CN115894511A - Method for purifying crude pyromellitic dianhydride and method for preparing pyromellitic dianhydride - Google Patents
Method for purifying crude pyromellitic dianhydride and method for preparing pyromellitic dianhydride Download PDFInfo
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- CN115894511A CN115894511A CN202111160482.3A CN202111160482A CN115894511A CN 115894511 A CN115894511 A CN 115894511A CN 202111160482 A CN202111160482 A CN 202111160482A CN 115894511 A CN115894511 A CN 115894511A
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- VLDPXPPHXDGHEW-UHFFFAOYSA-N 1-chloro-2-dichlorophosphoryloxybenzene Chemical compound ClC1=CC=CC=C1OP(Cl)(Cl)=O VLDPXPPHXDGHEW-UHFFFAOYSA-N 0.000 title claims abstract description 146
- 238000000034 method Methods 0.000 title claims abstract description 63
- 238000000746 purification Methods 0.000 claims abstract description 64
- 238000002360 preparation method Methods 0.000 claims abstract description 6
- 238000000859 sublimation Methods 0.000 claims description 150
- 230000008022 sublimation Effects 0.000 claims description 148
- CYIDZMCFTVVTJO-UHFFFAOYSA-N pyromellitic acid Chemical compound OC(=O)C1=CC(C(O)=O)=C(C(O)=O)C=C1C(O)=O CYIDZMCFTVVTJO-UHFFFAOYSA-N 0.000 claims description 35
- 239000007787 solid Substances 0.000 claims description 29
- WFDIJRYMOXRFFG-UHFFFAOYSA-N Acetic anhydride Chemical compound CC(=O)OC(C)=O WFDIJRYMOXRFFG-UHFFFAOYSA-N 0.000 claims description 27
- 238000010438 heat treatment Methods 0.000 claims description 27
- RTZKZFJDLAIYFH-UHFFFAOYSA-N Diethyl ether Chemical compound CCOCC RTZKZFJDLAIYFH-UHFFFAOYSA-N 0.000 claims description 25
- 239000002826 coolant Substances 0.000 claims description 21
- 238000001035 drying Methods 0.000 claims description 17
- 150000008064 anhydrides Chemical class 0.000 claims description 15
- 239000002904 solvent Substances 0.000 claims description 12
- 238000005086 pumping Methods 0.000 claims description 10
- XEKOWRVHYACXOJ-UHFFFAOYSA-N Ethyl acetate Chemical compound CCOC(C)=O XEKOWRVHYACXOJ-UHFFFAOYSA-N 0.000 claims description 6
- 238000001816 cooling Methods 0.000 claims description 6
- 238000004519 manufacturing process Methods 0.000 claims description 5
- 238000001291 vacuum drying Methods 0.000 claims description 5
- 238000009833 condensation Methods 0.000 claims description 4
- 230000005494 condensation Effects 0.000 claims description 4
- 239000007788 liquid Substances 0.000 claims description 4
- 238000000926 separation method Methods 0.000 claims description 4
- DYHSDKLCOJIUFX-UHFFFAOYSA-N tert-butoxycarbonyl anhydride Chemical compound CC(C)(C)OC(=O)OC(=O)OC(C)(C)C DYHSDKLCOJIUFX-UHFFFAOYSA-N 0.000 claims description 4
- ZAFNJMIOTHYJRJ-UHFFFAOYSA-N Diisopropyl ether Chemical compound CC(C)OC(C)C ZAFNJMIOTHYJRJ-UHFFFAOYSA-N 0.000 claims description 2
- 239000003208 petroleum Substances 0.000 claims description 2
- WYVAMUWZEOHJOQ-UHFFFAOYSA-N propionic anhydride Chemical compound CCC(=O)OC(=O)CC WYVAMUWZEOHJOQ-UHFFFAOYSA-N 0.000 claims description 2
- 238000005057 refrigeration Methods 0.000 claims description 2
- 238000006116 polymerization reaction Methods 0.000 abstract description 7
- 150000002894 organic compounds Chemical class 0.000 abstract description 2
- 238000003883 substance clean up Methods 0.000 abstract description 2
- 238000009835 boiling Methods 0.000 description 17
- 239000013078 crystal Substances 0.000 description 15
- 238000005092 sublimation method Methods 0.000 description 11
- 239000007789 gas Substances 0.000 description 8
- 239000000203 mixture Substances 0.000 description 8
- 239000000047 product Substances 0.000 description 8
- 230000002349 favourable effect Effects 0.000 description 7
- 230000003647 oxidation Effects 0.000 description 7
- 238000007254 oxidation reaction Methods 0.000 description 7
- 238000010992 reflux Methods 0.000 description 7
- 238000000967 suction filtration Methods 0.000 description 7
- 239000006227 byproduct Substances 0.000 description 5
- 239000002994 raw material Substances 0.000 description 5
- ARCGXLSVLAOJQL-UHFFFAOYSA-N trimellitic acid Chemical compound OC(=O)C1=CC=C(C(O)=O)C(C(O)=O)=C1 ARCGXLSVLAOJQL-UHFFFAOYSA-N 0.000 description 4
- SRPWOOOHEPICQU-UHFFFAOYSA-N trimellitic anhydride Chemical compound OC(=O)C1=CC=C2C(=O)OC(=O)C2=C1 SRPWOOOHEPICQU-UHFFFAOYSA-N 0.000 description 4
- 230000009286 beneficial effect Effects 0.000 description 3
- 238000006243 chemical reaction Methods 0.000 description 3
