JPH085960B2 - Method for producing polycyanoaryl ether - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for producing a polycyanoaryl ether useful as a material for electronic and electric devices and various mechanical parts,
More specifically, it relates to a method for producing a polycyanoaryl ether capable of producing a polymer having a sufficiently high molecular weight.

[Conventional technology]

The polycyanoaryl ether produced from a dihalogenated benzonitrile and a dihydroxyaryl compound is
It is a resin with excellent heat resistance and mechanical strength, and is known as a high-performance engineering plastic useful as a material for electronic and electrical equipment and various mechanical parts. As a method for producing this polycyanoaryl ether, there is known a method in which a dihalogenated benzonitrile and a dihydroxyaryl compound are reacted in a polar solvent in the presence of an alkali metal carbonate or an alkali metal hydrogen carbonate (special feature: JP-A-59-206433, JP-A-62-225226, etc.). In addition, the dihalogenated benzonitrile that is a raw material for producing this polycyanoaryl ether has various other uses, and in particular, 2,6-dichlorobenzonitrile is often used as a raw material for producing a polycyanoaryl ether. It is also known as a pesticide herbicide. Impurities are not a problem when these dihalogenated benzonitriles are used for applications such as agricultural chemicals. However, when used as a raw material for a polymer produced by combining a polycyanoaryl ether, particularly a dihydroxyaryl compound such as resorcinol, impurities suppress an increase in molecular weight during polymerization and produce a polymer having a sufficiently high molecular weight. It was an obstacle to doing.

[Problems to be solved by the invention]

An object of the present invention is to solve the above problems and provide a method for producing a polycyanoaryl ether having a sufficiently high molecular weight.

[Means for solving problems]

The present inventors have conducted extensive studies to solve the above-mentioned problems, and as a result, lower carboxylic acids or salts thereof contained in the crude dihalogenated benzonitrile, particularly acetic acid or sodium acetate, suppress an increase in the molecular weight of the polymerized dihalogenated benzonitrile. Based on this finding, the present invention has been completed.

That is, the present invention provides a dihalogenation having a content of a lower carboxylic acid or a salt thereof of 30 to 500 ppm, which is obtained by washing a crude dihalogenated benzonitrile with at least one selected from a lower alcohol, a ketone, and water. Provided is a method for producing a polycyanoaryl ether, which comprises reacting benzonitrile and a dihydroxyaryl compound in a polar solvent in the presence of an alkali metal carbonate or an alkali metal hydrogen carbonate.

The dihalogenated benzonitrile used in the method of the present invention has a content of the lower carboxylic acid or its salt of 30 to 30.
It is 500 ppm. If the content of the lower carboxylic acid or its salt is less than 30 ppm, the polymerization rate may slow down. If it exceeds 500 ppm, an increase in molecular weight during polymerization is suppressed, and a polycyanoaryl ether having a sufficiently high molecular weight cannot be obtained.

Examples of the above lower carboxylic acid include acetic acid, formic acid,
Examples thereof include propionic acid, and examples of the salt include sodium salt, potassium salt, pyridine salt and the like.

The dihalogenated benzonitrile having a content of the above-mentioned lower carboxylic acid or a salt thereof can be obtained by purifying a crude dihalogenated benzonitrile, for example, a commercially available dihalogenated benzonitrile having an acetic acid content of about 1000 ppm. The crude dihalogenated benzonitrile is purified by washing with at least one selected from lower alcohols, ketones and water. In addition, purification by recrystallization can be considered, but when purified by recrystallization, the recovery rate is low and it is not industrially suitable. In addition, the content of the lower carboxylic acid or its salt becomes too low, and the polymerization may be delayed.

As the lower alcohol used for purification by the above washing, alcohols having 1 to 3 carbon atoms such as methanol, ethanol, propanol and i-propanol are preferably used. These lower alcohols can also be used as a mixture of two or more kinds. Further, as the ketone, for example, a ketone having 3 or 4 carbon atoms such as acetone or methyl ethyl ketone is preferably used. These ketones can also be used as a mixture of two or more kinds.

When cleaning is performed using at least one of alcohols, ketones, or water as described above, the cleaning method is not particularly limited, but usually, crude dihalogenated benzonitrile and at least one kind of alcohol, ketone, or water are used. The mixture with and may be stirred. However, it is desirable to stir at a temperature of 20 ° C or higher for 10 minutes or longer. Under this condition, it may not be sufficiently washed. The amount of alcohol, ketone, or water used is not particularly limited, but it is desirable to use 150 ml or more per 100 g of dihalogenated benzonitrile. If it is less than this, it may not be sufficiently washed.

