JPS5854145B2 - Method for isomerizing methyl↓-delta↓-4↓-tetrahydrophthalic anhydride - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for isomerizing methyl-delta-4-tetrahydrophthalic anhydride, and more specifically, the present invention relates to a method for isomerizing methyl-delta-4-tetrahydrophthalic anhydride. The following relates to a novel isomerization method for heat-treating methyl-delta-4-tetrahydrophthalic anhydride.

Methyl-delta-4-tetrahydrophthalic anhydride (hereinafter abbreviated as kai-Δ'-THPA) has been widely used as a curing agent for epoxy resins and as a component for unsaturated polyester resins.

However, this compound is solid at room temperature, which is a major drawback as an epoxy resin curing agent, which is often required to be in a liquid state for handling.

Therefore, a method has been developed to obtain a liquid material by isomerizing Me-Δ'-THPA.
64597), sulfuric acid, phosphoric acid, etc. (U.S. Pat. No. 295
9599), silica-alumina, and acidic ion exchange resin (Japanese Patent Publication No. 4313455).

All of these methods generate structural isomers by shifting the position of the double bond in the cyclohexene ring, and lower the melting point by eutectic melting of each structural isomer.

On the other hand, a method for sterically geometric isomerizing Me-Δ'-THPA without causing movement of the double bond is also known.

For flk 3-Me-Δ5-THPA, cis-3-methyl-4-cyclohexene-cis.

Cysto 2-dicarboxylic anhydride (melting point 63°C), trans-3-methyl-4-cyclohexene-cis, cysto 2-dicarboxylic anhydride (melting point 41'C), cis-3
-Methyl-4-cyclohexene-cis, trans-1.
2-dicarboxylic anhydride (melting point 133°C) and trans-3-methyl 4-cyclohexene-cis, trans-1
・Four types of geometric isomers of dicarboxylic acid anhydride (melting point 121'C) are known (Journal of American Chemical Society VOL, 72 No. 167)
8-1681, April 1950), but the literature states that the melting point is 63.
By heating cis-3-methyl-4-cyclohexene-cis,cysto-2-dicarboxylic anhydride at 175°C for 4 hours in the presence of dibutylaniline, the melting point was 3.
Experimental examples have been reported in which a mixture of isomers was obtained at 0°C.

However, there are no reports of obtaining a liquid product through geometric isomerization, and the reality is that there is little knowledge about the catalysts used for this reaction.

The main objective of the present invention is to use a novel catalyst to
It is an object of the present invention to provide a method for isomerizing THPA, and a further object is to provide an isomerization method that enables the production of a liquid isomer mixture.

Therefore, these objects of the present invention are based on Me-△4-THPA
This is achieved by heat treating in the presence of a nitrogen-containing compound having a nitrogen atom bonded to a carbon atom of a carbonyl group.

Me-Δ'-THPA used in the present invention is 3-
Me-Δ'-THPA, 4-Me-Δ4-THPA or a mixture thereof, and these compounds are, for example, 1
- It can be easily obtained by subjecting 3-pentadiene, imprene, or a mixture thereof and maleic anhydride to a Diels-Alder reaction.

Among these compounds, 3-Me-Δ'-THPA is more likely to cause isomerization than 4-Me-Δ'-THPA, and in particular, 3-Me- △4-THPA 100-20% by weight, even 95-25% by weight and 4-Me -△'-T HP
A It is possible to use it in a range of 0 to 80% by weight, or even 5 to 75% by weight.

In the present invention, such Me-Δ'-THPA is heat-treated in the presence of a nitrogen-containing compound containing a nitrogen atom bonded to a carbon atom of a carbonyl group, thereby progressing isomerization.

Here, the nitrogen-containing compound refers to a compound containing a nitrogen atom bonded to a carbon atom of a carbonyl group such as an amide bond, imide bond, urethane bond, urea bond, billet bond, allophanate bond, etc. Specific examples thereof include Examples include formamide, acetamide, propionamide,
Butyramide, valeramide, benzamide, N-ethylacetamide, N-N-dimethylformamide, N-
N-dimethylacetamide, N-methylbenzamide,
Amides such as N-phenylacetamide, N-phenylpropionamide, ε-cabrolactam, γ-butyrolactam, etc. or their derivatives niacetylimide, maleic acid imide, succinimide, phthalic acid imide, tetrahydrophthalic acid imide, methyltetrahydrophthalic acid imide , N-butyl-methyltetrahydrophthalic acid imide or derivatives thereof.

Carbamate esters such as methyl carbamate, ethyl carbamate, phenyl carbamate or derivatives thereof: urea, N-methylurea, N-ethylurea, N-N'
-dimethylurea, N-N-dimethylurea, N-N-N'
-) IJ dimethylurea N・N-N'-N'-tetramethylurea, N-phenylurea, N-N'-ethylideneurea, N-acetylurea, N-acetyl-N'-methylurea, biulet, N - Urea or its derivatives such as methyl biuret, N-ethyl biuret, N-benzoyl biuret, methyl allophanate, propyl allophanate, isoamyl allophanate; semicarbazide, ■-acetyl semicarbazide, 1-phenyl semicarbazide, 4-
Examples include semicarbazides such as phenylsemicarbazide and derivatives thereof.

These nitrogen-containing compounds can be prepared in advance and used, but compounds that react with Me-Δ4-THPA to produce these nitrogen-containing compounds in the reaction system,
For example, it can also be prepared in-system using ammonia, primary amines, secondary amines, incyanate compounds, and the like.

