JP2002167390A - Synthesizing method of tetrakis(acyloxy)borate(1-) and substituted onium tetrakis(acyloxy)borate(1-) - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a synthesizing method of a tetrakis(asyloxy)borate(1-) in which material compounds has high solubility in organic solvents during synthesis and the obtained compound has no residual ionic impurity. SOLUTION: Boric acid, a carboxylic acid anhydride represented by formula (2) [wherein, R1 is an alkyl group, an aryl group or an aralkyl group] and an amine represented by formula (3) [wherein, R2-R4 are an alkyl group, an aryl group, or two or more of R2-R4 are groups that form rings] react to form a tetrakis(asyloxy)borate(1-) represented by formula (l) [wherein, R1 is an alkyl group, an aryl group or an aralkyl group; R2-R4 are an alkyl group, an aryl group, or two or more of R2-R4 are substituents that form rings].

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a substituted onium tetrakis (acyloxy) borate (1-) useful as a curing accelerator for an epoxy resin for electric / electronic materials and the like, and a precursor thereof, tetrakis (acyloxy) borate (1). -).

[0002]

2. Description of the Related Art Conventionally, the following two methods are known for synthesizing tetrakis (acyloxy) borate (1-). (1) A method of reacting triacetate borate with potassium acetate in the presence of acetic anhydride (IG Lewis, V.A.
N. Plahotnik Journal of Inorganic Chemistry VOL. 1
3, 2050 (1968)). (2) A method of reacting a tetra-substituted phosphonium tetra-substituted borate with an n-valent (n ≧ 1) -valent organic acid having at least one or more protons capable of being released outside the molecule (JP-A-8-196911) .

However, in the method (1), since an alkali metal is used as a cation, low solubility in an organic solvent in a synthesis process, ionic impurities remaining in electric and electronic materials, and the like remain. Is a problem. On the other hand, the method (2) is carried out at a high temperature of 200 ° C. or more during the reaction. Therefore, when the borate substituent of the tetra-substituted phosphonium tetra-substituted borate is an alkyl group, the borate side is unstable in the air, Difficult to handle.
When the borate substituent is a phenyl group or another aryl group, there is a problem in cost. In particular, the use of tetra-substituted phosphonium tetraphenyl borate is undesirable because benzene, which is harmful to the human body, is produced as a by-product during the reaction.

[0004]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and has good solubility in organic solvents in synthesis, no generation of harmful substances, and no ionic impurities remaining. The present invention provides a method for synthesizing substituted onium tetrakis (acyloxy) borate (1-) having excellent stability and tetrakis (acyloxy) borate (1-) as a precursor thereof.

[0005]

According to the present invention, there is provided (1) tetrakis (acyloxy) borate (1-) represented by the general formula (1) comprising boric acid and anhydrous carboxylic acid represented by the general formula (2). A method for synthesizing tetrakis (acyloxy) borate (1-) obtained by reacting an acid with an amine represented by the general formula (3);

Embedded image (R ₁ is a group selected from the group consisting of an alkyl group, an aryl group, and an aralkyl group; R _{2 to} R ₄ are an alkyl group, an aryl group, or at least two substituents of three substituents R _{2 to} R ₄ Is a substituent forming a ring)

[0006]

Embedded image (R ₁ is a group selected from the group consisting of an alkyl group, an aryl group, and an aralkyl group)

[0007]

Embedded image (R _{2 to} R ₄ are an alkyl group, an aryl group, or R _{2 to} R ₄
A group in which at least two of the three substituents form a ring) (2) R _{2 to} R _{4 in} the general formula (3) are selected from a methyl group, an ethyl group, a propyl group, a butyl group, and a pentyl group (1) The method for synthesizing tetrakis (acyloxy) borate (1-) according to item (1), which is at least one member selected from the group consisting of: (3) tetrakis (acyloxy) borate (1-) represented by general formula (4). ) Is obtained by reacting boric acid, a carboxylic anhydride represented by the general formula (2), and an amidine represented by the general formula (5), wherein tetrakis (acyloxy) borate (1-) is obtained. Synthesis method,

[0008]

Embedded image(R₁Is an alkyl, aryl, or aralkyl group.
A group selected from the group _Five~ R₇Is an alkyl group, aryl
Group or R_Five~ R₇At least two of the three substituents
A group in which the substituent forms a ring)

[0009]

Embedded image (R ₁ is a group selected from the group consisting of an alkyl group, an aryl group, and an aralkyl group)

[0010]

Embedded image (R _{5 to} R ₇ are an alkyl group, an aryl group, or a group in which at least two of the three substituents of R _{5 to} R ₇ form a ring). (4) Items (1) to (3) The tetrakis (acyloxy) borate (1) obtained by any one of the synthesis methods described in any of the above.
-) And an onium salt selected from the group consisting of a tetra-substituted phosphonium salt, a tetra-substituted ammonium salt and a tri-substituted sulfonium salt, wherein the substituted onium tetrakis (acyloxy) borate (1) is obtained.
The synthesis method of-).

