JP2007031429A - Method for producing tetrafluorobenzenecarbaldehyde alkylacetal - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a tetrafluorobenzenecarbaldehyde alkylacetal and tetrafluorobenzenecarbaldehyde useful as raw materials or intermediates for producing agrochemicals, medicines, etc. <P>SOLUTION: The method for producing the tetrafluorobenzenecarbaldehyde alkylacetal represented by general formula (II) comprises reducing a tetrafluorocyanobenzene represented by general formula (I) (m is 1 or 2 and n is 0 or 1 and m+n=2) in the presence of an alkylalcohol represented by the formula R-OH (R is an alkyl group) and an acid by a metal catalyst containing a platinum group metal. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention is a general formula (II) useful as a raw material for producing agricultural chemicals, pharmaceuticals and the like, and an intermediate.

(In the formula, m is 1 or 2, n is 0 or 1, and m + n = 2. R represents an alkyl group having 1 to 4 carbon atoms.) A process for producing tetrafluorobenzenecarbaldehyde alkyl acetal In addition, the acetal is hydrolyzed to give the general formula (III)

(Wherein m and n are the same as those in formula (II) above), and then purified by extraction with a solvent that separates into two phases from water after conversion to tetrafluorobenzene carbaldehyde. The present invention relates to a method for producing carbaldehyde.

  More specifically, a method for producing tetrafluorobenzenecarbaldehyde alkyl acetals useful as an intermediate of cyclopropanecarboxylic acid esters having excellent insecticidal action by a reaction using tetrafluorocyanobenzene as a raw material was obtained. The present invention relates to a method for producing tetrafluorobenzenecarbaldehyde having a high purity by hydrolyzing acetal and then purifying it by a simple method.

Conventionally, as a method for producing tetrafluorobenzenecarbaldehyde alkylacetals, for example, a method of producing tetrafluorobenzene by reduction using a sponge nickel catalyst from tetrafluorodicyanobenzene (Patent Document 1, Non-Patent Document 1) has been disclosed. According to these documents, the target compound can be produced. However, since sponge nickel as a catalyst is added to sulfuric acid, the catalyst is dissolved, and the amount of the catalyst used increases. In addition, the dissolved catalyst cannot be repeatedly used. Furthermore, the problem that the reaction yield is not so high remains. As another method for producing tetrafluorobenzene carbaldehyde, a method of performing reduction and hydrolysis from tetrafluorodicyanobenzene in the presence of water using a sponge nickel catalyst is disclosed (Patent Document 2). This method is the same as the above problem because the catalyst is a reaction of sponge nickel in sulfuric acid.
International Publication No. 00/68173 Pamphlet JP 2001-158754 A Journal of Fluorine Chemistry, 125, 451-454, 2004

  An object of the present invention is to provide a production method capable of industrially advantageously carrying out tetrafluorobenzenecarbaldehyde alkylacetal compounds and tetrafluorobenzenecarbaldehyde compounds useful as production raw materials and intermediates for agricultural chemicals and pharmaceuticals. To do.

  As a result of intensive studies, the present inventors have been able to produce the target compound with high yield and high purity by reducing tetrafluorocyanobenzene as a raw material and using a metal catalyst containing a platinum group metal as a catalyst. The inventors have found that the problem can be solved and have completed the present invention.

The present invention includes the following matters.
[1] General formula (I)

(Wherein m is 1 or 2, n is 0 or 1, and m + n = 2), R-OH (wherein R is an alkyl group having 1 to 4 carbon atoms) In the presence of an alkyl alcohol and an acid represented by the general formula (II)

(Wherein, m and n represent the same as those in formula (I), R represents an alkyl group having 1 to 4 carbon atoms), and a method for producing tetrafluorobenzenecarbaldehyde alkyl acetal.
[2] The method for producing a tetrafluorobenzenecarbaldehyde alkyl acetal according to the above [1], wherein a metal catalyst containing a platinum group metal is used after being pretreated in a solvent at 100 ° C. or less in a hydrogen atmosphere.

  [3] The tetrafluorobenzenecarbaldehyde alkyl as described in [1] or [2] above, wherein the amount of acid used is 1 mol% to 10 mol% with respect to the nitrile group of tetrafluorocyanobenzene. A method for producing acetal.

