JP2005112745A - Method for producing aromatic fluorocompound - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing an aromatic fluorocompound, by which an corresponding aromatic fluorocompound (for example, pentafluorobenzonitrile) can be produced in a high yield by the halogen exchange reaction of an aromatic halogen compound (for example, pentachlorobenzonitrile) with a fluorinating agent (for example, potassium fluoride). <P>SOLUTION: This method for producing the aromatic fluorocompound is characterized by supplying the aromatic halogen compound of raw material as particles having an average particle diameter of 20 to 200μm. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for producing an aromatic fluorine compound, and more particularly to a method for producing a corresponding aromatic fluorine compound in a high yield by using an aromatic halogen compound as a raw material and fluorinating it with a fluorinating agent.

  It is generally known to produce a corresponding aromatic fluorine compound by a halogen exchange reaction between an aromatic halogen compound and a fluorinating agent.

  For example, a method for producing a corresponding aromatic fluorine compound by subjecting an aromatic halogen compound to a halogen exchange reaction with a fluorinating agent in a benzonitrile at a temperature range of 190 to 400 ° C. under a naturally occurring pressure is known (Patent Document). 1, 2).

Japanese Examined Patent Publication No. 62-24417 Japanese Patent Publication No. 3-13206

  In production on an industrial scale, it is desirable to obtain the target aromatic fluorine compound in a high yield, and developing a method for producing an aromatic fluorine compound in a higher yield than conventional is a technology in the field. It is an ongoing issue for the elderly.

  Thus, an object of the present invention is to provide a method for producing an aromatic halogen compound in a high yield by a halogen exchange reaction between an aromatic halogen compound and a fluorinating agent.

  According to the study by the present inventors, the aromatic halogen compound as a raw material is appropriately adjusted to an average particle diameter in a specific range by grinding or the like, and then subjected to a halogen exchange reaction, the aromatic fluorine compound is obtained at a higher yield than conventional. It was found that can be manufactured. The present invention has been completed based on such findings.

  That is, the present invention relates to the general formula (1)

(In the formula, X represents a halogen atom of chlorine, bromine or iodine, -A represents -CN, -NO ₂ , -COF or -COCl, and a represents the number of substitutions of A. , 0, 1 or 2, and b is the number of substitutions of X and is an integer of 2 or more (provided that a + b ≦ 6).
Or general formula (2)

(In the formula, X is as defined in general formula (1), c is the number of substitutions of X, is an integer of 1 to 4, and -Z- is -O- or

(Wherein R represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms or an aryl group). ) Is fluorinated with a fluorinating agent in an organic solvent to give a general formula (3)

(In the formula, A, X and a have the same meanings as in the general formula (1), F represents a fluorine atom, d represents the number of substitutions of F, and is an integer of 1 or more, bd represents This is the number of substitutions of residual X (where a + b ≦ 6).
Or general formula (4)

(In the formula, -Z- and X have the same meaning as in formula (2), F represents a fluorine atom, e is the number of substitutions of F, and is an integer of 1 to 4, c-e Is the number of substitutions of residual X.) In producing the aromatic fluorine compound represented by the following formula, the aromatic aromatic compound is subjected to the reaction as particles having an average particle diameter of 20 to 200 μm. It is a manufacturing method of a fluorine compound.

  According to the method of the present invention, an aromatic fluorine compound can be produced in a higher yield than conventional. Moreover, since the halogen exchange reaction can be completed in a short time, the productivity of the aromatic fluorine compound is improved, and the aromatic fluorine compound can be produced industrially advantageously.

  The aromatic halogen compound used as a raw material in the present invention is represented by the general formula (1) or (2), and is usually solid at room temperature. In the general formula (1), when there are a plurality of A, these may be the same or different.

  Bd in the general formula (3) means the residual X, that is, the number of substitutions of non-fluorine-substituted halogen atoms. In other words, d of the halogen atoms b of the raw material aromatic halogen compound is fluorine-substituted. , Means that the remaining bd are halogen atoms. Similarly, ce in the general formula (4) means the residual X, that is, the number of substitutions of non-fluorine-substituted halogen atoms. In other words, e out of c halogen atoms of the raw material aromatic halogen compound is fluorine. Substituted means that the remaining ce are halogen atoms. In the present invention, it is preferable that all of the halogen atoms of the starting aromatic halogen compound are fluorine-exchanged (that is, when b = d and c = e).