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, tetrakis (acyloxy) borate (1-) represented by the general formula (1) or (4) is composed of boric acid and an anhydride represented by the general formula (2). Although it can be obtained by a method of synthesizing by reacting with a carboxylic acid, an amine represented by the general formula (3) or an amidine represented by the general formula (5), the present invention provides a compound represented by the general formula (1) or the general formula (4) The tetrakis (acyloxy) borate (1-) represented by the formula (1) is a salt of an amine or amidine which is an organic compound, and therefore has good solubility in a solvent.
One of its features is that it is extremely easy to handle. The boric acid used in the present invention can be obtained as an industrial product or a reagent, and any form may be used.

The carboxylic anhydride represented by the general formula (2) used in the present invention is a group in which R ₁ is a group selected from the group consisting of an alkyl group, an aryl group and an aralkyl group. Examples of R ₁ include a methyl group, an ethyl group, a propyl group, a phenyl group, a tolyl group, an anisyl group, a nitrophenyl group, a naphthyl group, a benzyl group and the like.
Examples of carboxylic anhydrides include acetic anhydride, propionic anhydride, butyric anhydride, benzoic anhydride, methylbenzoic anhydride, methoxybenzoic anhydride, nitrobenzoic anhydride, paranitrobenzoic anhydride, 1-naphthoic anhydride, and anhydrous 1-naphthoic acid. Examples include 1-phenylacetic acid and trifluoroacetic anhydride.

The amine represented by the general formula (3) or the amidine represented by the general formula (5) is not particularly limited. However, when a hydrogen atom is bonded to a nitrogen atom, amide is used as a side reaction. Tertiary amines are preferred for formation. These are trimethylamine, triethylamine,
Tertiary alkylamines substituted with an alkyl group such as tripropylamine and tributylamine, tertiary amines substituted with an aryl group such as diphenylmethylamine, 1,8-diazabicyclo [5,4,0] uncene-7 (bicyclic Formula amidine compound), 1,5-diazabicyclo [4,3,0] non-5-ene (bicyclic amidine compound), and acyclic amidines.

Examples of the method for synthesizing the tetrakis (acyloxy) borate (1-) of the present invention include boric acid, a carboxylic anhydride represented by the general formula (2), an amine represented by the general formula (3) or The reaction is carried out by reacting an amidine represented by the general formula (5).
Under relatively mild conditions of less than 200 ° C.
The reaction can be completed in 8 hours. In the reaction, with or without the use of a solvent, when the amine represented by the general formula (3) or the amidine represented by the general formula (5) is used in a large excess, these amines and amidines are used as a solvent. In addition, by using an amine represented by the general formula (3) or an amidine represented by the general formula (5) and an carboxylic anhydride represented by the general formula (2) in excess, these can be dissolved in a solvent. It is also possible to use as. Further, an inert solvent which dissolves the reactants, such as dimethoxyethane, dimethyldiglycol, dimethyltriglycol, etc. can be used.

As the tetra-substituted phosphonium salt, tetra-substituted ammonium salt and tri-substituted sulfonium salt used in the present invention, halide salts thereof can be used, but the salts are not particularly limited, and the above-mentioned tetrakis ( (Asiloxy) borate (1-) as long as a reaction occurs in which the ammonium ion or amidinium ion on the cation side of the cation side is replaced with the corresponding tetra-substituted phosphonium, tetra-substituted ammonium, or tri-substituted sulfonium, Onium carboxylate and onium phenolate may be used, and any may be used. The method for synthesizing the substituted onium tetrakis (acyloxy) borate (1-) of the present invention comprises a general-purpose onium halide such as a tetra-substituted phosphonium halide, a tetra-substituted ammonium halide, a tri-substituted sulfonium halide, and the aforementioned tetrakis (acyloxy) borate (1-). , For example, by dissolving tetrakis (acyloxy) borate (1-) in an aprotic solvent having good inertness and good solubility, and dissolving a general-purpose onium halide in methanol, water, or the like. When mixed, the ammonium ion or amidinium ion on the cation side of tetrakis (acyloxy) borate (1-) is replaced with the corresponding tetra-substituted phosphonium, tetra-substituted ammonium, or tri-substituted sulfonium, and the corresponding substituted onium tetrakis (acyloxy) volley (1) are produced.

