JPH0681736B2 - Process for producing 4- (parafluorobenzoyl) phenol - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing 4- (parafluorobenzoyl) phenols, which are important as monomers for heat-resistant polymers or intermediates for agricultural chemicals, pharmaceuticals and the like.

(Prior Art and Problems) As a method for producing 4- (parafluorobenzoyl) phenol, a method of reacting parafluorobenzoic acid and phenol in a large amount of polyphosphoric acid (Japanese Patent Publication No. 50-4653), a large amount of Reaction in anhydrous hydrogen fluoride (JP-A-53-9735), reaction in a large amount of methanesulfonic acid (JP-A-57-154140), reaction in a large amount of trifluoromethanesulfonic acid Method (JP-A-58)
-62132) has been proposed, but these methods are expensive due to the high cost of parafluorobenzoic acid, the use of a large amount of strong acid, and the water produced by the dehydration reaction. The acid is diluted and must be concentrated in order to maintain the required acid concentration, but it has drawbacks such as the large affinity of these acids with water and the difficulty in separating them. There is. Further, a method of carrying out the Friedel-Crafts reaction of parafluorobenzoic acid chloride and phenol (Japanese Patent Laid-Open No. 53-9735 and Japanese Patent Laid-Open No. 58-15936) is also proposed, but parafluorobenzoic acid chloride is also proposed. Is even more expensive.

Further, a method of reacting fluorinated benzene and parahydroxybenzoic acid in anhydrous hydrogen fluoride-boron trifluoride (JP-A-58-15936), a method of reacting in a large amount of trifluoromethanesulfonic acid ( JP-A-58-62132) has also been proposed, but the fact that parahydroxybenzoic acid is a relatively expensive raw material and the separation of water generated by the dehydration reaction from these strong acids is mentioned above. It has drawbacks such as difficulty.

(Means for Solving the Problems) Therefore, the present inventors inexpensively produced 4- (parafluorobenzoyl) phenols from simple compounds such as fluorinated benzene, carbon monoxide, and alkali metal salts of phenols. As a result of extensive studies on the method of manufacturing, the present invention has been completed.

That is, the present invention includes: a) an iodination step of reacting iodine and / or hydrogen iodide with fluorinated benzene in the presence of an oxidizing agent to obtain paraiodofluorobenzene; and b) the paraiodofluorobenzene, An esterification step of reacting with carbon monoxide and an alkali metal salt of a phenol having no substituent at the para position without adding a catalyst to obtain parafluorobenzoic acid phenyl esters, and c) A method for producing 4- (parafluorobenzoyl) phenols, which comprises a rearrangement reaction step of rearranging parafluorobenzoic acid phenyl esters into 4- (parafluorobenzoyl) phenols in the presence of an acid catalyst. Is.

The method of the present invention is represented by the following reaction formula.

a) Iodination process b) Esterification process c) Rearrangement reaction step (In the formula, R ¹ , R ² , R ³ , and R ⁴ are each hydrogen, or a lower alkyl group, a lower alkoxy group, a fluorine atom, a nitro group,
It represents a substituent selected from a cyano group, and these may be the same. M represents an alkali metal atom. ) In the iodination step of the present invention, the iodination reaction is carried out by reacting an iodination agent comprising iodine and / or hydrogen iodide and an oxidizing agent with fluorinated benzene. It is preferable to carry out the benzene selectivity and yield as high as possible, and it is necessary to obtain an iodinated fluorobenzene mixture containing at least 80 mol% of paraiodofluorobenzene. To do this, 2 mol per mol of iodine
It is preferable to use more than 1 mol of fluorinated benzene, more preferably 2.5 to 10 mol of fluorinated benzene. If the amount of fluorinated benzene used is less than 2 mol per 1 mol of iodine, the amount of polyiodofluorobenzene such as diiodofluorobenzene is increased as a by-product, and unreacted iodine remains, resulting in paraiodofluoro. The yield and selectivity of benzene decrease. Further, more than 10-fold mole of fluorinated benzene may be used, but this is not so preferable method because the reactor becomes large and the amount of unreacted fluorinated benzene to be separated increases.

