JPH07567B2 - Method for producing high-purity para-iodofluorobenzene - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention provides a high yield of high-purity paraiodofluorobenzene, which is important as a monomer for heat-resistant polymers and an intermediate for pesticides, pharmaceuticals, etc., from fluorobenzene. Relates to a method of manufacturing.

[Conventional technology and problems]

Paraiodofluorobenzene is important as a reagent for introducing a parafluorophenyl group by utilizing the fact that iodine in the para position with respect to fluorine is active in various reactions. In particular, high-purity para-iodofluorobenzene is desired to be developed as a monomer raw material for an aromatic polymer having excellent heat resistance and chemical resistance, at a low cost.

As a method for producing para-iodofluorobenzene from fluorinated benzene and iodine, for example, there are
Annale der Chemie, 634 , 84 (196
0); Chemical Abstracts (Chemical Abstract)
s), 55 , 8347 (1961) and the like, but the yields are low at 60 to 70%. Also, a method of using antimony pentachloride as one of the reaction reagents [Bulletin of the Chemical Society of Japan (Bulletin of
the Chemical Society of Japan), 47 , 147 (1974)]
Is also proposed, but the yield is about 70%.

[Means for solving problems]

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

That is, according to the present invention, in producing high-purity paraiodofluorobenzene from fluorinated benzene, I) by reacting iodine and / or hydrogen iodide with fluorinated benzene in the presence of an oxidizing agent, Iodination step to obtain an iodinated fluorobenzene mixture containing para-iodofluorobenzene as a main component II) Separation and separation of high-purity para-iodofluorobenzene by distillation or / and crystallization from the iodinated fluorobenzene mixture Purification step, and III) A hydrogenolysis reaction is carried out by reacting the iodinated fluorobenzene mixture remaining as a result of the separation operation in the above II with hydrogen in the presence of a hydrocracking catalyst and a base to give a fluorinated benzene. And hydroiodide of the base, and then recovers fluorinated benzene and hydroiodide, respectively. Another object of the present invention is to provide a method for producing high-purity paraiodofluorobenzene, which comprises a decomposition / recovery step consisting of the following.

In the iodination step of the present invention, the iodination reaction is carried out by reacting an iodination agent consisting of iodine and / or hydrogen iodide and an oxidizing agent with fluorinated benzene. It is preferable to carry out so that the selectivity and the yield thereof are as high as possible, and it is particularly preferable to carry out so as 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, oxidative inorganic acids such as nitric acid, nitrous acid, and sulfuric acid; oxidative nitrogen oxides such as NO ₂ and N ₂ O ₃ ; halogen oxyacids such as iodic acid and periodic acid; peracetic acid, Peroxides such as hydrogen peroxide 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, orthoiodofluorobenzene, which may be present in excess during the reaction, and in some cases, metaiodofluorobenzene and diiodofluorobenzene. An iodinated product of polyiodofluorobenzene, and a reduced product of the oxidant or, optionally, an unreacted oxidant left over by the use of excess amount. It consists of Mizube.

If the amount of water or the amount of oxidant present is smaller than that of the organic part, the organic part can be separated directly by a method such as distillation.
Although it can be recovered, it is usually preferable to separate the organic part by two-layer separation or the like, wash it with water, and then carry out the separation / purification step of the organic part.

Separation / purification of the iodinated fluorobenzene mixture is carried out by distillation or / and crystallization operation to obtain highly pure paraiodofluorobenzene. High purity in the present invention means 95% or more, preferably 98% or more, more preferably
This means a purity of 99.5% or higher, and by performing the distillation operation and the crystallization operation individually or in combination, the required purity of paraiodofluorobenzene can be obtained. Paraiodofluorobenzene and its ortho and meta isomers have relatively close boiling points, but the difference in melting points is large. Therefore, if you want to obtain paraiodofluorobenzene with a purity of 99.5% or more, carry out a crystallization operation. Is preferred. For example, the boiling points of para-iodofluorobenzene and orthofluorobenzene, which are the main by-products, are 182 to 184 ° C and 188 to 189 ° C at atmospheric pressure, respectively, while the melting points are -20 ° C and -41.5 ° C, respectively. is there.

