JP2020143078A - Manufacturing method of high purity 1,3-dialkylcyclobutanoic-1,2,3,4-tetracarboxylic acid-1,2,3,4-dianhydride - Google Patents

Abstract

To provide an efficient manufacturing method of high purity 1,3-dialkyl-1,2,3,4-cyclobutanetetracarboxylic acid-1,2,3,4-dianhydride that is a raw material of polyimide or the like.SOLUTION: A mixture containing 1,3-dialkylcyclobutanoic-1,2,3,4-tetracarboxylic acid-1,2,3,4-dianhydride and 1,2-dialkylcyclobutanoic-1,2,3,4-tetracarboxylic acid-1,2,3,4-dianhydride at a mass ratio of 70:30 to 99.5 to 0.5 is heated in an organic solvent selected from the group consisting of acetic acid anhydride, acetonitrile and ethyl acetate, cooled, followed by filtering.SELECTED DRAWING: None

Description

The present invention is a high-purity 1,3-dialkylcyclobutane-1,2,3,4-tetracarboxylic acid-1,2: 3,4-dianhydride that can be a raw material monomer such as polyimide for optical materials. Regarding the manufacturing method.

In general, polyimide resin is widely used as an electronic material such as a protective material and an insulating material in a liquid crystal display element or a semiconductor because of its characteristics such as high mechanical strength, heat resistance, insulating property, and solvent resistance. Recently, it is also expected to be used as a material for optical communication such as a material for an optical waveguide.
In recent years, the development of this field has been remarkable, and in response to this, more and more advanced properties are required for the materials used. That is, it is expected that not only the heat resistance and the solvent resistance are excellent, but also a large number of performances according to the application.

However, the total aromatic polyimide resin, which is made from aromatic tetracarboxylic dianhydride and aromatic diamine, exhibits a deep amber color and is colored, which poses a problem in applications requiring high transparency. are doing. On the other hand, a polyimide resin in which a polyimide precursor is formed by a polycondensation reaction between an alicyclic tetracarboxylic acid dianhydride and an aromatic diamine and the precursor is imidized is relatively less colored and highly transparent. It is known (see Patent Documents 1 and 2).

As an alkylcyclobutanoic acid dianhydride, which is one of the alicyclic tetracarboxylic dianhydrides which is a raw material of a highly transparent polyimide with relatively little coloring, Patent Document 3 shows the following scheme. 1,3-Dimethylcyclobutane-1,2,3,4-tetracarboxylic acid-1,2: 3,4-dianhydride by photodimerization reaction of citraconic anhydride (abbreviated as MMA). A mixture of the substance (1,3-DMCBDA) and 1,2-dimethylcyclobutane-1,2,3,4-tetracarboxylic acid-1,2: 3,4-dianhydride (1,2-DMCBDA) is obtained. It is disclosed that

On the other hand, when 1,3-DMCBDA and 1,2-DMCBDA are compared, the former 1,3-DMCBDA having a highly symmetric structure is produced, and the latter polyimide having a higher molecular weight than 1,2-DMCBDA is produced. It is known to be possible and more useful.
However, although Patent Document 3 describes that a mixture of 1,3-DMCBDA and 1,2-DMCBDA can be obtained, the former 1,3-DMCBDA, which is highly useful, can be obtained with high purity. There is no description about obtaining with high efficiency.

Special Fair 2-24294 Gazette JP-A-58-208322 Japanese Unexamined Patent Publication No. 4-106127 Publication of International Patent Application WO2010 / 092989

An object of the present invention is a 1,3-dialkylcyclobutane-1,2,3,4-tetracarboxylic acid-1,2: 3,4-dianhydride obtained by a photodimerization reaction of a maleic anhydride compound or the like. Hereinafter, along with 1,3-DACBDA), 1,2-dialkylcyclobutane-1,2,3,4-tetracarboxylic acid-1,2: 3,4-dianhydride (hereinafter, 1,2-). It is an object of the present invention to provide a method for obtaining the former 1,3-DACBDA with high purity and high efficiency from a mixture containing (also referred to as DACBDA).