  Representative examples of the aromatic halogen compounds include 1,3,5-trichlorobenzene, 1,3,5-tribromobenzene, 1,2,4,5-tetrachlorobenzene, 1,2,4,5-tetra Bromobenzene, pentachlorobenzene, hexachlorobenzene, pentachlorobenzonitrile, 2,6-dichlorobenzonitrile, 2,4,6-trichlorobenzonitrile, 3,4,5,6-tetrachlorophthalonitrile, 2,4,5 , 6-tetrachloroisophthalonitrile, tetrachlorophthalic anhydride, tetrachlorophthalic anhydride amide, N-alkyltetrachlorophthalic anhydride amide (alkyl groups: methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl N-phenyltetrachlorophthalic anhydride amide, 2,3,4-trick B nitrobenzene, etc. pentachloronitrobenzene can be exemplified. Of these, 3,4,5,6-tetrachlorophthalonitrile, pentachlorobenzonitrile and 2,6-dichlorobenzonitrile are preferably used.

  The object of the present invention is an aromatic fluorine compound represented by the general formula (3) or (4) obtained by halogen exchange reaction between the aromatic halogen compound and the fluorinating agent.

  Representative examples of the aromatic fluorine compound include 1,3,5-trifluorobenzene, 1,2,4,5-tetrafluorobenzene, pentafluorobenzene, hexafluorobenzene, 2,6-difluorobenzonitrile, 3 , 4,5,6-tetrafluorophthalonitrile, 2,4,5,6-tetrafluoroisophthalonitrile, 5-chloro-2,4,6-trifluoroisophthalonitrile, tetrafluorophthalic anhydride, tetrafluoro Phthalic anhydride amide, N-alkyltetrafluorophthalic anhydride amide (alkyl group: methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, etc.), N-phenyltetrafluorophthalic anhydride amide, 2, 3, Examples include 4-trifluoronitrobenzene and pentafluoronitrobenzene It is possible. Of these, 3,4,5,6-tetrafluorophthalonitrile, pentafluorobenzonitrile and 2,6-difluorobenzonitrile are preferable.

  The feature of the present invention is that the aromatic halogen compound is subjected to the reaction as particles having an average particle size of 20 to 200 μm, preferably 40 to 170 μm, more preferably 50 to 150 μm. Specifically, for example, an aromatic halogen compound is added together with an organic solvent and a fluorinating agent, or after an organic solvent and a fluorinating agent are previously charged in a reaction vessel, the particles are placed in the reaction vessel as particles having an average particle diameter of 20 to 200 μm. Prepare. By doing in this way, the yield of the target aromatic fluorine compound can be improved. In addition, the average particle diameter in this invention was calculated | required using the measuring apparatus using a laser beam diffraction scattering method and LA-920 by Horiba.

  When the average particle diameter exceeds 200 μm, the yield of the target aromatic fluorine compound is lowered. This is presumably because the solubility or dissolution rate of the aromatic halogen compound in the organic solvent decreases and the contact efficiency with the fluorinating agent during the reaction decreases. On the other hand, when the average particle size is smaller than 20 μm, it floats on the surface of the organic solvent and is not sufficiently dispersed in the organic solvent, or it takes a long time to disperse, and in a severe case, it does not dissolve (remains in a cocoon shape). As a result, the reaction yield decreases. Furthermore, enormous energy is required to form fine particles, and a large amount of dust is generated, which causes problems such as loss of raw materials and deterioration of the working environment.

  In addition, aromatic halogen compound particles having an average particle size of 20 to 200 μm are generally known for particle size adjustment such as a method of mechanically pulverizing with a pulverizer such as a ball mill or a hammer mill, and a method of sieving the pulverized one. It can be easily obtained by appropriately selecting the means. Further, the purification conditions during the production of the aromatic halogen compound may be optimized and adjusted to the above average particle size range.

  In the present invention, the halogen exchange reaction between the aromatic halogen compound and the fluorinating agent is carried out according to a generally known method except that the aromatic halogen compound is used as particles having an average particle diameter in the range of 20 to 200 μm. Can do.

