JPH11255734A - Production method for obtaining aromatic cyanate ester with high purity - Google Patents

Abstract

(57) [Problem] To provide a process for producing an aromatic cyanate ester which is safe and convenient in terms of process and which can obtain a high-purity aromatic cyanate ester in a high yield. SOLUTION: The following general formula (I): (A is each independently a hydrogen atom or a carbon atom having 1 or more 6
The following alkyl groups, X represents a single bond, an organic group having 1 to 20 carbon atoms, a carbonyl group, a sulfone group, a divalent sulfur atom or an oxygen atom, and I represents an integer of 0 or more and 4 or less. A) a phenolate aqueous solution prepared from a phenol, an alkali metal hydroxide and water represented by the formula (1), and an aqueous solution containing a cyanogen halide and a tertiary amine, the pH of which is adjusted to acidic by adding a mineral acid; A method for producing an aromatic cyanate ester with high purity, characterized by contacting and reacting.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to sealing electronic parts,
The present invention relates to a method for producing a thermosetting aromatic cyanate ester useful as a laminate, a composite material, a molding material, and an adhesive.

[0002]

2. Description of the Related Art One of the conventional methods for producing a cyanate ester is to use an alkali metal hydroxide as a base in order to avoid by-products of dialkyl cyanoamide, a liquid impurity having low volatility. A reaction between a metal salt and a cyanogen halide is known (KA Je).
nsen et al. , In the Chemi
try of cyanates and theei
r Thio Derivatives, Part
1, ed. S. Patai Wiley, New
York pp. 569-617 (1977)).
In the case of this method, since the produced cyanate ester reacts with phenoxide to produce imide carbonate, it is considered that this method cannot be applied to any other than an alcoholic or phenolic compound having a bulky substituent at a position adjacent to a hydroxyl group. (R. Strohet al, An
gew. Chem. , 72, 1000 (196
4)). On the other hand, a method for producing a cyanate ester of a phenol having no substituent using a mixed solvent of water and an organic solvent has been reported (Japanese Patent Publication No. 56-3859). As described above, according to a recent analysis method, it has been revealed that this method produces a large amount of imidocarbonates as a by-product and cannot obtain a cyanate ester in a high yield.

[0003]

SUMMARY OF THE INVENTION In view of the above-mentioned problems, an object of the present invention is to provide an aromatic cyanate ester which is safe and simple in terms of process and which can obtain a high-purity aromatic cyanate ester in a high yield. It is to provide a manufacturing method.

[0004]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies on a method for producing a cyanate ester, and as a result, by using water alone as a reaction solvent and performing a specific operation, a high conversion rate was obtained. It was found that a stable aromatic cyanate ester was formed and precipitated in water, and the present invention was completed. That is, the present invention provides the following general formula (I)

[0005]

Embedded image (Wherein, A is each independently a hydrogen atom or carbon atom 1
An alkyl group of 6 or more and X is a single bond, and having 1 to 2 carbon atoms.
0 represents an organic group, carbonyl group, sulfone group, divalent sulfur atom or oxygen atom, and I represents an integer of 0 or more and 4 or less. A) a phenolate aqueous solution prepared from a phenol, an alkali metal hydroxide and water represented by the formula (1), and an aqueous solution containing a cyanogen halide and a tertiary amine and adjusted to an acidic pH by adding a mineral acid to The present invention relates to a method for producing an aromatic cyanate ester with high purity, which is characterized by contacting and reacting.

