A preparation method of cyclobutanetetracarboxylic dianhydride

Abstract

The present invention is applicable to the field of fine chemical technology and provides a method for preparing cyclobutanetetracarboxylic dianhydride, comprising: 50 The photodimerization reaction of dimethyl fumarate with a size of 150 to 300 μm is carried out under aqueous phase conditions to obtain a crude cyclobutane tetracarboxylic acid ester; the crude cyclobutane tetracarboxylic acid ester is subjected to an acidification treatment, the acidification treatment temperature is 100-110 ° C, the acidification end control temperature is 5 to 20 ° C, and the holding time is 0.5 to 2h to obtain cyclobutane tetracarboxylic acid; the cyclobutane tetracarboxylic acid is refluxed under the action of acetic anhydride. The present application is beneficial to the penetration of ultraviolet light by controlling the particle size of dimethyl fumarate, and obtains a crude cyclobutane tetracarboxylic acid ester with high conversion rate; and then utilizing the solubility difference, most of the by-product fumaric acid is removed during the acidification process; the acetic anhydride refluxes the cyclobutane tetracarboxylic acid ring, and further dissolves the residual by-products to obtain a high-purity cyclobutane tetracarboxylic dianhydride product.

Description

Technical Field

[0001] The present application belongs to the field of fine chemical technology, and in particular relates to a method for preparing cyclobutanetetracarboxylic dianhydride. Background Art

[0002] Cyclobutanetetracarboxylic dianhydride is a rigid alicyclic dianhydride monomer with promising applications in optoelectronic displays. CN1765870A discloses a method for preparing cyclobutanetetracarboxylic acid esters by photodimerization of fumarate esters, addressing the low yield of cyclobutanetetracarboxylic dianhydride in Publication No. 2003-192685. However, the patent fails to disclose the conversion rate of the starting materials for the photodimerization reaction. Furthermore, the examples show a molar conversion rate of cyclobutanetetracarboxylic acid dehydration exceeding 100%, which is clearly unreasonable. Therefore, the patent's advancement is unclear, both in terms of the photodimerization reaction and the overall yield. Because photodimerization is a reversible process, varying degrees of residual starting materials are typically present. Cyclobutanetetracarboxylic acid ester and its starting fumarate ester are both solids with similar polarity, making separation difficult. CN115850075A utilizes a sublimation method to purify cyclobutanetetracarboxylic acid ester, which consumes a lot of energy and results in some product loss, making it unsuitable for industrial production.

[0003] It can be seen that the existing preparation process of cyclobutanetetracarboxylic dianhydride has the problem of low purity and is not conducive to industrial production. Summary of the Invention

[0004] The purpose of the embodiments of the present application is to provide a method for preparing cyclobutanetetracarboxylic dianhydride, aiming to solve the problem that the existing preparation process of cyclobutanetetracarboxylic dianhydride has low purity and is not conducive to industrial production.

[0005] The present invention is achieved by a method for preparing cyclobutanetetracarboxylic dianhydride, comprising:

[0006] The particle size D 50 Dimethyl fumarate with a particle size of 150 to 300 μm is subjected to a photodimerization reaction in an aqueous phase to obtain a crude cyclobutane tetracarboxylate; the mass ratio of the dimethyl fumarate to water is 1:5 to 20;

[0007] The crude cyclobutane tetracarboxylic acid ester is subjected to acidification treatment at a temperature of 100-110° C., the acidification end temperature is controlled at 5-20° C., and the holding time is 0.5-2 h to obtain cyclobutane tetracarboxylic acid;

[0008] The cyclobutanetetracarboxylic acid is refluxed under the action of acetic anhydride to obtain cyclobutanetetracarboxylic dianhydride.

[0009] The preparation method of cyclobutane tetracarboxylic dianhydride provided in the embodiment of the present application is conducive to the penetration of ultraviolet light by controlling the particle size of dimethyl fumarate, thereby obtaining a high-conversion crude cyclobutane tetracarboxylic ester; and then utilizing the solubility difference to remove most of the byproduct fumaric acid during the acidification process; acetic anhydride refluxes the cyclobutane tetracarboxylic acid to close the ring, and dissolves the residual byproducts to obtain a high-purity cyclobutane tetracarboxylic dianhydride product; in addition, the photodimerization reaction uses water as a solvent, which is green and pollution-free; the crystallization and acetic anhydride reflux method are used for purification, and the process steps are simple, which is conducive to industrial production. Compared with the existing technology, on the one hand, the liquid chromatography purity of the cyclobutane tetracarboxylic dianhydride obtained in the embodiment of the present application is higher, up to 99.6%; on the other hand, the existing technology is generally gram-scale and cannot be scaled up for production, while the embodiment of the present application is kilogram-scale production, with a hundred-fold amplification of the single output, and there is no significant difference in the reaction time of each step, which is conducive to industrial production and higher production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 This is the HPLC spectrum of cyclobutanetetracarboxylic dianhydride provided in Example 1 of the present application.

