JP2002012574A - Method for extracting aromatic fluorine compound - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for efficiently extracting an aromatic fluorine compound from an aqueous solution of the aromatic fluorine compound. SOLUTION: This method for extracting the aromatic fluorine compound such as 3-hydroxy-2,4,5-trifluorobenzoic acid from an aqueous medium containing the aromatic fluorine compound with an organic solvent comprises carrying out the extraction by using a ketone-based organic solvent as the organic solvent. Methyl ethyl ketone, methyl isopropyl ketone, diisopropyl ketone, methyl isobutyl ketone and the like can be used as the organic solvent.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for extracting an aromatic fluorine compound, and more particularly to a method for efficiently extracting an aromatic fluorine compound from an aqueous solution containing the aromatic fluorine compound.

[0002]

2. Description of the Related Art As a method for extracting an aromatic fluorine compound from an aqueous medium containing an aromatic fluorine compound with an organic solvent, for example, Japanese Patent Application Laid-Open No. 1-6235 discloses a method for decarboxylation of an acid or alkaline substance. It describes that the reaction is carried out in the presence and the resulting 3-hydroxy-2,4,5-trifluorobenzoic acid is extracted from the aqueous reaction solution with isopropyl ether. That is, the reaction aqueous solution after the decarboxylation reaction is mixed with isopropyl ether,
After transferring hydroxy-2,4,5-trifluorobenzoic acid into isopropyl ether, it is separated into an aqueous phase and an isopropyl ether phase, and 3-hydroxy-2,4,5-trifluorobenzoic acid is separated from the isopropyl ether phase. It is to recover the acid. However, this isopropyl ether is not sufficiently satisfactory as an extraction solvent.

[0003]

SUMMARY OF THE INVENTION 3-Hydroxy-2,
It is to provide a method for efficiently extracting an aromatic fluorine compound such as 4,5-trifluorobenzoic acid.

[0004]

The object of the present invention is solved by the following invention. (1) A method for extracting an aromatic fluorine compound from an aqueous medium containing the aromatic fluorine compound with an organic solvent, wherein a ketone organic solvent is used as the organic solvent.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The aromatic fluorine compound of the present invention means a compound having an elemental fluorine and other substituents on an aromatic ring. Specifically, for example, the following general formula (1):

[0006]

Embedded image

(Where X is COOH or NH ₂ , Y is COOH, OH, NH ₂ , Br, CH ₃ or H, and m is 1
An integer of 4 to 4, n is 0 or 1, and m + n ≦ 5. )).

Specific examples of the aromatic fluorine compound include tetrafluoroisophthalic acid, tetrafluoroterephthalic acid, pentafluorobenzoic acid, 2,3,4,5-
Tetrafluorobenzoic acid, 3,4,5,6-tetrafluorophthalic acid, 2,3,5,6-tetrafluoroaniline, 2,4,5-trifluoroaniline, 2,4,5-
Trifluorobenzoic acid, 3-hydroxy-2,4,5-
Trifluorobenzoic acid, 3-amino-2,4,5-trifluorobenzoic acid, 3-bromo-2,4,5-trifluorobenzoic acid, 3-methyl-2,4,5-trifluorobenzoic acid and the like Is mentioned.

By using the ketone organic solvent of the present invention, the aromatic fluorine compound can be efficiently extracted from the aqueous medium containing the aromatic fluorine compound.

The method of the present invention can be used, for example, in aqueous media.
-Hydroxy-3,5,6-trifluorophthalic acid is subjected to a decarboxylation reaction to produce 3-hydroxy-2,4,5-trifluorobenzoic acid, and 3-hydroxy-2,4,5- Used to extract trifluorobenzoic acid. There is no particular limitation on the decarboxylation reaction of 4-hydroxy-3,5,6-trifluorophthalic acid, and it can be carried out by a method generally used for this type of reaction. Specifically, for example, 4-hydroxy-3,5,6-trifluorophthalic acid is converted to 90 to 200 ° C. in an aqueous medium, usually in water in the presence of an acid or an alkaline substance.
Heating. For details, reference can be made to the description in JP-A-1-6355.

[0011] In addition, Japanese Patent Publication No. 1-1700,
JP-A-8-268979, WO95 / 10502
And aromatic compounds obtained from the aqueous medium obtained by the methods described in JP-A-6-212756 and the like.