As a result of diligent research to solve the above problems, the present inventors have found that 1,3-DACBDA and 1,2-DACBDA have a solubility in a heated organic solvent, particularly a specific organic solvent. We found that the solubility of the former was extremely small compared to that of the latter, and found a method of separating the two by utilizing the difference in solubility to obtain high-purity 1,3-DACBDA with high efficiency. Was completed.
The present invention has the following gist.

1. High-purity 1,3-dialkyl-1,3-dialkyl-1,2,3,4-by heating, cooling and then filtering a mixture of 1,3-DACBDA and 1,2-DACBDA in an organic solvent. A method for producing 1,3-DACBDA, which comprises filtering cyclobutanetetracarboxylic acid-1,2: 3,4-dianhydride as a solid.
2. 2. The production method according to 1 above, wherein the organic solvent is an ester or anhydride of an organic carboxylic acid or a carbonic acid ester having a boiling point of 50 to 200 ° C.
3. 3. The production method according to 1 above, wherein the soluble solvent is acetic anhydride.
4. The production method according to any one of 1 to 3 above, wherein the soluble solvent is used in an amount of 2 to 20 parts by mass with respect to I parts by mass of a mixture of 11,3-DACBDA and 1,2-DACBDA.
5. The production method according to any one of 1 to 4 above, wherein the mixture is heated in an organic solvent at a temperature of 10 ° C. to the boiling point of the organic solvent.
6. The production method according to any one of 1 to 5 above, wherein after the heating, the mixture is cooled to −10 to 50 ° C.
7. The production method according to any one of 1 to 6 above, wherein the mass ratio of 1,3-DACBDA and 1,2-DACBDA in the mixture is 50:50 to 99.5: 0.5.
8. The production method according to any one of 1 to 7 above, wherein the mixture of 1,3-DACBDA and 1,2-DACBDA is obtained by a photodimerization reaction of maleic anhydride.
9. The production method according to any one of 1 to 8 above, wherein the alkyl group of 1,3-DACBDA and 1,2-DACBDA is a methyl group.

According to the production method of the present invention, high-purity 1,3-dialkylcyclobutane-1,2,3,4-tetracarboxylic acid-1,2: 3,4-dianhydride (1,3-DACBDA) is produced. It can be obtained easily, efficiently, and with a high recovery rate.

The mixture of 1,3-DACBDA and 1,2-DACBDA, which is the raw material in the production method of the present invention, is typically obtained by the photodimerization reaction of the maleic anhydride compound represented by the formula (1) as follows. Can be obtained with the reaction scheme of.

上記式中、Ｒは、炭素数が１〜２０、好ましくは１〜１２、より好ましくは１〜６のアルキル基を表す。特にメチルが好ましい。

In the above formula, R represents an alkyl group having 1 to 20, preferably 1 to 12, more preferably 1 to 6 carbon atoms. Methyl is particularly preferable.

The alkyl group having 1 to 20 carbon atoms may be either a linear or branched saturated alkyl group or a linear or branched unsaturated alkyl group. Specific examples thereof include methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, s-butyl, t-butyl, n-pentyl, 1-methyl-n-butyl, 2-methyl-. n-butyl, 3-methyl-n-butyl, 1,1-dimethyl-n-propyl, n-hexyl, 1-methyl-n-pentyl, 2-methyl-n-pentyl, 1,1-dimethyl-n- Butyl, 1-ethyl-n-butyl, 1,1,2-trimethyl-n-propyl, n-heptyl, n-octyl, n-nonyl, n-decyl, n-dodecyl, n-eicosyl, 1-methylvinyl , 2-allyl, 1-ethylvinyl, 2-methylallyl, 2-butenyl, 2-methyl-2-butenyl, 3-methyl-2-butenyl, 3-methyl-3-butenyl, 2-hexenyl, 4-methyl-3 -Pentenyl, 4-methyl-4-pentenyl, 2,3-dimethyl-2-butenyl, 1-ethyl-2-pentenyl, 3-dodecenyl, propargyl, 3-butynyl, 3-methyl-2-propynyl, 9-decynyl And so on.
Note that n represents normal, i represents iso, s represents secondary, and t represents tertiary.