  [4] The tetrafluorobenzenecarbaldehyde alkyl acetal according to [1] to [3], wherein the hydrogen reduction is performed at a reaction temperature of 30 to 100 ° C. and a hydrogen partial pressure of atmospheric pressure to 1.5 MPa. Manufacturing method.

  [5] General formula (II)

(Wherein, m is 1 or 2, n is 0 or 1, and m + n = 2. R represents an alkyl group having 1 to 4 carbon atoms) and tetrafluorobenzenecarbaldehyde alkyl acetal represented by water And hydrolyzing the alkyl alcohol by separating it by distillation to give a general formula (III)

(Wherein m and n are the same as those in formula (II)), and then purified by extraction with a solvent that separates into two phases from water after being converted to tetrafluorobenzenecarbaldehyde. A process for producing tetrafluorobenzene carbaldehyde.

  In the production method of the present invention, tetrafluorobenzene carbaldehyde alkyl acetal compound and tetrafluorobenzene carbaldehyde compound are efficiently obtained, and there is almost no production of by-products. Since the load can be reduced, it is industrially useful.

Hereinafter, the present invention will be described in more detail.
Specific examples of the tetrafluorocyanobenzene represented by the general formula (I) used in the production method of the present invention include, for example, tetrafluoromonocyanobenzenes (2,3,4,5-tetrafluorobenzonitrile, 2, 3,5,6-tetrafluorobenzonitrile, 2,3,4,6-tetrafluorobenzonitrile), tetrafluorodicyanobenzenes (3,4,5,6-tetrafluoroorthophthalonitrile, 2,4,5 , 6-tetrafluoroisophthalonitrile, 2,3,5,6-tetrafluoroterephthalonitrile).

Among these, tetrafluorodicyanobenzenes are preferable, and 2,3,5,6-tetrafluoroterephthalonitrile is more preferable.
Some of these are commercially available and are readily available. Further, it can be synthesized from terephthaloyl chloride by, for example, the method described in Journal of Fluorine Chemistry, Vol. 125, pages 451-454 (issued in 2004).

  In the production method according to the present invention, tetrafluorocyanobenzene represented by the general formula (I) is catalytically reduced with a metal catalyst containing a platinum group metal in the presence of an alkyl alcohol and an acid, and represented by the general formula (II). This is a method for producing a tetrafluorobenzenecarbaldehyde alkylacetal compound.

In the production method of the present invention, the hydrogenolysis reaction is preferably performed using hydrogen in a solvent in the presence of a catalyst. Examples of the catalyst to be used include metal catalysts, but a catalyst containing a platinum group metal is preferably used. The platinum group metal refers to elements of ruthenium, rhodium, palladium, osmium, iridium and platinum among the elements belonging to group 8 of the periodic table (Iwanami Dictionary of Physical and Chemical Dictionary 4th Edition, page 984). The form of the catalyst may be a metal or may be used in a supported form.

  A supported catalyst is a catalyst in which fine metal or metal oxide particles containing one or more metal species are supported in a highly dispersed manner on a support such as silica, alumina, silica alumina, activated carbon, diatomaceous earth, and the like. Examples of the catalyst include a supported ruthenium catalyst, a supported rhodium catalyst, a supported palladium catalyst, a supported osmium catalyst, a supported iridium catalyst, and a supported platinum catalyst.

  Furthermore, supported catalysts modified by adding one or more of the above metal species and other metal species, specifically, supported platinum-alumina catalysts, supported palladium-rhenium-alumina catalysts, etc. Can be mentioned.

  Examples of preferable catalysts include, for example, supported palladium catalysts, supported rhodium catalysts, supported platinum catalysts, and the like. Among these catalysts, supported rhodium catalysts are particularly preferable.

Next, the catalytic reduction reaction in the present invention will be described.
The amount of the catalyst added during the reaction is not particularly limited and varies depending on the form of the catalyst, but generally 0.1% by mass or more of the catalyst is used with respect to the tetrafluorocyanobenzene of the general formula (I). It is preferable. More preferably, it is 0.1-100 mass%, Most preferably, it is 0.1-30 mass%. When the catalyst amount is less than 0.1% by mass, the reaction does not proceed smoothly, a large amount of raw material remains, and the conversion rate may not increase. On the other hand, when the amount of the catalyst exceeds 100% by mass, the side reaction tends to proceed, and the nitrile group may cause a hydrodecyano reaction or be converted to an excessively hydrogenated amino group, which is not preferable.

