JP4386153B2

JP4386153B2 - Crystallization method of acid dianhydride

Info

Publication number: JP4386153B2
Application number: JP34298398A
Authority: JP
Inventors: 義和大塚; 英樹小林; 康之中島
Original assignee: Nissan Chemical Corp
Current assignee: Nissan Chemical Corp
Priority date: 1998-12-02
Filing date: 1998-12-02
Publication date: 2009-12-16
Anticipated expiration: 2018-12-02
Also published as: JP2000159772A

Description

【０００１】
【産業上の利用分野】
本発明は、酸二無水物の晶析方法に関するものであり、本発明で得られる酸二無水物はポリイミド等のポリマーの原料として利用される有用な化合物である。
【０００２】
【従来の技術】
一般式（２）で表される酸二無水物は、例えばＪｏｕｎａｌｏｆＡｍｅｒｉｃａｎＣｈｅｍｉｃａｌＳｏｃｉｅｔｙ，８１巻、４２７３ページ、１９５９年、ＪｏｕｎａｌｏｆＡｍｅｒｉｃａｎＣｈｅｍｉｃａｌＳｏｃｉｅｔｙ，８２巻、６３４２ページ、１９６０年及び特開平２−３０６９３５号公報に報告されている。しかしこれらの文献ではその収率は低いか又は不明であり、また純度としてもポリマー原料として用いるには不満足な点を有する。
【０００３】
【発明が解決しようとする課題】
本発明者らはこのような現状に鑑み、本酸二無水物を収率良く又純度良く得るために種々の検討を行い、工業的に可能な方法を見出した。
【０００４】
本酸二無水物は無水酢酸には比較的溶解するが、その他の溶媒類には難溶で温度による溶解度差も低いことが認められた。これらの知見より無水酢酸と難溶性の溶媒類とによる混合溶媒での晶析条件を検討し、適当な比率によって、純度、収率良く目的物を得る方法を見出した。
【０００５】
【課題を解決するための手段】
即ち、本発明は、式（１）
【０００６】
【化３】

【０００７】
で表されるビシクロ［３．３．０］オクタン−２，４，６，８−テトラカルボン酸を無水酢酸と反応して式（２）
【０００８】
【化４】

【０００９】
で表されるビシクロ［３．３．０］オクタン−２，４，６，８−テトラカルボン酸二無水物を製造する際に、反応終了後、無水酢酸及び酢酸を濃縮した溶液に５０℃〜沸点までの温度で、本酸二無水物の溶解度の低い溶媒を添加し冷却して本酸二無水物を晶析し、濾過、単離することを特徴とする酸二無水物の晶析方法に関する。
【００１０】
【発明の実施の形態】
以下、更に本発明を詳細に説明する。
【００１１】
前記式（１）で表されるビシクロ［３．３．０］オクタン−２，４，６，８−テトラカルボン酸（以下ＢＯＴＣと略す。）は、上記文献に記載されている方法で合成できる。即ち、２，５−ノボルナジエンとジシクロペンタジエンをオートクレーブ中１９０℃で２０時間反応させ、テトラシクロ［６．２．１．１〈３，６〉．０〈２，７〉］ドデカ−４，９−ジエンを合成する。これをメタノール中−３０℃以下でオゾン酸化を行った後、蟻酸と酢酸の混合溶媒中、過酸化水素を用いた酸化分解を行うことで得ることができる。また、テトラシクロ［６．２．１．１〈３，６〉．０〈２，７〉］ドデカ−４，９−ジエンを過マンガン酸カリウムによる酸化によっても得ることができる。
【００１２】
式（１）で表されるテトラカルボン酸と無水酢酸の反応は、前記テトラカルボン酸を２〜１０当量の無水酢酸に溶解し、８０〜１２０℃で２〜５時間反応させて式（２）で表されるビシクロ［３．３．０］オクタン−２，４，６，８−テトラカルボン酸二無水物（以下ＢＯＤＡと略す。）に変換する。この際反応温度が１２０℃以上では立体異性体（後記の式（４）で表される。）の生成が生じるので、温度コントロールを管理することが必要である。目的物を純度良く得るためには無水酢酸の量は１０当量用いるのが望ましい。
【００１３】
反応終了後、減圧下５０〜１２０℃で無水酢酸及び生成した酢酸を濃縮する。この際後の晶析を考慮して、基質の１〜５倍重量まで濃縮するのが良い。好ましくは基質の２〜３倍重量まで濃縮する。
【００１４】
この溶液に５０〜１２０℃で本化合物が難溶な溶媒を添加していく。溶媒としてはトルエン、キシレン等の沸点５０℃以上の炭化水素類、クロロベンゼン等のハロゲン化炭化水素類、酢酸エチル、酢酸ブチル等の沸点５０℃以上のエステル類、ジイソプロピルエーテル等の沸点５０℃以上のエーテル類又はメチルイソブチルケトン等の沸点５０℃以上のケトン類などが用いられる。好ましくはトルエン、キシレン等の炭化水素類または酢酸エチル等のエステル類が望ましい。
【００１５】
添加する溶媒量は基質の２〜２０倍重量の範囲で任意に選ぶことができる。好ましくは、２〜１０倍重量が望ましい。
この溶液を５０〜１２０℃で１時間程撹拌洗浄した後、０〜２５℃まで冷却し、析出した結晶を濾取する。少量の難溶溶媒で洗浄した後、減圧下乾燥することで目的物を純度、収率良く得ることができる。
【００１６】
本反応、特に後処理工程においては空気中の水分を排除するために不活性ガス（窒素等）雰囲気下で行うのが望ましい。
式（１）で表されるＢＯＴＣは、式（３）、式（４）及び式（５）
【００１７】
【化５】

