JPS6221786B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for isomerizing tetrahydrophthalic anhydride and its derivatives. Tetrahydrophthalic anhydride and its derivatives can be obtained by the addition reaction of various dienes obtained from naphtha cracked oil or synthetic diene oligomers with maleic anhydride. Tetrahydrophthalic anhydride and its derivatives have various uses, including as a curing agent for epoxy resins and as an acid component for alkyd resins. It may be desirable to isomerize for this purpose. The present invention relates to a method for isomerizing tetrahydrophthalic anhydride and its derivatives used for such purposes. Hitherto, various methods have been proposed for isomerizing tetrahydrophthalic anhydride and its derivatives, but the conventional methods have not always been fully satisfactory. For example, in US Pat. No. 2,764,597, △ ¹ -tetrahydrophthalic anhydride is obtained by isomerizing △ ⁴ -tetrahydrophthalic anhydride, its free acid, and its esters using Pd or Ru as an isomerization catalyst. However, this method has the disadvantage of requiring expensive noble metals as an isomerization catalyst. Furthermore, in Japanese Patent Publication No. 15495/1987, 3 (and 4)-methyl-4-cyclohexene-1,2-
A method has been proposed in which dicarboxylic acid anhydride is liquefied by heat treatment in the presence of polyphosphoric acid or BF ₃ complex (ethyl ether, acetic acid) as an isomerization catalyst, but this method is
Effective liquefaction only for methyl-4-cyclohexene-1,2-dicarboxylic anhydride, that is, a mixture of 3-methyl-△ ⁴ -tetrahydrophthalic anhydride and 4-methyl-△ ⁴ -tetrahydrophthalic anhydride. cannot be effective. That is, this method cannot achieve the purpose of liquefying a single compound of 3-methyl-△ ⁴ -tetrahydrophthalic anhydride or 4-methyl-△ ⁴ -tetrahydrophthalic anhydride. The present inventors conducted various studies on isomerization reactions of tetrahydrophthalic anhydride and its derivatives, and as a result, succeeded in developing a method that can extremely effectively isomerize tetrahydrophthalic anhydride using an inexpensive isomerization catalyst. That's what I did. That is, the present invention provides the general formula (In the formula, R represents hydrogen or an alkyl group having 1 to 6 carbon atoms.) Tetrahydrophthalic anhydride and its derivatives represented by bromine, iodine, alkali metal bromide, alkali metal iodide, alkaline earth bromide This is a method for isomerizing tetrahydrophthalic anhydride and its derivatives, which is characterized by carrying out a heat treatment in the presence of one or more isomerization catalysts selected from the group consisting of metals and alkaline earth metal iodides. Tetrahydrophthalic anhydride and its derivatives to be subjected to the isomerization reaction in the present invention are compounds represented by the above general formula (). Examples of such compounds include ^Δ4 -tetrahydrophthalic anhydride, 3-methyl- ^Δ4 -tetrahydrophthalic anhydride, 4-methyl- ^Δ4 -tetrahydrophthalic anhydride, 3-butyl- ^Δ4 -tetrahydrophthalic anhydride, Examples include 3-butenyl-5-methyl- ^Δ4 -tetrahydrophthalic anhydride. These compounds can be used as a raw material for the present invention either as a single compound or as a mixture of two or more of them. In the isomerization method of the present invention, these △ ⁴ -tetrahydrophthalic anhydride and its alkyl derivative cause a double bond transfer reaction from the △ ⁴ -position to the △ ¹ -position as the main reaction, As a result, Δ ¹ -tetrahydrophthalic anhydride and its alkyl derivatives, namely maleic anhydride derivatives, are produced as the main products. Therefore, in other words, the isomerization method of the present invention can be said to be a method for producing maleic anhydride derivatives. Further, in the isomerization method of the present invention, when the raw material compound () is a compound that is solid at room temperature, the isomerized product is often obtained as a liquid at room temperature. It is presumed that several types of geometric and structural isomers are produced through the isomerization reaction, and the coexistence of these several types of isomers lowers the freezing point. Therefore, the isomerization method of the present invention can be used as a method for liquefying a solid raw material compound (). As the isomerization catalyst in the present invention, bromine, iodine, alkali metal bromide, alkali metal iodide, alkaline earth metal bromide, and alkaline earth metal iodide are used. The alkali metals in the catalyst include lithium, sodium, potassium, rubidium and cesium, and the alkaline earth metals include calcium, magnesium and barium. Two or more of these isomerization catalysts may be used in combination. The amount of the isomerization catalyst used in the present invention is 0.005% by weight or more, preferably 0.01 to 3.0% by weight based on the compound represented by the above general formula () as the starting material.
It is. These isomerization catalysts may be added directly to the anhydrous raw material heated and melted, or may be added by other methods such as dissolved in a solvent such as water or acetone. Alternatively, the isomerization catalyst supported on a suitable carrier may be packed in a packed column, and the steam of the raw material acid anhydride may be passed through the packed bed at a desired reaction temperature to perform the heat treatment of the present invention. It is possible. Regarding the heat treatment conditions in the present invention, if the heating temperature is too low, it will take a long time for isomerization, and if the heating temperature is too high, the decomposition reaction and resin compound formation reaction will increase, reducing the yield of the desired isomerized product. And the reaction temperature is usually 120-250℃, preferably
The temperature is 150-230℃. Further, the heat treatment time varies depending on the amount of catalyst and the reaction temperature, and cannot be generally specified, but it is usually 10 minutes to 10 hours, preferably 0.5 to 3 hours. In addition, as mentioned above, an isomerization catalyst is supported on a carrier such as pumice, activated carbon, diatomaceous earth, silica gel, or molecular sieve, and the vapor of the raw material acid anhydride is passed through the supported catalyst layer to continuously heat it. can be processed, but in such cases 200 to 250