  As the fluorinating agent, a fluorinating agent generally used for this kind of reaction can be used. Specifically, for example, alkali metal fluorides such as sodium fluoride, potassium fluoride and cesium fluoride; alkaline earth metal fluorides such as calcium fluoride and barium fluoride; N-fluoropentachloropyridinium salt, tetraethyl Examples thereof include a salt of an organic base such as ammonium fluoride and tetrabutylammonium fluoride with fluorine. Among these, alkali metal fluorides such as sodium fluoride, potassium fluoride, and cesium fluoride, particularly spray-dried particulate potassium fluoride is preferably used.

  The fluorinating agent may contain an inorganic compound such as silica. Typical examples of the inorganic compound include oxides of elements such as silicon, aluminum, titanium, and zirconium. Specific examples include finely pulverized silica; a mixture of silica and alumina such as zeolite and diatomaceous earth; and compounds mainly composed of titania and zirconia. Among these, fine particle silica synthesized by a vapor phase method using silicon tetrachloride as a raw material is preferable.

  About the usage-amount of a fluorinating agent, it needs to be at least equimolar with respect to the chlorine atom contained in the aromatic chlorine compound of the raw material compound substituted by a fluorine atom, Generally, with respect to one chlorine atom, A fluorinating agent is used so that the number of fluorine atoms is 1 to 1.5.

Examples of the organic solvent include dimethyl sulfoxide (DMSO), sulfolane (TMSO ₂ ), N, N-dimethyl sulfoxide (DMF), N-methyl-2-pyrrolidone (NMP), dimethyl sulfone (DMSO ₂ ), benzonitrile and the like. The aprotic polar solvent can be used. Of these, benzonitrile is preferably used. About the preparation ratio of an organic solvent and an aromatic halogen compound, an aromatic halogen compound is 1-100 mass parts with respect to 100 mass parts of organic solvents, Preferably it is 5-80 mass parts, More preferably, it is 10-70 mass parts. Generally, it is used at a ratio of

  Reaction temperature is 150-400 degreeC normally, Preferably it is 180-380 degreeC, More preferably, it is 200-360 degreeC. Although there is no restriction | limiting in particular about a pressure, You may react while recirculating | refluxing under a normal pressure within the said temperature range, and you may carry out under naturally generated pressure. Alternatively, the reaction may be performed by increasing the pressure with nitrogen gas or the like. Although there is no restriction | limiting in particular in the reaction container, Generally, it is good to use the pressure-resistant reaction container which used the chemical-resistant raw materials, such as SUS316, and arrange | positioned the stirring blade. The reaction time is usually 3 to 30 hours, preferably 6 to 25 hours, and more preferably 8 to 20 hours.

  The invention is further illustrated by the following examples, which illustrate advantageous embodiments of the invention.

In the following Examples and Comparative Examples, the average particle size was determined using LA-920 manufactured by Horiba.
Example 1
The pentachlorobenzonitrile particles having an average particle diameter of 73 μm were obtained by sieving pentachlorobenzonitrile produced according to the gas phase chlorination method described in Japanese Patent Application No. 2002-87918.

  A 1 L SUS autoclave was charged with 300 g of benzonitrile, 90.3 g (0.328 mol) of the pentachlorobenzonitrile particles and 100 g (1.721 mol) of spray-dried potassium fluoride, and the air in the autoclave was replaced with nitrogen. Thereafter, the reaction was carried out at 340 ° C. for 18 hours with stirring.

After completion of the reaction, the reaction solution was analyzed by gas chromatography. As a result, 60.5 g (0.313 mol) of pentafluorobenzonitrile as the target product and 3,5-dichloro-2,4 as the active ingredient were contained in the reaction solution. , 6-trifluorobenzonitrile 2.9 g (0.013 mol). The yields of pentafluorobenzonitrile and 3,5-dichloro-2,4,6-trifluorobenzonitrile were 96.5 mol% and 3.0 mol%, respectively.
Example 2
The tetrachlorobenzonitrile produced in the same manner as in Example 1 was sieved to obtain tetrachlorobenzonitrile particles having an average particle diameter of 114 μm.

  A 1 L SUS autoclave was charged with 300 g of benzonitrile, 104.1 g (0.391 mol) of the tetrachlorobenzonitrile particles and 100 g (1.721 mol) of spray-dried potassium fluoride, and the air in the autoclave was replaced with nitrogen. Then, reaction was performed at 280 degreeC for 20 hours, stirring.