As an example of the maleic anhydride compound represented by the formula (1), citraconic anhydride, 2-ethylanhydride maleic acid, 2-isopropylanhydride maleic acid, 2-n-butylanhydride maleic acid, 2-t-butylanhydride Maleic acid, 2-n-pentylmaleic anhydride, 2-n-hexylmaleic anhydride, 2-n-heptylmaleic anhydride, 2-n-octylmaleic anhydride, 2-n-nonylmaleic acid Anhydride, 2-n-decylmaleic anhydride, 2-n-dodecylmaleic anhydride, 2-n-eicosylmaleic anhydride, 2- (1-methylvinyl) maleic anhydride, 2-( 2-allyl) maleic anhydride, 2- (1-ethylvinyl) maleic anhydride, 2- (2-methylallyl) maleic anhydride, 2- (2-butenyl) maleic anhydride, 2- (2-) Hexenyl) maleic anhydride, 2- (1-ethyl-2-pentenyl) maleic anhydride, 2- (3-dodecenyl) maleic anhydride, 2-propargylmaleic anhydride, 2- (3-butynyl) Examples thereof include maleic anhydride, 2- (3-methyl-2-propynyl) maleic anhydride, 2- (9-decynyl) maleic anhydride and the like.

An example of the production conditions of a mixture of 1,3-DACBDA and 1,2-DACBDA by a photodimerization reaction of a maleic anhydride compound is described below.
As the solvent used in the photodimerization reaction, methyl formate, ethyl formate, n-propyl formate, i-propyl formate, n-butyl formate, i-butyl formate, methyl acetate, ethyl acetate, n-propyl acetate, i-acetate Propyl, n-butyl acetate, i-butyl acetate, methyl propionate, ethyl propionate, n-propyl propionate, i-propyl propionate, ethylene glycol diformate, ethylene glycol diacetate, ethylene glycol dipropionate, carbonic acid Dimethyl, diethyl carbonate and the like can be listed.

The amount of the solvent used is preferably 3 to 300 times by mass, preferably 3 to 100 times by mass, that of the maleic anhydride compound.
The amount of the reaction solvent used is preferably small when the reaction is to be accelerated or when the yield of the product is to be increased. For example, when the concentration of the maleic anhydride compound is increased, the reaction is accelerated and the obtained product is obtained. Yield is high. Therefore, when it is desired to accelerate the reaction or increase the yield of the product, the amount of the solvent used is preferably 3 to 10 times by mass as compared with that of the maleic anhydride compound.

In the photodimerization reaction, the wavelength of light is preferably 200 to 400 nm, more preferably 250 to 350 nm, and particularly preferably 280 to 330 nm. As the light source, a low pressure mercury lamp, a medium pressure mercury lamp, a high pressure mercury lamp, an ultrahigh pressure mercury lamp, a xenon lamp, an electrodeless lamp, a light emitting diode and the like are used.
In particular, light emitting diodes with wavelengths of 275-500 nm gave 1,3-DACBDA with improved selectivity. Further, by changing the light source cooling tube from quartz glass to Pyrex glass, adhesion of colored polymer and impurities to the light source cooling tube are reduced, and 1,3-DACBDA can be obtained with an improved selectivity.

The reaction temperature is preferably -20 to 80 ° C. because the polymer is by-produced when the temperature is high, while the solubility of the maleic anhydride compound is lowered and the production efficiency is lowered when the temperature is low. More preferably, it is −10 to 50 ° C., and particularly at 0 to 20 ° C., the production of by-products such as 1,2-DACBDA is suppressed, and 1,3-DACBDA can be obtained with high selectivity and yield.

The reaction time varies depending on the amount of the maleic anhydride compound charged, the type of the light source, and the irradiation amount, but the reaction time should be 0 to 40%, preferably 0 to 10% of the unreacted maleic anhydride compound. Can be done. The conversion rate can be easily measured by analyzing the reaction solution by gas chromatography or the like.