【００１８】
の立体異性体が存在するが、それらは混合物として用いられるが、式（３）の立体構造を有するものを９０％以上、好ましくは９５％以上含有するのを主原料として用いるのが望ましい。これらの立体配置は、本発明方法では、そのまま維持されて酸二無水物として合成される。
【００１９】
【実施例】
次に実施例を挙げ本発明の内容を具体的に説明するが、本発明はこれらに限定されるものではない。尚、実施例及び比較例で用いた式（１）で表されるＢＯＴＣは、式（３）で表される立体異性体を９７．０％及び式（５）で表される立体異性体３．０％含有するものを用いた。
【００２０】
実施例１
ＢＯＴＣ２０ｇ（０．０７ｍｏｌ）、無水酢酸１４０ｇ（１．３２ｍｏｌ）を５００ｍＬ反応容器中、１００℃にて４時間撹拌した。次に反応溶液を８０〜９５Ｃにて減圧濃縮し（２００〜８０ｍｍＨｇ）、総重量４０ｇとした。ｍ−キシレンを２００ｇ投入し、１００℃で一時間撹拌加熱した。この溶液を１５℃まで冷却し、一夜撹拌した。溶液を減圧濾過し、ｍ−キシレン１０ｍＬにて２回洗浄した。濾取した結晶を１時間減圧乾燥（７０〜８０℃、２０ｍｍＨｇ）し、無色結晶１７ｇを得た（収率９７．２％）。
Ｇ．Ｃ．分析結果からこの結晶は純度９７．９％の式（３）の酸二無水物（式（５）の酸二無水物２．１％含有）であることが確認できた。
【００２１】
実施例２
ＢＯＴＣ５．０ｇ（１７．５ｍｍｏｌ）、無水酢酸３５ｇ（３３０ｍｍｏｌ）を３００ｍＬ反応容器中、１００℃にて４時間撹拌した。次に反応溶液を８０〜９５℃にて減圧濃縮し（２００〜８０ｍｍＨｇ）、総重量１０ｇとした。酢酸エチルを６０ｇ投入し、１時間加熱還流した。この溶液を１５℃まで冷却し、一夜撹拌した。溶液を減圧濾過し、酢酸エチル１０ｍＬにて２回洗浄した。濾取した結晶を１時間減圧乾燥（７０〜８０℃、２０ｍｍＨｇ）し、無色結晶３．９ｇを得た（収率８９．２％）。
Ｇ．Ｃ．分析結果からこの結晶は純度９８．５％の一般式（３）の酸二無水物（一般式（５）の酸二無水物１．５％含有）であることが確認できた。
【００２２】
実施例３
ＢＯＴＣ５．０ｇ（１７．５ｍｍｏｌ）、無水酢酸３５ｇ（３３０ｍｍｏｌ）を３００ｍＬ反応容器中、１００Ｃにて４時間撹拌した。次に反応溶液を８０〜９５℃にて減圧濃縮し（２００〜８０ｍｍＨｇ）、総重量２０ｇとした。酢酸エチルを６０ｇ投入し、１時間加熱還流した。この溶液を１５℃まで冷却し、一夜撹拌した。溶液を減圧濾過し、酢酸エチル１０ｍＬにて２回洗浄した。濾取した結晶を１時間減圧乾燥（７０〜８０℃、２０ｍｍＨｇ）し、無色結晶３．８ｇを得た（収率８６．９％）。
Ｇ．Ｃ．分析結果からこの結晶は純度９８．９％の一般式（３）の酸二無水物（一般式（５）の酸二無水物１．１％含有）であることが確認できた。
【００２３】
実施例４
ＢＯＴＣ５．０ｇ（１７．５ｍｍｏｌ）、無水酢酸３５ｇ（３３０ｍｍｏｌ）を３００ｍＬ反応容器中、１００℃にて４時間撹拌した。次に反応溶液を８０〜９５℃にて減圧濃縮し（２００〜８０ｍｍＨｇ）、総重量１０ｇとした。酢酸エチルを２５ｇ投入し、１時間加熱還流した。この溶液を１５℃まで冷却し、一夜撹拌した。溶液を減圧濾過し、酢酸エチル２８ｍＬにて２回洗浄した。濾取した結晶を１時間減圧乾燥（７０〜８０℃、２０ｍｍＨｇ）し、無色結晶４．０３ｇを得た（収率９２．２％）。