[0011] Figure 2 The cyclobutane tetracarboxylic dianhydride provided in Example 1 of the present application 1 HNMR spectrum. DETAILED DESCRIPTION

[0012] In order to make the purpose, technical solutions and advantages of this application more clearly understood, the present application is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0013] In order to solve the problem that the existing preparation process of cyclobutanetetracarboxylic dianhydride has low purity and is not conducive to industrial production, the embodiment of the present application provides a preparation method of cyclobutanetetracarboxylic dianhydride. By controlling the particle size of dimethyl fumarate, the penetration of ultraviolet light is facilitated, and a crude cyclobutanetetracarboxylic dianhydride with high conversion rate is obtained; then, by utilizing the solubility difference, most of the by-product fumarate is removed during the acidification process; acetic anhydride is refluxed to close the ring of cyclobutanetetracarboxylic acid and dissolve the residual by-products to obtain a high-purity cyclobutanetetracarboxylic dianhydride product; in addition, water is used as a solvent in the photodimerization reaction, which is green and pollution-free; and purification is carried out by crystallization precipitation and acetic anhydride reflux method, which has simple process steps and is conducive to industrial production.

[0014] Specifically, the present invention provides a method for preparing cyclobutanetetracarboxylic dianhydride, comprising the following steps:

[0015] Step (1): Set the particle size D 50Dimethyl fumarate with a particle size of 150 to 300 μm is subjected to a photodimerization reaction in an aqueous phase to obtain a crude cyclobutane tetracarboxylate;

[0016] Step (2): acidifying the crude cyclobutane tetracarboxylic acid ester to obtain cyclobutane tetracarboxylic acid;

[0017] Step (3): reflux the cyclobutanetetracarboxylic acid under the action of acetic anhydride to obtain cyclobutanetetracarboxylic dianhydride.

[0018] In the embodiment of the present application, in step (1), the mass ratio of dimethyl fumarate to water is 1:5-20; preferably, the mass ratio of dimethyl fumarate to water is 1:8-15.

[0019] In the embodiment of the present application, in step (1), in the photodimerization reaction, the temperature is 5 to 25° C., the wavelength of ultraviolet light is 200 to 400 nm, and the illumination reaction time is 0.5 to 30 h.

[0020] Preferably, during the photodimerization reaction, the temperature is 15-25°C.

[0021] Preferably, in the photodimerization reaction, the wavelength of ultraviolet light is 250 to 320 nm.

[0022] In the embodiment of the present application, in step (1), the residual rate of raw materials in the crude cyclobutanetetracarboxylic dianhydride is ≤15%, more preferably ≤10%.

[0023] In the embodiment of the present application, in step (2), in the acidification treatment, the acidifying agent is at least one of sulfuric acid and hydrochloric acid aqueous solution, the hydrogen ion concentration is 1 to 5 mol / L, and the molar ratio of hydrogen ions to the crude cyclobutane tetracarboxylic acid ester is 5 to 10:1.

[0024] In the embodiment of the present application, in step (2), the acidification treatment temperature is 100-110° C. and the time is 5 to 30 hours.

[0025] In the embodiment of the present application, in step (2), the temperature at the end of acidification is controlled to be 5 to 20° C., and the holding time is 0.5 to 2 h.

[0026] In the embodiment of the present application, in step (3), the mass ratio of cyclobutanetetracarboxylic acid to acetic anhydride is 1:3-10.

[0027] In the embodiment of the present application, in step (3), the cyclobutanetetracarboxylic acid is refluxed under the action of acetic anhydride, the reflux temperature is 140-150° C., and the reaction time is 5-30 h.

[0028] The following are examples of certain embodiments of the present application, which are not intended to limit the scope of the present application.

[0029] In addition, it should be noted that the materials and processing methods mentioned in this application, unless otherwise stated, are common materials and familiar technical means in the art. The numerical values ​​given in the following examples are as accurate as possible, but those skilled in the art will understand that due to unavoidable measurement errors and experimental operation problems, each number should be understood as an approximation rather than an absolutely accurate value.

[0030] Example 1

[0031] Photocatalysis: Add 4 kg of dimethyl fumarate (particle size D 50 =247μm) and 40kg of water, the reaction temperature was controlled at 15 ° C., and after irradiation with a high-pressure mercury lamp for 24 hours under stirring, 3.56kg of crude cyclobutanetetracarboxylic acid tetramethyl ester was obtained after filtration and drying (yield 89%, gas phase purity 90%);

[0032] Acidification: Mix 3 kg of crude tetramethyl cyclobutanetetracarboxylate with 20 kg of 4.5 mol / L hydrochloric acid solution, heat to 105°C, keep warm for 20 hours, cool to 10°C, keep warm for 12 hours, and filter; evaporate the filtrate under reduced pressure to remove the solvent to obtain cyclobutanetetracarboxylic acid;

[0033] Anhydration: Add 15 kg of acetic anhydride, heat to 145 ° C and reflux, keep warm for 24 hours, then cool to room temperature, filter and dry to obtain 1.59 kg of high-purity cyclobutanetetracarboxylic dianhydride (total yield 47.1%, HPLC purity 99.53%).