- 239000007791 liquid phase Substances 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- 150000008065 acid anhydrides Chemical class 0.000 description 2
- GCAIEATUVJFSMC-UHFFFAOYSA-N benzene-1,2,3,4-tetracarboxylic acid Chemical compound OC(=O)C1=CC=C(C(O)=O)C(C(O)=O)=C1C(O)=O GCAIEATUVJFSMC-UHFFFAOYSA-N 0.000 description 2
- 239000012043 crude product Substances 0.000 description 2
- SQNZJJAZBFDUTD-UHFFFAOYSA-N durene Chemical compound CC1=CC(C)=C(C)C=C1C SQNZJJAZBFDUTD-UHFFFAOYSA-N 0.000 description 2
- 238000002844 melting Methods 0.000 description 2
- 230000008018 melting Effects 0.000 description 2
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- 238000012986 modification Methods 0.000 description 2
- 239000012071 phase Substances 0.000 description 2
- UOHMMEJUHBCKEE-UHFFFAOYSA-N prehnitene Chemical compound CC1=CC=C(C)C(C)=C1C UOHMMEJUHBCKEE-UHFFFAOYSA-N 0.000 description 2
- 238000007670 refining Methods 0.000 description 2
- 238000007086 side reaction Methods 0.000 description 2
- 229920006259 thermoplastic polyimide Polymers 0.000 description 2
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 1
- GTDPSWPPOUPBNX-UHFFFAOYSA-N ac1mqpva Chemical compound CC12C(=O)OC(=O)C1(C)C1(C)C2(C)C(=O)OC1=O GTDPSWPPOUPBNX-UHFFFAOYSA-N 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 239000003054 catalyst Substances 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 239000012024 dehydrating agents Substances 0.000 description 1
- 230000018044 dehydration Effects 0.000 description 1
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- 229920006351 engineering plastic Polymers 0.000 description 1
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- 229910017604 nitric acid Inorganic materials 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
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- Heterocyclic Carbon Compounds Containing A Hetero Ring Having Oxygen Or Sulfur (AREA)
Abstract
The invention relates to the technical field of organic compound purification, in particular to a purification method of crude pyromellitic dianhydride, which comprises the following steps: under the negative pressure state, crude pyromellitic dianhydride is sublimated to obtain pyromellitic dianhydride steam, the steam is desublimated to obtain purified pyromellitic dianhydride, and the purification process of the present invention can raise the purity of pyromellitic dianhydride. The purification method has short process flow and simple and convenient operation, and the purified pyromellitic dianhydride has high purity and can meet the requirements of industrial polymerization grade. According to the preparation method of the pyromellitic dianhydride, the crude pyromellitic dianhydride prepared by the method is particularly suitable for purification by the purification method, and the purity of the purified pyromellitic dianhydride can reach 99%.
Description
Technical Field
The invention relates to the technical field of organic compound purification, in particular to a purification method of crude pyromellitic dianhydride and a preparation method of pyromellitic dianhydride.
Background
The pyromellitic dianhydride (MPDA) is an organic chemical intermediate, and the Thermoplastic Polyimide (TPI) special engineering plastic produced by taking high-purity MPDA as a raw material has wide application in the fields of electromechanics, electronics, aviation and the like.
There are generally two methods for industrially producing pyromellitic dianhydride: one is a gas-phase oxidation method, namely, durene and oxygen in the air are subjected to chemical reaction under the action of a catalyst to generate MPDA; the other is liquid phase oxidation, using continuous tetramethylbenzene as raw material, using nitric acid to make liquid phase oxidation to produce continuous benzene tetracarboxylic acid, further dewatering to produce MPDA. In both the gas phase oxidation and the liquid phase oxidation, the reaction produces MPDA and also side reactions, which produce some solid by-products of partial or excessive oxidation, such as trimellitic acid or trimellitic anhydride (TMA). Because MPDA has high melting point (198.5-205.5 ℃) and high boiling point (492.8-558.8 ℃), byproducts also have the characteristics of high melting point and high boiling point, and some crude anhydrides with different impurity (byproduct) contents are often obtained in the recovery process of MPDA, the purification process of the homogeneous anhydride for separating the byproducts from the homogeneous anhydride in the crude anhydride is a key link in MPDA production.
