JPH0720895B2 - Method for producing high-purity para-bromofluorobenzene - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a monomer intermediate for a heat resistant polymer, an agricultural chemical,
The present invention relates to a method for producing high-purity para-bromofluorobenzene, which is important as an intermediate for medicines, from fluorinated benzene in high yield.

[Conventional technology and problems]

Para-bromofluorobenzene is important as a reagent for introducing a para-fluorophenyl group by utilizing the fact that bromine in the para position with respect to fluorine is active in various reactions.
Various manufacturing methods have been proposed. As a method for producing para-bromofluorobenzene from fluorinated benzene and bromine, for example, a method in a gas phase without a catalyst or in a liquid phase in the presence of an iron catalyst [Journal of Chemical Society Tay (Journal of Chemical Society), 1823 (19
57)], Method using a large amount of Y-type zeolite catalyst partially ion-exchanged with calcium ions [Journal of Catalysis,
60 , 110 (1979)] and the like, and it is known that para-bromofluorobenzene is produced with a considerable selectivity. Also, a method for increasing the utilization rate of bromine by adding antimony pentachloride as a reaction reagent [Bulletin of the Chemical Society of Japan, 47 ,
147 (1974)] has also been proposed, and para-bromofluorobenzene was obtained in a yield of about 90%, but bromine and an equivalent amount of antimony pentachloride were required.

In these conventional methods, the selectivity of para-bromofluorobenzene exceeds 90%, but in all cases, isomers such as ortho-bromofluorobenzene and meta-bromofluorobenzene and polybrominated fluorobenzene such as dibromofluorobenzene. Benzene is by-produced and high-purity para-bromofluorobenzene cannot be obtained. In addition, since fluorinated benzene is a relatively expensive raw material, the target para-bromofluorobenzene becomes expensive if a method that can be effectively used even if these by-products are separated is found. was there.

[Means for solving problems]

Therefore, the present inventors have conducted extensive studies on a method for producing high-purity para-bromofluorobenzene with high yield from fluorinated benzene and a brominating agent, and as a result, have found that the bromination step, separation / purification step and decomposition / The inventors have found that the objective can be achieved by combining it with a recovery step, and have completed the present invention.

That is, according to the present invention, in producing high-purity para-bromofluorobenzene from fluorinated benzene, I) Bromination with para-bromofluorobenzene as a main product by reacting fluorinated benzene with a brominating agent. Bromination step for obtaining a fluorobenzene mixture II) Separation / purification step for separating and obtaining high-purity para-bromofluorobenzene by distillation or / and crystallization from the brominated fluorobenzene mixture, and III) As a result, the remaining brominated fluorobenzene mixture is hydrolyzed by reacting it with hydrogen in the presence of a hydrocracking catalyst and a base to decompose it into fluorinated benzene and hydrobromide of the base. , And then a decomposition and recovery step comprising recovering fluorinated benzene and hydrobromide respectively. It is to provide a method for producing a high-purity para-bromofluorobenzene to symptoms.

In the bromination step of the present invention, a method of reacting fluorinated benzene and bromine in a liquid phase, and reacting fluorinated benzene and hydrogen bromide or a mixture of hydrogen bromide and bromine in a gas phase in the presence of oxygen The method and a combination of these methods are preferably carried out so that the selectivity and the yield of parabromofluorobenzene are as high as possible, and the brominated fluoropolymer containing at least 90 mol% parabromofluorobenzene. It is particularly preferred to carry out such that a benzene mixture is obtained. One of the preferred methods for achieving this purpose is to react fluorinated benzene and bromine in the liquid phase in the presence of a catalyst, in which case 1 mol or more of fluorinated benzene is used per mol of bromine. It is preferable to use benzene, more preferably 1.1 to 5 mol of fluorinated benzene. If the amount of fluorinated benzene used is less than 1 mol per 1 mol of bromine, the amount of polybrominated benzene such as dibromofluorobenzene increases by-product, or unreacted bromine remains, resulting in parabromofluorobenzene Yield and selectivity decrease. Although more than 5-fold molar amount of fluorinated benzene may be used, it is not so preferable because the reaction vessel becomes large and the amount of unreacted fluorinated benzene to be separated increases. The liquid phase reaction is preferably carried out at a temperature as low as possible, but if the reaction temperature is too low, the reaction rate becomes slow, which is not a preferable method. The range of −20 to 100 ° C. is preferable, and the range of −10 to 80 ° C. is more preferable. A catalyst is used for the purpose of increasing the reaction rate at low temperature and improving the selectivity of para-bromofluorobenzene. As such a catalyst,
Iron-based catalysts such as iron powder, iron chloride, iron bromide and iron iodide; aluminum-based catalysts such as aluminum chloride and aluminum iodide; iodine and the like are used. Iron-based catalysts are particularly preferable.