  Pretreatment of the catalyst before carrying out the reduction reaction is desirable in order to improve the activity and selectivity of the catalyst. The pretreatment of the catalyst can be carried out by heating and stirring in a solvent under hydrogen pressure. The hydrogen pressure is not particularly limited, and can be carried out in the range from atmospheric pressure to increased pressure, but is preferably carried out under a partial pressure of hydrogen from atmospheric pressure to 1 MPa. The temperature is preferably in the range of 30 to 100 ° C, particularly preferably in the range of 30 to 80 ° C. The solvent used for the catalyst pretreatment is not particularly limited, but preferable examples include saturated aliphatic and alicyclic hydrocarbon solvents, aromatic hydrocarbon solvents, alcohol solvents, aliphatic and alicyclic. A hydrocarbon ether solvent, and water. Specifically, for example, saturated aliphatic and alicyclic hydrocarbon solvents include n-hexane, n-octane, isooctane, cyclohexane and the like, and aromatic hydrocarbons include benzene, toluene, xylene and the like. Examples of alcohol solvents include alcohols having 1 to 4 carbon atoms such as methanol, ethanol, n-propanol, isopropanol, and n-butanol, and ether solvents for aliphatic and alicyclic hydrocarbons such as diethyl ether and diisopropyl. Examples include ether, methyl-tertiary butyl ether, tetrahydrofuran, dioxane, dioxolane and the like. It is simple to use the solvent used in the reaction as it is, and preferred examples are methanol, ethanol, n-propanol, isopropanol, and n-butanol.

A solvent can be used in the catalytic reduction reaction of the present invention. The solvent is not particularly limited, but preferred examples include saturated aliphatic and alicyclic hydrocarbon solvents, aromatic hydrocarbon solvents, alcohol solvents, aliphatic and alicyclic hydrocarbon ether solvents, And water. Specifically, for example, saturated aliphatic and alicyclic hydrocarbon solvents include n-hexane, n-octane, isooctane, cyclohexane and the like, and aromatic hydrocarbons include
Examples of the alcohol solvent include methanol, ethanol, n-propanol, isopropanol, and n-butanol, and ethers of aliphatic and alicyclic hydrocarbons. Examples of the solvent include diethyl ether, diisopropyl ether, methyl tertiary butyl ether, tetrahydrofuran, dioxane, dioxolane and the like.

  These solvents can be used alone or as a mixed solvent of two or more. Moreover, when using as a mixed solvent, it can also be used in the state which is not mixed uniformly. Preferred solvents include toluene, methanol, dioxane as a single solvent, and toluene-methanol, toluene-water, toluene-methanol-water, and dioxane-water as mixed solvents. The usage-amount of a solvent is 0.5-30 mass times normally with respect to tetrafluoro cyanobenzene, Preferably it is 1-20 mass times. If the amount of the solvent is less than 0.5 mass times, there may be a problem in heat removal. On the other hand, if it exceeds 30 mass times, it is not preferable because the solvent needs to be distilled off when isolating the target product, and it is not preferable that the amount is more than necessary.

  Examples of the alkyl alcohol represented by R—OH (wherein R represents an alkyl group having 1 to 4 carbon atoms) used in the present invention include an alkyl alcohol having 1 to 4 carbon atoms. Specifically, methanol, ethanol, n-propanol, isopropanol, n-butanol and the like are used, but methanol having a small steric hindrance is most preferable in order to promote the acetalization reaction. The alcohol is used in an amount of 2 times mol or more with respect to the nitrile group of the tetrafluorocyanobenzene of the general formula (I), but it is desirable to use 10 times mol or more.

  In the present invention, an acid is required. Examples of the acid to be used include sulfuric acid, hydrochloric acid, phosphoric acid, formic acid, acetic acid, monochloroacetic acid, dichloroacetic acid, trifluoroacetic acid and the like, and sulfuric acid can be particularly preferably used. The amount of the acid used is desirably in the range of 1 to 10 moles relative to the nitrile group of the tetrafluorocyanobenzene of general formula (I). If the amount of the acid is less than 1 mol, the imine formed during the reaction cannot be stabilized and the reaction may not proceed smoothly. On the other hand, if it exceeds 10 moles, the catalyst may be deactivated by an acid, which is not preferable.