[0006]

DETAILED DESCRIPTION OF THE INVENTION The phenols used in the present invention can be used as long as they satisfy the general formula (I), but they can be partially or wholly soluble in water as phenolates. It is necessary to be. That is, when at least 1 part by weight or more of a phenol and an alkali metal hydroxide are mixed with respect to 100 parts by weight of water, it is necessary to form a uniform solution. Specific examples of phenols include 4,4'-dihydroxydiphenyl, 3,3 ', 5,5'-tetramethyl-4,
4'-dihydroxydiphenyl, bis (4-hydroxyphenyl) methane, bis (4-hydroxy-3-methylphenyl) methane, bis (4-hydroxy-3-t-butylphenyl) methane, bis (4-hydroxy-3) −i
-Propylphenyl) methane, bis (4-hydroxy-
3,5-dimethylphenyl) methane, bis (2-hydroxy-3-t-butyl-5-methylphenyl) methane,
Bis (4-hydroxyphenyl) ethane, bis (4-hydroxy-3-methylphenyl) ethane, bis (4-hydroxy-3-t-butylphenyl) ethane, bis (4
-Hydroxy-3-i-propylphenyl) ethane, bis (4-hydroxy-3,5-dimethylphenyl) ethane, bis (2-hydroxy-3-t-butyl-5-methylphenyl) ethane, 2,2- Bis (4-hydroxyphenyl) propane (formula

[0007] It is represented by ), 2,2-bis (4-hydroxy-3-
Methylphenyl) propane, 2,2-bis (4-hydroxy-3-t-butylphenyl) propane, 2,2-bis (4-hydroxy-3-i-propylphenyl) propane, 2,2-bis (4 -Hydroxy-3,5-dimethylphenyl) propane, 2,2-bis (2-hydroxy-3-t-butyl-5-methylphenyl) propane,
2,2-bis (4-hydroxy-3-t-butyl-6-
Methylphenyl) propane, 2,2-bis (3-allyl-4-hydroxyphenyl) propane, 1,1-bis (4-hydroxyphenyl) butane, 1,1-bis (4
-Hydroxy-3-methylphenyl) butane, 1,1-
Bis (4-hydroxy-3-t-butylphenyl) butane, 1,1-bis (4-hydroxy-3-i-propylphenyl) butane, 1,1-bis (4-hydroxy-
3,5-dimethylphenyl) butane, 1,1-bis (2
-Hydroxy-3-t-butyl-5-methylphenyl)
Butane, 1,1-bis (4-hydroxy-3-t-butyl-6-methylphenyl) butane, 2,2-bis (3-
Allyl-4-hydroxyphenyl) propane, 1,1-
Bis (3-allyl-4-hydroxyphenyl) butane,
1,1-bis (4-hydroxyphenyl) cyclohexane, 1,1-bis (4-hydroxy-3-methylphenyl) cyclohexane, bis (4-hydroxyphenyl)
Sulfide, bis (4-hydroxy-3-methylphenyl) sulfide, bis (4-hydroxy-3-t-butylphenyl) sulfide, bis (4-hydroxy-3-
i-propylphenyl) sulfide, bis (4-hydroxy-3,5-dimethylphenyl) sulfide, bis (2-hydroxy-3-t-butyl-5-methylphenyl) sulfide, bis (4-hydroxyphenyl) sulfone, Bis (4-hydroxy-3-methylphenyl) sulfone, bis (4-hydroxy-3-t-butylphenyl) sulfone, bis (4-hydroxy-3-i-propylphenyl) sulfone, bis (4-hydroxy-3) , 5
-Dimethylphenyl) sulfone, bis (2-hydroxy-3-t-butyl-5-methylphenyl) sulfone, bis (4-hydroxyphenyl) ether, bis (4-hydroxy-3-methylphenyl) ether, bis (4 −
Hydroxy-3-t-butylphenyl) ether, bis (4-hydroxy-3-i-propylphenyl) ether, bis (4-hydroxy-3,5-dimethylphenyl) ether, bis (2-hydroxy-3-t) -Butyl-5-methylphenyl) ether, bis (4-hydroxyphenyl) carbonyl, bis (4-hydroxy-3-
Methylphenyl) carbonyl, bis (4-hydroxy-
3-t-butylphenyl) sulfide, bis (4-hydroxy-3-i-propylphenyl) carbonyl, bis (4-hydroxy-3,5-dimethylphenyl) carbonyl, bis (2-hydroxy-3-t-butyl) -5-methylphenyl) carbonyl and the like. Especially 2,2
-Bis (4-hydroxyphenyl) propane is industrially available.