The required high-purity para-iodofluorobenzene can be separated and obtained by such a distillation or crystallization operation, but the higher the purity, the lower the acquisition rate. This reduces the yield of paraiodofluorobenzene, which results in expensive paraiodofluorobenzene.

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

A method has been found for recovering fluorinated benzene and iodine components from the separated residue in high yield. That is, in the decomposition / recovery step of the present invention, the remaining iodinated fluorobenzene mixture, which may contain paraiodofluorobenzene, is reacted with hydrogen in the presence of a hydrocracking catalyst and a base to produce hydrogen. A chemical decomposition reaction is carried out to decompose into fluorinated benzene and hydroiodide of the base, and then fluorinated benzene and hydroiodide are respectively recovered. Each of the recovered components can be reused in the iodination step after being appropriately treated as required, and as a result, high purity paraiodofluorobenzene for the supplied fluorinated benzene and the iodinating agent can be supplied. It was possible to greatly improve the yield and selectivity.

Preferable hydrocracking catalysts are platinum group metal catalysts such as palladium, platinum, ruthenium and rhodium; nickel catalysts. In these metal-based catalysts, metal black such as palladium black, platinum black, ruthenium black, rhodium black, etc., and reduced metal powder such as Raney-Nitzkel, and these metal components are 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 It is preferably used.

Examples of the base used in the hydrogenolysis reaction include various kinds of 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, dioxide trioxide Alkali metal oxides such as cesium, cesium superoxide, and cesium ozonate; beryllium oxide,
Oxides of alkaline earth metals such as magnesium oxide, calcium oxide, calcium peroxide, strontium oxide, strontium peroxide, barium oxide and barium peroxide; lithium hydroxide, sodium hydroxide, potassium hydroxide, rubidium hydroxide, Alkali metal and alkaline earth metal hydroxides such as cesium hydroxide, beryllium hydroxide, magnesium hydroxide, calcium hydroxide, strontium hydroxide, and barium hydroxide; sodium carbonate, sodium hydrogen carbonate, potassium carbonate, hydrogen carbonate Potassium, barium carbonate, sodium silicate, magnesium silicate, potassium aluminate, calcium aluminate,
Salts of strong bases and weak acids such as sodium borate and barium borate; carbides such as calcium carbide and cesium carbide; aluminum group metals such as aluminum hydroxide, potassium hydroxide, indium hydroxide, thallium hydroxide and thallium oxide. Hydroxides and oxides; oxides and hydroxides of rare earth elements such as lanthanum oxide, cerium oxide, and cerium hydroxide; lithium hydride, sodium hydride, sodium borohydride, calcium hydride, lithium hydride Aluminum hydrides; sodium sulfide, sodium hydrogen sulfide, potassium sulfide, calcium sulfide, and other alkali metal or alkaline earth metal sulfides and sulfides; tetraethylammonium hydroxide, tetrapropylammonium hydroxide, etc. Quaternary ammonium hydroxide compounds; hydroxide Tilt riff enyl phosphonium,
Quaternary phosphonium hydroxide compounds such as tetramethylphosphonium hydroxide; Tertiary sulfonium hydroxide compounds such as triethylsulfonium hydroxide and triphenylsulfonium hydroxide; Sodium acetate, potassium benzoate,
Salts of strong bases and weak organic acids such as rubidium oxalate and barium propionate; alkali metal and alkaline earth metal alcoholates such as sodium methylate, sodium ethylate, calcium ethylate; sodium phenolate, potassium ferratoate , Alkali metal and alkaline earth metal fluates such as magnesium ferrate; alkali metal and alkaline earth metal amides such as lithium amide, sodium amide, calcium amide, lithium 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-pentamethylperidine, 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 (however, those having no NH group); crown ethers, azacrown ethers, thiacrown ethers, azacrown and other crowns Compounds and complexes of these crown compounds with alkali metal or alkaline earth metal ions are used.

