JP3254619B2 - Synthetic method of phosphorus-based latent catalyst - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for synthesizing a curing catalyst such as an epoxy compound, in particular, a curing catalyst having a latent property and a tetrasubstituted phosphonium tetraorganic acid borate.

[0002]

2. Description of the Related Art As a latent catalyst, Japanese Patent Publication No. 51-2439
As a method for synthesizing a tetra-substituted phosphonium tetra-substituted borate as disclosed in JP-A-9, a reaction represented by the following formula [I] is conventionally used.

[0003]

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(X in the formula represents a halogen.) That is, a method of reacting a tetra-substituted phosphonium halide with a sodium salt of a tetra-substituted borate in water or a mixture of water and an organic solvent is typically known. . In the reaction of the above formula [I], the sodium salt of the tetra-substituted borate as a starting material is represented by the following formulas [II] and [III]:

[0005]

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[0006]

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It is obtained by a two-stage reaction. However, this reaction uses a Grignard reagent called RMgX shown in the formula [II] and does not proceed unless it is completely anhydrous, so that it is difficult to synthesize industrially.

[0008]

DISCLOSURE OF THE INVENTION The present invention is a latent catalyst useful as a curing catalyst for epoxy compounds and the like in a high yield without going through the synthesis method described in the preceding section, tetrasubstituted phosphonium tetraorganic acid borate. An object of the present invention is to provide a synthesis method of (C).

[0009]

The inventors of the present invention have made intensive studies to solve the above-mentioned problems, and as a result, completed the present invention. That is, the present invention provides a tetra-substituted phosphonium tetra-substituted borate (A) represented by the general formula (1):

[0010]

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(Wherein R ¹ , R ² , R ³ and R ⁴ each represent a substituent selected from the group consisting of an organic group containing a monovalent aromatic ring or a monovalent aliphatic residue, R ⁵ , R ⁶ , R ⁷ and R ⁸ in the formula represent a hydrocarbon group (such as an alkyl group, a phenyl group and a substituted phenyl group), and are the same as each other. And at least one proton capable of being released out of the molecule represented by the general formula (2) in the molecule.
≧ 1) valent organic acid (B),

[0012]

Embedded image (Y in the formula is formed by the organic acid (B) releasing a proton.
Represents a conjugate base. )

All the substituents R ⁵ , R ⁶ , R ⁷ and R ⁸ on the boron side of the tetra-substituted phosphonium tetra-substituted borate (A) formed by the thermal reaction of A latent catalyst represented by the general formula (3), which is substituted with a group by a root which is released one outside the molecule;
Tetra-substituted phosphonium tetra organic acid borate (C)

[0014]

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(Wherein R ¹ , R ² , R ³ and R ⁴ and Y are as defined above).

[0016]

According to the present invention, a latent catalyst, a tetrasubstituted phosphonium tetraorganic acid borate (C), is synthesized by a thermal reaction between a tetrasubstituted phosphonium tetrasubstituted borate (A) and an organic acid (B). Organic acid (B) per mole of tetra-substituted borate (A)
The outline is shown below, taking a 4 mol reaction as an example.

[0017]

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In this reaction, the tetra-substituted phosphonium tetra-substituted borate (A) is heated by heating in the presence of the organic acid (B) to form R ⁵ which is a boron-side substituent of the tetra-substituted phosphonium tetra-substituted borate (A). , R ⁶ , R ⁷
And the hydrocarbon group of R ⁸ is replaced by a radical formed by the release of one proton of the organic acid (B) out of the molecule to form a latent catalyst, tetrasubstituted phosphonium tetraorganic acid borate (C). The eliminated R ⁵ , R ⁶ , R ⁷ and R ⁸ hydrocarbon groups receive protons from the organic acid (B), respectively, and form by-products R ⁵ H, R ⁶ H, R ⁷ H and R ⁸ H Becomes

In the above reaction, since the reaction is carried out in one step using commercially available tetra-substituted phosphonium tetra-substituted borate (A), the desired latent catalyst, tetra-substituted phosphonium tetra-organic acid borate, is obtained in a very high yield. (C) can be obtained. The substituents R ¹ , R ² , R ³ and R ⁴ may be the same or different, and the position of a specific substituent is not limited at all.