In the liquid-phase bromination reaction of fluorinated benzene with bromine, it is also preferable to carry out 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, and for example, lower aliphatic carboxylic acids such as acetic acid and propionic acid; carbon tetrachloride, chloroform, methylene chloride, Lower aliphatic halogenated hydrocarbons such as trichloroethane; ethers such as ether and dioxane; carbon disulfide and the like.

This liquid-phase bromination reaction can be carried out in either a batch system or a flow system, but it is important to carry out the reaction in the reaction system in a state where fluorinated benzene is present in excess of the equivalent amount with respect to bromine.

By the liquid-phase bromination reaction using such an element as a brominating agent, a brominated fluorobenzene mixture containing 90 mol% or more of para-bromofluorobenzene can be obtained.

Another preferred method for carrying out the bromination step is the oxybromination of fluorobenzene using molecular oxygen and hydrogen bromide as brominating agents. In the case of this oxybromination reaction, either the gas phase or liquid phase method can be used, but the gas phase reaction is more preferable in view of high productivity and explosion limit.

This gas phase oxybromination reaction can be carried out without a catalyst, but a catalyst is used for the purpose of further improving the yield and selectivity of parabromofluorobenzene, lowering the reaction temperature, and improving the reaction rate. Is a more preferable method. As such a catalyst, a copper catalyst, an iron catalyst that can be used in the first step, a catalyst obtained by mixing these, and the like are preferably used, and a solid catalyst containing copper is particularly preferable. Such copper catalysts include copper metal such as copper powder; halides such as copper chloride, copper bromide and copper iodide; salts such as copper nitrate, copper sulfate and copper acetate; cuprous oxide and oxidation. Various copper compounds such as oxides such as cupric acid and copper sulfide and sulfides are used.

These metallic coppers or copper compounds can be used alone or, for example, activated carbon, graphite, silica, alumina, silica-alumina, silica-titania,
It may be supported on a carrier such as titania, zirconia, barium sulfate, calcium carbonate, asbestos, bentonite, diatom sugar, polymer, ion exchange resin, zeolite, molecular sieve, magnesium silicate or magnesia.

Further, as the solid catalyst containing copper, zeolite ion-exchanged with copper ions is also preferably used. Such copper ion-exchanged zeolite, by immersing the zeolite in an aqueous solution containing copper ions, after exchanging sodium cations in the zeolite with a predetermined amount of copper cations,
It is a dried product and can be easily obtained. The exchange amount of copper ions is 5% or more of the ion exchange capacity,
It is more preferably 10% or more. Incidentally, AlO ₄ The ion exchange capacity here is an anion of the zeolite ^-
It is the total amount of the cation portion paired with.

As such a zeolite, Y-type zeolite, mordenite, ZSM-5 and the like are preferably used, but Y-type zeolite is particularly preferable.

The molar ratio of fluorinated benzene to hydrogen bromide in the raw material for the gas phase oxybromination reaction is in the range of 1.0 to 10 and more preferably in the range of 1.2 to 8. If this ratio is less than 1.0, unreacted hydrogen bromide remains and the amount of by-produced polybrominated fluorobenzene increases, which is not preferable. Further, if this ratio is carried out at 10 or more, there is no adverse effect on the reaction, but the space-time yield of para-bromofluorobenzene decreases and the amount of unreacted fluorinated benzene to be separated increases. is not.