It is desirable to carry out the treatment at a high temperature of °C for a short time. If the amount of catalyst is small, the isomerized product obtained by processing according to the method of the present invention may be purified by distillation as it is, but it may be colored by free halogen. It is preferable to wash it with, for example, a 10% aqueous solution of sodium thiosulfate (Hybo) and then distill it. Also, activated carbon treatment for decolorization,
After adding superimposing agents such as diatomaceous earth, and further treating with an appropriate dehydrating agent to remove moisture,
May be distilled. The isomerization products obtained by the process of the invention can be advantageously used as hardeners for epoxy resins and as acid components of alkyd resins. This product also includes amides, imides, esters, chlorine adducts,
It can be used as a rust preventive after being modified into an alkylene oxide adduct, and can also be used as a base oil for grease as a salt of magnesium or aluminum, and as a plasticizer for rubber or resin (especially vinyl chloride) as a diester. In particular, this isomerization product can be used for various epoxy resins, such as those described in Chapters 3 and 4 of ``Epoxy Resins'' edited by Hiroshi Kakiuchi and published by Shokodo on September 30, 1970. It can exhibit excellent curing properties when used as a curing agent for various epoxy resins. When this isomerized product is used as an epoxy resin curing agent, the amount used is usually 50 to 120 parts by weight, preferably 50 to 120 parts by weight, per 100 parts by weight of the epoxy resin.
It is 70-100 parts by weight. Furthermore, when this isomerized product is used as an epoxy resin curing agent, other curing agents such as acid anhydride curing agents may be used in combination as necessary. Examples include hexahydrophthalic anhydride, tetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, methyl nadic anhydride, phthalic anhydride, pyromellitic anhydride, dodecenylsacnic anhydride, nadic anhydride, and chlorendic anhydride. It will be done. Furthermore, when this isomerized product is used as an epoxy resin curing agent, a curing accelerator can be used in combination, if necessary. For example, hexoates of trialkylamines, N-dimethylbenzylamine, triethanolamine, piperidine, dimethylaminomethylphenol, tris(dimethylaminomethyl)phenol, tris(dimethylaminomethyl)phenol, imidazoles (e.g. 2-ethyl-4 -methylimidazole), dicyandiamide, triphenylphosphine, etc. can be used in combination as a curing accelerator. The amount of the curing accelerator used is preferably 0.1 to 5 parts by weight per 100 parts by weight of the epoxy resin. Next, 4, which is one of the compounds represented by the above general formula (), which is the starting material in the method of the present invention.
-Methyl-△ ⁴ -tetrahydrophthalic anhydride (hereinafter referred to as "4-Me-△ ⁴ -THPA")
The following describes production examples, examples, comparative examples, and experimental examples of 3-methyl-△ ⁴ -tetrahydrophthalic anhydride (hereinafter referred to as "3-Me-△ ⁴ -THPA"). 4-Me-△ ⁴ -THPA production example Put 196 g (2.0 mol) of maleic anhydride into a four-necked flask with a capacity of 1 equipped with a stirrer, thermometer, condenser, dropping funnel, and nitrogen inlet tube, and add 100 ml of toluene. added. 143 g (2.1 mol) of isoprene was gradually added while stirring at room temperature. Since the temperature rose due to the heat of reaction, the reaction temperature was maintained at 70-80°C by cooling with a water bath. Approximately 0.5 hours or so once finished administering isoprene. Further, the mixture was stirred at 70 to 80°C for about 1 hour to complete the reaction. After the reaction was completed, excess isoprene and toluene as a solvent were distilled off by suction using an aspirator at a temperature of 100° C. or less (degree of vacuum: 20 mmHg). Furthermore, by distilling under reduced pressure (0.5-1 mmHg, distillation temperature 105-115℃),
-Me-△ ^{4 -} Obtained THPA. 3-Me- ^Δ4 -THPA production example 196 g (20 mol) of maleic anhydride, 143 g (2.1 mol) of 1,3-pentadiene, and 100 ml of xylene were placed in a stainless steel autoclave with a capacity of 2. The mixture was stirred for 3 hours while maintaining the temperature at about 90 to 100° C. while controlling the temperature rise due to reaction heat. After the reaction was completed, excess 1,3-pentadiene and xylene as a solvent were removed by suction using an aspirator at a temperature of 100° C. or less (degree of vacuum: 20 mmHg). Furthermore, vacuum distillation (0.5 to 1 mmHg, distillation temperature 100
~110°C), 3-Me-△ ⁴ -THPA was obtained. Example 1 50 g of commercially available △ ⁴ -tetrahydrophthalic anhydride (hereinafter referred to as "△ ⁴ -THPA") was mixed with a stirrer,
The mixture was placed in a four-necked flask equipped with a thermometer, condenser, and nitrogen inlet tube, and heated to about 130°C to dissolve. 0.15 g of sodium iodide was added to this, and the mixture was stirred at 200°C for 6 hours. After the reaction was completed, 50 ml of toluene was added, and the mixture was washed with 50 ml of 10% sodium thiosulfate aqueous solution.
Next, after washing with water, remove the aqueous layer, add anhydrous sodium sulfate as a dehydrating agent to the oil layer, dehydrate it, and reduce the pressure to 0.5~
Simple distillation was performed at 1 mmHg. Approximately 50g as a fraction of 110-150℃/0.6-1mmHg
A white solid product was obtained. The melting point of this thing is 73~
It was 74℃. Further, the NMR spectrum analysis results of this product were as shown in FIG. That is, the spectrum showed a dotted line spectrum in contrast to the solid line spectrum of the raw material Δ ⁴ -THPA. From these data, this product is △ ¹ -tetrahydrophthalic anhydride (hereinafter “△
^1- THPA”. ) was confirmed to be the main component. Examples 2 to 10 The type of catalyst, amount of catalyst, reaction time, reaction temperature and catalyst addition method were as shown in Table 1, and the other conditions were the same as in Example ^1.
- THPA was heat treated. After the product was post-treated in the same manner as in Example 1, the yield and melting point of the product were as shown in Table 1. Furthermore, it was confirmed from the results of NMR spectrum analysis and the like that the main component of the products obtained in Examples 2 to 10 was Δ ¹ -THPA.