The existing refining methods of pyromellitic dianhydride mainly comprise a rectification method, a solvent method and a high-temperature gas carrying method. The rectification method is to utilize different boiling points of the rectification raw materials to extract different fractions from the top or the middle part of a rectification tower, but the method has strict requirements on the purity and the boiling point of the raw materials, and the purity of the common raw materials needs to be more than 95 percent; the solvent method is to purify substances by utilizing the solubility of different substances in a solvent, if a high-purity extract is required to be obtained, the product needs to be refined for many times, but the loss of the product is increased correspondingly; and the high-temperature gas carries the method and adopts high-temperature gas to make the product sublime utilizing the sublimed characteristic of product, and the mixed gas of recooling makes the product desublimate out, if need large-scale production must use a large amount of gas to carry, gas heating and cooling also need large-scale equipment, especially require harsh to cooling arrangement, if cooling arrangement is less, can make the mixed gas velocity of flow too fast, and then lead to the tiny particle product that desublimation gets off not subside, increase the loss of purification product.
Disclosure of Invention
The invention aims to solve the problems of complex refining method of crude pyromellitic dianhydride and low purity of the obtained product in the prior art, and provides a purification method of crude pyromellitic dianhydride; the purification method has the advantages of short process flow, simple and convenient operation, and high purity of the purified pyromellitic dianhydride, and can meet the requirements of industrial polymerization grade.
In order to achieve the above object, the present invention provides, in a first aspect, a method for purifying pyromellitic dianhydride, the method comprising: under the negative pressure state, the crude pyromellitic dianhydride is sublimated to obtain pyromellitic dianhydride vapor, and the vapor is sublimated to obtain purified pyromellitic dianhydride.
Preferably, the purification method is carried out in a sublimation purification apparatus comprising: a sublimation chamber, a sublimation finger;
the sublimation chamber is used for containing crude pyromellitic dianhydride and heating the crude pyromellitic dianhydride to sublimate the crude pyromellitic dianhydride into vapor, and the sublimation chamber can maintain a negative pressure state through an external vacuum-pumping device;
the sublimation finger is arranged in the sublimation cavity and used for condensing the pyromellitic dianhydride vapor;
the purification method comprises the following steps:
under the negative pressure state, the heating sublimation cavity is used for sublimating the crude pyromellitic dianhydride to obtain pyromellitic dianhydride vapor, and the vapor is sublimed in the sublimation chamber to obtain the purified pyromellitic dianhydride.
According to a second aspect of the present invention, there is provided a method for producing pyromellitic dianhydride, comprising:
1) Adding pyromellitic acid into the second anhydride to obtain a solution, and heating;
2) Cooling the solution to room temperature, adding a poor solvent to precipitate a solid, and drying the solid after solid-liquid separation to obtain crude pyromellitic dianhydride;
3) The crude pyromellitic dianhydride was purified according to the aforementioned purification method.
According to the purification method of the pyromellitic dianhydride, the pyromellitic dianhydride is sublimated-desublimated under the negative pressure state by utilizing the sublimation points of different acid anhydrides to purify the pyromellitic dianhydride, and the purity of the pyromellitic dianhydride can be improved through multiple purifications; the method is preferably carried out in the sublimation purification device disclosed by the invention, the sublimation purification device is simple in structure, the purification method is short in process flow and simple and convenient to operate, and the purified pyromellitic dianhydride has high purity and can meet the requirement of industrial polymerization grade.
According to the preparation method of the pyromellitic dianhydride, the crude pyromellitic dianhydride prepared by the method is particularly suitable for purification by the purification method, and the purity of the purified pyromellitic dianhydride can reach 99%.
Drawings
Fig. 1 is a sublimation purifying apparatus provided in a preferred embodiment of the present invention.
Description of the reference numerals
1-sublimation chamber
2-sublimation finger
3-first cooling medium circulation interface
4-second cooling medium circulation interface
5-evacuation interface
6-first valve
Detailed Description
The endpoints of the ranges and any values disclosed herein are not limited to the precise range or value, and such ranges or values should be understood to encompass values close to those ranges or values. For ranges of values, between the endpoints of each of the ranges and the individual points, and between the individual points may be combined with each other to give one or more new ranges of values, and these ranges of values should be considered as specifically disclosed herein.