Ｇ．Ｃ．分析結果からこの結晶は純度９７．２％の一般式（３）の酸二無水物（一般式（５）の酸二無水物２．８％含有）であることが確認できた。
【００２４】
実施例５
ＢＯＴＣ５．０ｇ（１７．５ｍｍｏｌ）、無水酢酸３５ｇ（３３０ｍｍｏｌ）を３００ｍＬ反応容器中、１００℃にて４時間撹拌した。次に反応溶液を８０〜９５℃にて減圧濃縮し（２００〜８０ｍｍＨｇ）、総重量１０ｇとした。酢酸エチルを１００ｇ投入し、１時間加熱還流した。この溶液を１５℃まで冷却し、一夜撹拌した。溶液を減圧濾過し、酢酸エチル１１０ｍＬにて２回洗浄した。濾取した結晶を１時間減圧乾燥（７０〜８０℃、２０ｍｍＨｇ）し、無色結晶４．０５ｇを得た（収率９２．７％）。
Ｇ．Ｃ．分析結果からこの結晶は純度９８．０％の一般式（３）の酸二無水物（一般式（５）の酸二無水物２．０％含有）であることが確認できた。
【００２５】
実施例６
ＢＯＴＣ１５０ｇ（０．５２４ｍｏｌ）、無水酢酸１０７１ｇ（１０．５ｍｏｌ）を３Ｌ反応容器中、１００℃にて４時間撹拌した。２時間ほどで完全溶解した後、反応生成物が析出しはじめた。次に反応溶液を８０〜９５℃にて減圧濃縮し（２００〜８０ｍｍＨｇ）、総重量５００ｇとした。酢酸エチル（脱水品：水分１５〜３０ｐｐｍ）を１３５０ｇ投入し、一時間加熱還流した。この溶液を１５℃まで冷却し、一夜撹拌した。溶液を減圧濾過し、酢酸エチル５０ｍＬで２回洗浄した。濾取した結晶を１時間減圧乾燥（７０〜８０℃、２０ｍｍＨｇ）し、無色結晶１２５．０ｇを得た（収率９５．３％）。
融点２０５〜２０６℃
Ｇ．Ｃ．分析結果からこの結晶は純度９８．４％の一般式（３）の酸二無水物（一般式（５）の酸二無水物１．６％含有）であることが確認できた。
【００２６】
実施例７
ＢＯＴＣ１５０ｇ（０．５２４ｍｏｌ）、無水酢酸１０７１ｇ（１０．５ｍｏｌ）を３Ｌ反応容器中、１００Ｃにて４時間撹拌した。２時間ほどで完全溶解した後、反応生成物が析出しはじめた。次に反応溶液を８０〜９５℃にて減圧濃縮し（２００〜８０ｍｍＨｇ）、総重量５００ｇとした。トルエン（脱水品）を１３５０ｇ投入し、１００℃で１時間加熱撹拌した。この溶液を１５℃まで冷却し、一夜撹拌した。溶液を減圧濾過し、トルエン５０ｍＬで２回洗浄した。濾取した結晶を１時間減圧乾燥（７０〜８０℃、２０ｍｍＨｇ）し、無色結晶１２５．３ｇを得た（収率９５．６％）。
融点２０７〜２１０℃
Ｇ．Ｃ．分析結果からこの結晶は純度９７．４％の一般式（３）の酸二無水物（一般式（５）の酸二無水物２．６％含有）であることが確認できた。
【００２７】
比較例１（アセトニトリル再結晶）
ＢＯＴＣ５．０ｇ（１７．５ｍｍｏｌ）、無水酢酸３５ｇ（３３０ｍｍｏｌ）を３００ｍＬ反応容器中、１００℃にて４時間撹拌した。次に反応溶液を８０〜９５℃にて減圧下（２００〜８０ｍｍＨｇ）で完全留去した。アセトニトリル（脱水品）を５０ｇ投入し、１時間加熱還流した。この溶液を１５℃で冷却し、一夜撹拌した。溶液を減圧濾過し、アセトニトリル１０ｍＬにて２回洗浄した。濾取した結晶を１時間減圧乾燥（７０〜８０℃、２０ｍｍＨｇ）し、無色結晶２．４ｇ（５４．９％）得た。
Ｇ．Ｃ．分析結果からこの結晶は純度９７．０％の一般式（３）の酸二無水物（一般式（５）の酸二無水物２．４％含有）であることが確認できた。
【００２８】
【発明の効果】