[Table] Example 11 4-Me-△ ^4- obtained in the above production example
Put 60g of THPA into a four-necked flask equipped with a stirrer, thermometer, condenser, and nitrogen inlet tube, and add approximately
It was heated to 100°C and dissolved. To this was added 0.3 g of sodium iodide, and the mixture was heated and stirred at 210°C for 4 hours. After the reaction was completed, 50 ml of chloroform was added, and the mixture was washed with 50 ml of 10% sodium thiosulfate aqueous solution. After washing with water, the aqueous layer was removed, and anhydrous sodium sulfate was added as a dehydrating agent to the oil layer for dehydration, followed by simple distillation at a reduced pressure of 0.5 to 1 mmHg. As a fraction of 105-115℃/0.5-1mmHg,
54 g (yield 90%) of a pale yellow liquid product was obtained. This product had an acid value of 82-84. Furthermore, it was confirmed by GC, IR and NMR that this product is an isomer mixture containing 4-Me-△ ¹ -THPA as the main component.
This was confirmed from the analysis results. FIG. 2 shows the spectra of the raw material 4-Me-△ ⁴ -THPA (solid line) and its product (dotted line) in Example 11. This liquid product was left in a refrigerator at 5°C, in a freezer at -20°C, and at room temperature (20 to 25°C) for 2 months, but did not crystallize. Further, its viscosity (E-type viscometer) was 42 cps at 25°C. Examples 12 to 19 4-Me-△ ¹ -THPA produced in the above production example
and (or) 3-Me-△ ⁴ -THPA,
The type of catalyst, amount of catalyst, reaction time, reaction temperature, and catalyst addition method were as shown in Table 2, and the heat treatment was otherwise performed in accordance with the method of Example 11. The obtained products were post-treated according to the method of Example 11, and liquid products having the viscosities shown in Table 2 were obtained at the yields shown in the table. This example 12
The product obtained in ~19 is also 4-Me-△ ^1-
It was confirmed by NMR analysis etc. that THPA is the main component. All of the liquid products obtained in Examples 12 to 19 had excellent liquid stability, and although they were kept at the same temperatures for two months as in Example 11, no crystals were formed in any of them.

