JPH11228522A - Production of cyanic acid ester using aqueous solution of cyanogen halide - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method having safety and simplicity with respect to a process, capable of producing a high-purity cyanic acid ester in a high yield. SOLUTION: This method for producing a high-purity cyanic acid ester comprises dissolving a phenol of the formula (A is each independently hydrogen atom or a 1-6C alkyl group; X is a single bond, a 1-20C organic group, a carbonyl group, a sulfone group, a bifunctional sulfur atom or oxygen atom; (i) is an integer value of >=0 and <=4) in water in the presence of an alkali metal hydroxide to give an aqueous solution of a phenolate, mixing a cyanogen halide and a tertiary amine with water and maintaining the mixture at -5 to 30 deg.C to give an aqueous solution and blending and reacting both the aqueous solutions.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a thermosetting cyanate ester which is useful for sealing electronic parts, for laminates, composite materials, molding materials and adhesives.

[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 which is safe and simple in terms of process, and in which a high-purity cyanate ester can be obtained in a high yield.

[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 inventors have found that a cyanate ester having a high conversion rate is stably generated and precipitated, and the present invention has been completed.

That is, the present invention provides the following general formula (I)

[0006]

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. A phenolate aqueous solution obtained by dissolving a phenol represented by the formula (1) in water in the presence of an alkali metal hydroxide, and a cyanogen halide and a tertiary amine are mixed with water. And an aqueous solution obtained by holding the mixture for 30 minutes or more and reacting the mixture with each other.

[0007]

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-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

[0008]

Embedded image 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 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.

In the method of the present invention, the cyanogen halide is mixed with water together with a tertiary amine, and the mixture is maintained for at least 30 minutes to prepare an aqueous solution. The holding temperature is preferably 0 to 15 ° C., and the holding time is preferably 1 hour or more. The amount of water for mixing the cyanogen halide and the tertiary amine is desirably equal to or higher than the solubility of the cyanogen halide in water. If a smaller amount of water is used, the cyanogen halide does not dissolve in water, and the improvement in yield by holding the mixture for a specific time cannot be expected. On the other hand, when the amount of water is large, 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.

[0013] Purification is performed as needed. In this method, the organic solvent is heated and dissolved in an organic solvent which can be separated from water, washed with water and separated to obtain an organic solvent solution. 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. Concentration is 12
It is preferable to carry out the reaction by evaporating the organic solvent under reduced pressure at a temperature of 0 ° C. or lower, and it is not preferable to raise the temperature too much because trimerization starts. 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 they can be used to recover cyanate esters in good yield. 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 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 is reduced.
The cyanate ester obtained by the production method of the present invention is useful for sealing electronic components, for laminates, for composite materials, for molding materials, and for adhesives.

[0016]

EXAMPLES Examples of the present invention will be described below, but the present invention is not limited to these examples. Example 1 20 g (0.0865 mol) of 2,2-bis (4-hydroxyphenyl) propane (manufactured by Mitsui Toatsu Chemicals) and 18.25 g (0.438 mol) of 96% caustic soda were uniformly dissolved in 500 g of water. After cooling, a phenolate solution was prepared. Separately, 31.92 g of cyanogen chloride (0.5
19 mol) and 0.15 g (0.0
015 mol) to 400 g of water and stirred at 5 ° C.
For 70 minutes to prepare a solution containing cyanogen chloride.
Into a reactor equipped with a thermometer, stirrer, dropping funnel and reflux condenser, the above-mentioned phenolate solution and the above-mentioned solution containing cyanogen chloride were added in parallel at a constant dropping rate at 5 ° C. (The solution contained was 39 minutes, and the phenolate solution was dropped in 30 minutes.) The mixture was kept at the same temperature for 30 minutes. After methyl isobutyl ketone was added thereto and the mixture was separated at 40 ° C., the organic layer was washed with water at the same temperature. Next, the organic layer was concentrated under reduced pressure, isopropyl alcohol was added dropwise, cooled, and stirred for 1 hour. The obtained slurry was filtered, washed with isopropyl alcohol, and air-dried to obtain 20.97 g (86% yield) of white crystals having a melting point of 80 ° C. When the obtained product was analyzed by liquid chromatography (LC), unreacted starting bisphenol and monocyanate were not detected. No imidocarbonate generated by a side reaction was detected (purity 99 +%). Analysis by potentiometric titration using silver nitrate revealed that the detected chlorine ion was 10 ppm or less.