The molar ratio of molecular oxygen to hydrogen bromide in the feed gas is in the range of 0.5 to 10, more preferably 0.6 to 5. If this ratio is less than 0.5, unreacted hydrogen bromide remains, which is not preferable. On the other hand, if it is more than 10, the space-time yield of the product is lowered, which is not preferable.

This molecular oxygen may be pure oxygen or oxygen-containing oxygen, and may be air, or other gas that does not interfere with the reaction with air or pure oxygen, such as nitrogen, argon, helium, carbon dioxide, or the like. It may be diluted with active gas.

The reaction temperature of the gas phase oxybromination reaction is not particularly limited as long as it is a temperature that can maintain the reaction system in the gas phase, but if the temperature is too high, the selectivity or yield of para-bromofluorobenzene decreases, so it is usually 60 ~ 400 ° C, preferably 100-300
C., more preferably 150 to 250.degree.

The gas phase oxybromination reaction can be carried out under any of reduced pressure, normal pressure and increased pressure, but is usually carried out in the range of 0.5 to 10 atm, preferably 0.8 to 5 atm.

By such a gas phase oxybromination reaction, a brominated fluorobenzene mixture containing 90 mol% or more of para-bromofluorobenzene can be obtained.

It is of course possible to use not only hydrogen bromide but also a mixture of hydrogen bromide and bromine as the bromine source in the gas phase oxybromination reaction.

In the case of the bromination reaction using bromine, hydrogen bromide is usually produced as a by-product, and it is also a preferable method to use this by-produced hydrogen bromide in the oxybromination reaction. In this case, the by-product hydrogen bromide can be taken out of the system and reacted in another oxybromination reaction device, or molecular oxygen or nitric acid, which is an oxidant, can be added to the bromination reaction system using bromine. Therefore, it is also possible to carry out the oxybromination reaction concurrently.

Of course, it is also possible to take out by-product hydrogen bromide or its form in the form of a salt to the outside of the bromination reaction system and recover it as bromine by a known method.

The brominated fluorobenzene mixture obtained by such a bromination reaction contains para-bromofluorobenzene as a main component, but usually contains a small amount of orthobromofluorobenzene, and in some cases, a small amount of meta- Although it may contain bromofluorobenzene or dibromofluorobenzene, a separation / purification step is carried out in order to separate these by-products and obtain the desired para-bromofluorobenzene with high purity.

High purity in the present invention means a purity of 95% or higher, preferably 98% or higher, more preferably 99.5% or higher.

The separation / purification step is carried out by distillation and / or crystallization, but the distillation operation and the crystallization operation may be carried out individually or in combination to obtain the required purity of p-bromofluorobenzene. You can Although the boiling points of para-bromofluorobenzene and its ortho- and meta-isomers are relatively close, the difference in melting points is large, so 99.5
When it is desired to obtain para-bromofluorobenzene having a purity of not less than%, it is preferable to carry out a crystallization operation. For example,
The boiling points of para-bromofluorobenzene and ortho-bromofluorobenzene, which are the main by-products, are each 153 at atmospheric pressure.
℃ and 156-157 ℃, the melting point is -8 ℃
And below -50 ° C.

By performing such distillation and crystallization operations alone or in combination, the required high-purity para-bromofluorobenzene can be separated and obtained, but the higher the purity, the higher the acquisition rate. Is decreasing. This reduces the yield of para-bromofluorobenzene,
As a result, para-bromofluorobenzene becomes expensive.

Therefore, in order to increase the yield of para-bromofluorobenzene and make it as inexpensive as possible, it is important to efficiently recover the fluorinated benzene component and bromine component from the separation residue obtained by separating high-purity para-bromofluorobenzene. Come on.

A method has been found for recovering fluorinated benzene and bromine components from the separated residue in high yield. That is, in the decomposition / recovery step of the present invention, the remaining bromofluorobenzene mixture of the separation operation, which may contain para-bromofluorobenzene, is reacted with hydrogen in the presence of a hydrocracking catalyst and a base. Then, a hydrocracking reaction is performed to decompose into fluorinated benzene and hydrobromide of the base, and then fluorinated benzene and hydrobromide are respectively recovered. Each of the recovered components can be reused in the bromination step after appropriate treatment as required, and as a result, high purity para-bromofluorobenzene for the supplied fluorinated benzene and brominating agent can be obtained. It was possible to greatly improve the yield and selectivity.

