JPH11228521A - Method for producing high-purity aromatic cyanate esters - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To provide a production process which is safe and simple in terms of process, and in which aromatic cyanates of high purity can be obtained in high yield. The following general formula (I): (I) (A is each independently a hydrogen atom or a carbon atom having 1 or more 6
The following alkyl groups, X is 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 is an integer of 0 or more and 4 or less. Is dissolved in water in the presence of an alkali metal hydroxide to form an aqueous solution, and the aqueous solution and cyanogen halide are added together in water containing a tertiary amine. Is added, and an aqueous solution of an alkali metal hydroxide is poured into the water.
A method for producing a high-purity aromatic cyanate ester, wherein H is added while adjusting the alkalinity.

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 compound is a phenol alkali metal hydroxide using an alkali metal hydroxide as a base in order to avoid by-products of dialkyl cyanoamide, a liquid impurity having low volatility. The reaction of a salt with 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 reacts with phenoxide to produce imide carbonate,
It has been reported that the method cannot be applied to compounds other than alcoholic or phenolic compounds having a bulky substituent at the position adjacent to the hydroxyl group (R. Stroh et al., Angew.
Chem. , 72, 1000 (1964)).
On the other hand, cyanate esterification of phenols having no substituents has been reported using a mixed solvent of water and an organic solvent (Japanese Patent Publication No. 56-3859). It became clear that many carbonates were produced as by-products and that cyanate esters could not be obtained in high yield (see Comparative Example 1 described later).

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide a process for producing aromatic cyanate esters of high purity in a high yield, which is safe and simple in process.

[0004]

Means for Solving the Problems The present inventors have conducted intensive studies on a method for producing a cyanate ester. As a result, by using water alone as a reaction solvent and adopting a specific method, water can be obtained. The present inventors have found that aromatic cyanate having a high conversion rate can be stably formed and precipitated, thereby completing the present invention. That is, the present invention provides the following general formula (I)

Embedded image (I) (wherein, A is each independently a hydrogen atom or a carbon number 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, 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. Is dissolved in water in the presence of an alkali metal hydroxide to form an aqueous solution, and the aqueous solution and cyanogen halide are added together in water containing a tertiary amine. And then adding an aqueous solution of an alkali metal hydroxide to the water while adjusting the pH to alkaline, to a method for producing a high-purity aromatic cyanate ester.

[0005]

DETAILED DESCRIPTION OF THE INVENTION As the phenol used in the present invention, any phenol can be used as long as it satisfies the general formula (I). It is necessary to be. That is, it is necessary to mix a phenol, an alkali metal hydroxide, and water to form a uniform aqueous solution in which at least 1 part by weight of the phenol is dissolved with respect to 100 parts by weight of water. 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-iso-propylphenyl) methane, bis (4-hydroxy-3,5-dimethylphenyl) methane, bis (2-hydroxy- 3-tert-butyl-5
-Methylphenyl) methane, bis (4-hydroxyphenyl) ethane, bis (4-hydroxy-3-methylphenyl) ethane, bis (4-hydroxy-3-tert-)
Butylphenyl) ethane, bis (4-hydroxy-3-
iso-propylphenyl) ethane, bis (4-hydroxy-3,5-dimethylphenyl) ethane, bis (2-
Hydroxy-3-tert-butyl-5-methylphenyl) ethane, 2,2-bis (4-hydroxyphenyl)
Propane (formula

[0006]