本発明の晶析方法は式（１）のテトラカルボン酸から式（２）の酸二無水物を純度、収率良く製造できる方法である。この方法により製造コストを低減でき、比較的安価なポリマー原料として供給可能で工業的生産にも適用可能となりうるものである。[0001]
[Industrial application fields]
The present invention relates to a method for crystallizing acid dianhydride, and the acid dianhydride obtained in the present invention is a useful compound used as a raw material for polymers such as polyimide.
[0002]
[Prior art]
The acid dianhydride represented by the general formula (2) is, for example, Journal of American Chemical Society, 81, 4273, 1959, Journal of American Chemical Society, 82, 6342, 1960, and JP-A-2- No. 306935 is reported. However, in these documents, the yield is low or unknown, and the purity is unsatisfactory for use as a polymer raw material.
[0003]
[Problems to be solved by the invention]
In view of the present situation, the present inventors have conducted various studies in order to obtain the acid dianhydride with high yield and high purity, and found an industrially possible method.
[0004]
The acid dianhydride was relatively soluble in acetic anhydride, but was found to be hardly soluble in other solvents and have a low solubility difference due to temperature. Based on these findings, the crystallization conditions in a mixed solvent of acetic anhydride and hardly soluble solvents were studied, and a method for obtaining the desired product with high purity and yield at an appropriate ratio was found.
[0005]
[Means for Solving the Problems]
That is, the present invention provides the formula (1)
[0006]
[Chemical 3]