Specific examples of the organic acid (B) having n (n ≧ 1) valence and having at least one proton which can be released outside the molecule include fatty acids such as acetic acid and trifluoroacetic acid. Aromatic carboxylic acids, benzoic acids, naphthoic acids and those having a functional group on the aromatic nucleus, polyfunctional aromatic carboxylic acids such as phthalic acid, trimellitic acid, pyromellitic acid, 2,6-naphthalenedicarboxylic acid, stearyl alcohol Aliphatic alcohols, such as phenol and naphthol,
Examples thereof include those having a functional group in the aromatic nucleus of phenol or naphthol, isocyanuric acid, 1,2,3-benzotriazole and the like.

The substituent R ^{1 of the} tetra-substituted phosphonium tetra-substituted borate (A) represented by the general formula (1), the latent catalyst represented by the general formula (3), and the tetra-substituted phosphonium tetra-organic acid borate (C) Examples of R ² , R ^3, and R ⁴ include groups containing an aromatic ring such as phenyl, tolyl, ethylphenyl, methoxyphenyl, naphthyl, and benzyl, and alkyl groups such as ethyl and butyl.

The synthesis method of the present invention comprises heating the corresponding organic acid (B) to the tetra-substituted phosphonium tetra-substituted borate (A) under a nitrogen atmosphere for 1 to 12 hours, preferably 4 to 6 hours. This is a method of synthesizing a latent catalyst, tetra-substituted phosphonium tetra-organic acid borate (C). The number of moles of organic acid (B) per mol of tetra-substituted phosphonium tetra-substituted borate (A) is 4
The above is preferable, and when it is less than 4, unreacted tetra-substituted phosphonium tetra-substituted borate (A) remains. At room temperature, the tetra-substituted phosphonium tetra-substituted borate (A) is N, N-dimethylformamide or N-methyl-2-pyrrolidone. It is difficult to remove because it is soluble only in strong polar solvents such as

The reaction is carried out at a temperature not lower than the melting point of the organic acid (B), preferably at a temperature not lower than 200 ° C. and not lower than the melting point of the organic acid (B) for prompt reaction.
⁵ H, R ⁶ H, R ⁷ H and R ⁸ H are removed while being removed from the system. The reaction is carried out in a solvent-free system, but in some cases, a solvent having a boiling point of 200 ° C. or higher may be used.

After the reaction is completed under the above conditions, the latent product and the tetrasubstituted phosphonium tetraorganic acid borate (C) are recovered by separating, washing and drying the product by a conventional method.

[0025]

Next, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples.

Example 1 65.8 g (0.10 mol) of commercially available tetraphenylphosphonium tetraphenylborate (TPP-K manufactured by Hokuko Chemical Industry Co., Ltd.), benzoic acid 4
8.8 g (0.40 mol) was charged into a flask equipped with a thermometer, an azeotropic separating funnel, a condenser and a stirrer, and reacted at 230 ° C. for 4 hours under a nitrogen atmosphere. At that time, benzene as a by-product was removed from the system. After completion of the reaction, the mixture was cooled, washed with toluene and dried to obtain a latent catalyst of white crystals, tetraphenylphosphonium tetrabenzoate borate. The melting point was 211 ° C. and the yield was 101 g (98% yield). The analysis result is consistent with the compound corresponding to the following structure (a).

[0027]

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Example 2 32.9 g (0.05 mol) of commercially available tetraphenylphosphonium tetraphenylborate (TPP-K manufactured by Hokuko Chemical Co., Ltd.), 34.4 g (0.20 mol) of 1-naphthoic acid ) Was charged into a flask equipped with a thermometer, an azeotropic separator, a condenser and a stirrer, and reacted at 260 ° C. for 5 hours under a nitrogen atmosphere. At that time, benzene as a by-product was removed from the system. After completion of the reaction, the mixture was cooled, washed and dried with methanol, and a latent catalyst of white crystals
Tetraphenylphosphonium tetra (1-naphthoic acid)
Got a borate. This melting point is 239 ° C. and the yield is 48 g.
(93% yield). The analysis result is consistent with the compound corresponding to the following structure (b).

[0029]

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Example 3 65.8 g (0.10 mol) of commercially available tetraphenylphosphonium tetraphenylborate (TPP-K manufactured by Hokko Chemical Industry Co., Ltd.) and 115.2 g (0.40 mol) of 1-naphthol Was charged into a flask equipped with a thermometer, an azeotropic separating funnel, a condenser and a stirrer, and reacted at 240 ° C. for 6 hours under a nitrogen atmosphere. At that time, benzene as a by-product was removed from the system. After completion of the reaction, the mixture was cooled, reprecipitated, washed and dried to obtain a latent catalyst of white crystals, tetraphenylphosphonium tetra (1-naphthol) borate. The melting point was 206 ° C. and the yield was 141 g (94% yield). The analysis result is consistent with the compound corresponding to the following structure (c).