As the oxidizing agent which is combined with iodine and / or hydrogen iodide to serve as an iodination agent, various oxidizing agents can be used. For example, nitric acid, nitrous acid, sulfuric acid, and other oxidative inorganic acids; NO ₂ , N ₂ O _3, and other oxidative nitrogen oxides; iodic acid, periodic acid, and other halogen oxyacids; peracetic acid, peroxide Peroxide substances such as hydrogen oxide are preferably used. Particularly preferred are nitric acid and / or nitrogen oxides having oxidizing power, which are inexpensive and have good reactivity.

The amount of the oxidizing agent used is preferably 2 moles or more in the case of a one-electron oxidizing agent and 1 mole or more in the case of a two-electron oxidizing agent per 1 mole of iodine.

The iodination reaction is preferably carried out at a temperature as low as possible in order to maximize the selectivity of paraiodofluorobenzene in the iodinated fluorobenzene mixture,
If the reaction temperature is too low, the reaction rate becomes slow, which is not a preferable method. The selectivity of paraiodofluorobenzene is 80% or more, and in order to react at an appropriate reaction rate, the range of 10 to 150 ° C is preferable, and the range of 30 to 100 ° C is more preferable.

It is not necessary to use a catalyst in the iodination reaction,
It is also possible to use iron-based catalysts such as iron powder, iron chloride, iron bromide and iron iodide, and aluminum-based catalysts such as aluminum chloride and aluminum iodide.

Further, it is also a preferable method to carry out the iodination step without using a solvent other than fluorinated benzene, but a solvent can be used if necessary. As such a solvent, any solvent can be used as long as it does not adversely affect the reaction, for example, lower aliphatic carboxylic acids such as acetic acid and propionic acid; carbon tetrachloride, chloroform, methylene chloride, trichloroethane, etc. Lower aliphatic halogenated hydrocarbons; ethers such as ether and dioxane; carbon disulfide; water and the like.

Depending on the type of iodizing agent used and, in some cases, the type of solvent used, the iodination reaction may be carried out in a heterogeneous liquid phase. , The reaction can proceed smoothly.

The iodination step can be carried out in either a batch system or a flow system,
In the reaction system, it is important to react with the iodination agent in a state in which the fluorinated benzene is present in excess of the equivalent amount, and also to make the reaction rate of iodine and / or hydrogen iodide as high as possible. Reacting is also important.

A separation / purification step is carried out in order to separate and obtain paraiodofluorobenzene from the iodinated fluorobenzene mixture obtained in the iodination step. The reaction mixture that has undergone the iodination step usually contains unreacted fluorinated benzene and para-iodofluorobenzene, which are present in excess during the reaction, orthoiodofluorobenzene and, in some cases, metaiodofluorobenzene and diiodofluorobenzene. Water containing the iodinated product of polyiodofluorobenzene and the reduced product of the oxidant, or possibly unreacted oxidant left by the use of excess amounts. It is made up of divisions. When the amount of water or the amount of remaining oxidizing agent is smaller than that of the organic part, the organic part can be separated and recovered by a method such as distillation as it is, but usually the organic part is separated into two layers. After separating with etc., wash with water,
Then, it is preferable to carry out a separation / purification step of the organic portion.

Separation / purification of the iodinated fluorobenzene mixture is carried out by distillation or / and crystallization operation to obtain highly pure paraiodofluorobenzene.

In the esterification step of the present invention, the paraiodofluorobenzene obtained in the iodination step is reacted with carbon monoxide and an alkali metal salt of a phenol having no substituent at the para position without adding a catalyst. Then, parafluorobenzoic acid phenyl esters are obtained.