The substituted onium tetrakis (acyloxy) borate (1-) obtained by the synthesis method of the present invention and its precursor, tetrakis (acyloxy) borate (1-)
Can be used as a curing accelerator for an epoxy resin for electric / electronic materials.

[0017]

EXAMPLES The present invention will be further described below with reference to examples, but the present invention is not limited to the examples. [Synthesis of Tetrakis (acyloxy) borate (1-)] (Example 1) 1.55 g of boric acid (25 mmol) was placed in a flask.
l), 65.2 g of 1-naphthoic anhydride (200 mmol)
l), 4.3 g (25 mmol) of 1-naphthoic acid, 12.1 g (50 mmol) of tributylamine, and 1
The mixture was heated and stirred at 60 ° C for 4 hours. As a result, tributylamine tetrakis (1-naphthoyloxy) borate (1-) of the formula (6) was obtained. This was dissolved in acetone and filtered to remove excess tributylamine, 1-naphthoic anhydride and 1-naphthoic acid, and the filtrate was recrystallized by adding hexane to a poor solvent. Yield 17.8
g (85% yield based on boric acid)

[0018]

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(Example 2) 1.55 g of boric acid was placed in a flask.
(25 mmol) excess trifluoroacetic anhydride
Then, 0 g (200 mmol), 8.6 g (50 mmol) of 1-benzyl 2-methylimidazole and 200 g of dimethyldiglycol were charged, and the mixture was heated and stirred at 160 ° C. for 4 hours. Thereby, tetrakis (1-trifluoroacetate) of 1-benzyl 2-methylimidazole of the formula (7)
A borate salt was obtained. This was dissolved in acetone and filtered to remove 1-benzyl 2-methylimidazole and hydrofluoride, and the filtrate was recrystallized by adding hexane to a poor solvent. Yield 14.8 g (78% yield based on boric acid)

[0020]

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(Examples 3 to 8) Example 1 was performed using boric acid, carboxylic anhydride, amine or amidine shown in Table 1.
Alternatively, tetrakis (acyloxy) borate (1-) was synthesized by the same operation as in Example 2.

[Table 1]

[0022]

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[0023]

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[0024]

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[0025]

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Comparative Example 1 39 g of acetic anhydride was placed in a flask.
(200 mmol) and 8.88 g (25
mmol) and triacetate borate 1 of formula (12)
7.07 g (25 mmol) was charged, acetic anhydride was refluxed at 160 ° C. for 1 hour, and the mixture was cooled at room temperature.
Crystals of potassium tetrakis acetate borate (1-) salt of the formula (13) were obtained. The yield is 19.2 g (78% based on triacetate borate) (Reference: Journal of Inorganic Chemistry, Vol. 13, 2050 (1968)).
USSR)

[0027]

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[0028]

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(Comparative Example 2) 1.55 g of boric acid was placed in a flask.
(25 mmol), 65.2 in excess of 1-naphthoic anhydride.
g (200 mmol), 1-naphthoic acid potassium salt 2
1.0 g (100 mmol) was charged into a flask, and 16 g
The mixture was heated and stirred at 0 ° C. for 15 hours, but was not reacted.

[Substituted onium tetrakis (acyloxy)
Synthesis of borate (1-)] (Example 7) A 10% by weight solution of tributylaminetetrakis (1-naphthoyloxy) borate (1-) salt (formula (6)) of Example 1 in tetrahydrofuran was prepared. . This solution was added dropwise to a previously prepared isopropanol solution containing 10% by weight of tetraphenylphosphonium bromide at room temperature. A white precipitate formed simultaneously with the addition.
This was filtered, washed several times with methanol, and dried by heating under vacuum to obtain tetraphenylphosphonium tetrakis (1-naphthoyloxy) borate (1-) salt of the formula (14). The yield was 22.0 g (tributylamine tetrakis (1-naphthoyloxy) borate (1
-) Salt (85% yield based on the formula (6)). The resulting substituted onium salt, tetraphenylphosphonium tetrakis (1-naphthoyloxy) borate (1
-) 1.00 g of salt was weighed, and pressure cooker treatment was performed in 50.0 g of pure water at 125 ° C for 20 hours.
No potassium ion was detected.