As the reaction time becomes longer and the conversion rate of the maleic anhydride compound increases, the amount of 1,3-DACBDA deposited increases, and the generated 1,3-DACBDA begins to adhere to the outer wall (reaction liquid side) of the light source cooling tube. , Crystal coloring due to the combined decomposition reaction, and decrease in light efficiency (yield per unit power x time) are observed. Therefore, in order to increase the conversion rate of the maleic anhydride compound, it is not preferable to spend a long time in one batch because the production efficiency is lowered in practice. The reaction can be carried out in batch or flow mode, and can also be carried out under normal pressure or pressure.

After the photodimerization reaction, the precipitate in the reaction solution is filtered, the filtrate is washed with an organic solvent, and dried under reduced pressure to obtain a mixture of 1,3-DACBDA and 1,2-DACBDA. ..
The amount of the organic solvent used for washing the filtrate may be an amount that can transfer the precipitate remaining in the reaction vessel to the filter, but if the amount of the organic solvent is large, the target product is transferred to the filtrate. The recovery rate tends to decrease due to migration. Therefore, the amount of the organic solvent used for washing the filtrate is preferably 0.5 to 10 times by weight, more preferably 1 to 2 times by weight, that of the maleic anhydride compound used in the reaction.

The solvent used for cleaning the filtrate is not particularly limited, but if a solvent having a high solubility of the target product 1,3-DACBDA is used, the target product is transferred to the filtrate and the recovery rate tends to decrease. Therefore, the organic solvents used for washing the filtrate are methyl formate, ethyl formate, n-propyl formate, i-propyl formate, n-butyl formate, i-butyl formate, which are the solvents used for the photodimerization reaction. Methyl acetate, ethyl acetate, n-propyl acetate, i-propyl acetate, n-butyl acetate, i-butyl acetate, methyl propionate, ethyl propionate, n-propyl propionate, i-propyl propionate, ethylene glycol diform Mates, ethylene glycol diacetate, ethylene glycol dipropionate, dimethyl carbonate, diethyl carbonate, etc. and solvents that do not dissolve products such as toluene, hexane, heptane, acetonitrile, acetone, chloroform, anhydrous acetic acid, etc., and mixed solvents thereof, etc. Can be mentioned. Of these, ethyl acetate and dimethyl carbonate are preferable, and ethyl acetate, dimethyl carbonate and acetic anhydride are more preferable.

The photodimerization reaction of the maleic anhydride compound can also be carried out in the presence of a sensitizer. As the sensitizer, benzophenone, anthraquinone, acetophenone, benzaldehyde and the like are preferable. In particular, benzophenone substituted with an electron-attracting group, acetophenone substituted with an electron-attracting group, or benzaldehyde substituted with an electron-attracting group have high photoreaction efficiencies, and 1,3-DACBDA and 1,2-DACBDA It is preferable because it produces a mixture of.
The amount of the sensitizer used is preferably 0.1 to 20 mol%, more preferably 0.1 to 5 mol% with respect to the maleic anhydride compound.

In the present invention, a reaction mixture solution containing a mixture of 1,3-DACBDA and 1,2-DACBDA is obtained as described above. In the reaction mixture solution, 1,3-DACBDA and 1,2-DACBDA are both present as solids. Therefore, the reaction mixture solution was filtered and isolated as 1,3-DACBDA and 1,2-DACBDA. It is used as a raw material for obtaining high-purity 1,3-DACBDA in the present invention.

The organic solvent contained in the reaction mixture containing the mixture of 1,3-DACBDA and 1,2-DACBDA is an organic solvent that can be used to obtain the subsequent high-purity 1,3-DACBDA. In some cases, the reaction mixture containing the mixture of 1,3-DACBDA and 1,2-DACBDA can be used as a raw material as it is. Further, when a mixture of 1,3-DACBDA and 1,2-DACBDA is isolated from the reaction mixture solution and preferably washed, high-purity 1,3-DACBDA can be easily obtained, which is preferable.