As the hydrocracking catalyst, platinum group metal-based catalysts such as palladium, platinum, ruthenium, rhodium; nickel-based catalysts and the like are preferable. In these metal-based catalysts, palladium black, platinum black, ruthenium black, metal powder in a reduced state such as Raney-Nitzkel and black metal such as rhodium black, and these metal components, activated carbon, graphite, silica, alumina, silica -Alumina, silica-titania, titania, zirconia, barium sulfate, calcium carbonate, asbestos, bentonite, diatomaceous earth, polymers, ion exchange resins, zeolites, molecular sieves, magnesium silicate, magnesia, etc. It is preferably used.

Examples of the base used in the hydrogenolysis reaction include various inorganic and organic bases. For example, lithium oxide, lithium peroxide, sodium oxide, sodium peroxide, sodium superoxide, potassium oxide, potassium peroxide, dipotassium trioxide, potassium superoxide, rubidium oxide, rubidium peroxide, rubidium trioxide, rubidium superoxide. , Rubidium ozonide, cesium oxide, cesium peroxide, cesium trioxide, cesium superoxide, cesium ozonide, and other alkali metal oxides; beryllium oxide, magnesium oxide, calcium oxide, calcium peroxide, strontium oxide, peroxide Alkaline earth metal oxides such as strontium oxide, barium oxide and barium peroxide; lithium hydroxide, sodium hydroxide, potassium hydroxide, rubidium hydroxide, cesium hydroxide, beryllium hydroxide, magnesium hydroxide, hydroxide calcium
Alkali metal and alkaline earth metal hydroxides such as strontium hydroxide and barium hydroxide; sodium carbonate, sodium hydrogen carbonate, potassium carbonate, potassium hydrogen carbonate, barium carbonate, sodium silicate, magnesium silicate, potassium aluminate , Salts of strong bases and weak acids such as calcium aluminate, sodium borate and barium borate; carbides such as calcium carbide and cesium carbide; aluminum hydroxide, potassium hydroxide, indium hydroxide, thallium hydroxide, thallium oxide, etc. Aluminum group metal hydroxides and oxides; lanthanum oxide, cerium oxide, cerium hydroxide and other rare earth element oxides and hydroxides; lithium hydride, sodium hydroxide,
Hydride such as sodium borohydride, calcium hydride, lithium aluminum hydride; alkali metal or alkaline earth metal sulfide and sulfide such as sodium sulfide, sodium hydrogen sulfide, potassium sulfide, calcium sulfide; water Quaternary ammonium hydroxide compounds such as tetraethylammonium oxide and tetrapropylammonium hydroxide; Quaternary phosphonium hydroxide compounds such as methyltriphenylphosphonium hydroxide and tetramethylphosphonium hydroxide; triethylsulfonium hydroxide and hydroxide Tertiary sulfonium hydroxide compounds such as triphenylsulfonium; salts of strong bases and weak organic acids such as sodium acetate, potassium benzoate, rubidium oxalate, barium propionate; sodium methylate, sodium ethylate Alkylates of alkali metals and alkaline earth metals such as calcium ethylate; alkali metal and alkaline earth metal phenolates such as sodium phenolate, potassium phenolate, magnesium phenolate; lithium amide, sodium amide, calcium amide, lithium Amides of alkali metals and alkaline earth metals such as dimethylamide; trimethylamine, triethylamine, tri-n-butylamine, triphenylamine, diethylmethylamine, N,
N-diethylaniline, N-methylpiperidine, N, N'-
Diethylpiperazine, N-methylmorpholine, triethylenediamine, hexamethylenetetramine, N, N, N ',
N'-tetramethylethylenediamine, dicyclohexylethylamine, 1,2,2,6,6-pentamethylpiperidine, pyridine, quinoline, phenanthroline, indole, N-methylimidazole, 1,8-diazabicyclo- [5,4,0]- Undecene-7 (DBU), 1,5-diazabicyclo- [4,3,0] -nonene-5 (DBN) and other tertiary amines and cyclic nitrogen-containing compounds (provided that they have an NH group) Those which do not exist); crown compounds such as crown ether, azacrown ether, thiacrown ether, and azacrown, and complexes of these crown compounds with alkali metal or alkaline earth metal ions.