The structural formula of the pyromellitic dianhydride is shown as the structural formula (I); the structural formula of the pyromellitic acid (MPA) is shown as a formula (II):
according to a first aspect of the present invention, there is provided a method for purifying pyromellitic dianhydride, comprising:
under the negative pressure state, the crude pyromellitic dianhydride is sublimated to obtain pyromellitic dianhydride vapor, and the vapor is sublimated to obtain purified pyromellitic dianhydride. The method utilizes the sublimation points of different acid anhydrides to sublimate and desublimate the pyromellitic dianhydride in a negative pressure state to purify the pyromellitic dianhydride. In the prior art, the crude product of the pyromellitic dianhydride is hydrolyzed to obtain the pyromellitic acid, and then the pyromellitic acid is dehydrated to form anhydride for purification.
According to a preferred embodiment of the invention, the sublimation conditions comprise: the sublimation temperature is 150-250 ℃; under the sublimation condition, the purity of the pyromellitic dianhydride is improved.
In the present invention, the sublimation time is determined according to the temperature, and according to a preferred embodiment of the present invention, the sublimation conditions include: the sublimation time is 1-20 h; under the sublimation condition, the method is favorable for improving the purity of the pyromellitic dianhydride.
According to the present invention, the conditions of desublimation include: the condensation temperature is-10 ℃ to 20 ℃.
In the present invention, the degree of vacuum can be selected within a wide range as long as the pyromellitic dianhydride can be sublimed, and according to a preferred embodiment of the present invention, the sublimation conditions include: the vacuum degree is 0.01-0.05 kPa; under the sublimation condition, the purity of the pyromellitic dianhydride is improved.
The object of the invention is achieved in that the aforementioned process according to the invention is carried out without particular requirements as regards the equipment used, and according to a preferred embodiment of the invention the purification process is carried out in a sublimation purification apparatus comprising: a sublimation chamber, a sublimation finger;
the sublimation chamber is used for accommodating crude pyromellitic dianhydride and heating the crude pyromellitic dianhydride to sublimate into steam, and the sublimation chamber can maintain a negative pressure state through an external vacuum-pumping device;
the sublimation finger is arranged in the sublimation cavity and used for condensing the pyromellitic dianhydride vapor;
the purification method comprises the following steps:
under the negative pressure state, the heating sublimation cavity is used for sublimating the crude pyromellitic dianhydride to obtain pyromellitic dianhydride steam, and the steam is sublimed in a sublimation finger to obtain purified pyromellitic dianhydride. Is favorable for improving the purity of the pyromellitic dianhydride.
According to a preferred embodiment of the present invention, the purification method is carried out in a sublimation purification apparatus, and the sublimation conditions include: the sublimation temperature is 150-250 ℃; under the sublimation condition, the purity of the pyromellitic dianhydride is improved.
According to a preferred embodiment of the invention, the purification process is carried out in a sublimation purification apparatus, the sublimation conditions comprising: the sublimation time is 1-20 h; under the sublimation condition, the purity of the pyromellitic dianhydride is improved.
According to a preferred embodiment of the invention, the purification process is carried out in a sublimation purification apparatus, the sublimation conditions comprising: the vacuum degree is 0.01-0.05 kPa; under the sublimation condition, the purity of the pyromellitic dianhydride is improved.
According to a preferred embodiment of the invention, the purification process is carried out in a sublimation purification apparatus, the sublimation conditions comprising: sublimation means that the condensation temperature is-10-20 ℃; under the sublimation condition, the purity of the pyromellitic dianhydride is improved.
According to a preferred embodiment of the invention, the operation of sublimation-desublimation is repeated 2-5 times; preferably, the latter sublimation time is greater than the former sublimation time. For example, the second sublimation-desublimation time is greater than the first sublimation-desublimation time; for example, the sublimation time of the second purification and the third purification is 10 to 50 hours; is favorable for improving the purity of the pyromellitic dianhydride.
According to a preferred embodiment of the present invention, the sublimation purification apparatus is shown in fig. 1, wherein the sublimation purification apparatus comprises: the device comprises a sublimation cavity 1, a sublimation finger 2, a vacuumizing interface 5 and a first valve 6;
the sublimation chamber 1 is used for containing crude pyromellitic dianhydride and heating the crude pyromellitic dianhydride to sublimate the crude pyromellitic dianhydride into vapor, and the sublimation chamber 1 can maintain a negative pressure state with an external vacuumizing device through a vacuumizing interface 5; the first valve 6 is used for controlling the vacuum degree;
the sublimation finger 2 is arranged in the sublimation cavity 1 and is used for condensing the pyromellitic dianhydride vapor; the sublimation finger 2 comprises a first cooling medium circulation interface 3 and a second cooling medium circulation interface 4, and cooling medium enters the sublimation finger 2 from the first cooling medium circulation interface 3 for refrigeration and flows out from the second cooling medium circulation interface 4.