  In the catalytic reduction reaction of the present invention, hydrogen is introduced to the gas phase part and then heated to a predetermined temperature, or hydrogen is introduced after the gas phase part is replaced with an inert gas and heated to a predetermined temperature. Can be done. There is no limitation on the method of supplying hydrogen, and the hydrogen may be blown into the reaction solution, or may be circulated or intermittently supplied to the gas phase. The hydrogen gas used in this reaction does not necessarily have to be highly pure, and may contain an inert gas that does not particularly affect the hydrogenation reaction. The reaction is usually carried out at a temperature of 30 to 100 ° C., preferably 30 to 90 ° C., more preferably 50 to 80 ° C. When the temperature is low, amine by-product and denitrile reaction proceed due to excessive hydrogenation, and the yield of the target product may be low. On the other hand, when the reaction temperature is high, the catalyst is deactivated by the acid, the hydrogen absorption rate is lowered, and as a result, the yield of the target product may be lowered. In the present invention, the hydrogen partial pressure at the reaction temperature is not particularly limited as long as the reaction proceeds, but it is desirable that the hydrogen partial pressure be low in order to suppress amine by-product and denitrile reaction by excessive hydrogenation. The pressure is preferably atmospheric pressure to 1.5 MPa, more preferably atmospheric pressure to 0.9 MPa, and particularly preferably atmospheric pressure to 0.5 MPa.

The reaction format is not particularly limited, but a method such as a catalyst suspension flow method, a fixed bed flow method, a trickle head, or a batch method can be employed.
The tetrafluorobenzenecarbaldehyde alkyl acetal of the general formula (II) produced by the reduction reaction of the present invention can be isolated and purified by filtering off the catalyst after the reaction and distilling off the solvent, extraction, recrystallization, etc. Is possible.

  By hydrolyzing the tetrafluorobenzenecarbaldehyde alkyl acetal of the general formula (II) in the presence of water and an acid, it can be converted to a tetrafluorobenzenecarbaldehyde represented by the general formula (III). Although it is not particularly limited to the amount of water, it is required to be twice or more moles relative to the nitrile group of the tetrafluorocyanobenzene of the general formula (I). In order to proceed the reaction smoothly, there is no problem even if an excessive amount of water is used.

  In the hydrolysis reaction, the alcohol contained in the raw material and the alcohol produced by the reaction are distilled off to shift the equilibrium to the product side. It becomes possible to efficiently convert the alkyl acetal to tetrafluorobenzenecarbaldehyde represented by the general formula (III). According to this reactive distillation, the equilibrium can be efficiently shifted to the product side, so that the amount of acid and water used in the hydrolysis reaction can be greatly reduced.

  The tetrafluorobenzenecarbaldehyde represented by the general formula (III) obtained by the hydrolysis reaction can be purified by methods such as distillation, extraction, and two-phase separation, but extraction with an organic solvent is simple and preferable. The solvent to be extracted is not particularly limited as long as it is a solvent that separates into two phases from water. Examples include saturated aliphatic and alicyclic hydrocarbon solvents, aromatic hydrocarbon solvents, aliphatic and alicyclic hydrocarbon ethers. Examples of the solvent include saturated aliphatic halogen solvents, and aromatic hydrocarbons such as toluene are preferably used.

[Example]
EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated further in detail, this invention does not receive any limitation by these description.

The analytical instruments and analysis conditions used in the examples are as follows.
Gas chromatography analysis (hereinafter referred to as “GC analysis”)
Analytical instrument: HP 6850 manufactured by HP
Column: J & W DB-1 30 m × 0.32 mm × 1 μm
Column temperature: 80 ° C. 5 ° C./min Temperature rise to 200 ° C. 15 ° C./min Temperature rise to 290 ° C. Hold for 11 minutes Integrator: HP3396
Injection temperature: 300 ° C
Detector temperature: 300 ° C
Flow rate: Constant pressure 7.91 psi (68.5 ml / min 80 ° C.)
Split ratio: 50
Detector: FID H ₂ 30 ml / min Air 300 ml / min
Carrier gas: He
-Gas chromatography quantitative analysis (hereinafter referred to as "GC quantitative analysis")
Internal standard: 1,2-dichlorobenzene