One of the major characteristics of the present invention is that no catalyst component is added in this esterification step. This eliminates the need for operations such as separation / recovery of the catalyst component after the reaction, which not only makes the process inexpensive, but also, as shown in the reaction formula of the above-mentioned esterification step, in this reaction, the Since only a simple salt, an alkali metal iodide, is by-produced, it is shown that separation from the reaction product, parafluorobenzoic acid phenyl ester, becomes very easy. For example, when the reaction is carried out in an organic medium in which alkali metal iodide is hardly dissolved, after the reaction, the organic solution of parafluorobenzoyl esters and the solid alkali metal iodide are formed, and the reaction is conducted by filtration. The alkali metal iodide can be easily separated, and the ester compound in the organic solution can be easily obtained in high purity by distilling off the organic medium. Further, for example, the alkali metal iodide can be removed by washing the esterification reaction mixture with water to obtain highly pure parafluorobenzoic acid phenyl esters.

By a system of carbonylation reaction in which paraiodofluorobenzene and an alkali metal salt of phenols having no substituent at the para position are combined, a completely uncatalyzed parafluorobenzoic acid has never been known so far. It has become possible to manufacture phenyl esters with high yield and high selectivity.

Further, the alkali metal iodide thus separated can be recovered as hydrogen iodide or iodine by a known method, and these can be recycled and reused in the iodination step.

The alkali metal salt of a phenol having no substituent at the para position used in the present invention has the general formula The compound represented by the formula (1) is a compound in which a hydrogen atom of a hydroxyl group of a phenol is substituted with an alkali metal atom. (However, R ¹ , R ² , R ³ , R ⁴ , and M are as described above.) Such a compound may be obtained by any method, for example, an alkali metal atom. It can be easily obtained from a basic substance containing a and a phenol having no substituent at the para position. As the basic substance containing an alkali metal atom, for example, an alkali metal, an alkali metal oxide,
Examples thereof include alkali metal hydroxides, alkali metal carbonates and alkali metal bicarbonates. In particular, the method by the reaction of a phenol with an alkali metal hydroxide such as lithium hydroxide, sodium hydroxide, potassium hydroxide, rubidium hydroxide or cesium hydroxide is the easiest.

Examples of such phenols as a raw material of alkali metal salts of phenols having no substituent at the para-position include phenol, cresol, dimethylphenol, trimethylphenol, tetramethylphenol, ethylphenol, diethylphenol, triethylphenol,
Ethyl cresol, methoxyphenol, ethoxyphenol, dimethoxyphenol, methoxycresol,
Fluorophenol, difluorophenol, fluorocresol, nitrophenol, dinitrophenol,
Nitrocresol, cyanophenol, dicyanophenol, cyanocresol, fluoronitrophenol,
Fluoronitrocresol, fluorocyanophenol, nitrocyanophenol, cyclohexylphenol, cyclohexylcresol, cyclohexylfluorophenol and the like are used (however, in the case of substituted phenols, those in which the para position is substituted with respect to the hydroxyl group are excluded).

Of these alkali metal salts of phenols, sodium salt or potassium salt of phenol or 2,6-dimethylphenol is particularly preferably used.

The carbon monoxide may be pure carbon monoxide, or may be diluted with another gas such as nitrogen, argon, helium, or lower hydrocarbon that does not adversely affect the reaction. Carbon monoxide has a partial pressure of 0.1 to 300 kg / cm ² , preferably 1 to 200 kg /
Used in the cm ² range.

Alkali metal salts of phenols having no substituents at the para position are preferred for para iodofluorobenzene.
In the range of 0.5 to 2.0 equivalents, even more preferably 0.8 to 1.5
Used in the equivalent range.

In the esterification step of the present invention, a reaction solvent may not be used, but a solvent which does not adversely influence the reaction can be used if necessary.

Examples of such a solvent include aliphatic hydrocarbons such as hexane, heptane, octane, decane, and pentadecane; aliphatic hydrocarbons such as cyclohexane and methylcyclohexane; aromatic hydrocarbons such as benzene, toluene, xylene, and mesitylene. Hydrogens; Nitriles such as acetonitrile and benzonitrile; Sulfones such as sulfolane, methylsulfolane and dimethylsulfolane; Ethers such as tetrahydrofuran, 1,4-dioxane and 1,2-dimethoxyethane; Ketones such as acetone and methyl ethyl ketone Esters such as ethyl acetate and ethyl benzoate; amides such as N, N-dimethylformamide, N, N-dimethylacetamide, N-methylpyrrolidone and hexamethylphosphoramide.