In the case of washing with water, first, the crude dihalogenated benzonitrile is dissolved in a water-insoluble solvent, the resulting solution is extracted with water, and the solvent of the organic layer is distilled off to produce the purified dihalogenated benzonitrile. The method of obtaining the nitrile is preferred.

Examples of the water-insoluble solvent include methylene chloride, toluene, benzene, carbon tetrachloride and the like.
The amount of this water-insoluble solvent is sufficient as long as it is sufficient to dissolve the crude dihalogenated benzonitrile, but usually 1000 ml with respect to 100 g of the crude dihalogenated benzonitrile.
Is desirable. The amount of water used for extraction is
Although not particularly limited, it is desirable to repeat extraction several times by using 200 g of water for 100 g of crude dihalogenated benzonitrile for one extraction.

The dihalogenated benzonitrile used in the method of the present invention is a dihalogenated benzonitrile in which two halogen atoms such as a fluorine atom and a chlorine atom are bonded to carbon atoms of a benzene ring, and at least one cyano group is bonded. Benzonitriles.

As the dihalogenated benzonitrile, for example,
2,4-dichlorobenzonitrile, 2,6-dichlorobenzonitrile, 2,4-difluorobenzonitrile, 2,6-difluorobenzonitrile, 2-chloro-6-fluorobenzonitrile, 2,6-dichloro-1, 4-dibenzonitrile, 2,
6-dichloro-4-methylbenzonitrile and the like can be mentioned. Of these, 2,6-dichlorobenzonitrile and 2,6-difluorobenzonitrile are particularly preferable.

The dihydroxyaryl compound in the present invention is an aromatic compound having two phenolic hydroxyl groups (hydroxyl groups directly bonded to carbon atoms constituting an aromatic ring).

Examples of the dihydroxyaryl compound include 1,2-dihydroxybenzene, 1,3-dihydroxybenzene and 1,4
-Dihydroxybenzenes such as dihydroxybenzene, 2-methyl-1,4-dihydroxybenzene, 2,6-dimethyl-1,4-dihydroxybenzene and 2-methoxy-1,4-dihydroxybenzene; 4,4'-dihydroxy Dihydroxybiphenyls such as biphenyl, 3,5'-dihydroxybiphenyl, 3,5-dihydroxybiphenyl, 3-methyl-4,4'-dihydroxybiphenyl, 2,2'-dimethyl-4,4'-dihydroxybiphenyl; 1 , 2-dihydroxynaphthalene, 1,3-dihydroxynaphthalene, 1,4-dihydroxynaphthalene, 1,5-dihydroxynaphthalene,
1,6-dihydroxynaphthalene, 1,7-dihydroxynaphthalene, 1,8-dihydroxynaphthalene, 2,3-dihydroxynaphthalene, 2,6-dihydroxynaphthalene, 2,7-
Dihydroxynaphthalene, dihydroxynaphthalene such as 4,8-dimethyl-2,6-dihydroxynaphthalene; 4,4 ′
And dihydroxydiphenyl ethers such as dihydroxydiphenyl ether. A particularly preferred dihydroxyaryl compound is 1,3-dihydroxybenzene (resorcinol).

The amounts of the dihalogenated benzonitrile and the dihydroxyaryl compound used are determined in relation to the degree of polymerization of the desired polymer. Both need only be used in approximately equimolar amounts, but there is no inconvenience even if they are not in equimolar amounts.

The alkali metal carbon salt used in the method of the present invention is preferably sodium carbonate or potassium carbonate. The alkali metal hydrogen carbonate used in the method of the present invention is preferably sodium hydrogen carbonate or potassium hydrogen carbonate.

The amount of the alkali metal carbonate or the alkali metal hydrogen carbonate used may be an amount sufficient to convert the dihydroxyaryl compound into the alkali salt. Usually, an alkali metal carbonate or an alkali metal hydrogen carbonate is used in a molar ratio of 1.0 to 3.0 with respect to the dihalogenobenzonitrile.