In the present invention, it is usually 0.01 to 5 parts by weight, preferably 0.01 to 5 parts by weight per 100 parts by weight of Me-Δ'-THPA.
The reaction is carried out in the presence of 2 parts by weight of catalyst at a temperature of 60-300°C, preferably 80-250°C.

At this time, as the reaction temperature decreases, the isomerization rate decreases, and conversely, as the reaction temperature decreases, the product becomes colored.

Other reaction conditions are not particularly limited, but
O, in an atmosphere of a gas inert to the reaction such as nitrogen or argon.
It is appropriate to react for about 1 to 30 hours, preferably about 1 to IO hours.

According to the method of the present invention, an isomer mixture with an excellent hue of Gardner color number 2 or less can be obtained without distillation by appropriately selecting reaction conditions such as catalyst usage, reaction temperature, and centering time. be able to.

However, if some coloration occurs or if a more transparent product is desired, the color can be easily removed by distillation.

In addition to the reaction conditions as described above, the starting material M
By appropriately controlling the composition of e-△4-THPA, it is possible to obtain a liquid isomer mixture at 20°C or even 0°C, especially for 3-Me~△4-THPA70~
50% by weight and 4-Me-Δ'-T HP A 30~
When using a 50% by weight mixture, a liquid isomer mixture can be obtained even at -20°C.

The isomer mixture thus obtained is used as a component of unsaturated polyesters and is also extremely useful as a curing agent for epoxy resins.

The present invention will be explained in more detail with reference to Examples below.

Note that all parts in the examples are based on weight.

Example 1 Melting point 61°C in a 500rnl separable flask with a stirrer
, Gardner color number 1 or less 3-Me-△4-■i+TH
100 parts of PA and 0.1 N-N-dimethylformamide
A reaction was carried out at 200° C. for 3 hours under a nitrogen atmosphere.

The product obtained was Gardner 1, even though no distillation was performed, and had a melting point of 10°C.

In addition, when analyzed by nuclear magnetic resonance spectroscopy, it was confirmed that no movement of the double bond of the cyclohexene ring occurred, and that several isomers were generated.

When the same treatment was performed in the absence of a catalyst, the melting point was 4.
The temperature was 6°C.

Example 2 3-Me -Δ'-T HP Melting point 64°C instead of A
When the reaction was carried out in the same manner as in Example 1 except that 4-Me-Δ'-THPA having a Gardner color number of 1 or less was used, a product with a Gardner color number of 1 and a melting point of 59° C. was obtained.

For comparison, the reaction was carried out in the absence of a catalyst, and the melting point of the product was 64°C.

Example 3 3-Me-Δ'-THPA, 4-Me-Δ'THPA
and various nitrogen-containing compounds in the proportions shown in Table 1,
The reaction was carried out in the same manner as in Example 1.

The properties of the obtained product are shown in Table 1. This result shows that any nitrogen-containing compound having a nitrogen atom bonded to a carbon atom of a carbonyl group exhibits good catalytic activity.

In addition, 3-Me-△′-THPA and 4-Me-△′ −
It can be seen that when THPA is used in combination, a product with an even lower melting point is obtained.

Example 4 Single @
3-Me-△4-THPA 60 parts, 4-Me-1s
40 parts of '-THPA and a predetermined amount of N-N-dimethylformamide were charged, and a reaction was carried out according to the predetermined reaction conditions listed in Table 2.

The results are shown in Table 2.

From this result, by appropriately controlling the reaction conditions,
It can be seen that a liquid isomer mixture can be obtained even at -20°C.

Example 5 60 parts of 3-Me-Δ'-THPA, 4-Me-Δ4-T
When 40 parts of HPA and 0.5 part of N-butyl-3-methyltetrahydrophthalimide were charged and the reaction was carried out in the same manner as in Example 1, a product having a melting point of -20°C or lower was obtained.

Example 6 60 parts of 3-Me-Δ'-THPA, 4-Me-Δ4TH
Prepare 40 parts of PA and 0.22 parts of n-butylamine,
The reaction was carried out in the same manner as in Example 1.

★★The amount of n-butylamine charged is 0.00% of the N-butyl-methyltetrahydrophthalic acid imide in the system.
This is the theoretical amount required to form 5 parts.

As a result, a product having a melting point of -20° C. or lower is obtained, and it can be seen that even when it is added in the form of a primary amine, it has the same effect as when it is added in advance as an imide.

Example 7 3 Me-Δ'-60 parts of THPA, 4 Me-Δ'
-40 parts of THPA and 0.5 parts of a nitrogen-containing compound shown in Table 3
The reaction was carried out at 180°C for 5 hours.

The results are shown in Table 3.

Claims (1)

[Scope of Claims] 1. Methyl-delta-4, which is characterized in that methyl-delta-4-tetrahydrophthalic anhydride is heat-treated in the presence of a nitrogen-containing compound having a nitrogen atom bonded to a carbon atom of a carbonyl group. - A method for isomerizing tetrahydrophthalic anhydride. 2 Methyl-delta-4-tetrahydrophthalic anhydride is 3-methyl-delta-4-tetrahydrophthalic anhydride 1
20% by weight of 4-methyl-delta-4-tetrahydrophthalic anhydride and 0-80% by weight of 4-methyl-delta-4-tetrahydrophthalic anhydride. 3. The method according to claim 1, wherein the heat treatment is carried out at a temperature of 60 to 300°C. 4. The method according to claim 1, wherein the nitrogen-containing compound is an amide, imide, carbamate, urea, semicarbazide, or a derivative thereof.