Embedded image It is represented by ), 2,2-bis (4-hydroxy-3-
Methylphenyl) propane, 2,2-bis (4-hydroxy-3-tert-butylphenyl) propane,
2-bis (4-hydroxy-3-iso-propylphenyl) propane, 2,2-bis (4-hydroxy-3,
5-dimethylphenyl) propane, 2,2-bis (2-
Hydroxy-3-tert-butyl-5-methylphenyl) propane, 2,2-bis (4-hydroxy-3-t
tert-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-te
rt-butylphenyl) butane, 1,1-bis (4-hydroxy-3-iso-propylphenyl) butane,
1,1-bis (4-hydroxy-3,5-dimethylphenyl) butane, 1,1-bis (2-hydroxy-3-t
tert-butyl-5-methylphenyl) butane, 1,1
-Bis (4-hydroxy-3-tert-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-tert-butylphenyl) Sulfide, bis (4-hydroxy-3-i
so-propylphenyl) sulfide, bis (4-hydroxy-3,5-dimethylphenyl) sulfide, bis (2-hydroxy-3-tert-butyl-5-methylphenyl) sulfide, bis (4-hydroxyphenyl) sulfone, Bis (4-hydroxy-3-methylphenyl) sulfone, bis (4-hydroxy-3-tert)
-Butylphenyl) sulfone, bis (4-hydroxy-
3-iso-propylphenyl) sulfone, bis (4-
Hydroxy-3,5-dimethylphenyl) sulfone, bis (2-hydroxy-3-tert-butyl-5-methylphenyl) sulfone, bis (4-hydroxyphenyl) ether, bis (4-hydroxy-3-methylphenyl) Ether, bis (4-hydroxy-3-tert
-Butylphenyl) ether, bis (4-hydroxy-
3-iso-propylphenyl) ether, bis (4-
Hydroxy-3,5-dimethylphenyl) ether, bis (2-hydroxy-3-tert-butyl-5-methylphenyl) ether, bis (4-hydroxyphenyl) carbonyl, bis (4-hydroxy-3-methylphenyl) Carbonyl, bis (4-hydroxy-3-te
rt-butylphenyl) sulfide, bis (4-hydroxy-3-iso-propylphenyl) carbonyl, bis (4-hydroxy-3,5-dimethylphenyl) carbonyl, bis (2-hydroxy-3-tert-butyl-5) -Methylphenyl) carbonyl and the like. In particular, 2,2-bis (4-hydroxyphenyl) propane is industrially easily available.

The alkali metal hydroxide used in the reaction 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, 1.0 to 5.0
It is twice equivalent, more preferably 1.0 to 3.5 times equivalent.

As the cyanogen halide, cyanogen chloride or cyanogen bromide is used. The reaction temperature in the case of using cyanogen chloride is -5 to 30C, more preferably -5 to 20C for safe handling, and the reaction temperature in the case of using cyanogen bromide is -5 to 65C. If the temperature is lower than −5 ° C., the reaction solution freezes, which is not preferable. The amount of the cyanogen halide to be used is preferably an excess with respect to the equivalent amount of the alkali metal hydroxide in order to suppress the by-product of the impurity imide carbonates. The equivalent is 0.5 to 6.0 equivalents, and more preferably 1.5 to 4.0 equivalents.

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. In the method of the present invention, a method of simultaneously adding an aqueous solution of a phenol and a cyanogen halide to water containing a tertiary amine includes, for example, adding an aqueous solution of a phenol to a reaction vessel containing water containing a tertiary amine. Any method can be used, such as simultaneously dropping cyanogen halide from different inlets. In this case, it is preferable to add the cyanogen halide in advance so that the cyanogen halide is present in the reaction solution in an amount equal to or more than that of caustic soda.

The aqueous alkali metal hydroxide solution includes:
A 0.1N to 10N aqueous solution of sodium hydroxide or potassium hydroxide is used. The aqueous alkali metal hydroxide solution is added while adjusting the reaction solution to pH 8 to 12. If the pH is lower than this, the reaction does not proceed, and if it is higher than this, impurities of imide carbonate are generated, which is not preferable. The pH is more preferably 10 to 11 in order to increase the purity and storage stability of the cyanate ester.

The purification of the aromatic cyanate ester is carried out as required. In this method, the organic solvent is dissolved in water and an organic solvent capable of being separated from the liquid by raising the temperature. The obtained organic solvent solution or a crude product obtained by concentrating the solution as necessary is contacted with a secondary solvent, a tertiary alcohol, or a poor solvent arbitrarily selected from aliphatic hydrocarbons, This is performed by crystallization or precipitation. The concentration is preferably carried out by evaporating the organic solvent under reduced pressure at a temperature of 120 ° C. or lower. In this case, if the temperature is too high, trimerization starts, which is not preferable. Crystallization or precipitation is carried out by cooling an organic solvent capable of being separated from water, adding it to a poor solvent, adding it in reverse, or cooling a mixture of the poor solvent and the poor solvent.