Esterification reaction is usually 150 ~ 400 ℃, preferably 180 ~ 3
It is performed in the range of 50 ° C. At temperatures lower than 150 ° C., the esterification reaction is slow, which is not advantageous to carry out industrially. On the other hand, if the temperature is higher than 400 ° C., there are many side reactions and the yield of the target ester is lowered, which is not preferable. Within this temperature, particularly in the range of 230 to 300 ° C., the reaction rate is fast and the selectivity of the target ester is high, so that it is preferable for industrial implementation.

The reaction pressure is usually 1 to 500 kg / cm ² , preferably 5
It is carried out in the range of up to 300 kg / cm ² .

By carrying out such a carbonylation reaction, the fluorine atom of paraiodofluorobenzene is not replaced,
Parafluorobenzoic acid phenyl esters in which only the iodine atom is substituted with an aryloxycarbonyl group,
It has been found that a high yield of 90% or more and a high selectivity can be obtained.

In the rearrangement reaction step of the present invention, the parafluorobenzoic acid phenyl ester obtained in the esterification step is subjected to a rearrangement reaction in the presence of an acid catalyst to give the desired 4- (parafluorobenzoyl) phenols. obtain.

As the acid catalyst that can be used in the rearrangement reaction step, it is possible to use an acid catalyst that does not substantially contain water, but in order to maximize yield and selectivity, Lewis acid, and It is preferable to use a strong acidic protonic acid. Such Lewis acids include halides of Group III elements such as boron, aluminum, gallium, indium, thallium, scandium, and yttrium; halides of Group IV elements such as silicon, germanium, tin, titanium, and zirconium. Kind;
Halides of Group V elements such as antimony, boss mass, vanadium, niobium, and tantalum, and metal halides such as iron, copper, and zinc are used. Examples of the strongly acidic protic acid include hydrogen fluoride anhydride; fluorocarboxylic acids such as trifluoroacetic acid and perfluoropropionic acid; sulfonic acids such as methanesulfonic acid, ethanesulfonic acid and benzenesulfonic acid; fluorosulfonic acid,
Halogenated sulfonic acids such as chlorosulfonic acid, trifluoromethanesulfonic acid, trichloromethanesulfonic acid, perfluoroethanesulfonic acid and halogenated alkanesulfonic acids are used. Also, high silica content zeolite which is a solid acid, strong acid cation exchange resin,
Acids called solid superacid can also be used in the rearrangement reaction of the present invention. The solid super strong acid is a solid strong acid having a stronger acid strength than 100% sulfuric acid, and examples thereof include SbF ₅ , TaF ₅ , BF ₃ , CF ₃ SO ₃ H, SbF ₅ -HF, SbF
₅ -FSO ₃ H or a mixture thereof is used as SiO ₂ -Al ₂ O ₃ , SiO ₂ -Ti
_{O 2, SiO 2 -ZrO 2,} TiO 2 -ZrO 2, Al 2 O 3 -B 2 O 3, SiO 2 -WO 3, HF
-Zeolite, Al ₂ O ₃ , SiO ₂ , graphite, cation exchange resin, activated carbon, those supported on fluorinated graphite, fluorinated sulfonic acid resin, etc. may be mentioned. Here, the fluorinated sulfonic acid resin is -CF ₂ SO ₃ H
A resin having a group and / or a CFSO ₃ H group.

These acids can be used alone or in combination of two or more.

Further, this rearrangement reaction may be carried out without a solvent, but it is also possible to use a solvent which does not adversely influence the reaction. Examples of such a solvent include carbon disulfide; halogenated hydrocarbons such as chloroform, methylene chloride, carbon tetrachloride, dichloroethane, trichloroethane and tetrachloroethane;
Chlorobenzene, dichlorobenzene, bromobenzene,
Halogenated aromatic hydrocarbons such as chlornaphthalene;
Nitro compounds such as nitrobenzene, nitrotoluene and nitromethane are used.