According to the study of the present inventors, ketones have been compared with extraction solvents such as diisopropyl ether and ethyl acetate which have been conventionally used for extracting aromatic fluorine compounds from aqueous solutions containing aromatic fluorine compounds. It has been found that organic organic solvents are excellent in extraction efficiency and solvent stability. That is, the ketone-based organic solvent has a significantly higher extraction efficiency when extracting the aromatic fluorine compound described in the present invention from the aqueous solution as compared with diisopropyl ether, and also has a higher extraction efficiency than an acetate such as ethyl acetate. Low solvent loss due to low solubility in water.
Further, acetates, when used as an extraction solvent, have drawbacks such as solvent loss due to hydrolysis of the acetate itself as seen when an extraction operation is performed, particularly when heated. Since the ketone-based organic solvent is thermally stable, such a decomposition reaction does not occur.

Therefore, when the aromatic fluorine compound is extracted from the aqueous solution containing the aromatic fluorine compound with a ketone-based organic solvent, the extraction operation must be performed with high extraction efficiency and without causing loss or decomposition of the solvent. Can be.
Moreover, after the extraction, in order to separate the aromatic fluorine compound as the target product, the ketone-based organic solvent is recovered by a recovery method such as evaporation, and the ketone-based organic solvent is economically reused. The extraction operation can be repeatedly performed, which is industrially extremely advantageous.

Examples of the ketone-based organic solvent used in the present invention include methyl ethyl ketone, methyl isopropyl ketone, diisopropyl ketone, and methyl isobutyl ketone. Among them, methyl isobutyl ketone and the like are preferably used. This ketone-based organic solvent can be used in combination with another organic solvent. In this case, as the other organic solvent, an aromatic solvent, an aliphatic solvent, or an ester organic solvent can be used in combination. Examples of the aromatic solvent include benzene, toluene, xylene and the like, and examples of the aliphatic solvent include n-hexane,
Examples thereof include n-heptane and cyclohexane, and examples of the ester organic solvent include ethyl acetate, n-propyl acetate, isopropyl acetate, n-butyl acetate, isobutyl acetate, and sec-butyl acetate.

When the ketone-based organic solvent and the above-mentioned other organic solvents are used as a mixture, the ratio is not particularly limited.
It can be determined appropriately. Usually ketone organic solvent 1
10 to 100 parts by mass, preferably 30 to 100 parts by mass
６０60 parts by mass. The amount of the organic solvent used is also not particularly limited, and may be appropriately selected from an amount sufficient to effectively extract the intended aromatic fluorine compound from the reaction aqueous solution. 10
It is 0 to 1000 parts by mass, preferably 300 to 600 parts by mass.

The extraction method according to the present invention can be carried out in the presence or absence of an inorganic salt in an aqueous medium containing an aromatic fluorine compound, but the extraction can be carried out efficiently. It is desirable to carry out the extraction in the presence of an inorganic salt. As the inorganic salt, there is a soluble salt in an aqueous medium such as an inorganic salt generated when synthesizing an aromatic fluorine compound as a target substance or an inorganic salt generated by adding an acid or an alkali to an aqueous medium during extraction. Just do it. As inorganic salts, sodium sulfate,
Examples thereof include potassium sulfate, sodium chloride, and potassium chloride, and sodium sulfate is preferred.

The reason why the extraction can be carried out efficiently when the extraction is performed in the presence of the inorganic salt is that when the inorganic salt is present in the aqueous medium, a part of the target aromatic fluorine compound is separated from the aqueous medium. It is considered that the extraction can be performed more efficiently than in a state where the target aromatic fluorine compound is uniformly dissolved in the aqueous medium.

The temperature at the time of extraction is preferably 10 to 90 ° C, preferably 20 to 70 ° C, and more preferably 30 to 60 ° C. If the temperature is lower than 10 ° C., not only does the extraction efficiency decrease, but also, for example, when sodium sulfate is present in the aqueous medium as an inorganic salt, sodium sulfate is deposited and the extraction operation cannot be performed smoothly. If the temperature is higher than 90 ° C., evaporation of the extraction solvent occurs, not only loss of the solvent occurs, but also it becomes impossible to perform a sufficient extraction operation, which is not economically preferable.

The concentration of the aromatic fluorine compound may be a concentration at which the aromatic fluorine compound to be extracted is dissolved in the aqueous medium, and is usually 1 to 90%, preferably 5 to 70%.
%, More preferably 10 to 50%. If it is lower than 1%, the loss of the extraction solvent with respect to the aromatic fluorine compound increases, which is uneconomical. If it exceeds 90%, a large amount of the extraction solvent must be used, which is economically undesirable.