[Table] In addition, as in Examples 11 to 19, 4-Me
-△ ⁴ -THPA or 3-Me-△ ⁴ -The reason why a liquid product is produced when the isomerization method of the present invention is applied to THPA is that several geometric and structural isomers are generated by the isomerization reaction. However, it is assumed that their coexistence lowers the freezing point. Experimental example Epicoat 828 [trade name, Siel Kagaku Co., Ltd., epoxy equivalent weight 189, glycidyl ether of 2,2-bis-(4-hydroxyphenyl)propane] 100 parts (parts by weight, same hereinafter) obtained in Example 11 80 parts of liquid 4-Me- ^Δ4 -THPA and 1 part of benzyldimethylamine as a curing accelerator were uniformly stirred and mixed at room temperature, and defoamed under reduced pressure (2 mmHg or less) to prepare an epoxy resin composition. The viscosity of this composition was about 20 poise at 25°C, and casting etc. were extremely easy. When this resin composition was precured at 80°C for 3 hours and then at 120°C for 6 hours, a strong cured resin was obtained as shown in Table 3. For comparison, Table 3 also includes the formulations of epoxy resin compositions containing known curing agents and the physical properties of the cured resins.

【table】

[Table] As can be seen from Table 3, the liquid isomerization product obtained in Example 11 was more effective as an epoxy resin curing agent than the existing hexahydrophthalic anhydride curing agent. No inferiority was observed in the physical and electrical properties. Also, examples
Almost similar results were obtained for the liquid isomerization products obtained in Examples 12 to 19.

[Brief explanation of the drawing]

Figure 1 shows the raw material △ ⁴ -THPA in Example 1.
(solid line) and product △ ¹ -THPA (dotted line) NMR
The spectrum is shown. Further, FIG. 2 shows the NMR spectra of the raw material 4-Me-Δ ⁴ -THPA (solid line) and the product 4-Me-Δ ₁ -THPA (dotted line) in Example 11.

Claims (1)

[Claims] 1. General formula (In the formula, R represents hydrogen or an alkyl group having 1 to 6 carbon atoms.) Tetrahydrophthalic anhydride and its derivatives represented by bromine, iodine, alkali metal bromide, alkali metal iodide, alkaline earth bromide 1. A method for isomerizing tetrahydrophthalic anhydride and its derivatives, the method comprising heating in the presence of one or more isomerization catalysts selected from the group consisting of metals and alkaline earth metal iodides. 2. Tetrahydrophthalic anhydride and its derivatives are Δ ⁴ -tetrahydrophthalic anhydride, 3-methyl-Δ ⁴ -tetrahydrophthalic anhydride, 4-methyl-Δ ⁴ -tetrahydrophthalic anhydride, or any two of these. The method according to claim 1, which is a mixture of the above. 3. The method according to claim 1 or 2, wherein the isomerization catalyst is present in an amount of 0.005% by weight or more based on tetrahydrophthalic anhydride and its derivatives. 4. The method according to claim 1, 2 or 3, wherein the heat treatment temperature is 120 to 250°C.