Further, two or more of these basic groups may be present in the molecule, and they may form a part of a polymer such as an anion exchange resin having a quaternary ammonium hydroxide group. May be. Further, these basic substances or groups having basicity may be supported on a solid or chemically bound. These bases may be used alone or in combination of two or more.

Hydrocracking catalysts typically contain 0.000 catalyst metal atoms per bromine in the brominated fluorobenzene mixture to be cracked.
Used in the range of 01-100 equivalents. Further, it is usually preferable to use an equivalent amount of the base per bromine in the brominated fluorobenzene mixture to be decomposed, but it may be smaller than this amount, and if it has a solvent action, it may be used in an amount larger than the equivalent amount. it can.

The hydrogen used in the hydrocracking reaction may be pure hydrogen, or other gas that does not adversely affect the reaction, for example, an inert gas such as nitrogen, argon or helium, or a lower carbonization such as methane, ethane or propane. It may contain hydrogen gas or the like. In some cases, it may contain a small amount of carbon monoxide, carbon dioxide, or the like.

The hydrocracking reaction is carried out under hydrogen atmosphere or under hydrogen pressure. The preferred hydrogen partial pressure is in the range of 0.1 to 200 kg / cm ² , more preferably 0.5 to 100 kg / cm ² . The reaction temperature is preferably in the range of 0 to 250 ° C, more preferably 10 to 200 ° C. Such a temperature range has a suitable reaction rate and a small side reaction.

The hydrocracking reaction may be carried out without using any other solvent since the brominated fluorobenzene mixture itself or the fluorinated benzene produced by the hydrocracking may act as a reaction solvent. A solvent inert to the reaction can be used if necessary. Examples of such a solvent include aliphatic hydrocarbons such as pentane, hexane, heptane, and octane; alicyclic hydrocarbons such as cyclohexane and methylmicrohexane; aromatic hydrocarbons such as benzene, toluene, and xylene; methanol, Alcohols such as ethanol, propanol, butanol; phenols such as phenol and cresol; amides such as dimethylformamide, dimethylacetamide, N-methylpyrrolidone, hexamethylphosphoramide, tetramethylurea; sulfoxides such as dimethyl sulfoxide and sulfolane. And sulfones; tertiary amines such as trimethylamine, triethylamine, tributylamine, pyridine, quinoline; diethyl ether,
Ethers such as tetrahydrofuran, dioxane and diphenyl ether; esters such as methyl acetate, ethyl acetate and methyl benzoate; water and the like are used.

By carrying out the hydrocracking reaction by such a method,
From mono- and polybrominated fluorinated benzenes, it has become possible to replace only bromine atoms with hydrogen atoms while leaving the fluorine atoms bonded to the benzene ring as they are. If this is expressed by a reaction formula in the case of using a monovalent base, for example, it will be as follows.

(However, n represents an integer of 1 to 5, and Base represents a base.) By-product hydrogen bromide is a salt with a base, and fluorinated benzene is easily separated from this mixture by distillation or the like.・
Can be collected. Further, from the salt of hydrogen bromide, hydrogen bromide can be recovered with a strong acid, or can be recovered as bromine by allowing a strong acid and an oxidizing agent such as chlorine to act. Also, bromine can be recovered by electrolytic oxidation of a salt of hydrogen bromide.

〔The invention's effect〕

According to the method of the present invention, parabromofluorobenzene having a high yield and a high selectivity and high purity can be produced from a fluorinated benzene and a brominating agent.