20.6 g of 95% sulfuric acid was slowly added dropwise to 70 g (2.2 mol) of methanol in an Erlenmeyer flask under ice cooling. A 300 ml glass autoclave was charged with 0.25 g of a sulfuric acid / methanol solution and a 5% Rh / C catalyst (manufactured by NE Chemcat) (hydrated product) in terms of dry weight. The system was replaced with hydrogen, and the hydrogen pressure was adjusted to 0.1 MPa at room temperature. The heating and stirring of the autoclave was started and kept for 1 hour after reaching 40 ° C. After cooling, 10 g (50 mmol) of tetrafluoroterephthalonitrile (manufactured by Tokyo Chemical Industry) was added to the autoclave, and the temperature was raised to 70 ° C. in a nitrogen atmosphere. Hydrogen introduction was started at 70 ° C. The reaction pressure was adjusted so that the hydrogen absorption rate was 10 ml / min or less. Hydrogen absorption stopped after 6 hours and 30 minutes. The hydrogen absorption was 119% with respect to the theoretical hydrogen absorption. The reaction solution was filtered to remove the catalyst, and methanol was distilled off at normal pressure. Thereafter, 100 g of water was added to the residue, and the mixture was heated to reflux at an internal temperature of 100 ° C. for 60 minutes, and then methanol generated by hydrolysis of acetal was distilled off at normal pressure. When the top temperature of distillation reached 99 ° C., the distillation was terminated, and after cooling to room temperature, extraction was performed three times with 30 g of toluene.

  A small sample was taken from the toluene extract and subjected to GC analysis. As a result of analysis, the peak of the raw material tetrafluoroterephthalonitrile is below the detection limit, tetrafluoroterephthalaldehyde is 92.0 mol%, 2,3,5,6-tetrafluorobenzene is 0.94 mol% and 2,3,5,6-tetrafluorobenzonitrile was 0.79 mol%. On the other hand, the water phase was neutralized before GC analysis. As a result of analysis, 3.39 mol% of 2,3,5,6-tetrafluorobenzylamine was present. The results are shown in Table 1.

  In Example 1, the same procedure as in Example 1 was performed except that 0.25 g of 5% Pd / C catalyst (manufactured by N Chemcat) (water-containing product) was charged in terms of dry weight. 3.3 Absorption of hydrogen stopped after 3 hours. The hydrogen absorption was 117% of the theoretical hydrogen absorption. The reaction solution was treated in the same manner as in Example 1.

  A small sample was taken from the toluene extract and subjected to GC analysis. As a result of analysis, the peak of the raw material tetrafluoroterephthalonitrile was below the detection limit, and tetrafluoroterephthalaldehyde was 68.9 mol%. On the other hand, the water phase was neutralized before GC analysis. As a result of analysis, 14.8 mol% of 2,3,5,6-tetrafluorobenzylamine was present. The results are shown in Table 1.

  The same procedure as in Example 1 was performed except that the hydrogen pretreatment of the catalyst in Example 1 was changed from 40 ° C to 50 ° C. Hydrogen absorption stopped after 5.5 hours. The hydrogen absorption was 106% of the theoretical hydrogen absorption. The reaction solution was treated in the same manner as in Example 1.

  A small sample was taken from the toluene extract and subjected to GC analysis. As a result of analysis, the peak of the raw material tetrafluoroterephthalonitrile is below the detection limit, tetrafluoroterephthalaldehyde is 89.4 mol%, 2,3,5,6-tetrafluorobenzene is 1.31 mol% and 2,3,5,6-tetrafluorobenzonitrile was 1.03 mol%. On the other hand, the water phase was neutralized before GC analysis. As a result of analysis, 2.35 mol% of 2,3,5,6-tetrafluorobenzylamine was present. The results are shown in Table 1.

  The same operation as in Example 1 was performed except that the reaction temperature was changed from 70 ° C. to 80 ° C. in Example 1. Hydrogen absorption stopped after 5.5 hours. The hydrogen absorption was 99% of the theoretical hydrogen absorption. The reaction solution was treated in the same manner as in Example 1.