This rearrangement reaction is preferably performed under substantially anhydrous conditions. When water is present in the reaction system, hydrolysis of the phenyl ester of p-fluorobenzoic acid occurs, and the desired 4
This is because the yield of-(parafluorobenzoyl) phenol decreases. Therefore, not to mention the water content in the acid catalyst, when using a solvent, it is preferable to keep the water content in the solvent as low as possible.

The temperature and reaction time for carrying out this rearrangement reaction vary depending on other reaction conditions such as the type of catalyst and solvent used, but are usually in the temperature range of -30 to 250 ° C, preferably -20 to 200 ° C.
It ranges from a few minutes to a few tens of hours.

By carrying out such a rearrangement reaction, 4- (parafluorobenzoyl) phenols can be obtained from parafluorobenzoic acid phenyl esters with high yield and high selectivity.

(Effects of the Invention) It is clear that the method of the present invention can produce 4- (parafluorobenzoyl) phenols from fluorinated benzene, carbon monoxide, and alkali metal salts of phenols with high yield and high selectivity. Natsuta.

(Examples) Hereinafter, the present invention will be further described with reference to Examples, but the present invention is not limited to these Examples.

Example 1 288 g of fluorinated benzene and iodine were placed in a flask equipped with a reflux condenser.
Add 254g and heat to 65-70 ° C, then stir with 61% nitric acid.
840 g was gradually added dropwise. After completion of dropping, stirring was continued for further 3 hours to complete the reaction. Iodine was completely consumed. The reaction mixture was separated into two layers, and the organic layer was washed with water, an aqueous sodium carbonate solution and water in this order, and then distilled.
After distilling off the excess fluorinated benzene and a small amount of water, the composition was para-iodofluorobenzene.
91.9%, orthoiodofluorobenzene 7.6%, metaiodofluorobenzene 0.5%, the weight is 44.2g
(99.5% yield as monoiodofluorobenzene).

The following esterification step was carried out using paraiodofluorobenzene obtained by rectifying this monoiodofluorobenzene using a packed column rectification apparatus equipped with a reflux device.

After reacting paraiodofluoroorobenzene 22.2 g, phenol and an equivalent amount of sodium hydroxide in an aqueous solution,
Sodium phenoxide 12.8 obtained by dehydration and drying
g, Toluene 60 ml was put into the autoclave, the inside of the autoclave was replaced with carbon monoxide, and the carbon monoxide was reduced to 50%.
Pressed into kg / cm ² . After reacting at 250 ° C. for 2 hours with stirring, the mixture was cooled, filtered, and the filtrate was analyzed. As a result, the reaction rate of paraiodofluorobenzene was 100%.
Parafluorobenzoic acid phenyl ester was obtained with a yield of 99% and a selectivity of 99%. The slag was sodium iodide containing unreacted sodium phenoxide that was present in excess. Iodine was quantitatively recovered as sodium iodide.

After the esterification reaction mixture was washed with water, parafluorobenzoic acid phenyl ester obtained by distilling off toluene was used to carry out the following rearrangement reaction step.

10.8 g of parafluorobenzoic acid phenyl ester and 22 g of trifluoromethanesulfonic acid were placed in a flask and stirred 4
The reaction was carried out at 5 to 50 ° C for 2 hours. After that, most of trifluoromethanesulfonic acid was distilled off under reduced pressure, and then the reaction mixture was put into cold water. The white crystals thus formed were separated by filtration, dried under reduced pressure and analyzed. As a result, it was found that 4- (parafluorobenzoyl) phenol was obtained in a yield of 96% and a selectivity of 96%.

Since the unreacted fluorinated benzene can be recovered and reused in the iodination step by circulation, in this example, 4- (parafluorobenzoyl) phenol was obtained in a yield of 87% and a selectivity of 87 with respect to the reacted fluorinated benzene. It shows that it was obtained in%.

