous layer. The precipitated crystals were separated by filtration. The obtained crystals were dried to obtain 38.4 g of F ₃ BrBA (purity 98.0% by weight, yield 99.0% based on F ₃ BrPA). Obtained F ₃ Br
The physical properties of BA were as follows.

Melting point: 106-107 ° C Mass spectrum (EI): m / z = 254 ¹⁹ F-NMR: (CDCl ₃ solvent, CF ₃ COOH internal standard, ¹ H-decoupling) (ppm) δ = −28.9 (1F, d) −d, J = 4.89Hz, 14.64Hz) −4
4.6 (1F, d−d, J = 4.89Hz, 21.97Hz) −28.9 (1F, d−d,
(J = 14.64 Hz, 21.97 Hz) Example 3 Distilled water was added to the reaction solution obtained by carrying out the reaction in the same manner as in Example 1.
After adding 0 g and cooling to room temperature (20 ° C.), extraction was performed by adding 86.6 g (0.245 mol) of tri-n-octylamine to obtain 167 g of an extract. After washing the extract with about 5 wt% aqueous solution of sodium hydrogen carbonate 412 g (0.245 mol) for 1 hour decarboxylation at 140 ° C., in the same manner as the following Example 4 F ₃ Br
BA) 55.9 g (purity: 98.1% by weight, yield based on F ₃ BrPN: 87.7)
%).

────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Hiroshi Shibuchi 388-1 Hiratsuka City Public Office, Kanagawa Prefecture Nippon Carbide Industry Co., Ltd. Shonan Dormitory Examiner Koji Ito (56) References Cbem. Soc. (C), Volume 3, pages 456-462 (1970) (58) Fields investigated (Int. Cl. ⁶ , DB name) C07C 63/72 C07C 63/70 C07C 51/38 C07C 51/08

Claims (4)

(57) [Claims] (1) 4-bromo-3,5,6-trifluorophthalic acid. 2. A method for hydrolyzing 4-bromo-3,5,6-trifluorophthalonitrile, comprising the steps of:
Method for producing 3,5,6-trifluorophthalic acid. 3. A method for decarboxylating 4-bromo-3,5,6-trifluorophthalic acid, comprising the steps of:
Manufacturing method of trifluorobenzoic acid. 4. The process according to claim 3, wherein 4-bromo-3,5,6-trifluorophthalonitrile is hydrolyzed and then decarboxylated.