JP2719935B2 - Stereoisomerization of methyl-delta-4-tetrahydrophthalic anhydride. - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a process for the stereoisomerization of methyl-delta-4-tetrahydrophthalic anhydride, and more particularly to methyl-delta-4-tetrahydrophthalic anhydride.
The present invention relates to a method for subjecting delta-4-tetrahydrophthalic anhydride to stereoisomerization by heat treatment in the presence of an alkali metal.

ART methyl - delta 4-tetrahydrophthalic anhydride (. Hereinafter abbreviated as Me-Δ ⁴ -THPA) is a useful compound which is used as such components of the curing agent and an unsaturated polyester resin having an epoxy resin .

However, cis obtained by Diels-Alder reaction the trans piperylene and maleic anhydride-3-methyl - delta 4-tetrahydrophthalic anhydride (. Hereinafter abbreviated as cis -3Me-Δ ⁴ -THPA) or isoprene 4-methyl can be obtained by maleic anhydride to Diels-Alder reaction - delta-4 tetrahydrophthalic anhydride (. which hereinafter abbreviated as 4Me-Δ ⁴ -THPA) has a melting point are each 61 ° C. and 64 ° C. Solid at room temperature. Therefore, it is not suitable as an epoxy resin curing agent which is required to be liquid at room temperature for handling. Therefore, these cis -3Me-Δ ⁴ -THPA and /
Or 4Me-delta ⁴ and structural isomers and / or stereoisomers of the -THPA With isomer mixtures, isomerization process to liquefy at room temperature have been developed.

Meanwhile, conventionally, as follows is disclosed as a method of stereoisomeric the Me-Δ ⁴ -THPA.

(B) by heating the cis -3Me-Δ ⁴ -THPA a Diels-under-adduct to maleic anhydride trans piperylene in the presence of di-heptyl aniline, corresponding trans -3Me-Δ ⁴ -THPA To stereoisomerization (Journal of American Chemical Society)
1950, Vol. 72, pp. 1678-1681).

(B) heating the cis -3Me-Δ ⁴ -THPA in the presence of an alkali metal compound, the corresponding method of stereoisomerization trans body (Sho 57-34834 Patent Publication).

(C) Me-Δ ⁴ -THPA stereoisomerization method of heating in the presence of an alkaline earth metal oxide (JP-B 58-54146 JP)
And so on.

Moreover, the presence of the present invention have also the periodic table Group IVB metal compound, cis -3Me-Δ ⁴ -TH by performing heat treatment
It proposes stereoisomerization method of PA or cis -3Me-Δ ⁴ -THPA and 4Me-Δ ⁴ -THPA mixture (Japanese Patent Application No. Sho 63-181787
issue).

Problems to be Solved by the Invention However, the above disclosed known stereoisomerization methods have the following problems. That is, in the stereoisomerization method in the presence of a tertiary amine such as dibutylaniline or an alkali metal compound, the distillation residue increases during the rectification of the product due to by-products of heavy substances, and the yield decreases. Has problems. Further, in this method, since the catalyst is dissolved in the product, it is difficult to separate the catalyst,
Therefore, there is also a problem in industrial practice that it is difficult to reuse the catalyst.

In addition, when the present inventors re-tested the stereoisomerization method in the presence of an alkaline earth metal oxide, the stereoisomerization rate was low, and the reaction required a high temperature and a long time. There was found.

Upon invention stereoisomeric the Me-Δ ⁴ -THPA,
By-production of heavies is large, re-use of the catalyst is difficult, which is the reaction rate to solve the problems associated with the prior art that slow, Me-delta ⁴ inexpensive efficient solid of -THPA It is intended to provide an isomerization method.

SUMMARY The present inventors of the Invention The problem is, Me-Δ ⁴ -THPA stereoisomers of method in which various studies, the presence of an alkali metal, by heat treatment, less expensive The present inventors have found an efficient stereoisomerization method and have completed the present invention. That is, the present invention
The Me-Δ ⁴ -THPA in the presence of an alkali metal, to a stereoisomeric Act of Me-Δ ⁴ -THPA, characterized in that the heat treatment.

^{Me-Δ 4 -THPA Me-Δ} 4 -THPA used in the present invention is the cis -3Me-Δ ⁴ -THPA or trans piperylene is obtained by Diels-Alder reaction of trans-piperylene and maleic acid Isoburen mixture a mixture of cis obtained by reacting maleic anhydride and Diels-Alder -3Me-Δ ⁴ -THPA and 4Me-Δ ⁴ -THPA of the like.

The isomerization process of Me-Δ ⁴ -THPA of the present invention, a so-called location-based movement of the double bond, structured isomerization does not occur, resulting only stereoisomerization.