As the aqueous medium, water or a mixture with a water-miscible organic solvent such as alcohols and organic acids is used. As alcohols, methanol,
Ethanol, n- or isopropanol, butanol and the like, and organic acids include formic acid, acetic acid, propionic acid, butyric acid, lactic acid and the like. Industrially, water is most preferably used for economic reasons.

[0021]

By using a ketone-based organic solvent,
An aromatic fluorine compound can be extracted from an aromatic fluorine compound-containing aqueous solution with high extraction efficiency.

This ketone organic solvent does not cause loss or decomposition of the solvent in the extraction operation, and can be recovered and reused.

Therefore, the method of the present invention is industrially extremely advantageous since the extraction operation can be repeatedly performed economically.

[0024]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. Example 1 1 liter (L) equipped with thermometer, cooling pipe and stirrer
895 g of 54% sulfuric acid and 224 g of tetrafluorophthalonitrile were charged into a glass reactor of
The reaction was performed at reflux for 20 hours. After the reaction was completed, the reaction solution was cooled to 91 ° C., and white crystals were deposited.
The reaction solution was kept at 91 ° C for 1 hour, and then cooled to 15 ° C. The reaction solution containing the precipitated crystals was filtered using a 110-φ filter (filter cloth ventilation rate 1 ml / min / cm ² ). The cake after filtration was further washed with 250 g of 50% sulfuric acid, followed by suction filtration. Wet cake weighs 29
It was 5 g. When analyzing this wet cake,
The liquid content is 10%, and tetrafluorophthalic acid 265
g, 30 g of sulfuric acid and 1 g of ammonium sulfate.

295 g of the above wet cake is mixed with 450 g of water.
After dissolving in water, a thermometer, a cooling pipe and a stirrer
An L glass reactor was charged. To this, 515 g of 48% sodium hydroxide was added dropwise with stirring while the internal temperature of the solution did not exceed 60 ° C. After completion of the dropwise addition, the internal temperature was raised to 75 ° C, and the reaction was carried out at 75 ° C for 3 hours. Further, the internal temperature was raised to 105 ° C, and the reaction was carried out at 105 ° C with stirring for 3 hours. After completion of the reaction, the reaction solution was cooled to 50 ° C., 45 g of calcium hydroxide was added, and the mixture was kept at 50 ° C. for 12 hours with stirring. Thereafter, the generated CaF ₂ was filtered. The filtrate amount was 1421 g, and the filtrate was subjected to LC (liquid chromatography) analysis. As a result, the yield of 4-hydroxy-3,5,6-trifluorophthalic acid was 100%.
Met.

The filtrate (containing 4-hydroxy 3,5,6-trifluorophthalic acid) obtained above is stirred with a stirrer,
It was charged into a 1 L glass reactor equipped with a thermometer and a cooling tube. Next, after adding 251 g of sulfuric acid, the temperature was raised to 100 ° C., and a decarboxylation reaction was performed for 18 hours. After the completion of the reaction, the reaction solution was analyzed by LC. As a result, the conversion of 4-hydroxy-3,5,6-trifluorophthalic acid was 99.
5%.

After adding 28 g of sodium sulfate to the above reaction solution, 950 g of MIBK (methyl isobutyl ketone) was added.
Extraction was performed. The reaction solution was separated into an aqueous layer and a MIBK extract layer. The MIBK extract layer was washed twice with 100 g of water,
Evaporated to dryness. The obtained solid content was 211 g (yield 99
%)Met. 3-hydroxy-2,4,5 in the aqueous layer
It contained no trifluorobenzoic acid (no product loss). Examples 2 to 6 In the extraction step of Example 1, the organic solvent shown in Table 1 was used as the organic solvent, and the amount of sodium sulfate was changed as shown in Table 1 in the same manner as in Example 1. An extraction was performed. Table 1 shows the results. Comparative Examples 1 and 2 Extraction was performed in the same manner as in Example 1 except that toluene or diisopropyl ether was used instead of MIBK. Table 1 shows the results.