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 usually contain 0.000 catalyst metal atoms per iodine in the iodinated fluorobenzene mixture to be decomposed.
Used in the range of 01-100 equivalents. Further, it is usually preferable to use an equivalent amount of iodine per iodine in the iodinated 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 excess 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 iodinated fluorobenzene mixture itself or the fluorinated benzene produced by the hydrocracking may act as a reaction solvent. However, 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 methylcyclohexane; 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; trimethylamine, triethylamine, tributylamine, pyridine,
Tertiary amines such as quinoline; ethers such as diethyl ether, tetrahydrofuran, dioxane, diphenyl ether; esters such as methyl acetate, ethyl acetate, methyl benzoate; water and the like are used.

By carrying out the hydrocracking reaction by such a method,
From mono- and poly-iodinated fluorinated benzenes, it has become possible to replace only iodine atoms with hydrogen atoms while keeping 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, it will be as follows.

(However, n represents an integer of 1 to 5, and Base represents a base.) Hydrogen iodide produced as a by-product forms a salt with a base. From this mixture, fluorinated benzene can be easily obtained by distillation or the like. Can be separated and collected. Also, from the salt of hydrogen iodide,
Hydrogen iodide can be recovered with a strong acid, or iodine can be recovered by allowing a strong acid and an oxidizing agent such as chlorine to act. Iodine can also be recovered by electrolytic oxidation of hydrogen iodide or its salt.

〔The invention's effect〕

According to the method of the present invention, fluorinated benzene and iodine and /
Alternatively, it has become possible to produce high-purity paraiodofluorobenzene with high yield and high selectivity from hydrogen iodide and an oxidizing 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 1 288 g of fluorinated benzene and 2 iodine in a flask equipped with a reflux condenser
Add 54g and heat to 65-70 ℃, then stir 8% 61% nitric acid.
40 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, the organic layer was washed with water, an aqueous solution of sodium carbonate 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.
The content was 91.9%, orthoiodobenzene 7.6%, and metaiodobenzene 0.5%, and the weight thereof was 442 g (99.5% yield as monoiodofluorobenzene).

This monoiodofluorobenzene was rectified using a packed column rectification device equipped with a reflux device.

Fractionation at a reflux ratio of 12 gave 341 g (77.1% yield) of a fraction consisting of 99.0% paraiodofluorobenzene and 1% orthoiodofluorobenzene. Distillation residual liquid is 67.9% paraiodofluorobenzene, 29.9% orthoiodofluorobenzene, 2.2% metaiodofluorobenzene.
It was made of.

100 g of this residual liquid, 120 g of a methanol solution containing 30% sodium methoxide, 200 ml of methanol, 3 g of pd / C carrying 10% of palladium on activated carbon were placed in a flask equipped with a reflux condenser, and the temperature was 40 to 45 ° C. The reaction was carried out for 3 hours while bubbling hydrogen into the liquid with stirring. After the reaction, the liquid components were analyzed and as a result, all of the iodinated fluorobenzene was consumed, and instead, fluorinated benzene was produced in a yield of 99.5%, which was easily recovered by distillation. Iodine was quantitatively recovered as sodium iodide.

Fluorinated benzene recovered by hydrocracking can be recycled and reused in the iodination process.
Of paraiodofluorobenzene was obtained with a yield and selectivity of 98.5% based on the fluorous benzene consumed.

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 50-54.
Heat to ℃. 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.

The same post-treatment as in Example 1 was carried out to give paraiodofluorobenzene 92.2% and orthoiodofluorobenzene 7.4.
%, Monoiodofluorobenzene consisting of 0.4% of meta-iodofluorobenzene was obtained with a yield of 99.6%.

By cooling this iodofluorobenzene mixture to −30 to −40 ° C., para-iodofluorobenzene crystallized was obtained. By repeating this crystallization operation four times, paraiodofluorobenzene having a purity of 99.2% was obtained at a yield of 62%.