[0007]
A bicyclo [3.3.0] octane-2,4,6,8-tetracarboxylic acid represented by the formula (2) is reacted with acetic anhydride.
[0008]
[Formula 4]

[0009]
Bicyclo [3 . 3 . 0] When producing octane-2,4,6,8-tetracarboxylic dianhydride, after the completion of the reaction, acetic anhydride and acetic acid were concentrated in a solution at a temperature from 50 ° C. to boiling point. The present invention relates to a method for crystallizing acid dianhydride, characterized by adding a solvent having low solubility of the product and cooling to crystallize the acid dianhydride, and filter and isolate.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be further described in detail.
[0011]
The bicyclo [3.3.0] octane-2,4,6,8-tetracarboxylic acid (hereinafter abbreviated as BOTC) represented by the formula (1) can be synthesized by the method described in the above document. . That is, 2,5-nobornadiene and dicyclopentadiene were reacted in an autoclave at 190 ° C. for 20 hours, and tetracyclo [6.2.1.1 <3,6>. 0 <2,7>] dodeca-4,9-diene is synthesized. This can be obtained by performing ozone oxidation in methanol at −30 ° C. or less and then performing oxidative decomposition using hydrogen peroxide in a mixed solvent of formic acid and acetic acid. In addition, tetracyclo [6.2.1.1 <3,6>. 0 <2,7>] dodeca-4,9-diene can also be obtained by oxidation with potassium permanganate.
[0012]
The reaction between the tetracarboxylic acid represented by formula (1) and acetic anhydride is obtained by dissolving the tetracarboxylic acid in 2 to 10 equivalents of acetic anhydride and reacting at 80 to 120 ° C. for 2 to 5 hours. Bicyclo [3 . 3 . 0] Conversion into octane-2,4,6,8-tetracarboxylic dianhydride (hereinafter abbreviated as BODA). At this time, when the reaction temperature is 120 ° C. or higher, stereoisomers (represented by the following formula (4)) are produced, and therefore it is necessary to control the temperature control. In order to obtain the desired product with high purity, it is desirable to use 10 equivalents of acetic anhydride.
[0013]
After completion of the reaction, acetic anhydride and produced acetic acid are concentrated under reduced pressure at 50 to 120 ° C. At this time, in consideration of the subsequent crystallization, it is preferable to concentrate to 1 to 5 times the weight of the substrate. Preferably, it is concentrated to 2-3 times the weight of the substrate.
[0014]
A solvent in which the present compound is hardly soluble is added to this solution at 50 to 120 ° C. Solvents include hydrocarbons having a boiling point of 50 ° C or higher such as toluene and xylene, halogenated hydrocarbons such as chlorobenzene, esters having a boiling point of 50 ° C or higher such as ethyl acetate and butyl acetate, and boiling points of 50 ° C or higher such as diisopropyl ether. Ketones having a boiling point of 50 ° C. or higher such as ethers or methyl isobutyl ketone are used. Preferably, hydrocarbons such as toluene and xylene or esters such as ethyl acetate are desirable.
[0015]
The amount of the solvent to be added can be arbitrarily selected within the range of 2 to 20 times the weight of the substrate. Preferably, the weight is 2 to 10 times.
The solution is stirred and washed at 50 to 120 ° C. for about 1 hour, then cooled to 0 to 25 ° C., and the precipitated crystals are collected by filtration. After washing with a small amount of a hardly soluble solvent, the desired product can be obtained with good purity and yield by drying under reduced pressure.
[0016]
In this reaction, particularly in the post-treatment step, it is desirable to carry out in an inert gas (nitrogen or the like) atmosphere in order to eliminate moisture in the air.
BOTC represented by Formula (1) is expressed by Formula (3), Formula (4), and Formula (5).
[0017]
[Chemical formula 5]