In the present invention, a mixture of 1,3-DACBDA and 1,2-DACBDA is heated in an organic solvent as described above, cooled, and then filtered to obtain a high-purity 1,3-dialkyl-1. , 2,3,4-Cyclobutanetetracarboxylic acid-1,3,3,4-dianhydride can be obtained by filtration as a solid to obtain 1,3-DACBDA with high recovery rate and high purity. ..

As the organic solvent used here, many organic solvents do not react with 1,3-DACBDA and 1,2-DACBDA in the heated state, and have low solubility in 1,3-DACBDA, while 1, It can be used because of its high solubility in 2-DACBDA.
The organic solvent preferably has a boiling point of preferably 30 to 200 ° C, more preferably 50 to 180 ° C. As such an organic solvent, hexane, heptane, acetonitrile, acetone, chloroform, toluene and the like can also be used. In particular, as the organic solvent, an ester or anhydride of an organic carboxylic acid or a carbonic acid ester is preferable.

As the ester of the organic carboxylic acid, the formula: R ¹ COOR ² (where R ¹ is hydrogen or an alkyl group having preferably 1 to 4 carbon atoms, more preferably 1 or 2 carbon atoms, and R ² has carbon atoms. The fatty acid alkyl ester represented by 1 to 4, more preferably 1 to 3 alkyl groups) is preferable.
Preferred examples of esters of organic carboxylic acids include ethyl formate, n-propyl formate, i-propyl formate, n-butyl formate, i-butyl formate, methyl acetate, ethyl acetate, n-propyl acetate, i-propyl acetate, Examples thereof include n-butyl acetate, i-butyl acetate, methyl propionate, ethyl propionate, n-propyl propionate, i-propyl propionate, n-butyl propionate and i-butyl propionate. Further, ethylene glycol diformate, ethylene glycol diacetate, ethylene glycol dipropionate and the like can also be used.

The anhydrous organic carboxylic acid is preferably represented by the formula: (R ¹ CO) ² O (where R ¹ is synonymous with the above, including preferred embodiments). Preferred specific examples are propionic anhydride, butyric anhydride, trifluoroacetic anhydride, or acetic anhydride. Of these, acetic anhydride is preferable because 1,3-DACBDA can be obtained with a higher recovery rate.
Further, as the carbonic acid ester, a carbonic acid dialkyl ester having an alkyl carbon number of preferably 1 to 3, more preferably 1 or 2 is preferable. Preferred examples thereof include dimethyl carbonate, diethyl carbonate, or a mixture thereof.

In addition, a mixture of 1,3-DACBDA and 1,2-DACBDA may be partially hydrolyzed during removal or storage, but when carboxylic acid anhydride is used, it can be heated and stirred. The partially hydrolyzed product can also be made anhydrous, which is also preferable in that high-purity 1,3-DACBDA can be stably obtained.

Further, in many solvents, if the water content in the solvent is large, the hydrolyzate is partially hydrolyzed during purification, so that it is necessary to adjust the water content of the solvent. However, in the case of the anhydrous organic carboxylic acid, the hydrolyzate can be closed. Therefore, it is also preferable that high-purity 1,3-DACBDA can be obtained without adjusting the water content of the solvent.

The amount of the organic solvent is preferably 2 to 20 parts by mass with respect to 1 part by mass of the mixture of 1,3-DACBDA and 1,2-DACBDA, and 3.5 to 6 parts by mass from the viewpoint of purification efficiency and volumetric efficiency. More preferred.

The temperature when heating in an organic solvent is usually from 10 ° C. to the boiling point of the organic solvent used, but in terms of efficiently dissolving 1,2-DACBDA, the organic solvent used from 50 ° C. The temperature up to the boiling point of is preferable. The heating time is preferably 30 minutes to 10 hours, and if it is too short, the purity may decrease. Therefore, 1 to 6 hours is preferable.
After the above heating, the crystals of 1,3-DACBDA are precipitated as a solid by cooling to preferably −10 to 50 ° C., more preferably −10 to 20 ° C. The liquid containing the solid 1,3-DACBDA is filtered, and the crystals of 1,3-DACBDA are collected by filtration to separate from 1,2-DACBDA dissolved in the liquid, and the high-purity 1,3-DAC is separated. DACBDA can be obtained.