[0028]

[Table 1]

Example 7 In a 1 L autoclave, 3,4,5,6-tetraflu
120 g of orophtalic acid, 500 g of water and calcium hydroxide
And 6 hours of heating and stirring at 190 ° C.
I was sorry. After completion of the reaction, the mixture was cooled to 60 ° C.
Neutralize by adding 7 g, and filter while hot while keeping the temperature at 60 ° C.
Then, solid contents such as calcium sulfate were removed. That
Thereafter, the filtrate is kept at 50 ° C., and methyl isobutyl ketone is
(MIBK) Add 300 ml, stir for 30 minutes and extract
Out operation. After 30 minutes, stop stirring and leave
Separated into two layers. Separate the lower layer (aqueous layer) and add 100 ml of water
, And stirred for 10 minutes to remove fluorine ions in the MIBK layer.
The ON was removed by a water wash. Then, the upper layer (MIBK
Layer) is evaporated to dryness to give white 2,3,4,5-tetra
95.0 g of lafluorobenzoic acid were obtained (yield 97.
1 mol%). Example 8 300 equipped with heating device, stirrer, thermometer and cooler
162 g of sulfuric acid and 108 g of pure water in a glass reactor
60 mass% sulfuric acid aqueous solution consisting of
Heated. In this reactor, the raw material 4-amino-2,
135 g of 3,5,6-tetrafluorobenzonitrile
And water are supplied little by little and react at 140 ° C with stirring
Was done. 2,3,5,6-tetra generated by the reaction
Fluoroaniline is immediately azeotroped with water and
And distilled off. And the azeotropic content is cooled and condensed by the cooler
I received it in a receiver. Stop the reaction 20 hours after the start of the reaction
Was. 2,3,5,6-tetrafluoroa introduced into the receiver
The amount of the diline-containing fraction was 101.5 g,
95.3% of 5,6-tetrafluoroaniline (yield 8
2.5%). 101.5 g of this fraction was added to 5
Transfer to a 00 ml stirring tank and add 200 ml MIBK
Then, the mixture was stirred at 30 ° C. for 30 minutes to perform an extraction operation. 30
After one minute, stop stirring, separate, and separate the upper layer to dryness.
Was. The dried fraction is 2,3,5,6-tetrafluoro
Contains 96.7 g of aniline (82.5% yield)
Was. Example 9 Autoclay provided with pressure-resistant condenser with back pressure valve
3,4,5,6-tetraf in a tube (capacity: 300 ml)
20 g (0.084 mol) of fluorophthalic acid, calcium hydroxide
3.28 g (0.043 mol) of sodium and ammonia
12.6 g (0.74 mol) (as free ammonia)
80 g of an aqueous solution containing
The amination reaction was performed for 4 hours. The pressure during the reaction is 9-1.
0kg / cm^TwoMet. Subsequently, ammonia gas
7.5 g (0.44 mol) was slowly withdrawn and 30% sulfuric acid
The pH was adjusted to 4.0 by adding 12 g of an aqueous solution. In addition,
The reaction solution after pH adjustment contains organic ammonium salt, sulfuric acid
Contains ammonium, calcium sulfate and calcium fluoride
Exist. 12 hours at 156-158 ° C in their presence
A decarboxylation reaction was performed. The pressure during the reaction is
8kg / cm^TwoAdjust it to become
Was. After completion of the reaction, the reaction solution is cooled to room temperature,
30%
The reaction product is neutralized by adding 27 g of sulfuric acid aqueous solution of
After methyl isobutyl ketone / n-butyl acetate (100 m
1/50 ml) to extract the organic material into the organic layer.
After washing the organic layer with water, the solvent is evaporated off and the remaining solid
By drying the form, 3-amino-2,4,5-
15.1 g of trifluorobenzoic acid (vs. 3,4,5,6-
94.1 mol% of tetrafluorophthalic acid, purity 98.8
%). Example 10 Pentafluoro in a 300 ml autoclave
10 g (0.047 mol) of benzoic acid in 28% ammonia
Dissolve in 90 g (1.48 mol) of water, 164-178 ° C
For 6 hours. The gauge pressure during the reaction is 25-
33kg / cm ^TwoMet. After completion of the reaction, the reaction solution is stirred.
When taken out into a glass container with a stirrer, it becomes a two-layer solution.
Was. Methyl isobutyl ketone / sec-butyl acetate
(100ml / 50ml) for 1 hour at 25 ° C
The mixture was stirred and an extraction operation was performed. Stop stirring.
Extract the layer (aqueous layer), add 100 ml of water, and add
The mixture was stirred for 1 hour and washed. After washing the organic layer with water,
The layer (aqueous layer) was extracted and mixed with the aqueous layer of the reaction solution. MI
Gas chromatographic analysis of the BK layer revealed that
6.60 g of 3,5,6-tetrafluoroaniline (yield
Rate of 84.8 mol%).

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Claims (1)

[Claims] 1. A method for extracting an aromatic fluorine compound from an aqueous medium containing the aromatic fluorine compound with an organic solvent, wherein a ketone organic solvent is used as the organic solvent. Method.