After completion of the reaction, the reaction solution was analyzed by gas chromatography. The reaction solution contained 75.7 g (0.378 mol) of tetrafluorophthalonitrile as the target product and 4-chloro-3,5,6 as the active ingredient. -2.5 g (0.011 mol) of trifluorophthalonitrile was contained. The yields of tetrafluorophthalonitrile and 4-chloro-3,5,6-trifluorophthalonitrile were 96.7 mol% and 2.9 mol%, respectively.
Comparative Example 1
Pentachlorobenzonitrile produced in the same manner as in Example 1 was sufficiently ground in a mortar to obtain pentachlorobenzonitrile particles having an average particle diameter of 10.6 μm.

  A 100 mL SUS autoclave was charged with 15 g of benzonitrile, 4.5 g (0.0164 mol) of the pentachlorobenzonitrile particles and 5.2 g (0.0895 mol) of spray-dried potassium fluoride, and the air in the autoclave was purged with nitrogen. After the substitution, the reaction was carried out at 320 ° C. for 12 hours with stirring.

  After completion of the reaction, the reaction solution was analyzed by gas chromatography. As a result, 4.87 g (0.0252 mol) of pentafluorobenzonitrile as an object and 3,5-dichloro-2,4 as an active ingredient were contained in the reaction solution. , 6-trifluorobenzonitrile 1.33 g (0.0059 mol). The yields of pentafluorobenzonitrile and 3,5-dichloro-2,4,6-trifluorobenzonitrile were 76.9 mol% and 18 mol%, respectively.

Since the average particle diameter of the raw material pentachlorobenzonitrile was too small, the raw material was left in an untreated state and the yield was lowered.
Comparative Example 2
3,4,5,6-tetrachlorophthalonitrile was recrystallized with benzene, and the precipitated crystals were separated by filtration to obtain 3,4,5,6-tetrachlorophthalonitrile particles having an average particle diameter of 235 μm.

  A 100 mL SUS autoclave is charged with 50 g of benzonitrile, 17.4 g (0.0654 mol) of the above 3,4,5,6-tetrachlorophthalonitrile particles and 16.7 g (0.2878 mol) of spray-dried potassium fluoride. After replacing the air in the autoclave with nitrogen, the reaction was performed at 260 ° C. for 18 hours with stirring.

  After completion of the reaction, the reaction solution was analyzed by gas chromatography. The reaction solution contained 6.22 g (0.0311 mol) of the target product, 3,4,5,6-tetrafluorophthalonitrile and 3 as the active ingredient. -1.62 g (0.0075 mol) of chloro-4,5,6-trifluorophthalonitrile. The yields of 3,4,5,6-tetrachlorophthalonitrile and 3-chloro-4,5,6-trifluorophthalonitrile were 75.8 mol% and 18.3 mol%, respectively.

Since the average particle diameter of the raw material 3,4,5,6-tetrachlorophthalonitrile was large, the yield decreased.

Claims (1)

General formula (1)

(In the formula, X represents a halogen atom of chlorine, bromine or iodine, -A represents -CN, -NO ₂ , -COF or -COCl, and a represents the number of substitutions of A. , 0, 1 or 2, and b is the number of substitutions of X and is an integer of 2 or more (provided that a + b ≦ 6).
Or general formula (2)

(In the formula, X is as defined in general formula (1), c is the number of substitutions of X, is an integer of 1 to 4, and -Z- is -O- or

(Wherein, R represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms or an aryl group). ) Is fluorinated with a fluorinating agent in an organic solvent to give a general formula (3)

(In the formula, A, X and a have the same meanings as in the general formula (1), F represents a fluorine atom, d represents the number of substitutions of F, and is an integer of 1 or more, bd represents This is the number of substitutions of residual X (where a + b ≦ 6).
Or general formula (4)

(In the formula, -Z- and X have the same meaning as in formula (2), F represents a fluorine atom, e is the number of substitutions of F, and is an integer of 1 to 4, c-e Is the number of substitutions of residual X.) In producing the aromatic fluorine compound represented by the following formula, the aromatic aromatic compound is subjected to the reaction as particles having an average particle diameter of 20 to 200 μm. A method for producing a fluorine compound.