The ratio of the mixture of 1,3-DACBDA and 1,2-DACBDA used above is not particularly limited, but the purity may decrease as the ratio of 1,2-DACBDA increases. Therefore, the mass ratio of 1,3-DACBDA to 1,2-DACBDA in the mixture used in the present invention is preferably 50:50 to 99.5: 0.5, more preferably 70. : 30 to 99.5: 0.5.

Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. The analytical method used in the examples is as follows.

<GC analysis conditions>
Equipment: GC-2010 Plus (SHIMADZU)
Column: DB-1 (GL Sciences) Diameter 0.25 mm x Length 30 m, Film thickness 0.25 um
Carrier gas: He
Detector: FID
Sample injection volume: 1 um
Injection temperature: 160 ℃
Detector temperature: 220 ° C
Column temperature: 70 ℃ (20min) -40 ℃ / min-220 ℃ (15min)
Split ratio: 1:50
Internal standard substance: butyl lactate

< ¹ H NMR analysis conditions>
Device: Fourier Transformed Superconducting Nuclear Magnetic Resonance Device (FT-NMR) INOVA-400 (Varian) 400 MHz
Solvent: DMSO-d6
Internal standard substance: Tetramethylsilane (TMS)
<Melting point analysis conditions>
Equipment: DSC1 (METTLER TOLEDO)
Temperature: 35 ℃ -5 ℃ / min-400 ℃
Bread: Au (sealed)

Reference example 1: Synthesis of 1,3-DM-CBDA and 1,2-DM-CBDA

Under a nitrogen atmosphere, in a 300 mL Pyrex® glass 5-neck flask, with respect to 35.0 g (312 mmol) of citraconic anhydride (CA) and 152 g (1720 mmol) of ethyl acetate (CA). (4.33 wt times) was charged and dissolved by stirring with a magnetic stirrer, and then irradiated with a 100 W high-pressure mercury lamp for 48 hours while stirring at 5-10 ° C. After confirming that the residual ratio of the raw material of the reaction solution was 16.4% by gas chromatography analysis, the precipitated white crystals were taken out by filtration at 5-10 ° C., and the crystals were extracted from 43.8 g (497 mmol, citraconic acid) of ethyl acetate. It was washed twice with 1.25 wt times the anhydride (CA). This was dried under reduced pressure to obtain 5.8 g of white crystals (yield 16.6%).

This crystal was obtained by ¹ H NMR analysis in a mixture containing 1,3-DM-CBDA and 1,2-DM-CBDA (1,3-DM-CBDA: 1,2-DM-CBDA = 92.2: 7.8). I confirmed that there was. In addition, the obtained crystals, filtrate, and washing liquid were quantitatively analyzed by ¹ H NMR analysis and gas chromatography, respectively, and the mass balance with respect to the charged amount was 93.1%.

Example 1: Production of high-purity 1,3-DM-CBDA (acetic anhydride)

A mixture containing 1,3-DM-CBDA and 1,2-DM-CBDA obtained in the same manner as in Reference Example 1 in a 200 mL four-necked flask under a nitrogen stream (1,3-DM-CBDA). : 1,2-DM-CBDA = 85: 15) 18.3 g was charged with 92 g of acetic anhydride, suspended at 25 ° C. under stirring with a magnetic stirrer, and then heated to reflux (130 ° C.) for 4 hours. Then, the mixture was cooled to 20 ° C. and stirred at 20 ° C. for 1 hour.