〔Example〕

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

Example 1 The first step is carried out using a four-necked flask equipped with a stirrer, a thermometer, a nitrogen inlet extending into the liquid, a cooling pipe and a gas outlet, and a dropping funnel having the inlet extending into the liquid. did.
40 g of fluorinated benzene and 0.2 g of iron powder were placed in the flask, and the system was cooled to 5 to 10 ° C. while gradually flowing dry nitrogen. Under stirring, 25 g of bromine was gradually added dropwise from the dropping funnel. Bromine was added so that the amount of hydrogen bromide gas generated was almost constant, and the reaction was carried out at 10 to 15 ° C. It took about 30 minutes. Then, as a result of continuing the reaction at 40 ° C. for about 30 minutes, bromine was completely consumed.

By distilling off unreacted fluorinated benzene from the liquid phase, 27.3 g of a brominated fluorobenzene mixture was obtained. The composition in the brominated fluorobenzene mixture was 98.5% parabromofluorobenzene, 1.0% orthobromofluorobenzene, 0.5% metafluorobromobenzene.

A small amount of n-hexane was added to this brominated fluorobenzene mixture and cooled to -30 ° C to obtain para-bromofluorobenzene which crystallized. By repeating this crystallization operation three times, 18.2 g of para-bromofluorobenzene having a purity of 99.8% was obtained.

9.1 g of a brominated fluorobenzene mixture obtained as a liquid component by a crystallization operation (96% para body, 2.7% ortho body,
(Meta body 1,3%), methanol 100 ml, methanol solution 15 g containing 30% sodium methoxide, Pd / C 1 g in which 10% palladium is supported on activated carbon is put in a flask equipped with a reflux condenser, and the temperature is 60 ° C. The reaction was carried out for 1.5 hours while bubbling hydrogen into the liquid while stirring. After the reaction, the liquid components were analyzed, and as a result, all of the brominated fluorobenzene was consumed, and instead, it was produced in a yield of 99% of fluorinated benzene, which was easily recovered by distillation. Brom was quantitatively recovered as sodium bromide.

The fluorinated benzene recovered by the hydrocracking can be recycled and reused in the bromination process.
It shows that% para-bromofluorobenzene was obtained with a yield and selectivity of 99% based on the fluorobenzene consumed.

Example 2 About 65% of sodium ions of Y-type zeolite was exchanged with divalent copper ions, and prepared by exchanging copper-Y-type zeolite as a catalyst. The gas phase oxybromination reaction of fluorinated benzene was carried out by introducing hydrogen gas, molecular oxygen, fluorinated benzene, and nitrogen as a diluent.

The feed composition is fluorinated benzene / HBr / O ₂ / N ₂ =
2/1/1/3, Fluorinated benzene standard WHSV was 10 hr ^-1 , reaction was carried out at a temperature of 190-200 ° C under normal pressure, and after reaching a steady state, the reaction product was analyzed and found to be brominated. The reaction rate of hydrogen is 10
At 0%, the reaction rate of fluorinated benzene is 49%, the composition in the brominated fluorobenzene mixture is 93.1% para-bromofluorobenzene, 2.7% ortho-bromofluorobenzene 2.7%, meta-bromofluorobenzene 3.0%, in mol%. It was 1.2% of dibromofluorobenzene.

This reaction mixture is distilled to recover the fluorinated benzene containing the reaction product water as the first fraction, and the main bromine contains a monobromofluorobenzene mixture containing a small amount of the fluorinated benzene and a small amount of the residual monobromofluorobenzene. Dibromofluorobenzene was obtained. The main distillate component is 2.5% fluorinated benzene and 91.9% para-bromofluorobenzene,
It consisted of 2.6% orthobromofluorobenzene and 3.0% metabromofluorobenzene.

100 g of this main distillate was crystallized in the same manner as in Example 1 to give 99.9% pure parabromofluorobenzene.
Obtained 62 g.

20 g of fluorobenzene added as a solvent to the residual liquid of crystallization, and 40 g of tri-n-butylamine and 3 g of 10% Pd / C 2
Put it in a 00 ml autoclave, replace the inside of the autoclave with hydrogen, then pressurize with hydrogen 5 kg / cm ² and stir 120 ~
As a result of reacting at 125 ° C. for 15 hours, all of the monobromofluorobenzene was hydrolyzed into fluorinated benzene.
Fluorinated benzene was almost completely recovered by distillation. Bromine was quantitatively recovered as a hydrobromide salt of tri-n-butylamine.