Examples of the organic solvent 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 or aromatic solvents are preferable because aromatic cyanates can be recovered in good yield when they are used. Among them, methyl isobutyl ketone and toluene are preferred. Most preferred is methyl isobutyl ketone.

As the poor solvent, secondary or tertiary alcohol solvents such as isopropyl alcohol, amyl alcohol and tert-butyl alcohol, and aliphatic hydrocarbons such as benzene, toluene, xylene, hexane and petroleum ether are preferred. 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 is reduced. Examples of the present invention will be described below, but the present invention is not limited to these examples.

[0014]

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 Then, the mixture was cooled to prepare a phenolate solution. 0.15 g of triethylamine was placed in a reactor equipped with a thermometer, a stirrer, a dropping funnel and a reflux condenser.
(0.0015 mol), 100 g of water at 0 to 5 ° C., and 7.97 g of cyanide chloride (0.130 m
ol) (to ensure that the cyanogen halide is at least equal to caustic soda), followed by the addition of a previously prepared phenolate solution to 23.94 g (0.38 g) of cyanogen chloride.
9 mol) at the same time as the temperature was kept at 0 to 10 ° C. Further, a 5N aqueous solution of caustic soda was added to this solution at pH
Was adjusted so as to be in the range of 10 to 11 and stirred. One hour later, the pH was adjusted to neutral (6 to 7) with dilute hydrochloric acid. Methyl isobutyl ketone was added until dissolved, and the mixture was separated. The organic layer was washed with water. Next, the organic layer was concentrated under reduced pressure to 30 g, and 100 g of isopropyl alcohol was added dropwise, cooled to 2 ° C., and stirred for 1 hour. The obtained slurry was filtered, washed with 10 g of isopropyl alcohol, and air-dried to obtain 21.7 g (89% yield) of white crystals having a melting point of 80 ° C. When the obtained product was analyzed by a liquid chromatography method (LC), no unreacted raw material bisphenol or monocyanate was detected. In addition, imidocarbonate generated by a side reaction was not detected (purity: 99 +%). Further, when analyzed by a potentiometric titration method using silver nitrate, the detected chlorine ion was 10 ppm or less.

Example 2 In Example 1, cyanide chloride (19.01 g, 0.31 mol) was used.
l) was added dropwise at the same time as the aqueous phenolate solution, and 21.45 g of white crystals were obtained (yield 88).
%). By the LC analysis of the product, no unreacted raw material bisphenol or monocyanate was detected.
No imidocarbonate generated by a side reaction was detected (purity 99 +%). Further, in the potentiometric titration using silver nitrate, the detected chlorine ion was 10 ppm or less.

Example 3 In Example 1, cyanide chloride (29.27 g, 0.470 m
ol) in 21.90 g (0.526 g) of 96% caustic soda.
mol)), except that it was added dropwise together with an aqueous phenolate solution containing 21.45 g of white crystals.
(88% yield). By the LC analysis of the product, no unreacted raw material bisphenol or monocyanate was detected. No imidocarbonate generated by a side reaction was detected (purity 99 +%). Further, in the potentiometric titration using silver nitrate, the detected chlorine ion was 10 ppm or less.

Example 4 The procedure of Example 1 was repeated, except that toluene was used instead of methyl isobutyl ketone, to obtain 21.2 g of white crystals (yield 87%). By the LC analysis of the product, no unreacted raw material bisphenol or monocyanate was detected. No imidocarbonate generated by a side reaction was detected (purity 99 +%). Further, in the potentiometric titration using silver nitrate, the detected chlorine ion was 10 ppm or less.

Example 5 The procedure of Example 1 was repeated, except that 100 g of an 86% aqueous solution of isopropyl alcohol was used for crystallization and washing, whereby 20.7 g of white crystals were obtained (yield: 85%). By LC analysis of the product, unreacted raw material bisphenol,
No monocyanate was detected. No imide carbonate generated by a side reaction was detected (purity 99
+%). Further, in the potentiometric titration using silver nitrate, the detected chlorine ion was 10 ppm or less.

Example 6 The procedure of Example 1 was repeated, except that 110 g of heptane was used for crystallization and washing.
Was obtained (yield: 85%).