According to a preferred embodiment of the present invention, the purification method comprises:
the sublimation cavity 1 is in a negative pressure state through the vacuumizing interface 5, the sublimation cavity 1 is heated to sublimate the crude pyromellitic dianhydride to obtain pyromellitic dianhydride vapor, and the vapor is sublimated in the sublimation finger 2 to obtain the purified pyromellitic dianhydride.
According to the present invention, while the reaction of pyromellitic acid to produce pyromellitic dianhydride, side reactions occur to produce some solid by-products of partial or excessive oxidation, such as trimellitic acid or trimellitic anhydride (TMA), according to a preferred embodiment of the present invention, the purity of crude pyromellitic dianhydride used for purification is 80.1% or more; the method is favorable for improving the purity of the pyromellitic dianhydride and simultaneously reducing the power consumption.
According to a preferred embodiment of the invention, the operation times and conditions of sublimation-desublimation are controlled so that the purity of purified pyromellitic dianhydride is more than or equal to 85 percent; more preferably, the purity is more than or equal to 96 percent; more preferably, the purity is not less than 98%.
According to a second aspect of the present invention, there is provided a method for producing pyromellitic dianhydride, comprising:
1) Adding pyromellitic acid into the second anhydride to obtain a solution, and heating;
2) Cooling the solution to room temperature, adding a poor solvent to precipitate a solid, and drying the solid after solid-liquid separation to obtain crude pyromellitic dianhydride;
3) The crude pyromellitic dianhydride was purified according to the aforementioned purification method. The preparation method of the pyromellitic dianhydride is beneficial to improving the purity of the pyromellitic dianhydride and reducing the power consumption.
In the present invention, the second anhydride species may be widely selected and mainly used as the dehydrating agent, and according to a preferred embodiment of the present invention, the second anhydride is selected from one or more of acetic anhydride, BOC anhydride, and propionic anhydride.
In the present invention, the kind of the poor solvent is widely selected, and for the present invention, it is preferable that the poor solvent is one or more selected from the group consisting of diethyl ether, petroleum ether, ethyl acetate and isopropyl ether. The preparation method of the crude pyromellitic dianhydride is combined with the purification method of the crude pyromellitic dianhydride, which is provided by the invention, so that the purity of the pyromellitic dianhydride is further improved.
According to the present invention, the mass ratio of the pyromellitic acid to the second anhydride is wide in the selectable range, and any commonly used mass ratio can be used in the present invention, and for the present invention, in step 1), preferably, the mass ratio of the pyromellitic acid to the second anhydride is 1:7-9; is favorable for further improving the purity of the pyromellitic dianhydride.
According to the invention, in step 1), the heating is mainly used for dehydration, preferably, in step 1), the heating temperature is 140-180 ℃, preferably 150-170 ℃; at the temperature, the mixture is boiled and refluxed, which is beneficial to further improving the purity of the pyromellitic dianhydride.
According to the invention, in step 1), the heating time is determined according to the temperature, and according to the invention, in step 1), the heating time is preferably 1-5h, preferably 2-4h; the heating time is reasonably adjusted by the heating temperature, which is beneficial to further improving the purity of the pyromellitic dianhydride.
According to the invention, in the step 2), the mass content of the pyromellitic dianhydride in the cooled solution is 50-80wt%; is favorable for further improving the purity and the yield of the pyromellitic dianhydride.
According to the present invention, in step 2), pyromellitic dianhydride is precipitated by a poor solvent, and the mass ratio of the second dianhydride to the poor solvent is 1:2-5; is favorable for further improving the purity and the yield of the pyromellitic dianhydride.
The drying method of the crude product of the pyromellitic dianhydride obtained by solid-liquid separation is not particularly limited, and alternatively, the drying method can be air-blast drying and vacuum drying; in order to further improve the purity of the pyromellitic dianhydride, the drying mode is preferably vacuum drying; more preferably, the vacuum drying conditions include: the drying temperature is 50-90 ℃; the vacuum degree is 0.01-0.05kPa.
The present invention will be described in detail below by way of examples.