  A small sample was taken from the toluene extract and subjected to GC analysis. As a result of the analysis, the peak of the raw material tetrafluoroterephthalonitrile is below the detection limit, tetrafluoroterephthalaldehyde is 87.5 mol%, 2,3,5,6-tetrafluorobenzene is 2.00 mol%, and 2,3,5,6-tetrafluorobenzonitrile was 1.61 mol%. On the other hand, the water phase was neutralized before GC analysis. As a result of analysis, 2.16 mol% of 2,3,5,6-tetrafluorobenzylamine was present. The results are shown in Table 1.

  The same procedure as in Example 1 was performed except that the amount of sulfuric acid used in Example 1 was changed from 20.6 g to 12.9 g (125 mmol). Hydrogen absorption stopped after 7.0 hours. The hydrogen absorption was 73% of the theoretical hydrogen absorption. The reaction solution was treated in the same manner as in Example 1.

  A small sample was taken from the toluene extract and subjected to GC analysis. As a result of analysis, the peak of the raw material tetrafluoroterephthalonitrile is below the detection limit, tetrafluoroterephthalaldehyde is 84.5 mol%, 2,3,5,6-tetrafluorobenzene is 1.00 mol%, and 2,3,5,6-tetrafluorobenzonitrile was 0.83 mol%. On the other hand, the water phase was neutralized before GC analysis. As a result of analysis, 4.14 mol% of 2,3,5,6-tetrafluorobenzylamine was present. The results are shown in Table 1.

  The same operation as in Example 1 was conducted except that tetrafluoroterephthalonitrile was changed from 10 g to 20 g (100 mmol) in Example 1. Hydrogen absorption stopped after 8.3 hours. The hydrogen absorption was 76% of the theoretical hydrogen absorption. The reaction solution was treated in the same manner as in Example 1.

  A small sample was taken from the toluene extract and subjected to GC analysis. As a result of analysis, the peak of the raw material tetrafluoroterephthalonitrile is below the detection limit, tetrafluoroterephthalaldehyde is 89.6 mol%, 2,3,5,6-tetrafluorobenzene is 0.63 mol%, and 2,3,5,6-tetrafluorobenzonitrile was 0.54 mol%. On the other hand, the water phase was neutralized before GC analysis. As a result of analysis, 2.98 mol% of 2,3,5,6-tetrafluorobenzylamine was present. The results are shown in Table 1.

  The catalyst used in Example 1 was the same as in Example 1 except that the 5% Rh / C catalyst (manufactured by NP Chemcat) (water-containing product) was changed to the 2% Rh / C catalyst (manufactured by NM Chemcat) (water-containing product). Carried out. After 7.3 hours, hydrogen absorption stopped. The hydrogen absorption was 114% of the theoretical hydrogen absorption. The reaction solution was treated in the same manner as in Example 1.

  A small sample was taken from the toluene extract and subjected to GC analysis. As a result of analysis, the peak of the raw material tetrafluoroterephthalonitrile is below the detection limit, tetrafluoroterephthalaldehyde is 88.6 mol%, 2,3,5,6-tetrafluorobenzene is 1.15 mol% and The amount of 2,3,5,6-tetrafluorobenzonitrile was 2.63 mol%. On the other hand, the water phase was neutralized before GC analysis. As a result of analysis, 2.36 mol% of 2,3,5,6-tetrafluorobenzylamine was present. The results are shown in Table 1.

  In Example 1, after completion of the reaction, the catalyst was recovered by filtration. The same procedure as in Example 1 was performed except that the recovered catalyst was used again. Hydrogen absorption stopped after 10.3 hours. The hydrogen absorption was 91% of the theoretical hydrogen absorption. The reaction solution was treated in the same manner as in Example 1.

  A small sample was taken from the toluene extract and subjected to GC analysis. As a result of analysis, the peak of the raw material tetrafluoroterephthalonitrile is below the detection limit, tetrafluoroterephthalaldehyde is 80.5 mol%, 2,3,5,6-tetrafluorobenzene is 1.15 mol%, and 2,3,5,6-tetrafluorobenzonitrile was below the detection limit. On the other hand, the water phase was neutralized before GC analysis. As a result of analysis, 2.88 mol% of 2,3,5,6-tetrafluorobenzylamine was present. The results are shown in Table 1.