In the method of the present invention, the reaction is carried out in a polar solvent.
The polar solvent used is an organic solvent which is neutral, has a large polarity, and has a high solubility in an alcohol having 1 to 4 carbon atoms and / or a ketone having 3 to 7 carbon atoms, and is not an alcohol or a ketone. It is an organic solvent. In addition, a solvent having a large polarity generally means a solvent having a large dielectric constant and / or a dipole moment. For example, a solvent having a dielectric constant of 20 or more and a dipole moment of 3.0 Debye or more is usually included in a strongly polar solvent. Be done. Examples of such organic solvent include N-alkyl carboxylic acid amides such as N-methylformamide and N-ethylacetamide; N, N-dimethylformamide, N, N-diethylformamide and N, N-dimethylacetamide. N-dialkylcarboxylic acid amides; N such as N-methylpyrrolidone and N-ethylpyrrolidone
-Alkyl lactams; N-, such as N-methylpyrrolidinone
Alkyl carboximides; Sulfoxides such as dimethyl sulfoxide, diethyl sulfoxide; Sulfones such as dimethyl sulfone, diethyl sulfone, diphenyl sulfone; Cyclic sulfones such as sulfolane; Acetonitrile, propionnitrile, butyronitrile, succinonitrile, benzonitrile, etc. Nitriles; and mixtures thereof can be mentioned.

Among these neutral polar solvents, dimethyl sulfoxide, dimethyl sulfone, diethyl sulfone, diphenyl sulfone, sulfolane, N, N-dimethylacetamide, N, N-dimethylformamide, N-methylpyrrolidone, N-methylpyrrolidinone and the like Protic polar organic solvents and mixtures thereof are preferred, such as sulfolane, N
-Methylpyrrolidone and the like are particularly preferable.

The amount of the solvent used may be an amount sufficient to dissolve the dihalogenated benzonitrile, dihydroxyaryl compound, and alkali metal carbonate or alkali metal hydrogen carbonate used.

The reaction temperature is 140 to 350 ° C, preferably 160 to 250 ° C, and the reaction time is 1 to 6 hours, preferably 2 to 4 hours.
The reaction is usually carried out at atmospheric pressure in an inert atmosphere, for example in an argon gas atmosphere or a nitrogen gas atmosphere,
It may be carried out under pressure or under reduced pressure.

In this process, as a molecular weight regulator, the formula (In the formula, R represents any one of a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, an aryl group, an aralkyl group, and a cyano group.) You may add the monohydric phenol. Examples of the monohydric phenol represented by the above formula (I) include phenol, cresol, p-t-butylphenol, cumylphenol, isopropylphenol, methoxyphenol, and cyanophenol.

Further, the addition amount of the molecular weight regulator of the formula (I) is determined from the relationship with the molecular weight of the target polymer.

In the method of the present invention, it is preferable that the dihalogenated benzonitrile is first reacted with dichlorobenzonitrile and then with difluorobenzonitrile. According to this method, higher molecular weight is promoted and productivity can be increased.

In this case, the reaction in the first step using dichlorobenzonitrile is carried out at a reaction temperature of 150 to 250 ° C., preferably 180 to 210 ° C.
It is desirable to carry out at 5 ° C. for 2 to 5 hours, preferably 2.5 to 4 hours. Also in this process, the above-mentioned molecular weight modifier for monohydric phenol can be used.

Then, as a second step, difluorobenzonitrile is added as a dihalogenated benzonitrile to carry out the reaction. The amount of difluorobenzonitrile used is preferably a relative amount (molar ratio) of 0.001 to 0.05 with respect to the amount 1 of the dihydroxyaryl compound used. The reaction temperature is 180 to 250 ° C, preferably 190 to 220 ° C, and the reaction time is 0.5 to 5 hours, preferably 1.0 to 2.0 hours. In this process, it is preferable to add a monohalogenated hydrocarbon as a molecular weight regulator. Examples of such monohalogenated hydrocarbons include methyl chloride, 2-fluorobenzonitrile, 4-fluorobenzonitrile, 2-fluorobenzophenone, and 4-chlorodiphenylsulfone. Further, the addition amount of this molecular weight modifier is determined in relation to the molecular weight of the target polymer.

In the method of the present invention, the water generated from the reaction between the dihydroxyaryl compound and the alkali metal carbonate or the alkali metal hydrogen carbonate may be removed by azeotropic distillation with water and a solvent that forms an azeotrope. desirable. By removing water, a polycyanoaryl ether having a higher molecular weight can be obtained.
The water may be removed through the reaction or at the time of forming the prepolymer. As the solvent that can be used in the method of the present invention to form an azeotrope with water, benzene,
Examples include toluene, xylene, ethylbenzene, chlorobenzene and dichlorobenzene.