Example 1
1) Adding 5g of pyromellitic acid into 35g of acetic anhydride, heating and boiling at 150 ℃, keeping reflux, and gradually blackening the mixture in the boiling process to finally form a black solution;
2) After the solution is cooled, adding ether (70 g) to precipitate a pyromellitic dianhydride solid, then carrying out suction filtration, and drying the obtained solid in a vacuum oven at the temperature of 70 ℃ to obtain crude pyromellitic dianhydride;
3) Placing crude pyromellitic dianhydride into a sublimation chamber 1, wherein the sublimation temperature is 190 ℃, the sublimation time is 5 hours, continuously vacuumizing and keeping the vacuum degree at 0.05kPa during sublimation, and the temperature of coolant passing through a sublimation finger 2 is 20 ℃; and after the sublimation-desublimation operation is finished, taking down the crystals on the sublimation finger 2, putting the crystals into a sublimation chamber for secondary sublimation-desublimation and third sublimation-desublimation, wherein the sublimation temperature is 190 ℃, the sublimation time is 10 hours, and continuously vacuumizing in the sublimation process to keep the vacuum degree at 0.05kPa.
The light yellow solid is obtained after the third sublimation-desublimation purification, and the purity of the pyromellitic dianhydride of the third sublimation-desublimation purification is 85.5 percent, 95 percent and 98 percent respectively, which can meet the requirements of industrial polymerization grade.
Example 2
1) Adding 5g of pyromellitic acid into 45g of acetic anhydride, heating and boiling at 170 ℃, keeping reflux, and gradually blackening the mixture in the boiling process to finally form a black solution;
2) After the solution is cooled, adding ether (180 g) to precipitate a pyromellitic dianhydride solid, then carrying out suction filtration, and drying the obtained solid in a vacuum oven at 70 ℃ to obtain crude pyromellitic dianhydride;
3) Placing crude pyromellitic dianhydride into a sublimation chamber 1, wherein the sublimation temperature is 220 ℃, the sublimation time is 8 hours, continuously vacuumizing in the sublimation process to keep the vacuum degree at 0.05kPa, and the temperature of a coolant passing through a sublimation chamber 2 is-10 ℃; and after sublimation is finished, taking the crystal on the sublimation finger 2 down and putting the crystal into a sublimator for secondary sublimation-desublimation and third sublimation-desublimation, wherein the sublimation temperature is 195 ℃, the sublimation time is 16 hours, and the vacuum degree is kept to be 0.05kPa during continuous vacuum pumping in the sublimation process.
The yellowish solid is obtained after the third sublimation-desublimation purification, and the purity of the pyromellitic dianhydride after the third sublimation-desublimation purification is 86%, 95% and 98.2% respectively, which can meet the requirements of industrial polymerization grade.
Example 3
1) Adding 5g of pyromellitic acid into 40g of acetic anhydride, heating and boiling at 160 ℃, keeping reflux, and gradually blackening the mixture in the boiling process to finally form a black solution;
2) After the solution is cooled, adding diethyl ether (120 g) to precipitate a pyromellitic dianhydride solid, then carrying out suction filtration, and drying the obtained solid in a vacuum oven at the temperature of 90 ℃ to obtain crude pyromellitic dianhydride;
3) Placing crude pyromellitic dianhydride into a sublimation chamber 1, wherein the sublimation temperature is 210 ℃, the sublimation time is 10 hours, continuously vacuumizing in the sublimation process to keep the vacuum degree at 0.05kPa, and the temperature of a coolant passing through a sublimation finger 2 is 5 ℃; and after sublimation is finished, taking the crystal on the sublimation finger 2 down and putting the crystal into a sublimator for secondary sublimation-desublimation and third sublimation-desublimation, wherein the sublimation temperature is 210 ℃, the sublimation time is 20 hours, and the continuous vacuum pumping is carried out in the sublimation process to keep the vacuum degree at 0.05kPa.
The light yellow solid is obtained after the third sublimation-desublimation purification, the purity of the pyromellitic dianhydride after the third sublimation-desublimation is respectively 88 percent, 96 percent and 99 percent, and the industrial polymerization grade requirement can be met.
Example 4
1) Adding 5g of pyromellitic acid into 60g of acetic anhydride, heating and boiling at 130 ℃, keeping reflux, and gradually blackening the mixture in the boiling process to finally form a black solution;
2) After the solution is cooled, adding ether (100 g) to precipitate a pyromellitic dianhydride solid, then carrying out suction filtration, and drying the obtained solid in a vacuum oven at the temperature of 90 ℃ to obtain crude pyromellitic dianhydride;
3) Placing crude pyromellitic dianhydride into a sublimation chamber 1, wherein the sublimation temperature is 200 ℃, the sublimation time is 10 hours, continuously vacuumizing in the sublimation process to keep the vacuum degree at 0.03kPa, and the temperature of coolant passing through a sublimation chamber 2 is 0 ℃; and after sublimation is finished, taking the crystal on the sublimation finger 2 down and putting the crystal into a sublimator for secondary sublimation-desublimation and third sublimation-desublimation, wherein the sublimation temperature is 200 ℃, the sublimation time is 15 hours, and the continuous vacuum pumping is carried out in the sublimation process to keep the vacuum degree at 0.03kPa.