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Examples 8 to 13 Using the tetrakis (acyloxy) borate (1-) shown in Table 2 and a substituted onium salt,
The same operation as in Example 7 was repeated to synthesize substituted onium tetrakis (acyloxy) borate (1-). All of these reactions were possible at room temperature. The determination of potassium ion was performed in the same manner as in Example 7. As a result, no potassium ion was detected.

[Table 2]

[0032]

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[0033]

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[0034]

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[0035]

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[0036]

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[0037]

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[0038]

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[0039]

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Comparative Example 3 The potassium tetrakis acetate borate (1-) salt of Comparative Example 1 (formula (13)) was
An isopropanol solution containing weight% was prepared. This solution was added dropwise to a previously prepared isopropanol solution containing 10% by weight of tetraphenylphosphonium bromide at room temperature. A white precipitate formed simultaneously with the addition. Filter this,
After washing with methanol several times and drying by heating under vacuum, a tetraphenylphosphonium tetrakis acetate borate (1-) salt of the formula (22) was obtained. This tetraphenylphosphonium tetrakis acetate borate (1
-) The salt was treated in the same manner as in Example 7, and as a result, the extracted potassium ion was 1500 ppm, which was unsuitable for use in electrical and electronic equipment.

Comparative Example 4 10.6 Benzoic acid was added to a flask.
g (100 mmol) and 16.45 g (25 mmol) of tetraphenylphosphonium tetraphenylborate salt
, And stirred under heating at 230 ° C. for 4 hours to obtain the formula (2)
3) 23 mmol of tetraphenylphosphonium tetrakis (benzoyloxy) borate (1-) salt (92% yield based on tetraphenylphosphonium tetraphenylborate salt) was obtained, but this method generates harmful benzene, It is not preferable if the reaction is not performed at a very high temperature of 230 ° C.

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[0042]

The synthesis method of the present invention is more versatile than conventional synthesis methods, can react at low temperatures, does not generate harmful substances such as benzene, and does not contain free alkali metals. In addition, the reaction operation is simple and the desired product can be obtained in high yield. Further, tetra-substituted phosphonium tetra-substituted borate, tetra-substituted ammonium tetra-substituted borate, and tri-substituted sulfonium tetra-substituted borate are useful as a curing catalyst for anionic polymerization of an epoxy resin or the like.

Claims (4)

[Claims] 1. The method according to claim 1, wherein the tetrakis (acyloxy) borate (1-) represented by the general formula (1) is a boric acid,
A method for synthesizing tetrakis (acyloxy) borate (1-), which is obtained by reacting a carboxylic anhydride represented by the following formula with an amine represented by the general formula (3). Embedded image (R ₁ is a group selected from the group consisting of an alkyl group, an aryl group, and an aralkyl group; R _{2 to} R ₄ are an alkyl group, an aryl group, or at least two substituents of three substituents R _{2 to} R ₄ Is a substituent forming a ring) (R ₁ is a group selected from the group consisting of an alkyl group, an aryl group, and an aralkyl group) (R _{2 to} R ₄ are an alkyl group, an aryl group, or R _{2 to} R ₄
A group in which at least two of the three substituents form a ring) 2. R _{2 to} R _{4 in} the general formula (3) are a methyl group,
The method for synthesizing tetrakis (acyloxy) borate (1-) according to claim 1, which is at least one member selected from the group consisting of an ethyl group, a propyl group, a butyl group, and a pentyl group. 3. The tetrakis (A) represented by the general formula (4)
(Siloxy) borate (1-) is boric acid, a compound of the general formula (2)
A carboxylic anhydride represented by the general formula (5)
Characterized in that it is obtained by reacting with midine
A method for synthesizing kiss (acyloxy) borate (1-). Embedded image(R₁Is an alkyl, aryl, or aralkyl group.
A group selected from the group _Five~ R₇Is an alkyl group, aryl
Group or R_Five~ R₇At least two of the three substituents
A group in which the substituent forms a ring)(R₁Is an alkyl, aryl, or aralkyl group.
Group selected from the group consisting of(R_Five~ R₇Is an alkyl group, an aryl group or R_Five~ R₇of
At least two of the three substituents form a ring
Group) 4. A group consisting of tetrakis (acyloxy) borate (1-) obtained by the synthesis method according to claim 1 and a tetra-substituted phosphonium salt, a tetra-substituted ammonium salt, and a tri-substituted sulfonium salt. A method for synthesizing substituted onium tetrakis (acyloxy) borate (1-), which is obtained by reacting an onium salt selected from the following.