The alkali metal hydroxide used for preparing the aqueous phenolate solution is not particularly limited, but includes sodium hydroxide, potassium hydroxide, lithium hydroxide and the like generally used industrially. Particularly, sodium hydroxide is preferable because it can be obtained at low cost.
The amount of the alkali metal hydroxide used is preferably used in excess with respect to the hydroxyl group of the phenol.
Specifically, it is 1.0 to 5.0 times equivalent, more preferably 1.0 to 3.5 times equivalent.

As the cyanogen halide, cyanogen chloride or cyanogen bromide is used. The amount of the cyanogen halide used is preferably an excess with respect to the equivalent of the alkali metal hydroxide in order to suppress by-products of the imide carbonates as impurities. It is 0.05 to 6.0 equivalents, more preferably 1.5 to 4.0 equivalents.

An aqueous solution containing a cyanogen halide and a tertiary amine is prepared by dissolving a cyanogen halide and a tertiary amine in water. The amount of water at that time is preferably at least the minimum necessary for dissolving the cyanogen halide. If a smaller amount of water is used, the cyanogen halide will not be activated by the mineral acid, and an improvement in the yield of aromatic cyanate ester cannot be expected. On the other hand, when the amount of water is large, the productivity is undesirably reduced.

As the tertiary amine, trimethylamine,
Examples include triethylamine, tripropylamine, tributylamine, dimethylethylamine, dimethylaniline, diethylaniline, pyridine, quinoline and the like. Particularly, triethylamine is preferable because it has an appropriate boiling point and is easy to handle industrially. The tertiary amine is preferably used in an amount of 0.05 to 2.0 parts by weight based on 100 parts by weight of phenols, and more preferably 0.05 to 1.0 parts by weight to avoid by-products of dialkylcyanoamide. It is preferable to use parts by weight.

Mineral acids used for adjusting the pH of an aqueous solution containing a cyanogen halide and a tertiary amine include sulfuric acid, nitric acid, and the like.
Phosphoric acid and hydrochloric acid are used, and particularly, hydrochloric acid and sulfuric acid are easily available and preferred. The concentration of the mineral acid is not particularly limited, but a concentration of a dilute acid of 0.1 to 5 N is preferable since an aqueous solution containing a cyanogen halide and a tertiary amine is adjusted to a weak acid having a pH of 3 to 5.

[0013] In the present invention, an aqueous phenolate solution,
PH of aqueous solution containing cyanogen halide and tertiary amine
When reacting with an aqueous solution adjusted to be acidic, the reaction temperature in the reactor is preferably −5 to 30 ° C. when using cyanogen chloride as cyanogen halide, and more preferably for safer handling. Is −5 to 20 ° C. When using cyanogen bromide, the reaction temperature is -5 to 65.
C is preferred. If the temperature is lower than −5 ° C., the reaction solution freezes, which is not preferable.

[0014] In the present invention, an aqueous phenolate solution,
PH of aqueous solution containing cyanogen halide and tertiary amine
An aqueous solution adjusted to be acidic may be contacted and reacted by any method.For example, both of these aqueous solutions may be simultaneously or simultaneously introduced into the reactor from different inlets, continuously or intermittently. Is added dropwise.