Example 2 A flask equipped with a reflux condenser was charged with 884 g of fluorinated benzene, 687 g of finely ground iodine and 145 g of / 61% nitric acid, and the mixture was heated to 50-5.
Heat to 4 ° C. Then, 1 kg of 61% nitric acid was gradually added dropwise with stirring. After completion of dropping, stirring was continued for further 5 hours to complete the reaction. Iodine was completely consumed. Example 1
Perform post-treatment similar to that for paraiodofluorozenbene.
Monoiodofluorobenzene consisting of 92.2%, orthoiodofluorobenzene 7.4%, and metaiodofluorobenzene 0.4% was obtained with a yield of 99.6%.

By cooling this iodofluorobenzene mixture to −30 to 40 ° C., para-iodofluorobenzene crystallized was obtained. The following esterification step was performed using this paraiodofluorobenzene.

Paraiodofluorobenzene 22.2g, sodium-2,6-
The reaction and post-treatment were carried out in the same manner as in the esterification step of Example 1 using 15.8 g of dimethylphenoxide and 60 ml of toluene, and as a result, the reaction rate of paraiodofluorobenzene was found to be
At 100%, parafluorobenzoic acid-2,6-dimethylphenyl ester was obtained with a yield of 97% and a selectivity of 97%. In addition,
The sodium-2,6-dimethylphenoxide used was obtained by reacting 2,6-dimethylphenol with an equivalent amount of sodium hydroxide in an aqueous solution, dehydrated and dried.

Iodine was quantitatively recovered as sodium iodide.

19.5 g of this parafluorobenzoic acid-2,6-dimethylphenyl ester and 76 g of methanesulfonic acid were placed in a flask and reacted under stirring at 150 ° C for 1.5 hours, and then most of the methanesulfonic acid was distilled off under reduced pressure. did. Then, the reaction mixture was put into cold water to separate white crystals that had formed, and the crystals were dried under reduced pressure. The white crystals are 4- (parafluorobenzoyl)
It was -2,6-dimethylphenol with a yield of 97% and a selectivity of 99%.

Since the unreacted fluorinated benzene can be recovered and reused in the iodination step by circulation, in this example, 4- (parafluorobenzoyl) -2,6 is used as a reference based on the reacted fluorinated benzene.
-Indicates that dimethylphenol was obtained with a yield of 86% and a selectivity of 88%.

Example 3 192 g of fluorinated benzene, 63.5 g of iodine, 28.4 g of periodic acid dihydrate, 500 ml of acetic acid, 1 g of sulfuric acid were put in a flask, and 45-
The reaction was carried out at 50 ° C. for 5 hours with stirring. After the completion of the reaction, fluorinated benzene and acetic acid were distilled off, and the mixture was washed with an aqueous sodium carbonate solution and water and then dried.

The reaction product consisted of paraiodofluorobenzene 93.0%, orthoiodofluorobenzene 6.7%, and metaiodofluorobenzene 0.3%, and the yield as monoiodofluorobenzene was 98.8%.

This monoiodofluorobenzene mixture was subjected to a crystallization operation in the same manner as in Example 2 to obtain 22.2 g of para-iodofluorobenzene, phenol and an equivalent amount of potassium hydroxide were reacted in an aqueous solution. A reaction was carried out in the same manner as in the esterification step of Example 1 using 14 g of potassium phenoxide obtained by dehydration and drying and 60 ml of xylene. Removal of potassium iodide by filtering the esterification reaction mixture gave an almost colorless and transparent xylene solution. As a result of analyzing this solution, the reaction rate of paraiodofluorobenzene was 100%, and the yield of parafluorobenzoic acid phenyl ester was 99.5% with a selectivity of
Obtained in 99.5%. Using the parafluorobenzoic acid phenyl ester obtained by distilling off xylene from this solution, the following rearrangement reaction step was carried out.