Then, the precipitated white crystals were filtered, and the crystals were washed twice with 18 g of ethyl acetate and then dried under reduced pressure to obtain 14.4 g of white crystals (recovery rate: 92.6%). By ¹ H NMR analysis, this crystal had a ratio of 1,3-DM-CBDA to 1,2-DM-CBDA of 1,3-DM-CBDA: 1,2-DM-CBDA = 99.5: 0. It was confirmed that it had a composition of 5.
^{1 1} H NMR (DMSO−d6, δ ppm) (1,3-DM−CBDA): 1.38 (s, 6H), 3.89 (s, 2H).
^{1 1} H NMR (DMSO−d6, δ ppm) (1,2-DM−CBDA): 1.37 (s, 6H), 3.72 (s, 2H).
mp. (1,3-DM-CBDA): 316-317 ℃

Example 2: Production of high-purity 1,3-DM-CBDA (acetic anhydride)
A mixture containing 1,3-DM-CBDA and 1,2-DM-CBDA obtained in the same manner as in Reference Example 1 in a 100 mL four-necked flask under a nitrogen stream (1,3-DM-CBDA). : 1,2-DM-CBDA = 70:30) 5 g was charged with 25 g of acetic anhydride, suspended at 25 ° C. under stirring with a magnetic stirrer, and then heated to reflux (130 ° C.) for 4 hours. Then, the mixture was cooled to 20 ° C. and stirred at 20 ° C. for 1 hour.

Then, the precipitated white crystals were filtered, and the crystals were washed twice with 5 g of ethyl acetate and then dried under reduced pressure to obtain 3.3 g of white crystals (recovery rate: 94.3%). According to ¹ H NMR analysis, the ratio of 1,3-DM-CBDA to 1,2-DM-CBDA contained in this crystal is 1,3-DM-CBDA: 1,2-DM-CBDA = 99.5 :. It was confirmed that it was 0.5.

Example 3: Production of high-purity 1,3-DM-CBDA (acetonitrile)
A mixture containing 1,3-DM-CBDA and 1,2-DM-CBDA obtained in the same manner as in Reference Example 1 in a 500 mL four-necked flask under a nitrogen stream (1,3-DM-CBDA). : 1,2-DM-CBDA = 89: 11) 70 g and 420 g of acetonitrile were charged, suspended at 17 ° C. under stirring with a magnetic stirrer, and then stirred at 32 ° C. for 1 hour. Then, the mixture was cooled to an internal temperature of 10 ° C. and stirred at 10 ° C. for 1 hour.

Then, the precipitated white crystals were filtered, the crystals were washed twice with 70 g of acetonitrile, and then dried under reduced pressure to obtain 52.56 g of white crystals (recovery rate: 84.3%). According to ¹ H NMR analysis, the ratio of 1,3-DM-CBDA to 1,2-DM-CBDA contained in this crystal is 1,3-DM-CBDA: 1,2-DM-CBDA = 99.5 :. Confirmed to be 0.5

Example 4: Production of high-purity 1,3-DM-CBDA (ethyl acetate)
A mixture containing 1,3-DM-CBDA and 1,2-DM-CBDA obtained in the same manner as in Reference Example 1 in a 500 mL four-necked flask under a nitrogen stream (1,3-DM-CBDA). : 1,2-DM-CBDA = 89: 11) 80 g and 800 g of ethyl acetate were charged, suspended at 17 ° C. under stirring with a magnetic stirrer, and then stirred at 50 ° C. for 1 hour. Then, the mixture was cooled to 17 ° C. and stirred at 20 ° C. for 1 hour.
Then, the precipitated white crystals were filtered, the crystals were washed twice with 160 g of ethyl acetate, and the obtained white crystals were dried under reduced pressure to have a ratio of 1,3-DM-CBDA to 1,2-DM-CBDA. Obtained crystals of 1,3-DM-CBDA: 1,2-DM-CBDA = 99.0: 1. The ratio of 1,3-DM-CBDA and 1,2-DM-CBDA in this crystal was confirmed by ¹ H NMR analysis. Then, 800 g of ethyl acetate, the total amount of the obtained crystals, was charged into a 500 mL four-necked flask under a nitrogen stream, suspended at 17 ° C. under stirring with a magnetic stirrer, and then stirred at 50 ° C. for 1 hour.
Then, the mixture was cooled to an internal temperature of 20 ° C. or lower and stirred at 20 ° C. or lower for 1 hour. Then, the precipitated white crystals were filtered, and the crystals were washed twice with 160 g of ethyl acetate and then dried under reduced pressure to obtain 53.32 g of white crystals (recovery rate 74.9%). By ¹ H NMR analysis, this crystal had a ratio of 1,3-DM-CBDA to 1,2-DM-CBDA of 1,3-DM-CBDA: 1,2-DM-CBDA = 99.3: 0. It was confirmed that it was 7.

