JPS60112751A - Production of tetrafluorophthalonitrile - Google Patents

Abstract

PURPOSE:To obtain the titled compound in high yield, by reacting a tetrachlorophthalonitrile with a fluorinating agent in benzonitrile within a specific temperature range under autogenous pressure conditions to exchange halogens. CONSTITUTION:A tetrachlorophthalonitrile, e.g. tetrachloroisophthalonitrile, is reacted with a fluorinating agent, e.g. potassium fluoride, in benzonitrile medium within 190-400 deg.C temperature range under autogenous pressure conditions to give the aimed tetrafluorophthalonitrile, e.g. tetrafluoroisophthalonitrile. The benzonitrile is thermally stable, and usable within the above-mentioned temperature range necessary for the halogen exchange. There is no side reaction between the raw materials or products. The formation of carbonized materials in a large amount can be prevented with easy temperature control. The amount of the tetrachlorophthalonitrile to be used is within about 5-50pts.wt. range based on 100pts.wt. solvent.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides the preparation of tetrafluorophthalonitriles by the so-called halogen exchange reaction, in which tetrachloro heptalonitriles are reacted with a fluorinating agent, in particular potassium fluoride, in a benzonitrile medium in the temperature range from 190°C to 400°C. Concerning the manufacturing method of nitriles.

The so-called halogen exchange reaction, in which a halogen atom is exchanged with a fluorine atom by reacting an alkali fluoride or the like with an aromatic halide, has been known for a long time. At that time, the solvents generally used are dimethyl sulfoxide (DMSO), sulfolane (TMSCh), and N-dimethylformamide (
Aprotic polar solvents such as DMF), N-methyl-2-pyrrolidone (NMP), and dimethylsulfone (DMSO2) are mainly used, and the halogen exchange reaction is carried out at a temperature below the boiling point of the solvent [for example, Ishikawa, Journal of the Society of Synthetic Chemistry, 808. (1967), Hudlicky, M.
, Chemistry of Organic Flu
orine Compounds 112 pages (1976
2003) John Wi Iey & 5ons Publishing, etc.].

In some cases, there is an example 4 in which a phase transfer catalyst such as a crown compound is added to speed up the reaction rate. However, aromatic halides that can be halogen-exchanged by the above method are, for example, 2,6-cyclobenzonitrile Kara 2,6 described in Ishikawa et al., Journal of the Society of Organic Synthetic Chemistry, Vol. 27, p. 174 (1969). -As in the example of synthesizing refluorobenzonitrile, it is usually limited to aromatic halides with a small number of halogen substituents, and it is often difficult to perform complete halogen exchange with polyhalides with larger halogen substituents. Even if halogen exchange is possible, the yield is poor. Further, when an aromatic halide is halogen-exchanged by the above method, the meta position of the electron-withdrawing group (for example, -CN group, -No2 group, etc.) cannot be halogen-exchanged at all.

That is, the above method is not suitable for producing tetrafluoroisophthalonitrile from tetrachloroinphthalonitrile, which is a polyhalide and has halogen substituents at the meta positions of both cyano groups, as in the present invention.

In fact, in the conventional literature there is no method for synthesizing tetrafluoroisophthalonitrile from tetrachloroisophthalonitrile by halogen exchange. However, an example of halogen exchange of tetrachloroisophthalonitrile is described in Ishikawa et al., Industrial Chemistry Journal, Vol. 73, p. 447 (1970); Even if the halogen is exchanged using

-2,4,6-)lifluoroisophthalonitrile is produced, and completely substituted tetrafluoroisophthalonitrile is not produced at all.

A method for producing tetrafluoroterephthalonitrile by halogen exchange of polyhalide tetrachloroterephthalonitrile using a common solvent is described in French Patent No. 1,397,521 (1965) and Japanese Patent Application Laid-open No. No. 51-6940, but none of them have been able to provide a satisfactory yield of tetrafluoroterephthalonitrile.