[Comparative Example 1]
The same procedure as in Example 1 was performed except that the amount of catalyst used in Example 1 was changed from 0.25 g to 0.05 g in terms of dry weight. Hydrogen absorption stopped after 7.0 hours. The hydrogen absorption was 83% of the theoretical hydrogen absorption. The reaction solution was treated in the same manner as in Example 1.

  A small sample was taken from the toluene extract and subjected to GC analysis. As a result of the analysis, 21.0 mol% of tetrafluoroterephthalonitrile as a raw material remained, and only 5.0 mol% of tetrafluoroterephthalaldehyde was obtained. 1,3,5,6-tetrafluorobenzene was 0.65 mol% and 2,3,5,6-tetrafluorobenzonitrile was 0.53 mol%, and 1-cyano was reacted only on one side of the nitrile group. 63.1 mol% of -2,3,5,6-tetrafluorobenzaldehyde was obtained. On the other hand, the water phase was neutralized before GC analysis. As a result of analysis, 2.88 mol% of 2,3,5,6-tetrafluorobenzylamine was present. The results are shown in Table 2.

[Comparative Example 2]
The same procedure as in Example 1 was performed except that the catalyst used in Example 1 was used without hydrogen pretreatment. Hydrogen absorption stopped after 7.5 hours. The hydrogen absorption was 124% of the theoretical hydrogen absorption. The reaction solution was treated in the same manner as in Example 1.

  A small sample was taken from the toluene extract and subjected to GC analysis. As a result of analysis, the peak of the raw material tetrafluoroterephthalonitrile is below the detection limit, tetrafluoroterephthalaldehyde is 81.7 mol%, 2,3,5,6-tetrafluorobenzene is 1.37 mol%, and The amount of 2,3,5,6-tetrafluorobenzonitrile was 1.09 mol%. On the other hand, the water phase was neutralized before GC analysis. As a result of the analysis, 7.29 mol% of 2,3,5,6-tetrafluorobenzylamine was present. The results are shown in Table 2.

[Comparative Example 3]
The same procedure as in Example 1 was performed except that the amount of sulfuric acid used in Example 1 was changed from 20.6 g to 5.15 g (50 mmol). After 4.2 hours, hydrogen absorption stopped. The hydrogen absorption was 47% of the theoretical hydrogen absorption. The reaction solution was treated in the same manner as in Example 1.

  A small sample was taken from the toluene extract and subjected to GC analysis. As a result of analysis, the peak of tetrafluoroterephthalonitrile as a raw material was below the detection limit, and only 14.5 mol% of tetrafluoroterephthalaldehyde was obtained. 1,3-cyano in which 2,3,5,6-tetrafluorobenzene was 0.81 mol% and 2,3,5,6-tetrafluorobenzonitrile was 0.67 mol%, and only one nitrile group was reacted 54.0 mol% of -2,3,5,6-tetrafluorobenzaldehyde was obtained. On the other hand, the water phase was neutralized before GC analysis. As a result of the analysis, 0.04 mol% of 2,3,5,6-tetrafluorobenzylamine was present. The results are shown in Table 2.

[Comparative Example 4]
The same operation as in Example 1 was performed except that the reaction temperature was changed from 70 ° C. to 120 ° C. in Example 1. Hydrogen absorption stopped after 8.0 hours. The hydrogen absorption was 103% with respect to the theoretical hydrogen absorption. The reaction solution was treated in the same manner as in Example 1.

A small sample was taken from the toluene extract and subjected to GC analysis. As a result of analysis, the peak of the raw material tetrafluoroterephthalonitrile was below the detection limit, and only 2.6 mol% of tetrafluoroterephthalaldehyde was obtained. 1,3,5,6-tetrafluorobenzene is 1.08 mol% and 2,3,5,6-tetrafluorobenzonitrile is 0.87 mol%, and only one side of the nitrile group is reacted with 1-cyano 42.2 mol% of -2,3,5,6-tetrafluorobenzaldehyde was obtained. On the other hand, the water phase was neutralized before GC analysis. As a result of analysis, 2,3,5,6-tetrafluorobenzylamine was below the detection limit. The results are shown in Table 2.