The high-purity 1,3-dimethyl-1,2,3,4-cyclobutanetetracarboxylic acid-1,2: 3,4-dianhydride obtained in the present invention is a useful compound as a raw material for polyimide and the like. , The polyimide and the like are widely used as resin compositions used for electronic materials such as protective materials and insulating materials in liquid crystal display elements and semiconductors.
The entire contents of the specification, claims, drawings and abstract of Japanese Patent Application No. 2014-007189 filed on January 17, 2014 are cited here as disclosure of the specification of the present invention. It is something to incorporate.

Claims (8)

1,3-Dialkylcyclobutane-1,2,3,4-tetracarboxylic acid-1,2: 3,4-dianhydride and 1,2-dialkylcyclobutane-1,2,3,4-tetracarboxylic acid- A mixture containing 1,2: 3,4-dianhydride in a mass ratio of 70:30 to 99.5: 0.5 is heated in an organic solvent selected from the group consisting of anhydrous acetic acid, acetonitrile and ethyl acetate. By cooling, then filtering, and then filtering.
1,3-Dialkylcyclobutane-1,2,3,4-tetracarboxylic acid-1,2: 3,4-dianhydride and 1,2-dialkylcyclobutane-1,2,3,4-tetracarboxylic acid- High-purity 1,3-dialkylcyclobutane-1,2,3,4-tetracarboxylic acid-1,2: 3 containing 1,2: 3,4-dianhydride in a mass ratio of 99 or more and 1 or less. A method for producing 1,3-dialkylcyclobutane-1,2,3,4-tetracarboxylic acid-1,2: 3,4-dianhydride, which comprises collecting 4,5-dianhydride as a solid by filtration. .. The organic solvents are 1,3-dialkylcyclobutane-1,2,3,4-tetracarboxylic acid-1,2: 3,4-dianhydride and 1,2-dialkylcyclobutane-1,2,3,4. The production method according to claim 1, wherein 2 to 20 parts by mass is used with respect to 1 part by mass of a mixture of −tetracarboxylic acid-1,2: 3,4-dianhydride. The production method according to claim 1 or 2, wherein the mixture is heated in an organic solvent at a temperature of 10 ° C. to the boiling point of the organic solvent. The production method according to claim 1 or 2, wherein heating of the mixture in an organic solvent is performed at a temperature of 50 ° C. to the boiling point of the organic solvent. The production method according to any one of claims 1 to 4, wherein the temperature is cooled to −10 to 50 ° C. after the heating. The production method according to any one of claims 1 to 4, wherein the temperature is cooled to −10 to 20 ° C. after the heating. The 1,3-dialkylcyclobutane-1,2,3,4-tetracarboxylic acid-1,2: 3,4-dianhydride and 1,2-dialkylcyclobutane-1,2,3,4-tetracarboxylic acid A mixture with -1,2: 3,4-dianhydride is obtained by a photodimerization reaction of a maleic anhydride compound represented by the formula (1) (in the formula (1), R represents an alkyl group). The production method according to any one of claims 1 to 6.

1,3-Dialkylcyclobutane-1,2,3,4-tetracarboxylic acid-1,2: 3,4-dianhydride and 1,2-dialkylcyclobutane-1,2,3,4-tetracarboxylic acid- The production method according to any one of claims 1 to 7, wherein the alkyl group of the 1,2: 3,4-dianhydride is a methyl group.