Additionally, if the solvents commonly used in the above methods are heated to high temperatures or used for long periods of time to improve yields, decomposition reactions of the solvent or side reactions between the solvent and raw materials or products may occur. In the end, the yield cannot be improved. It also has the disadvantage that it is not easy to use industrially in terms of solvent recovery and reuse. In order to avoid the disadvantage that these solvents can be used at high temperatures, it is common to use an autoclave without a solvent and conduct the reaction at a high temperature of 200 to 500'C. te 300
Examples of halogen exchange of tetrafluoroterephthalonitrile from tetrachloroterephthalonitrile at a temperature of
Japan Vol. 40, p. 688. However, since no solvent is used, it is difficult to control the temperature due to the exothermic reaction, and a large amount of carbide adheres to the container after the reaction is completed, making it difficult to implement industrially.

When producing tetrafluorophthalonitriles, the inventors thought that it would be difficult to synthesize them using the general methods mentioned above, and even if they could be synthesized, there would be many drawbacks that would make industrial implementation impossible, and therefore, we conducted intensive studies on possible methods. As a result, using benzonitrile as a solvent under spontaneous pressure, tetrachlorophthalonitrile was added as a fluorinating agent at a temperature range of 190 to 400°C.

In particular, the inventors have found that tetrafluorophthalonitriles can be easily produced in good yield by reacting with potassium fluoride to exchange halogens, thereby completing the present invention.

The invention will be explained in more detail below.

The solvent benzene in the present invention is thermally stable, so it can be used even in the temperature range of 190 to 400°C, which is considered to be the temperature necessary for halogen exchange of tetrachlorophthalonitriles to tetrafluorophthalonitriles. It has the advantage that there is no side reaction between the solvent and raw materials or products, which occurs with other solvents. In addition, the use of this solvent has the advantage of being able to easily control the temperature and prevent the formation of large amounts of carbide, unlike a manufacturing method without a solvent, and is advantageous in that the desired product can be obtained in high yield during industrial implementation. have.

Examples of fluorinating agents used in the halogen exchange reaction include alkali fluorides such as cesium fluoride, potassium fluoride, and sodium heptafluoride, and fluoride salts of alkaline earth metals such as barium fluoride and calcium fluoride. many.

In some cases, transition metal fluorides such as antimony fluoride are also used. In the present invention, any commonly used fluorinating agent can be used.

Among these, particularly preferred is potassium fluoride, which is easy to handle and commercially available.

The amount of fluorinating agent required is at least equivalent to the chlorine atoms substituted by fluorine atoms in the raw material tetrachlorophthalonitrile, and in the case of potassium fluoride, the amount is 4 times the mole per mole of tetrachlorophthalonitrile. It is sufficient if there are more than that.

In particular, a range of 4 to 8 moles of potassium fluoride is suitable for tetrachlorophthalonitrile.

The reaction temperature of the present invention is preferably in the range of 190 to 400°C. In particular, when producing tetrafluoroisophthalonitrile, the temperature range is preferably 250 to 350°C, and when producing tetrafluoroterephthalonitrile, the temperature range is preferably 210 to 330°C.

When the reaction is carried out at a low temperature, a compound in which chlorine is not completely replaced by fluorine is likely to be produced, and at a high temperature, a carbide is produced, and in both cases, the yield of tetrafluorophthalonitriles is reduced.

In the present invention, in order to carry out the reaction under naturally occurring pressure, approximately 2 kg shoulder to 12 to 9/c It is
Gauge pressure is shown, but it may be further pressurized with an inert gas such as nitrogen.

The reaction time varies depending on the reaction temperature, but is suitably in the range of about 2 hours to 48 hours.

The raw material tetrachlorophthalonitrile is preferably added to the reaction system in an amount of about 5 parts to 50 parts per 100 parts by weight of the solvent.

It is generally said that it is preferable to carry out the nitrogen exchange reaction under anhydrous conditions as much as possible in order to increase the reaction rate and avoid side reactions.

Commonly used DMSO, TMSO,, DMF, N
M.P.

Aprotic polar solvents such as DMS Ot are highly hygroscopic and contain considerable water content. Therefore, prior to the reaction, it is necessary to add benzene, toluene, etc. and remove water by distillation as an azeotrope. In the present invention, benzonitrile does not have hygroscopic properties, so its operation is not required in principle. However, since the potassium fluoride used as a fluorinating agent is highly hygroscopic, in some cases it is preferable to add benzene, toluene, etc. to remove water in advance by distillation as an azeotrope.

In the present invention, a phase transfer catalyst may be present in the reaction system. That is, the presence of a phase transfer catalyst has the advantage of increasing the reaction rate and shortening the reaction time.