Example 2 The procedure of Example 1 was repeated, except that the mixed aqueous solution of cyanide chloride and triethylamine was stirred at 5 ° C. for 300 minutes to be maintained, and 20.72 g (yield: 85%) of white crystals were obtained. Obtained. 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, the amount of 96% caustic soda in preparing the aqueous phenolate solution was 21.90 g (0.526 mol).
1), and under the same conditions, except that the amount of cyanide chloride when preparing the aqueous solution containing cyanide chloride was 29.27 g (0.470 mol), 19.99 g (yield 82%) of white crystals was obtained. Was. 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 In Example 1, 0.1 g of triethylamine was used as a tertiary amine.
Was carried out under exactly the same conditions except that
9.50 g was obtained (80.0% 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 5 The procedure of Example 1 was repeated, except that trimethylamine was used as the tertiary amine.
Was obtained (80.0% 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 +%). Chloride ion detected by potentiometric titration using silver nitrate was 10 ppm.
It was below.

Example 6 In Example 1, 0.18 of tributylamine was used as a tertiary amine.
g of white crystals 1 except that g was used.
9.38 g was obtained (yield 79.5%). 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 7 The procedure of Example 1 was repeated, except that toluene was used instead of methyl isobutyl ketone, to obtain 18.53 g of white crystals (yield: 76.0%). Product LC
As a result of the analysis, no unreacted starting 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 8 The procedure of Example 1 was repeated, except that 100 g of an 86% aqueous isopropyl alcohol solution was used for crystallization and washing, to obtain 18.53 g of white crystals (yield: 76.0).
%). 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 9 The procedure of Example 1 was repeated, except that 110 g of heptane was used for crystallization and washing, and 18.04 g of white crystals were obtained.
Was obtained (yield 74.0%). 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 +%). Chloride ion detected by potentiometric titration using silver nitrate was 10 ppm.
It was below.

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. 16.9 ml (20.0 ml) of cyanogen chloride was added to the cooled toluene.
g, 0.3252 mol) and 0.1 g of triethylamine
(0.989 mmol), and the mixture was stirred at 600 rpm. Next, while maintaining the internal temperature of the flask at 5 ° C., the above aqueous phenolate solution was dropped into the solution containing cyanogen chloride. After completion of 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 the unreacted monocyanate compound was detected. Gel permeation chromatography (G
Analysis of (PC) revealed a high molecular weight peak at 50% in area percentage, which is likely to be imide carbonate.

Comparative Example 2 In preparing a solution containing cyanogen chloride, the mixed solution was stirred for 10 minutes instead of being kept for 70 minutes while stirring.
As a result of the same operation as described above, white crystals 1 having a melting point of 80 ° C.
8.53 g (yield 76%) was obtained.

As is clear from the examples, when preparing a solution containing cyanogen chloride, a solution in which the mixed solution was kept at a constant temperature for a certain period of time and an aqueous phenolate solution were dropped together in a reaction vessel. By reacting, dicyanate with high purity and high yield can be obtained. As shown in Comparative Example 1, in the method of reacting in a mixed system of an organic solvent solution containing cyanogen chloride and an aqueous phenolate solution as in the conventional method, it is difficult to remove the imidocarbonate-based compound as an by-product as an impurity. Met. In addition, as is apparent from the comparison between Example 1 and Comparative Example 2, in the case of the present invention (Example 1) in which a solution in which a cyanogen halide was held together with a tertiary amine in water for 1 hour or more was dropped, 10 minutes was applied. As compared with the case of Comparative Example 2 in which only the cyanate was retained, a cyanate ester could be obtained in a higher yield. Since the production method of the present invention uses only water as a solvent in the reaction, the risk of runaway reaction due to polymerization of cyanogen cyanide is very low and safe, and it can be said that it is an excellent process that can be performed on an industrial scale. .

[0027]

Industrial Applicability The production method of the present invention is safe and simple in terms of process, whereby a high-purity cyanate ester can be obtained in a 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. A phenolate aqueous solution obtained by dissolving a phenol represented by the formula (1) in water in the presence of an alkali metal hydroxide, and a cyanogen halide and a tertiary amine are mixed with water. A method for producing a high-purity cyanate ester, comprising mixing and reacting an aqueous solution obtained by holding for 30 minutes or more. 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 general formula (I). 5. A method according to claim 1, wherein cyanogen chloride is used as the cyanogen halide, and the amount thereof is 1.5 to 1.5 with respect to the hydroxyl group of the general formula (I).
The method according to claim 1, wherein 5.5 equivalents are used. 6. The method according to claim 1, wherein after mixing the cyanogen halide and the tertiary amine with water, the mixture is kept at a temperature of -5 to 30 ° C. for 1 hour or more. 7. A cyanate ester obtained by the production method according to claim 1, which is dissolved in a solvent capable of being separated from water, water is added to the resulting solution and washed with water, and then a secondary alcohol,
A method for producing a cyanate ester, comprising contacting a poor solvent arbitrarily selected from tertiary 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
The method according to claim 7, wherein ec-butyl alcohol or a hydroalcohol thereof, or pentane, hexane, heptane, cyclopentane, cyclohexane, cyclopentane or a mixture thereof is used.