The light yellow solid is obtained after the third sublimation-desublimation purification, the purity of the pyromellitic dianhydride after the third sublimation-desublimation is 85 percent, 96.3 percent and 96.9 percent respectively, and the industrial polymerization grade requirement can be met.
Example 5
1) Adding 5g of pyromellitic acid into 60g of acetic anhydride, heating and boiling at 130 ℃, keeping reflux, and gradually blackening the mixture in the boiling process to finally form a black solution;
2) After the solution is cooled, adding ether (50 g) to precipitate a pyromellitic dianhydride solid, then carrying out suction filtration, and drying the obtained solid in a vacuum oven at the temperature of 90 ℃ to obtain crude pyromellitic dianhydride;
3) Placing crude pyromellitic dianhydride into a sublimation chamber 1, wherein the sublimation temperature is 200 ℃, the sublimation time is 10 hours, continuously vacuumizing in the sublimation process to keep the vacuum degree at 0.03kPa, and the temperature of coolant passing through a sublimation chamber 2 is 0 ℃; and after sublimation is finished, taking the crystal on the sublimation finger 2 down and putting the crystal into a sublimator for secondary sublimation-desublimation and third sublimation-desublimation, wherein the sublimation temperature is 200 ℃, the sublimation time is 15 hours, and the continuous vacuum pumping is carried out in the sublimation process to keep the vacuum degree at 0.03kPa.
Obtaining light yellow solid after the third sublimation-desublimation purification, wherein the purity of the pyromellitic dianhydride after the third sublimation-desublimation is 82%, 90% and 95% respectively.
Example 6
1) Adding 5g of pyromellitic acid into 25g of acetic anhydride, heating at 130 ℃, keeping reflux, and gradually blackening the mixture in the boiling process to finally form a black solution;
2) After the solution is cooled, adding ether (100 g) to precipitate a pyromellitic dianhydride solid, then carrying out suction filtration, and drying the obtained solid in a vacuum oven at the temperature of 90 ℃ to obtain crude pyromellitic dianhydride;
3) Placing crude pyromellitic dianhydride into a sublimation chamber 1, wherein the sublimation temperature is 200 ℃, the sublimation time is 10 hours, continuously vacuumizing in the sublimation process to keep the vacuum degree at 0.03kPa, and the temperature of coolant passing through a sublimation chamber 2 is 0 ℃; and after sublimation is finished, taking the crystal on the sublimation finger 2 down and putting the crystal into a sublimator for secondary sublimation-desublimation and third sublimation-desublimation, wherein the sublimation temperature is 200 ℃, the sublimation time is 15 hours, and the continuous vacuum pumping is carried out in the sublimation process to keep the vacuum degree at 0.03kPa.
Obtaining light yellow solid after the third sublimation-desublimation purification, wherein the purities of the pyromellitic dianhydride after the third sublimation-desublimation are 76%, 88% and 92% respectively.
Comparative example 1
1) Adding 5g of pyromellitic acid into 60g of acetic anhydride, heating and boiling at 130 ℃, keeping reflux, and gradually blackening the mixture in the boiling process to finally form a black solution;
2) After the solution is cooled, adding ether (100 g) to precipitate a pyromellitic dianhydride solid, then carrying out suction filtration, and drying the obtained solid in a vacuum oven at the temperature of 90 ℃ to obtain crude pyromellitic dianhydride;
3) Placing crude pyromellitic dianhydride into a sublimation chamber 1, sublimating at 200 deg.C for 10 hr under normal pressure, and sublimating at 0 deg.C by sublimation to obtain coolant of 2; and after sublimation is finished, taking the crystal on the sublimation finger 2 down, putting the crystal into a sublimator for secondary sublimation-desublimation and third sublimation-desublimation, wherein the sublimation temperature is 200 ℃, the sublimation time is 15 hours, and the crystal is sublimated under normal pressure.
Obtaining light yellow solid after the third purification, wherein the purities of the pyromellitic dianhydride after the third purification are 73 percent, 85 percent and 87 percent respectively.
The preferred embodiments of the present invention have been described above in detail, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, many simple modifications can be made to the technical solution of the invention, including combinations of various technical features in any other suitable way, and these simple modifications and combinations should also be regarded as the disclosure of the invention, and all fall within the scope of the invention.
Claims (10)
1. A method for purifying crude pyromellitic dianhydride, which is characterized by comprising the following steps:
under the negative pressure state, the crude pyromellitic dianhydride is sublimated to obtain pyromellitic dianhydride vapor, and the vapor is sublimated to obtain purified pyromellitic dianhydride.