As a phase transfer catalyst, dibenzo-18-crown-6
- Crown compounds such as ethers, molecular weight 300-600
Polyethylene glycol and the like can be used.

The appropriate amount to be added is 0.01 mol to 0.25 mol based on the tetrachlorophthalonitrile.

Benzonitrile, the solvent of the present invention, can be easily separated from the product by distillation and can be reused as a solvent in the next reaction.

EXAMPLES The present invention will be explained in more detail with reference to Examples below, but the present invention is not limited thereto.

Example 1 Benzonitrile 2009. Tetrachloroinphthalonitrile so,of (o3 ot mol) and ultrafine dried potassium fluoride 83.9f (1,445 mol) were charged, the air in the reaction vessel was replaced with nitrogen gas, and the mixture was heated at 320°C.
The mixture was heated and stirred for 8 hours. After the reaction was completed, the mixture was cooled to room temperature and suspended potassium chloride and unreacted potassium fluoride were removed by filtration. Analyzing the mother liquor (penzoni) IJ solution using an internal standard method using a gas chromatograph using a packing material of 5E52171L and a column tank temperature of 60°C, it was found that 90.5 mol of tetrafluoroinphthalonitrile was found relative to the charged tetrachloroisophthalonitrile. It was raised. In this analysis chart, almost no peaks of other components such as the peak of unsubstituted isophthalonitrile were observed.

Note that this product peak can be seen in the mass spectrometry spectrum (70e
v; m/e=200.131.100.31)
It was confirmed that it was tetrafluoroinphthalonitrile. By distilling off the solvent benzonitrile from the above mother liquor by vacuum distillation, 52.59 crystals of tetrafluoroisophthalonitrile (M, P,; 73-76°C) were obtained.
was able to be recovered. The elemental analysis value of this crystal is 48.0% carbon.
, fluorine: 383%, and nitrogen: 13.7% (theoretical values: carbon: 48%, fluorine: 38%, nitrogen: 14%).

Example 2 Dipenzo-18-crown-6-ether 5.82(O
, OIS mol) was dissolved in benzonitrile, the same procedure as in Example 1 was carried out, and the mixture was charged into a 500 cc autoclave and heated and stirred at 280°C for 10 hours. After the reaction was completed, the mother liquor obtained in the same manner as in Example 1 was analyzed by gas chromatography, and it was found that the content was 2 mol %, 510 rho2.4.6-), based on the charged tetrachloroisophthalonitrile. ! J fluoroiso7talonitrile 18.7% mole exchanged.

Example 3 A 500 cc autoclave was charged in the same manner as in Example 1 except that tetrachloroterephthalonitrile was used instead of tetrachloroisophthalonitrile.
The mixture was heated and stirred at 70°C for 12 hours. After the reaction was completed, the mother liquor obtained in the same manner as in Example 1 was analyzed by gas chromatography, and it was found that 92.2 mol of tetrafluoroterephthalonitrile was found relative to the charged tetrachloroterephthalonitrile. Benzonitrile was distilled off from this mother liquor under reduced pressure to obtain crystals of tetrafluoroterephthalonitrile (M, P,: 195-197°C).

Claims (6)

[Claims] (1) A process for producing tetrafluoroheptalonitriles, which comprises reacting tetrachlorophthalonitriles with a fluorinating agent in a benzonitrile medium at a temperature in the range of 190 to 400° C. under spontaneous pressure. (2) The method according to claim (1), wherein the tetrachlorophthalonitrile is tetrachloroisophthalonitrile and the tetrafluorophthalonitrile is tetrafluoroinophthalonitrile. (3) The method according to claim (1), wherein the tetrachlorophthalonitrile is tetrachloroterephthalonitrile, and the tetrafluorophthalonitrile is tetrafluoroterephthalonitrile. (4) The fluorinating agent is at least one selected from the group consisting of alkali metal and alkaline earth metal fluoride salts.
The method according to claim (1), (2) or (3), which is a species. (5) The method according to patent application scope (1), (2) or (3), wherein the fluorinating agent is potassium fluoride. (6) The method according to claim (1), (2), (3), (4) or (5), wherein the reaction is carried out in the presence of a phase transfer catalyst.