That is, cis -3Me-Δ ⁴ -THPA is stereoisomerization trans -3Me-Δ ⁴ -THPA corresponding by isomerization, a low freezing point substance provides a mixture of cis- and trans-isomer.
In the case of using a mixture of cis -3Me-Δ ⁴ -THPA and 4Me-Δ ⁴ -THPA is provide further low freezing point material than the above, which cis -3Me-Δ ⁴ -THPA, trans -3Me −
It believed to be based on freezing point depression effect of three parties mixture of Δ ⁴ -THPA and 4Me-Δ ⁴ -THPA.

Catalyst The catalyst used in the present invention is an alkali metal. Examples of such a catalyst include metallic lithium, metallic sodium, metallic potassium, metallic rubidium, metallic cesium, and metallic francium. Of these, the use of metal lithium, metal sodium, and metal potassium as the catalyst is particularly preferred.

Fee catalysts are 5 to 10,000 ppm by weight relative to Me-Δ ⁴ -THPA, preferably 10 to 1,000 ppm by weight. The alkali metal which is the catalyst of the present invention may be used as it is, or may be used after being dispersed in paraffin wax or the like. Further, the product liquid isomer mixture and the catalyst of the present invention can be separated by known means such as distillation, and the catalyst separated in this manner can be reused.

Stereoisomerization Conditions The reaction format of the stereoisomerization reaction of the present invention may be either a batch system or a continuous system, and in the case of a continuous system, it is conventionally known as a fixed bed system, a moving bed system or a fluidized bed system. Can be selected as appropriate from the existing methods. The reaction temperature is from 80 to 250 ° C, preferably from 120 to 200 ° C.

The reaction time is 0.1 to 20 hours, preferably about 1 to 10 hours in the case of a batch system. The reaction pressure may be normal pressure or under pressure. A solvent may or may not be used, but if it is used, toluene, xylene, quinene, tetralin, decalin, or the like can be used.

Advantageous Effects The method of the present invention, generation of high boiling point by-products can be reduced, the although stereoisomeric mixtures Me-Δ ⁴ -THPA is obtained in connexion high yield. Also, the amount of catalyst used is very small,
In addition, since the product and the catalyst can be easily separated, the catalyst can be reused, which is excellent in industrial use value. Furthermore, the method of the present invention has the effects of requiring no high-temperature and long-time reaction due to a high rate of the stereoisomerization reaction, and having less coloring of the obtained liquid product (low Gardner color number).

Hereinafter, the present invention will be described with reference to examples, but the present invention is not limited to these examples. In the examples, ppm, parts and% are based on weight unless otherwise specified.

Cis four-necked flask 300ml with Example 1 agitator -3Me-Δ ⁴
-100 parts of THPA (melting point 61 ° C.) and 200 ppm of metallic sodium (manufactured by Wako Pure Chemical Industries, Ltd.) were added to cis-3Me-Δ ⁴ -THPA,
The isomerization reaction was performed at 180 ° C. for 2 hours while stirring in a nitrogen atmosphere. After the reaction, the product containing the catalyst is distilled under reduced pressure to give a pale yellow transparent liquid (Gardner color number <1).
96.3 parts were obtained.

Freezing point of the liquid product is 0 ° C., Atsuta results were analyzed by gas chromatography cis -3Me-Δ ⁴ -THPA23% and trans -3Me-Δ ⁴ mixture of -THPA 77%. Further, as a result of the nuclear magnetic resonance spectrum analysis, it was confirmed that the double bond of the cyclohexene ring did not move.

Example 2 An isomerization reaction was carried out in the same manner as in Example 1 except that 200 ppm of metal potassium (manufactured by Wako Pure Chemical Industries, Ltd.) was used instead of 200 ppm of metal sodium and the reaction time was 1 hour. . After the reaction, the product containing the catalyst was distilled under reduced pressure to obtain 97.1 parts of a pale yellow transparent liquid (Gardner color number <1).

The freezing point of the distillate was 0 ° C., and as a result of gas chromatography analysis, it was a mixture of 23% of the cis form and 77% of the trans form.

Example 3 An isomerization reaction was carried out in the same manner as in Example 1 except that 1000 ppm of metallic sodium (manufactured by Wako Pure Chemical Industries, Ltd.) was used instead of 200 ppm of metallic sodium and the reaction time was 3 hours. . After the reaction, the product containing the catalyst was distilled under reduced pressure to obtain 96.4 parts of a pale yellow transparent liquid (Gardner color number <1).

The distillate had a freezing point of 3 ° C., and was found to be a mixture of 30% cis-form and 70% trans-form as a result of gas chromatography analysis.

Example 4 An isomerization reaction was carried out in the same manner as in Example 1 except that 1000 ppm of metallic sodium was used as a catalyst and the reaction condition was 150 ° C. for 3 hours. After the reaction, the product containing the catalyst was distilled under reduced pressure to obtain 95.7 parts of a pale yellow transparent liquid (Gardner color number <1).