2. The purification method according to claim 1,
the sublimation conditions include:
the sublimation temperature is 150-250 ℃; and/or
The sublimation time is 1-20 h; and/or
The vacuum degree is 0.01-0.05 kPa; and/or
The desublimation conditions include: the condensation temperature is-10 ℃ to 20 ℃;
the purity of the crude pyromellitic dianhydride used for purification is more than or equal to 80.1 percent.
3. The purification method of claim 1, wherein the purification method is performed in a sublimation purification apparatus comprising: a sublimation chamber, a sublimation finger;
the sublimation chamber is used for accommodating crude pyromellitic dianhydride and heating the crude pyromellitic dianhydride to sublimate into steam, and the sublimation chamber can maintain a negative pressure state through an external vacuum-pumping device;
the sublimation finger is arranged in the sublimation cavity and used for condensing the pyromellitic dianhydride vapor;
the purification method comprises the following steps:
heating the sublimation cavity to sublimate the crude pyromellitic dianhydride to obtain pyromellitic dianhydride vapor under a negative pressure state, and sublimating the vapor in a sublimation mode to obtain purified pyromellitic dianhydride;
preferably, the sublimation purification apparatus includes: the device comprises a sublimation cavity (1), a sublimation finger (2), a vacuumizing interface (5), a first valve (6), a first cooling medium circulating interface (3) and a second cooling medium circulating interface (4);
the sublimation chamber (1) is used for containing crude pyromellitic dianhydride and heating the crude pyromellitic dianhydride to sublimate the crude pyromellitic dianhydride into vapor, and the sublimation chamber (1) can maintain a negative pressure state with an external vacuumizing device through a vacuumizing interface (5); the first valve (6) is used for controlling the degree of vacuum pumping of the vacuum pumping interface (5);
the sublimation finger (2) is arranged in the sublimation cavity (1) and is used for condensing the pyromellitic dianhydride vapor; the sublimation finger (2) comprises the first cooling medium circulation interface (3) and the second cooling medium circulation interface (4), and cooling medium enters the sublimation finger (2) from the first cooling medium circulation interface (3) for refrigeration and flows out from the second cooling medium circulation interface (4); preferably the purification method comprises:
the sublimation cavity (1) is in a negative pressure state through the vacuumizing interface (5), the sublimation cavity (1) is heated to sublimate the crude pyromellitic dianhydride to obtain pyromellitic dianhydride vapor, and the vapor is sublimated through the sublimation finger (2) to obtain purified pyromellitic dianhydride.
4. A purification method according to claim 3, wherein the sublimation conditions include:
the sublimation temperature is 150-250 ℃; and/or
The sublimation time is 1-20 h; and/or
The vacuum degree is 0.01-0.05kPa.
5. A purification method according to claim 3 or 4, wherein sublimation means that the condensation temperature is-10 ℃ to 20 ℃.
6. The purification method according to any one of claims 1 to 5, wherein the operation of sublimation-desublimation is repeated 2 to 5 times; preferably, the latter sublimation time is greater than the former sublimation time.
7. The purification method according to any one of claims 1 to 6, wherein the number of sublimation-desublimation operations and conditions are controlled so that the purity of purified pyromellitic dianhydride is not less than 85%; more preferably, the purity is more than or equal to 96 percent; more preferably, the purity is 98% or more.
8. A preparation method of pyromellitic dianhydride is characterized by comprising the following steps:
1) Adding pyromellitic acid into the second anhydride to obtain a solution, and heating;
2) Cooling the solution to room temperature, adding a poor solvent to precipitate a solid, and drying the solid after solid-liquid separation to obtain crude pyromellitic dianhydride;
3) Purifying crude pyromellitic dianhydride according to the purification method of any one of claims 1 to 7;
preferably, the second anhydride is selected from one or more of acetic anhydride, BOC anhydride and propionic anhydride;
preferably, the poor solvent is selected from one or more of diethyl ether, petroleum ether, ethyl acetate and isopropyl ether.
9. The production method according to claim 8,
in the step 1), the mass ratio of the pyromellitic acid to the second anhydride is 1-10; and/or
The heating temperature is 140-180 ℃; and/or
The heating time is 1-5h; and/or
In the step 2), the mass content of the pyromellitic dianhydride in the cooled solution is 50-80wt%; and/or
The mass ratio of the second anhydride to the poor solvent is 1:2-5.
10. The production method according to claim 8 or 9,
the drying mode is vacuum drying; preferably, the vacuum drying conditions include:
the drying temperature is 50-90 ℃; the vacuum degree is 0.01-0.05kPa.
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| US20100147564A1 (en) * | 2007-05-09 | 2010-06-17 | Jfe Chemical Corporation | Asymmetric linear polyimides and their polyimide precursors, and their manufacturing methods |
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