Since the fluorinated benzene recovered by the hydrocracking can be recycled and reused in the bromination process, the purity of the present example is 99.9.
It shows that% para-bromofluorobenzene was obtained almost quantitatively on the basis of the fluorobenzene consumed.

Example 3 Using a continuous reaction apparatus as shown in FIG. 1 in the bromination process, a liquid phase bromination reaction with bromine and a gas phase oxybromination reaction with hydrogen bromide produced as a by-product at that time are continuously performed. Carried out.

The first tank (1) of the liquid phase bromination reactor is 5-10 ° C, the second
The tank (2) is kept at 20 to 25 ° C and the third tank (3) is kept at 40 to 45 ° C, so that the average residence time is 40 minutes, respectively.
Fluorinated benzene and bromine were introduced into the first tank (1) at a molar ratio of 3: 1. The catalyst was added such that FeBr ₃ was 0.1 mol% with respect to the fluorobenzene.

The liquid phase reaction mixture flowing out from the third tank (3) at an overflow is led to a distillation apparatus (4), and fluorinated benzene is recovered from the top and monobromofluorobenzene is recovered from the middle stage, and from the bottom of the tower. The polybrominated fluorobenzene and the catalyst were separated.

Part of the fluorinated benzene recovered from the top and the hydrogen bromide gas produced by the liquid phase bromination reaction are introduced together with oxygen and nitrogen from the upper part of the gas phase oxybromination reactor (5). The molar ratio is fluorinated benzene / HBr / O ₂ / N ₂
= 1.2 / 1 / 0.8 / 3, the reaction mixture is led to the distillation apparatus (6) and separated. For the gas phase oxybromination reactor, the same Cu as used in Example 1 was used.
²⁺ ion-exchange Y zeolite is packed and reaction temperature
The reaction was carried out at 190 to 200 ° C. and WHSV of 7 hr ⁻¹ .

The selectivity of monobromofluorobenzene in the brominated fluorobenzene obtained by the liquid-phase bromination reaction was 99%, and the content of rose in the monobromofluorobenzene was 97%, the ortho form was 2%, and the meta form was 1%. there were.

The selectivity of monobromofluorobenzene in the brominated fluorobenzene obtained by the gas phase oxybromination reaction is
97%, and the rose body in monobromofluorobenzene is
It was 94%, ortho form 2%, and meta form 4%.

The monobromofluorobenzene fractions recovered from the middle stage of the distillation units (4) and (6) were mixed to obtain para-bromofluorobenzene 95.5% and ortho-bromofluorobenzene 2
%, Metabromofluorobenzene 2.5% was obtained.

This mixture was introduced into a continuous crystallizer cooled by a refrigerant at -25 to -30 ° C. The product obtained as the crystallized product was further repeated twice and introduced into this apparatus to obtain para-bromofluorobenzene having a purity of 99.6% at a rate of 80%.

The crystallization residual liquid consisted of 79.1% para-bromofluorobenzene, 20.9% ortho- and meta-bromofluorobenzene.

The mixture of the bottom components of the distillation units (4) and (6) is 80% monobromofluorobenzene and dibromofluorobenzene.
It was made up of 20%.

100 g of a mixture consisting of the crystallization residual liquid and this bottom component, 10% Pd / C
5 g, 70 g of sodium phenoxide and 200 g of methanol were put into an autoclave, and the reaction was carried out at 60 ° C. for 5 hours while keeping the hydrogen pressure at 4 to 5 kg / cm ² at all times. As a result, all the brominated fluorobenzene compounds were It was benzene. Fluorinated benzene is distilled from the reaction solution,
It was recovered almost quantitatively. All the bromine was recovered as sodium bromide.

Since the fluorinated benzene recovered by the hydrocracking can be recycled and reused in the bromination process, the purity of the present example is 99.6%.
It is shown that the para-bromofluorobenzene of 4 was obtained almost quantitatively on the basis of the fluorinated benzene consumed.