[0031]

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As examples of the analysis results, the analysis results of tetraphenylphosphonium tetrabenzoate borate of Example 1 are shown in FIG. 1, Table 1 and FIG.

FIG. 1 shows the results of differential thermal analysis (DSC) at a heating rate of 10 ° C./min, where tetraphenylphosphonium tetrabenzoate borate showed a sharp endotherm at 211 ° C.
This means that the compound is a single compound. Table 1 shows the results of elemental analysis, and shows good agreement with the theoretical values of the structural formula (a).

[0034]

[Table 1]

FIG. 2 shows the Fast Atom Bonbardment of mass spectrometry.
It is the result of having detected positive ion and negative ion by the method. In the positive ion mode, a peak having a mass number of 339 corresponding to a tetraphenylphosphonium portion was detected, and in the negative ion mode, a peak having a mass number of 495 corresponding to a tetrabenzoic acid borate portion was detected. From the above, it was found that tetraphenylphosphonium tetrabenzoate borate has a structure that can be represented by the structural formula (a).

[0036]

As is apparent from Examples 1 to 3, according to the synthesis method of the present invention, the objective latent catalyst, tetrasubstituted phosphonium tetraorganic acid borate, can be obtained industrially advantageously and efficiently. It is.

[Brief description of the drawings]

FIG. 1 shows the results of differential thermal analysis (DSC) of the tetraphenylphosphonium tetrabenzoate borate of Example 1 at a rate of temperature increase of 10 ° C./min.

FIG. 2 shows the results of Fast A of mass spectrometry for tetraphenylphosphonium tetrabenzoate borate of Example 1.
The result of having detected the positive ion and the negative ion by the tom Bonbardment method is shown.

──────────────────────────────────────────────────の Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) B01J 21/00-38/74 C08G 59/40 C08G 59/24 C08L 63/00-63/10 C08L 35 / 00

Claims (6)

(57) [Claims] 1. A tetrasubstituted phosphonium tetrasubstituted borate (A) represented by the general formula (1): (Wherein R ¹ , R ² , R ³ and R ⁴ each represent a substituent selected from the group consisting of a monovalent aromatic ring-containing organic group or a monovalent aliphatic residue. In the formula, R ⁵ , R ⁶ , R ⁷ and R ⁸ represent a hydrocarbon group (such as an alkyl group, a phenyl group and a substituted phenyl group), and may be the same or different. May be.)
And n (n ≧ 1) having at least one or more protons capable of being released outside the molecule represented by the general formula (2)
Divalent organic acid (B), (Y in the formula is formed by the organic acid (B) releasing a proton.
Represents a conjugate base. ) And a tetra-substituted phosphonium tetra-substituted borate (A)
All substituents R ⁵ , R ⁶ , R ⁷ and R ⁸ on the boron side of
A latent catalyst represented by the general formula (3), in which one proton of the organic acid (B) is released outside the molecule and substituted by a radical, a tetrasubstituted phosphonium tetraorganic acid borate (C) (Wherein R ¹ , R ² , R ³ and R ⁴ and Y have the same meanings as described above). 2. The method for synthesizing a latent catalyst and a tetra-substituted phosphonium tetraorganic acid borate (C) according to claim 1, wherein the tetra-substituted phosphonium tetra-substituted borate (A) is tetra-substituted phosphonium tetraphenyl borate. 3. The latent catalyst according to claim 1, wherein the organic acid (B) is a carboxylic acid having at least one carboxyl group in one molecule. Synthetic method. 4. The latent catalyst according to claim 1, wherein the organic acid (B) is an aromatic carboxylic acid having at least one carboxyl group in one molecule. ). 5. The latent catalyst according to claim 1, wherein the organic acid (B) is an alcohol having at least one hydroxyl group in one molecule, and the synthesis of the tetrasubstituted phosphonium tetraorganic acid borate (C). Law. 6. The latent catalyst according to claim 1, wherein the organic acid (B) is a phenol having at least one hydroxyl group in one molecule. Synthetic method.