15 g of parafluorobenzoic acid phenyl ester and 150 g of liquid anhydrous hydrogen fluoride were placed in a polyethylene flask equipped with a reflux condenser, and reacted at 0-10 ° C. for 10 hours with stirring. After the reaction
The system was raised to 20-40 ° C and anhydrous hydrogen fluoride was recovered by distillation. The obtained residue was washed with a small amount of diluted alkaline water and distilled water, and then dried under reduced pressure. As a result of analyzing the product, the reaction rate of parafluorobenzoic acid phenyl ester was 85%, and 4- (parafluorobenzoyl) phenol was produced in a yield of 84% and a selectivity of 99%. The isomer 2- (parafluorobenzoyl) phenol was only detected at 1%.

Unreacted para-iodofluorobenzene and para-fluorobenzoic acid phenyl ester can be recovered and reused in circulation in the iodination step and rearrangement reaction step. −
(This shows that parafluorobenzoylphenol was obtained with a yield of 90.5% and a selectivity of 90.5%.

Example 4 The following esterification step was performed using the paraiodofluorobenzene obtained in Example 2.

Using 22.2 g of paraiodofluorobenzene, 14 g of potassium-2,6-dimethylphenoxide and 60 ml of toluene, the reaction was carried out at 250 to 260 ° C. for 3 hours in the same manner as in the esterification step of Example 1. After completion of the reaction, the reaction mixture was cooled and the reaction mixture was filtered to remove potassium iodide, whereby an almost colorless and transparent toluene solution was obtained. As a result of analyzing this solution, the reaction rate of paraiodofluorobenzene was 100%, and parafluorobenzoic acid-2,6-dimethylphenyl ester was obtained with a yield of 99% and a selectivity of 99%.

Parafluorobenzoic acid-2,6-dimethylphenyl ester obtained by distilling toluene off from this solution 12.2 g, anhydrous aluminum chloride 7.3 g, dry ortho-dichlorobenzene 70 ml was put in a flask and stirred. And reacted for 4 hours. After the reaction, orthodichlorobenzene was distilled off under reduced pressure, and a hydrochloric acid aqueous solution was added to the residue and stirred. Then, extraction with ethyl acetate was performed, and ethyl acetate was distilled off from the extract to give 4- (parafluorobenzoyl) -2,6
-Dimethylphenol was obtained with a yield of 93%.

In this example, based on the reacted fluorinated benzene, 4-
It shows that (parafluorobenzoyl) -2,6-dimethylphenol was obtained in 84.5%.

The ortho and meta-iodofluorobenzene produced as a by-product in the iodination step of these Examples are subjected to a hydrogenolysis reaction in the presence of a catalyst and a base,
Since it can be quantitatively converted into a fluorinated benzene and a salt of hydrogen iodide and the base, if the fluorinated benzene recovered by carrying out this operation is recycled and reused, the fluorinated benzene in these examples can be used. It goes without saying that the yields of the standard 4- (parafluorobenzoyl) phenols increase to even higher values around 95%, respectively.

Preferred embodiments of the present invention are as follows.

(1) The method according to the claims, wherein the oxidizing agent is nitric acid and / or a nitrogen oxide having oxidizing power. (2) The alkali metal salt of phenols having no substituent at the para-position is phenol or 2, A method according to the claims, which is a sodium salt or a potassium salt of 6-dimethylphenol. (3) A method according to the claims, wherein the esterification reaction is carried out at a temperature range of 150 to 400 ° C. To the temperature range from 350 to 350 ° C. (5) The method according to claim, wherein the acid catalyst is a Lewis acid and / or a strongly acidic protic acid

Claims (1)

[Claims] 1. An a) iodination step of reacting iodine and / or hydrogen iodide with fluorinated benzene in the presence of an oxidizing agent to obtain para-iodofluorobenzene, and b) the para-iodofluorobenzene as a catalyst. Esterification step of reacting with carbon monoxide and an alkali metal salt of a phenol having no substituent at the para-position to give parafluorobenzoic acid phenylesters, without adding c. A method for producing 4- (parafluorobenzoyl) phenols, which comprises a rearrangement reaction step of converting fluorobenzoic acid phenyl esters into 4- (parafluorobenzoyl) phenols in the presence of an acid catalyst.