The distillate had a freezing point of 5 ° C., and was found to be a mixture of 37% cis-isomer and 63% trans-isomer by gas chromatography analysis.

Example 5 An isomerization reaction and distillation under reduced pressure were carried out in the same manner as in Example 4 except that the distillation residue separated in Example 4 was reused. Distillate is a pale yellow transparent liquid (Gardner color number <
1), and 97.6 parts were recovered. Distillation residue was 6.7 parts, but net was 2.4 parts after subtracting 4.3 parts of the residue of Example 4.
I was in the department.

The distillate had a freezing point of 5 ° C., and was found to be a mixture of 34% cis-isomer and 66% trans-isomer by gas chromatography analysis. This proved that the distillation residue containing the catalyst could be used repeatedly.

Example 6 Example 1 was repeated except that 10 ppm of metallic sodium was used as the catalyst and the reaction conditions were set at 200 ° C. for 5 hours.
The isomerization reaction and distillation under reduced pressure were carried out in the same manner as described above. The distillate was a pale yellow transparent liquid (Gardner color number <1), and 95.3 parts were recovered.

The distillate had a freezing point of 3 ° C., and was found to be a mixture of 27% cis-isomer and 73% trans-isomer by gas chromatography analysis.

Comparative Example 1 Isomerization reaction was performed in the same manner as in Example 1 except that 2 parts of dibutylaniline (manufactured by Tokyo Chemical Industry Co., Ltd.) was used instead of 200 ppm of metallic sodium and the reaction conditions were set to 200 ° C. for 5 hours. And vacuum distillation. As a distillate, 88.7 parts of a red liquid (Gardner color number 4) was obtained. 13.3 parts of heavy matter was left in the kettle.

The freezing point of the distillate was 10 ° C, and the result of gas chromatography analysis showed that the cis form was 40% and the trans form was 60%
Mixture.

Comparative Example 2 An isomerization reaction was carried out in the same manner as in Example 1, except that 5 parts of calcium oxide was used instead of 200 ppm of metallic sodium and that the reaction conditions were set at 200 ° C. for 5 hours. After the reaction, the product was solidified when cooled to room temperature, and its melting point was 42 ° C.

The product was analyzed by gas chromatography,
It was a mixture of 80% and a 20% trans form, and it was found that stereoisomerization in the presence of this catalyst resulted in a slow rate of the isomerization reaction to the trans form.

Comparative Example 3 One part of sodium hydroxide was used in place of 200 ppm of metallic sodium, and the reaction conditions were 200 ° C.,
An isomerization reaction and distillation under reduced pressure were carried out in the same manner as in Example 1 except that the time was changed. 87.6 parts of a pale yellow transparent liquid (Gardner color number <1) was obtained as a distillate.

The freezing point of the distillate was 3 ° C., and as a result of gas chromatography analysis, it was a mixture of cis-isomer 31% and trans-isomer 69%.

And metallic sodium be used in the case of an embodiment 7-10 cis -3Me-Δ ⁴ -THPA and 4Me-Δ ⁴ -THPA total 100 parts Table 1
Isomerization reaction and distillation under reduced pressure were carried out in the same manner as in Example 1 except that 100 ppm was used and the reaction time was set to 3 hours. Table 1 shows the distillation amount, the freezing point of the distillate, and the Gardner color number.

Based on these results, the method of the present invention produced heavy substances,
It turns out that all are few. Furthermore, cis-3Me-Δ ⁴ −
When using a mixture of THPA and 4Me-Δ ⁴ -THPA is less liquid products with a freezing point than with cis -3Me-Δ ⁴ -THPA alone is obtained.

In the above case, the ratio of the cis-form / trans-form in the product was as follows.

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Shoji Ishii 1-3-1 Nishitsurugaoka, Oi-machi, Irima-gun, Saitama Prefecture Toa Fuel Industry Co., Ltd. (72) Inventor Hiroshi Ueno Oimachi, Iruma-gun, Saitama 1-3-1 Nishitsurugaoka Toa Fuel Industry Co., Ltd. Research Laboratory

Claims (3)

(57) [Claims] 1. A method for stereoisomerizing methyl-delta-4-tetrahydrophthalic anhydride, comprising subjecting methyl-delta-4-tetrahydrophthalic anhydride to a heat treatment in the presence of an alkali metal. 2. The method according to claim 1, wherein the methyl-delta-4-tetrahydrophthalic anhydride is cis-3-methyl-delta-4-tetrahydrophthalic anhydride. 3. The method of claim 1, wherein the methyl-delta-4-tetrahydrophthalic anhydride is a mixture of cis-3-methyl-delta-4-tetrahydrophthalic anhydride and 4-methyl-delta-4-tetrahydrophthalic anhydride. The method according to item (1).