[0018]
These are used as a mixture, but it is desirable to use 90% or more, preferably 95% or more of the compound having the stereostructure of the formula (3) as a main raw material. These steric configurations are maintained as they are and synthesized as acid dianhydrides in the method of the present invention.
[0019]
【Example】
Next, the content of the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. The BOTC represented by the formula (1) used in Examples and Comparative Examples is 97.0% of the stereoisomer represented by the formula (3) and the stereoisomer 3 represented by the formula (5). The one containing 0.0% was used.
[0020]
Example 1
BOTC 20 g (0.07 mol) and acetic anhydride 140 g (1.32 mol) were stirred in a 500 mL reaction vessel at 100 ° C. for 4 hours. Next, the reaction solution was concentrated under reduced pressure at 80 to 95C (200 to 80 mmHg) to a total weight of 40 g. 200 g of m-xylene was added and stirred and heated at 100 ° C. for 1 hour. The solution was cooled to 15 ° C. and stirred overnight. The solution was filtered under reduced pressure and washed twice with 10 mL of m-xylene. The crystals collected by filtration were dried under reduced pressure for 1 hour (70 to 80 ° C., 20 mmHg) to obtain 17 g of colorless crystals (yield 97.2%).
G. C. From the analysis result, it was confirmed that the crystal was an acid dianhydride of the formula (3) having a purity of 97.9% (containing 2.1% of the acid dianhydride of the formula (5)).
[0021]
Example 2
BOTC 5.0 g (17.5 mmol) and acetic anhydride 35 g (330 mmol) were stirred in a 300 mL reaction vessel at 100 ° C. for 4 hours. Next, the reaction solution was concentrated under reduced pressure at 80 to 95 ° C. (200 to 80 mmHg) to a total weight of 10 g. 60 g of ethyl acetate was added and heated to reflux for 1 hour. The solution was cooled to 15 ° C. and stirred overnight. The solution was filtered under reduced pressure and washed twice with 10 mL of ethyl acetate. The crystals collected by filtration were dried under reduced pressure (70 to 80 ° C., 20 mmHg) for 1 hour to obtain 3.9 g of colorless crystals (yield 89.2%).
G. C. From the analysis results, it was confirmed that the crystal was an acid dianhydride of the general formula (3) having a purity of 98.5% (containing 1.5% of the acid dianhydride of the general formula (5)).
[0022]
Example 3
BOTC 5.0 g (17.5 mmol) and acetic anhydride 35 g (330 mmol) were stirred in a 300 mL reaction vessel at 100 C for 4 hours. Next, the reaction solution was concentrated under reduced pressure at 80 to 95 ° C. (200 to 80 mmHg) to a total weight of 20 g. 60 g of ethyl acetate was added and heated to reflux for 1 hour. The solution was cooled to 15 ° C. and stirred overnight. The solution was filtered under reduced pressure and washed twice with 10 mL of ethyl acetate. The crystals collected by filtration were dried under reduced pressure (70 to 80 ° C., 20 mmHg) for 1 hour to obtain 3.8 g of colorless crystals (yield 86.9%).
G. C. From the analysis results, it was confirmed that the crystal was an acid dianhydride of the general formula (3) (containing 1.1% of the acid dianhydride of the general formula (5)) having a purity of 98.9%.
[0023]
Example 4
BOTC 5.0 g (17.5 mmol) and acetic anhydride 35 g (330 mmol) were stirred in a 300 mL reaction vessel at 100 ° C. for 4 hours. Next, the reaction solution was concentrated under reduced pressure at 80 to 95 ° C. (200 to 80 mmHg) to a total weight of 10 g. 25 g of ethyl acetate was added and heated to reflux for 1 hour. The solution was cooled to 15 ° C. and stirred overnight. The solution was filtered under reduced pressure and washed twice with 28 mL of ethyl acetate. The crystals collected by filtration were dried under reduced pressure (70 to 80 ° C., 20 mmHg) for 1 hour to obtain 4.03 g of colorless crystals (yield 92.2%).
G. C. From the analysis results, it was confirmed that the crystal was an acid dianhydride of the general formula (3) (containing 2.8% of the acid dianhydride of the general formula (5)) having a purity of 97.2%.
[0024]
Example 5
BOTC 5.0 g (17.5 mmol) and acetic anhydride 35 g (330 mmol) were stirred in a 300 mL reaction vessel at 100 ° C. for 4 hours. Next, the reaction solution was concentrated under reduced pressure at 80 to 95 ° C. (200 to 80 mmHg) to a total weight of 10 g. 100 g of ethyl acetate was added and heated to reflux for 1 hour. The solution was cooled to 15 ° C. and stirred overnight. The solution was filtered under reduced pressure and washed twice with 110 mL of ethyl acetate. The crystals collected by filtration were dried under reduced pressure (70 to 80 ° C., 20 mmHg) for 1 hour to obtain 4.05 g of colorless crystals (yield 92.7%).