[0034] Example 2

[0035] Photocatalysis: 3.5 kg of dimethyl fumarate (particle size D50 = 247 μm) and 40 kg of water were added to a photocatalytic reaction apparatus. The reaction temperature was controlled at 20°C and irradiated with a high-pressure mercury lamp for 20 h under stirring. The mixture was filtered and dried to obtain 3.08 kg of crude tetramethyl cyclobutanetetracarboxylate (yield 88%, vapor phase purity 87%).

[0036] Acidification: Mix 3 kg of crude tetramethyl cyclobutanetetracarboxylate with 25 kg of 4 mol / L hydrochloric acid solution, heat to 105°C, and keep warm for 24 hours; cool to 10°C, keep warm for 2 hours, and filter; evaporate the solvent under reduced pressure to obtain cyclobutanetetracarboxylic acid;

[0037] Anhydration: Add 18 kg of acetic anhydride, heat to 145 ° C and reflux, keep warm for 24 hours, then cool to room temperature, filter and dry to obtain 1.54 kg of high-purity cyclobutanetetracarboxylic dianhydride (total yield 45.1%, HPLC purity 99.3%).

[0038] Example 3

[0039] Photocatalysis: 4 kg of dimethyl fumarate (particle size D50 = 247 μm) and 40 kg of water were added to a photocatalytic reaction apparatus. The reaction temperature was controlled at 20°C and irradiated with a 290-310 nm LED lamp for 15 h under stirring. After filtration and drying, 3.6 kg of crude tetramethyl cyclobutanetetracarboxylate was obtained (yield 90%, gas phase purity 91%).

[0040] Acidification: Mix 3 kg of crude tetramethyl cyclobutanetetracarboxylate with 28 kg of 3 mol / L hydrochloric acid solution, heat to 105°C, and keep warm for 24 hours; cool to 10°C, keep warm for 0.5 hours, and filter; evaporate the solvent under reduced pressure to obtain cyclobutanetetracarboxylic acid;

[0041] Anhydration: Add 18 kg of acetic anhydride, heat to 145 ° C and reflux, keep warm for 24 hours, then cool to room temperature, filter and dry to obtain 1.59 kg of high-purity cyclobutanetetracarboxylic dianhydride (total yield 47.7%, HPLC purity 99.6%).

[0042] Comparative Example 1

[0043] Photocatalysis: 4 kg of dimethyl fumarate (particle size D50 = 100 μm) and 40 kg of water were added to a photocatalytic reaction device. The reaction temperature was controlled at 15°C. After irradiation with a high-pressure mercury lamp for 24 h under stirring, 3.68 kg of crude tetramethyl cyclobutanetetracarboxylate was obtained after filtration and drying (yield 92%, gas phase purity 53.6%).

[0044] Comparative Example 2

[0045] Photocatalysis: 6 kg of dimethyl fumarate (particle size D50 = 247 μm) and 40 kg of water were added to a photocatalytic reaction apparatus. The reaction temperature was controlled at 15°C and irradiated with a high-pressure mercury lamp for 28 h under stirring. After filtration and drying, 5.4 kg of crude tetramethyl cyclobutanetetracarboxylate was obtained (yield 90%, vapor phase purity 76.6%).

[0046] Acidification: Mix 3 kg of crude tetramethyl cyclobutanetetracarboxylate with 20 kg of 4.5 mol / L hydrochloric acid solution, heat to 105°C, and keep warm for 20 hours; cool to 10°C, keep warm for 1 hour, and filter; evaporate the filtrate under reduced pressure to remove the solvent to obtain cyclobutanetetracarboxylic acid;

[0047] Anhydration: Add 15 kg of acetic anhydride, heat to 145 ° C and reflux, keep warm for 24 hours, then cool to room temperature, filter and dry to obtain 1.33 kg of high-purity cyclobutanetetracarboxylic dianhydride (total yield 39.9%, HPLC purity 98.5%).

[0048] Comparative Example 3

[0049] Photocatalysis: 3.5 kg of dimethyl fumarate (particle size D50 = 247 μm) and 40 kg of water were added to a photocatalytic reaction apparatus. The reaction temperature was controlled at 20°C and irradiated with a high-pressure mercury lamp for 20 h under stirring. The mixture was filtered and dried to obtain 3.08 kg of crude tetramethyl cyclobutanetetracarboxylate (yield 88%, vapor phase purity 87%).