After the reaction, post-treatment and purification of the reaction solution are performed by any method. For example, after the reaction is completed, a reaction solution containing a cyanate ester is mixed with water and an organic solvent capable of being separated from water, and an organic solvent layer containing a cyanate ester is separated and recovered from the mixed solution. Layer (concentrated if necessary)
After washing with water, secondary alcohols, tertiary alcohols,
It is carried out by contacting a poor solvent arbitrarily selected from aliphatic hydrocarbons to cause crystallization or precipitation. The concentration is preferably carried out under a reduced pressure at a temperature of 120 ° C. or lower. If the temperature is too high, trimerization starts, which is not preferable. Crystallization or precipitation is carried out by cooling the organic solvent solution containing the cyanate ester, adding it to the poor solvent, adding it in reverse, or cooling the mixture with the poor solvent. Will be

Organic solvents which can be separated from water include ketone solvents such as methyl ethyl ketone and methyl isobutyl ketone; aromatic solvents such as benzene, toluene and xylene;
Ether solvents such as diethyl ether and tetrahydrofuran, methylene chloride, chloroform, carbon tetrachloride, halogenated hydrocarbons such as chlorobenzene, nitrile solvents such as benzonitrile, nitro solvents such as nitrobenzene,
Ester solvents such as ethyl acetate and ethyl benzoate can be used. Among them, ketone solvents and aromatic solvents,
It is preferable to obtain a cyanate ester with good yield, and among them, methyl isobutyl ketone and toluene are preferable. Most preferred is methyl isobutyl ketone. As the poor solvent, secondary or tertiary alcohol solvents such as isopropyl alcohol, amyl alcohol and t-butyl alcohol, and aliphatic hydrocarbons such as benzene, toluene, xylene, hexane and petroleum ether are preferable. Alcohols may be mixed with water at any ratio. Further, the above-mentioned plural solvents may be arbitrarily mixed. Primary alcohols such as methanol and ethanol can be used, but are not preferred because the yield of cyanate ester is reduced.

The high-purity aromatic cyanate ester obtained by the production method of the present invention can be used as a thermosetting resin for sealing electronic parts, for laminates, for composite materials, for molding materials, and for adhesives. Used. Examples of the present invention will be described below, but the present invention is not limited to these examples.

[0018]

Example 1 20 g (0.0865 mol) of 2,2-bis (4-hydroxyphenyl) propane (manufactured by Mitsui Toatsu Chemicals, Inc.) and 18.25 g (0.438 mol) of 96% caustic soda in 500 g of water After uniformly dissolving the phenolate, the mixture was cooled to prepare an aqueous phenolate solution. 400 g of this phenolate solution, 31.92 g (0.519 mol) of cyanogen chloride and 0.15 g (0.0015 mol) of triethylamine were placed in a reactor equipped with a thermometer, a stirrer, a dropping funnel and a reflux condenser.
In water, and 1N hydrochloric acid (0.4 g) was added to the solution to pH 3.6.
And the solution adjusted to the above at the same time simultaneously from different dropping funnels, was dropped at a constant dropping rate at 0 to 10 ° C (dropping time 40 minutes), and after the dropping was completed, the inside of the vessel was kept at the same temperature for 15 minutes. Held. Next, methyl isobutyl ketone (as an organic solvent capable of liquid separation with water) was added thereto, followed by liquid separation, and the organic layer was washed with water. Next, the organic layer was concentrated under reduced pressure, isopropyl alcohol was added dropwise, cooled, and stirred for 1 hour. The resulting slurry was filtered, washed with isopropyl alcohol, and air-dried to obtain white crystals having a melting point of 80 ° C.
97 g (86% yield) were obtained. Liquid chromatography (LC)
As a result, no unreacted starting bisphenol or monocyanate was detected. No imidocarbonate generated by a side reaction was detected (purity 99 +%). Chloride ions detected by potentiometric titration using silver nitrate were 10 ppm or less.

Example 2 The procedure of Example 1 was repeated, except that a mixed aqueous solution of cyanogen chloride and triethylamine was adjusted to pH 4.3 with 1N hydrochloric acid to obtain 20.72 g (yield: 85%) of white crystals. .
When this was analyzed by LC, unreacted starting materials, bisphenol and monocyanate, were not detected. No imidocarbonate generated by a side reaction was detected (purity 99 +%). Chloride ions detected by potentiometric titration using silver nitrate were 10 ppm or less.