〔Example〕

Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples.

Examples 1 to 5, 2,6-dichlorobenzonitrile containing 750 ppm of acetic acid 1
00 g was washed under the conditions shown in Table 1, and the yield of purified 2,6-dichlorobenzonitrile and the amount of acetic acid contained therein were measured. The amount of acetic acid was measured using an ion chromatography-IC-100 manufactured by Yokogawa Corporation.

Since 2,6-difluorobenzonitrile was added in a small amount and the influence of impurities was small, it was used without purification.

Using purified 2,6-dichlorobenzonitrile and 2,6-difluorobenzonitrile, a polymerization reaction was carried out by the method shown below.

A separable flask with a capacity of 300 ml equipped with a Dean Stark trap, a stirrer, an argon gas injection tube, and a thermocouple was charged with 25.754 g of 2,6-dichlorobenzonitrile, 16.516 g of resorcinol, 17.5 g of sodium carbonate and 150 ml of N-methylpyrrolidone. The temperature was raised from 20 ° C to 200 ° C over 40 minutes in an argon gas atmosphere. After heating, 5 ml of toluene was added, and dehydration was performed for 90 minutes using a Dean Stark trap under reflux of toluene. After removing the toluene, heating and stirring was continued at 200 ° C. 50 minutes after dehydration, 2,6
-0.26 g of difluorobenzonitrile was added. The heating was stopped 120 minutes after the addition of 2,6-difluorobenzonitrile. The obtained polymer was ground with a blender, washed with methanol and water, dried, and then the reduced viscosity was measured.
The reduced viscosity is measured using p-chlorophenol as a solvent.
It was carried out at 60 ° C. for a solution having a concentration of 0.2 g / dl.

 The results are shown in Table 1.

However, in Example 2, heating was continued for 120 minutes or more after addition of 2,6-difluorobenzonitrile, sampling was performed, and the reduced viscosity was measured with time. The results are shown in Table 2.

Comparative Example 3 2,6-dichlorobenzonitrile 1 containing 750 ppm of acetic acid
00 g was dissolved in methylene chloride 1, 200 ml of water was shaken for 5 minutes using a separating funnel, and this was repeated 5 times. Then, the solvent was distilled off, and 2,6-dichlorobenzonitrile was deposited and dried to obtain purified 2,6-dichlorobenzonitrile. The recovery rate of 2,6-dichlorobenzonitrile and the amount of residual acetic acid are shown in Table 1. Then, the obtained purified 2,6-dichlorobenzonitrile was polymerized in the same manner as in Examples 1 to 5. The reduced viscosity of the obtained polymer is shown in Table 1.

Comparative Example 1 2,6-Dichlorobenzonitrile 1 containing 750 ppm of acetic acid
kg was recrystallized from 15 l of ethanol according to a conventional method. The recovery rate was 80% and the amount of residual acetic acid was 25 ppm. The obtained purified 2,6-dichlorobenzonitrile was used in Example 1
Polymerization was carried out in the same manner as in ~ 5. The reduced viscosity of the obtained polymer is shown in Table 1.

Comparative Example 2 Commercially available 2,6-dichlorobenzonitrile (acetic acid content: 75
Polymerization was carried out in the same manner as in Example 2 using 0 ppm), and the time-dependent change in reduced viscosity is shown in Table 2.

[Effect of the Invention] According to the method of the present invention, a polycyanoaryl ether having a sufficiently high molecular weight can be produced with high productivity in a short reaction time, and its industrial value is great.

Claims (3)

[Claims] 1. A dihalogenation obtained by washing a crude dihalogenated benzonitrile with at least one selected from a lower alcohol, a ketone, and water and having a content of a lower carboxylic acid or a salt thereof of 30 to 500 ppm. A method for producing a polycyanoaryl ether, which comprises reacting benzonitrile and a dihydroxyaryl compound in a polar solvent in the presence of an alkali metal carbonate or an alkali metal hydrogencarbonate. 2. The method for producing a polycyanoaryl ether according to claim 1, wherein resorcinol is used as the dihydroxyaryl compound. 3. A polycyanoaryl ether according to claim 1, wherein the dihalogenated benzonitrile obtained by washing is first reacted with dichlorobenzonitrile and then with difluorobenzonitrile. Production method.