[0050] Acidification: Mix 3 kg of crude tetramethyl cyclobutanetetracarboxylate with 25 kg of 4 mol / L hydrochloric acid solution, heat to 105°C, keep warm for 24 hours, and then evaporate the solvent under reduced pressure to obtain cyclobutanetetracarboxylic acid;

[0051] Anhydration: Add 18 kg of acetic anhydride, heat to 145 ° C and reflux, keep warm for 24 hours, then cool to room temperature, filter and dry to obtain 1.48 kg of high-purity cyclobutanetetracarboxylic dianhydride (total yield 43.4%, HPLC purity 98.9%).

[0052] Comparative Example 4

[0053] Photocatalysis: 4 kg of dimethyl fumarate (particle size D50 = 247 μm) and 40 kg of water were added to a photocatalytic reaction apparatus. The reaction temperature was controlled at 20° C. and irradiated with a 410-420 nm LED lamp for 15 h under stirring. After filtration and drying, 3.76 kg of crude tetramethyl cyclobutanetetracarboxylate was obtained (yield 94%, gas phase purity 15%).

[0054] In summary, a comparison between Example 1 and Comparative Example 1 reveals that the excessively small particle size of the dimethyl fumarate raw material affects its dispersion in water, thereby affecting the efficiency of the photocatalytic reaction. Compared to Example 1, the increased raw material ratio in Comparative Example 2 reduces the photochemical reaction efficiency. Although the reaction time is increased, a high amount of raw material remains, resulting in a decrease in the purity of the final product. A comparison between Example 2 and Comparative Example 3 reveals that the acidification process further improves product purity through cooling crystallization. Compared to Example 3, after adjusting the LED light wavelength in Comparative Example 4, the product conversion rate under the same conditions is significantly reduced.

[0055] The above-described embodiments merely represent several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person of ordinary skill in the art may make various modifications and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

[0056] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present application should be included in the scope of protection of the present application.

Claims

1. A method for preparing cyclobutanetetracarboxylic dianhydride, characterized in that: include: The particle size D 50 Dimethyl fumarate with a particle size of 150 to 300 μm is subjected to a photodimerization reaction in an aqueous phase to obtain a crude cyclobutane tetracarboxylate; the mass ratio of the dimethyl fumarate to water is 1:5 to 20; The crude cyclobutane tetracarboxylic acid ester is subjected to acidification treatment at a temperature of 100-110° C., the acidification end temperature is controlled at 5-20° C., and the holding time is 0.5-2 h to obtain cyclobutane tetracarboxylic acid; The cyclobutanetetracarboxylic acid is refluxed under the action of acetic anhydride to obtain cyclobutanetetracarboxylic dianhydride.

2. The preparation method of cyclobutanetetracarboxylic dianhydride according to claim 1, wherein The mass ratio of the dimethyl fumarate to water is 1:8-15.

3. The preparation method of cyclobutanetetracarboxylic dianhydride according to claim 1, wherein In the photodimerization reaction: the temperature is 5 to 25°C, the ultraviolet light wavelength is 200 to 400 nm, and the light irradiation reaction time is 0.5 to 30 hours.

4. The preparation method of cyclobutanetetracarboxylic dianhydride according to claim 3, wherein During the photodimerization reaction: the temperature is 15-25°C.

5. The preparation method of cyclobutanetetracarboxylic dianhydride according to claim 3, wherein In the photodimerization reaction: the ultraviolet light wavelength is 250 to 320 nm.

6. The preparation method of cyclobutanetetracarboxylic dianhydride according to claim 1, wherein The residual rate of raw materials in the crude cyclobutane tetracarboxylic dianhydride is ≦15%.

7. The preparation method of cyclobutanetetracarboxylic dianhydride according to claim 6, wherein The raw material residue rate in the crude cyclobutane tetracarboxylic dianhydride product is ≦10%.

8. The preparation method of cyclobutanetetracarboxylic dianhydride according to claim 1, wherein In the acidification treatment, the acidification agent is at least one of sulfuric acid and hydrochloric acid aqueous solution, the hydrogen ion concentration is 1-5 mol / L, and the molar ratio of hydrogen ion to crude cyclobutane tetracarboxylic acid ester is 5-10:

1.

9. The preparation method of cyclobutanetetracarboxylic dianhydride according to claim 1, wherein The mass ratio of cyclobutanetetracarboxylic acid to acetic anhydride is 1:3-10.

10. The preparation method of cyclobutanetetracarboxylic dianhydride according to claim 1, wherein The cyclobutane tetracarboxylic acid is refluxed under the action of acetic anhydride, the reflux temperature is 140-150° C., and the reaction time is 5-30 hours.

Images