Example 3 In Example 1, a 96% aqueous phenolate solution was prepared.
19.50 g of white crystals were obtained under the same conditions except that 21.90 g (0.526 mol) of caustic soda and 29.27 g (0.470 mol) of cyanogen chloride were used.
(80% yield). When the product was analyzed by LC, unreacted raw materials of bisphenol and monocyanate were not detected. No imidocarbonate generated by a side reaction was detected (purity 99 +%). Chloride ion detected by potentiometric titration using silver nitrate is 10p
pm or less.

Example 4 In Example 1, triethylamine 0.1 was used as the tertiary amine.
g of white crystals, except that g was used.
50 g was obtained (80.0% yield). When the product was analyzed by LC, unreacted raw materials of bisphenol and monocyanate were not detected. No imide carbonate generated by a side reaction was detected (purity 99+
%). Chloride ions detected by potentiometric titration using silver nitrate were 10 ppm or less.

Example 5 The procedure of Example 1 was repeated, except that trimethylamine was used as the tertiary amine, to obtain 19.38 g of white crystals (yield: 79.5%). When the product was analyzed by LC, unreacted raw materials of bisphenol and monocyanate were not detected. No imidocarbonate generated by a side reaction was detected (purity 99 +%). Chloride ion detected by potentiometric titration using silver nitrate is 10p
pm or less.

Example 6 In Example 1, 0.18 of tributylamine was used as a tertiary amine.
g of white crystals, except that g was used.
38 g were obtained (79.5% yield). When the product was analyzed by LC, unreacted raw materials of bisphenol and monocyanate were not detected. No imide carbonate generated by a side reaction was detected (purity 99+
%). Chloride ions detected by potentiometric titration using silver nitrate were 10 ppm or less.

Example 7 The procedure of Example 1 was repeated, except that toluene was used as a solvent capable of being separated from water after the completion of the reaction. Rate 76.0
%). When the product was analyzed by LC, unreacted raw materials of bisphenol and monocyanate were not detected. No imidocarbonate generated by a side reaction was detected (purity 99 +%). Chloride ions detected by potentiometric titration using silver nitrate were 10 ppm or less.

Example 8 The procedure of Example 1 was repeated, except that 100 g of an 86% aqueous solution of isopropyl alcohol was used as a poor solvent for crystallization and washing, and 18.53 g of white crystals were used.
Was obtained (76.0% yield). When the product was analyzed by LC, unreacted raw materials of bisphenol and monocyanate were not detected. No imidocarbonate generated by a side reaction was detected (purity 99 +%). Chloride ion detected by potentiometric titration using silver nitrate is 1
It was 0 ppm or less.

Example 9 The procedure of Example 1 was repeated, except that 110 g of heptane was used as a poor solvent for crystallization and washing, to obtain 18.04 g of white crystals (yield: 74.10 g). 0
%). When the product was analyzed by LC, unreacted raw materials of bisphenol and monocyanate were not detected. No imidocarbonate generated by a side reaction was detected (purity 99 +%). Chloride ions detected by potentiometric titration using silver nitrate were 10 ppm or less.

Comparative Example 1 20.0 g (0.0865 mol) of 2,2-bis (4-hydroxyphenyl) propane (manufactured by Mitsui Toatsu Chemicals, Inc.)
l), 7.3 g of 96% caustic soda (0.1752 mol)
l) was added to 500 g of water, and the temperature was raised while stirring to 65 ° C. When 2,2-bis (4-hydroxyphenyl) propane was completely dissolved, the mixture was cooled to 5 ° C or lower. On the other hand, 400 g of toluene was placed in a 1 L separable flask connected with a stirring blade, a dropping funnel, and a reflux tube, and cooled to 5 ° C. under a nitrogen atmosphere. Cyanide chloride 1 in cooled toluene
After adding 6.9 ml (20.0 g, 0.3252 mol) and 0.1 g (0.989 mmol) of triethylamine, the mixture was stirred at 600 rpm. Next, an aqueous phenolate solution was added dropwise while maintaining the internal temperature at 5 ° C. After dropping,
The oil layer was analyzed by LC. As a result, the yield of the obtained dicyanate compound based on bisphenol was as low as 40%, and 5% of unreacted monocyanate compound was detected. According to analysis by gel permeation chromatography (GPC), a high molecular weight peak considered to be imidocarbonate was 5% by area percentage.
0% was seen.