G. C. From the analysis result, it was confirmed that the crystal was an acid dianhydride of the general formula (3) having a purity of 98.0% (containing 2.0% of the acid dianhydride of the general formula (5)).
[0025]
Example 6
BOTC 150 g (0.524 mol) and acetic anhydride 1071 g (10.5 mol) were stirred in a 3 L reaction vessel at 100 ° C. for 4 hours. After complete dissolution in about 2 hours, the reaction product started to precipitate. Next, the reaction solution was concentrated under reduced pressure at 80 to 95 ° C. (200 to 80 mmHg) to a total weight of 500 g. 1350 g of ethyl acetate (dehydrated product: moisture 15 to 30 ppm) was added and heated to reflux for 1 hour. The solution was cooled to 15 ° C. and stirred overnight. The solution was filtered under reduced pressure and washed twice with 50 mL of ethyl acetate. The crystals collected by filtration were dried under reduced pressure (70 to 80 ° C., 20 mmHg) for 1 hour to obtain 125.0 g of colorless crystals (yield 95.3%).
Mp 205-206 ° C
G. C. From the analysis results, it was confirmed that this crystal was an acid dianhydride of the general formula (3) (containing 1.6% of the acid dianhydride of the general formula (5)) having a purity of 98.4%.
[0026]
Example 7
BOTC 150 g (0.524 mol) and acetic anhydride 1071 g (10.5 mol) were stirred in a 3 L reaction vessel at 100 C for 4 hours. After complete dissolution in about 2 hours, the reaction product started to precipitate. Next, the reaction solution was concentrated under reduced pressure at 80 to 95 ° C. (200 to 80 mmHg) to a total weight of 500 g. 1350 g of toluene (dehydrated product) was added, and the mixture was stirred with heating at 100 ° C. for 1 hour. The solution was cooled to 15 ° C. and stirred overnight. The solution was filtered under reduced pressure and washed twice with 50 mL of toluene. The crystals collected by filtration were dried under reduced pressure (70 to 80 ° C., 20 mmHg) for 1 hour to obtain 125.3 g of colorless crystals (yield 95.6%).
Melting point: 207-210 ° C
G. C. From the analysis results, it was confirmed that the crystal was an acid dianhydride of the general formula (3) (containing 2.6% of the acid dianhydride of the general formula (5)) having a purity of 97.4%.
[0027]
Comparative Example 1 (acetonitrile recrystallization)
BOTC 5.0 g (17.5 mmol) and acetic anhydride 35 g (330 mmol) were stirred in a 300 mL reaction vessel at 100 ° C. for 4 hours. Next, the reaction solution was completely distilled off at 80 to 95 ° C. under reduced pressure (200 to 80 mmHg). 50 g of acetonitrile (dehydrated product) was added and heated to reflux for 1 hour. The solution was cooled at 15 ° C. and stirred overnight. The solution was filtered under reduced pressure and washed twice with 10 mL of acetonitrile. The crystal collected by filtration was dried under reduced pressure (70 to 80 ° C., 20 mmHg) for 1 hour to obtain 2.4 g (54.9%) of colorless crystals.
G. C. From the analysis results, it was confirmed that the crystal was an acid dianhydride of the general formula (3) (containing 2.4% of the acid dianhydride of the general formula (5)) having a purity of 97.0%.
[0028]
【The invention's effect】
The crystallization method of the present invention is a method capable of producing the acid dianhydride of the formula (2) from the tetracarboxylic acid of the formula (1) with good purity and yield. This method can reduce the manufacturing cost, can be supplied as a relatively inexpensive polymer raw material, and can be applied to industrial production.

Claims

Formula (1)

A bicyclo [3.3.0] octane-2,4,6,8-tetracarboxylic acid represented by the formula (2) is reacted with acetic anhydride.

Bicyclo [3 . 3 . 0] When producing octane-2,4,6,8-tetracarboxylic dianhydride, after completion of the reaction, acetic anhydride and acetic acid were concentrated into a solution concentrated at 50 to 120 ° C. as low solvent solubility of the anhydride, by adding at least one solvent selected from the boiling point of 50 ° C. or more hydrocarbons and a boiling point of 50 ° C. or more esters, and crystallize the acid dianhydride was cooled, A method for crystallizing acid dianhydride, which is filtered and isolated.

The method for crystallizing acid dianhydride according to claim 1, wherein acetic anhydride and acetic acid are concentrated to 1 to 5 times the weight of the substrate.

The acid dianhydride crystallization method according to claim 1 or 2, wherein the solvent having a low solubility is added in an amount of 2 to 20 times the weight of the substrate.

Crystallization method of Examples low solubility solvents, toluene, xylene, ethyl acetate, claims 1 to 3 acid dianhydride described using at least one solvent selected butyl acetate Le or al.