[Comparative Example 5]
The same operation as in Example 1 was performed except that the reaction temperature was changed from 70 ° C. to 20 ° C. in Example 1. Hydrogen absorption stopped after 7.0 hours. The hydrogen absorption was 124% of the theoretical hydrogen absorption. The reaction solution was treated in the same manner as in Example 1.

  A small sample was taken from the toluene extract and subjected to GC analysis. As a result of analysis, the peak of tetrafluoroterephthalonitrile as a raw material was below the detection limit, and only 42.2 mol% of tetrafluoroterephthalaldehyde was obtained. 2,3,5,6-tetrafluorobenzene was 1.75 mol% and 2,3,5,6-tetrafluorobenzonitrile was 1.40 mol%. On the other hand, the water phase was neutralized before GC analysis. As a result of analysis, 2,3,5,6-tetrafluorobenzylamine was 28.1 mol%. The results are shown in Table 2.

[Comparative Example 6]
In Example 1, sponge nickel catalyst (R-239: manufactured by Nikko Rika) and 3 g of copper sulfate were added to a sulfuric acid / methanol solution as a catalyst to be used, and the sponge nickel was coated with copper. The same operation as in Example 1 was performed except that this was used as a catalyst. Hydrogen absorption stopped after 7.9 hours. The hydrogen absorption was 74% with respect to the theoretical hydrogen absorption. The reaction solution was treated in the same manner as in Example 1.

  A small sample was taken from the toluene extract and subjected to GC analysis. As a result of analysis, the peak of tetrafluoroterephthalonitrile as a raw material was below the detection limit, and 67.0 mol% of tetrafluoroterephthalaldehyde was obtained. However, the catalyst could not be reused to allow the reaction to proceed again. The results are shown in Table 2.

[Comparative Example 7]
In Comparative Example 6, the same procedure as in Comparative Example 6 was performed except that the reaction temperature was changed from 70 ° C. to 20 ° C. and the copper sulfate was changed from 3 g to 2 g. Hydrogen absorption stopped after 9.3 hours. The hydrogen absorption was 85% of the theoretical hydrogen absorption. The reaction solution was treated in the same manner as in Example 1.

  A small sample was taken from the toluene extract and subjected to GC analysis. As a result of analysis, the peak of the raw material tetrafluoroterephthalonitrile is below the detection limit, tetrafluoroterephthalaldehyde is 23.9 mol%, and only one side of the nitrile group is reacted with 1-cyano-2,3, 16.5 mol% of 5,6-tetrafluorobenzaldehyde was obtained. However, the catalyst could not be reused to allow the reaction to proceed again. The results are shown in Table 2.

Claims (5)

Formula (I)

(Wherein m is 1 or 2, n is 0 or 1, and m + n = 2), R-OH (wherein R is an alkyl group having 1 to 4 carbon atoms) In the presence of an alkyl alcohol and an acid represented by the general formula (II)

(Wherein, m and n represent the same as those in formula (I), R represents an alkyl group having 1 to 4 carbon atoms), and a method for producing tetrafluorobenzenecarbaldehyde alkyl acetal.   The method for producing a tetrafluorobenzenecarbaldehyde alkyl acetal according to claim 1, wherein a metal catalyst containing a platinum group metal is used after pretreatment in a solvent at 100 ° C or lower in a hydrogen atmosphere.   The method for producing a tetrafluorobenzenecarbaldehyde alkylacetal according to claim 1 or 2, wherein the acid is used in an amount of 1 mol% to 10 mol% based on the nitrile group of tetrafluorocyanobenzene.   The method for producing tetrafluorobenzenecarbaldehyde alkylacetal according to any one of claims 1 to 3, wherein the hydrogen reduction is performed at a reaction temperature of 30 to 100 ° C and a hydrogen partial pressure of atmospheric pressure to 1.5 MPa. . Formula (II)

(Wherein, m is 1 or 2, n is 0 or 1, and m + n = 2. R represents an alkyl group having 1 to 4 carbon atoms) and tetrafluorobenzenecarbaldehyde alkyl acetal represented by water And hydrolyzing the alkyl alcohol by separating it by distillation to give a general formula (III)

(Wherein m and n are the same as those in formula (II)), and then purified by extraction with a solvent that separates into two phases from water after being converted to tetrafluorobenzenecarbaldehyde. A process for producing tetrafluorobenzene carbaldehyde.