Comparative Example 2 The procedure of Example 1 was repeated, except that the pH of an aqueous solution of cyanogen chloride and triethylamine dissolved in water was not adjusted. As a result, 18.04 g of white crystals having a melting point of 80 ° C. (yield 74)
%). As is evident from the examples, by adjusting the aqueous solution containing cyanogen chloride and triethylamine to a specific pH and contacting it with an aqueous phenolate solution (preferably using an amount of caustic soda in excess of the hydroxyl equivalent of phenol), a high yield is obtained. A high purity dicyanate can be obtained at a high rate. As shown in Comparative Example 1, it was difficult to remove the imidocarbonate-based compound as an impurity by-produced in the conventional method in which the reaction was carried out in a mixed system of an organic solvent and water. In addition, in the case of the present invention (Example 1) in which an aqueous solution in which a cyanogen halide and a tertiary amine are dissolved was dropped after adjusting the pH, a cyanate ester was obtained in a higher yield than in Comparative Example 2 in which no adjustment was made. Was completed. The present invention
Since only water is used as a solvent in the reaction, the risk of runaway reaction due to polymerization of cyanogen halide is very low and safe,
It can be said that this is an excellent process that can be carried out on an industrial scale.

[0029]

According to the production method of the present invention, a high-purity aromatic cyanate ester can be obtained in a safe and simple process and at a high yield.

Claims (8)

[Claims] (1) The following general formula (I): (I) (wherein, A is each independently a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, X is a single bond,
To 20, an organic group, a carbonyl group, a sulfone group, a divalent sulfur atom or an oxygen atom, and I represents an integer of 0 or more and 4 or less. A) a phenolate aqueous solution prepared from a phenol, an alkali metal hydroxide and water represented by the formula (1), and an aqueous solution containing a cyanogen halide and a tertiary amine, the pH of which is adjusted to acidic by adding a mineral acid; A method for producing an aromatic cyanate ester with high purity, characterized by contacting and reacting. 2. The method according to claim 1, wherein the phenol has a solubility of 1% or more in water as an aqueous phenolate solution. 3. The method according to claim 1, wherein the phenol is represented by the following formula. Embedded image 4. The process according to claim 1, wherein caustic soda or caustic potash is used as the alkali metal hydroxide when preparing the aqueous phenolate phenolate solution, and the amount thereof is 1.5 to 5 equivalents to the hydroxyl group of the phenol. Method. 5. A method according to claim 1, wherein cyanogen chloride is used as the cyanogen halide, and the amount of the cyanogen is 1.5 to 1.5 with respect to the hydroxyl group of the phenol.
The method according to claim 1, wherein 5.5 equivalents are used. 6. After completion of the reaction, a reaction solution containing a cyanate ester is mixed with water and an organic solvent capable of being separated from water, and an organic solvent layer containing a cyanate ester is separated from the mixed solution and collected. After washing the organic solvent layer with water, secondary alcohols,
The production method according to claim 1, wherein a poor solvent arbitrarily selected from tertiary alcohols and aliphatic hydrocarbons is brought into contact with the mixture to cause crystallization or precipitation. 7. The production method according to claim 6, wherein methyl isobutyl ketone, toluene or a mixture thereof is used as the organic solvent capable of being separated from water. 8. A poor solvent comprising isopropyl alcohol, isobutyl alcohol, tert-butyl alcohol, s
The method according to claim 7, wherein ec-butyl alcohol and / or a hydroalcohol thereof, pentane, hexane, heptane, cyclopentane, cyclohexane, cyclopentane or a mixture thereof is used.