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 increased while stirring to 65 ° C. When 2,2-bis (4-hydroxyphenyl) propane was completely dissolved, the solution was cooled to 5 ° C or lower to prepare an aqueous phenolate solution. On the other hand, toluene 40 was placed in a 1 L separable flask connected with a stirring blade, a dropping funnel, and a reflux tube.
0 g was added and cooled to 5 ° C. under a nitrogen atmosphere. To the cooled toluene solution, 16.9 ml of cyanogen chloride (20.
0 g 0.3252 mol) and triethylamine 0.1
After adding g (0.989 mmol), the mixture was stirred at 600 rpm, and an aqueous phenolate solution was added dropwise while maintaining the internal temperature at 5 ° C. After the dropwise addition, 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. In addition, gel permeation chromatography (GP
According to the analysis of C), a high molecular weight peak considered to be imidocarbonate was found to be 50% in area percentage.

Comparative Example 2 After completion of the reaction, the same operation as in Example 1 was carried out except that 5N caustic soda was not added, and as a result, 19.99 g (yield 82%) of white crystals having a melting point of 80 ° C. were obtained. .

As is clear from the examples, by contacting cyanogen chloride with an aqueous phenolate solution and an aqueous solution containing a small amount of triethylamine, a high-purity dicyanate could be obtained in high yield. As shown in Comparative Example 1, it was difficult to remove the imidocarbonate-based compound by-produced as an impurity in the conventional method in which the reaction was carried out in a mixed system of an organic solvent and water. A method of reacting a cyanogen halide and phenol in the presence of a tertiary amine in an organic solvent has also been conventionally used. However, there is a concern that impurities such as dialkylcyanamide may be generated or a runaway reaction due to polymerization of the cyanogen halide may occur. Was. As is clear from the Examples, when the aqueous sodium hydroxide solution was dropped after adjusting the pH after the reaction (Example 1), the cyanate ester was obtained in a higher yield than in Comparative Example 2 where it was not dropped. Could be obtained. In the present invention, since only water is used as a solvent in this reaction, a runaway reaction due to polymerization of cyanogen halide can be suppressed, the risk of ignition is very low, and it can be carried out on a very safe and industrial scale. It can be said that this is an excellent process.

[0023]

According to the production method of the present invention, aromatic cyanates of high purity can be obtained in a safe and simple process and with high yield.

Claims (9)

[Claims] (1) The following general formula (I): (I) (wherein, A is each independently a hydrogen atom or a carbon number 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, 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. Is dissolved in water in the presence of an alkali metal hydroxide to form an aqueous solution, and the aqueous solution and cyanogen halide are added together in water containing a tertiary amine. , And then adding an aqueous solution of an alkali metal hydroxide to the water while adjusting the pH to alkaline, to produce a high-purity aromatic cyanate ester. 2. A phenol represented by the general formula [I]:
The method according to claim 1, wherein the aqueous phenolate solution has a solubility of 1% or more in water. 3. The method according to claim 1, wherein the phenol represented by the general formula [I] is represented by the following formula. Embedded image 4. The method according to claim 1, wherein caustic soda or caustic potash is used as the alkali metal hydroxide, and the amount thereof is 1.5 to 5 equivalents to the hydroxyl group of the phenol. 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. The production method according to claim 5, wherein 0.1N to 10N sodium hydroxide or potassium hydroxide is used as the alkali metal hydroxide aqueous solution to be added after the addition of the cyanogen halide and the aqueous solution of the alkali metal salt of phenol. 7. The cyanate ester obtained by the production method according to claim 1 is dissolved in a solvent capable of being separated from water, water is added to the resulting solution, and the resulting solution is washed with water. A method for producing an aromatic cyanate ester, comprising contacting a poor solvent selected from secondary alcohols and aliphatic hydrocarbons, and crystallization or precipitation for purification. 8. The method according to claim 7, wherein methyl isobutyl ketone, toluene or a mixture thereof is used as the solvent capable of separating water. 9. As a poor solvent, isopropyl alcohol, isobutyl alcohol, tert-butyl alcohol, s
ec-butyl alcohol or their hydrous alcohols, pentane, hexane, heptane, cyclopentane,
The method according to claim 7, wherein cyclohexane, cyclopentane, or a mixture thereof is used.