The iodinated fluorobenzene mixture obtained as the crystallization residual liquid consisted of 80.3% of paraiodofluorobenzene and 19.7% of ortho and meta-iodofluorobenzene.

100 g of this crystallization residual liquid, 100 g of tri-n-butylamine, 100 g of fluorinated benzene as a solvent, and 2 g of 10% pd / C were placed in an autoclave. After replacing the inside of the autoclave with hydrogen, hydrogen was introduced under pressure. The autoclave was heated to 120 to 125 ° C., and hydrogen was introduced so that the reaction pressure became 4 to 5 kg / cm ^2, and the reaction was performed for 5 hours while stirring. After the reaction, the liquid components were analyzed, and as a result, all of the iodinated fluorobenzene was consumed and the amount of fluorinated benzene increased by 43.2 g. This means that iodinated fluorobenzene was almost quantitatively converted into fluorinated benzene. Iodine was quantitatively recovered as a hydrogen iodide salt of tri-n-butylamine.

Since the fluorinated benzene recovered by the hydrocracking can be recycled and reused in the iodination step, the purity of the present example is 99.2.
It shows that% paraiodofluorobenzene was obtained with a yield and selectivity of 99%, based on the fluorinated benzene consumed.

Example 3 Fluorinated benzene (192 g), iodine (63.5 g), periodic acid dihydrate (28.4 g), acetic acid (500 mg) and sulfuric acid (1 g) were placed in a flask and the temperature was 45 to 50 ° C.
And reacted for 5 hours under 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 crystallized in the same manner as in Example 2.

As a result, paraiodofluorobenzene having a purity of 99.5% was obtained as a crystallization product at a yield of 60%.

The crystallization residue consisted of paraiodofluorobenzene 83.2%, ortho- and meta-iodofluorobenzene 16.8%.

100 g of this crystallization residual liquid, 3 g of Raney-Nickel catalyst, 30 g of potassium hydride and 300 ml of methanol were placed in an autoclave, and after replacing the inside of the autoclave with hydrogen, 10 kg / cm ² of hydrogen was introduced under pressure. The mixture was reacted at 80 ° C. for 5 hours with stirring. After the reaction
As a result of analyzing the liquid components, all the iodinated fluorobenzene was consumed, and fluorinated benzene was quantitatively produced. Iodine was quantitatively recovered as potassium iodide.

The fluorinated benzene recovered by the hydrocracking can be recycled and reused in the iodination step.
% Para-iodofluorobenzene was obtained with yields and selectivities above 98%.

Preferred embodiments of the present invention are as follows.

(1) The method according to claim 1, wherein the oxidizing agent is nitric acid and / or nitrogen oxide having oxidizing power. (2) The hydrogenolysis catalyst is a palladium catalyst and / or a nickel catalyst. (3) The method described in the claims, wherein the iodination reaction is carried out at a temperature in the range of 10 to 150 ° C. (4) The hydrogenolysis reaction is carried out at the temperature ranged from 10 to 200 ° C. Method

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Claims (1)

[Claims] 1. When producing high-purity paraiodofluorobenzene from fluorinated benzene, I) Paraiodofluorobenzene is obtained by reacting iodine and / or hydrogen iodide with fluorinated benzene in the presence of an oxidizing agent. An iodination step for obtaining an iodinated fluorobenzene mixture containing as a main product, II) a separation / purification step for separating and obtaining high-purity paraiodofluorobenzene by distillation or / and crystallization from the iodinated fluorobenzene mixture, And III) A hydrogenolysis reaction is carried out by reacting the iodinated fluorobenzene mixture remaining as a result of the separation operation in the above II with hydrogen in the presence of a hydrocracking catalyst and a base, to thereby react the fluorinated benzene and the base with each other. Decomposes with hydroiodide and then recovers fluorinated benzene and hydroiodide respectively. A method for producing high-purity para-iodofluorobenzene, characterized by including a decomposition and recovery process comprising