Instead of Example 4 Cu ²⁺ ion-exchanged Y-type zeolites, using CuBr ₂ / SiO ₂ carrying 18W% of CuBr ² in silica, using the same reactor as that used in the bromination step of Example 2 Then, the gas phase oxybromination reaction of fluorinated benzene with hydrogen bromide gas and oxygen was performed at 180-190 at a raw material composition of fluorinated benzene / HBr / O ₂ / N ₂ = 1.5 / 1 / 1.5 / 6. C., WHSV = 5.0 hr ⁻¹ , and normal pressure. After the steady state, the reaction products were analyzed, and the reaction rate of hydrogen bromide was 100%, the reaction rate of fluorinated benzene was 67%, and the composition in the brominated fluorobenzene mixture was mol%. Para-bromofluorobenzene 94.3%, ortho-bromofluorobenzene 2.0%, meta-bromofluorobenzene 2.5%, dibromofluorobenzene 1.2%.

This bromination reaction mixture was separated by distillation by the same distillation method as used in Example 3 to give 95.4% para-bromofluorobenzene and 2.ortho-bromofluorobenzene.
A monobromofluorobenzene mixture consisting of 0% and metabromofluorobenzene 2.6% was obtained.

This mixture was crystallized in the same manner as in Example 3,
Parabromofluorobenzene having a purity of 99.7% was obtained at a rate of 72%.

As a result of mixing the crystallization residual liquid and the distillation residual component, para-bromofluorobenzene 84.4%, ortho- and meta-bromofluorobenzene 12.2%, dibromofluorobenzene 3.4%
A mixture consisting of

50 g of this mixture, 2 g of Raney-Nitzkel catalyst, 70 g of a methanol solution containing 30% sodium methoxide, and methanol 2
00 ml was put into an autoclave, the inside of the autoclave was replaced with hydrogen, and then 10 kg / cm ² of hydrogen was injected under pressure. Under stirring
As a result of reacting at 100 ° C. for 4 hours, the brominated fluorobenzene compound was almost quantitatively converted to fluorinated benzene. Brom was quantitatively recovered as sodium bromide.

Since the fluorinated benzene recovered by the hydrocracking can be recycled and reused in the bromination process, the purity of the present example is 99.7.
It shows that% para-bromofluorobenzene was obtained almost quantitatively on the basis of the fluorobenzene consumed.

Preferred embodiments of the present invention are as follows.

(1) The method according to the claims, wherein the brominating step is carried out in a liquid phase reaction of fluorinated benzene and bromine in the presence of an iron catalyst. (2) The brominating step is conducted in the presence of a solid catalyst containing copper. The method according to claim, which is carried out in a gas phase reaction of oxygen with fluorinated benzene and hydrogen bromide, or a mixture of hydrogen bromide and bromine, and (3) the bromination step is performed with fluorinated benzene and bromine. A first step of producing brominated fluorobenzene and hydrogen bromide by the liquid phase reaction of, and a second step of reacting the hydrogen bromide with fluorinated benzene in the gas phase in the presence of oxygen. The method according to (4), wherein the hydrocracking catalyst is a palladium catalyst and / or a nickel catalyst.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing an example of a continuous flow reactor in the bromination process of the present invention.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location C07B 61/00 300

Claims (1)

[Claims] 1. When producing high-purity para-bromofluorobenzene from fluorinated benzene, I) brominated fluorobenzene containing para-bromofluorobenzene as a main product by reacting fluorinated benzene with a brominating agent. Bromination step for obtaining a mixture II) Separation / purification step for separating and obtaining high-purity para-bromofluorobenzene by distillation or / and crystallization from the brominated fluorobenzene mixture, and III) Result of the separation operation in the above II The brominated fluorobenzene mixture is reacted with hydrogen in the presence of a hydrocracking catalyst and a base to carry out a hydrocracking reaction to decompose into fluorinated benzene and a hydrobromide salt of the base, followed by fluorination. Characterized by including a decomposition / recovery step comprising recovering benzene and hydrobromide respectively. A method for producing high-purity para-bromofluorobenzene.