A preparation method of 9,9-bis(trifluoromethyl)-2,3,6,7-oxanthene tetracarboxylic dianhydride

Abstract

The invention provides a method for preparing 9,9-bis(trifluoromethyl)-2,3,6,7-oxanthene tetracarboxylic dianhydride, comprising the following steps: 5-indanol, hexafluoroacetone trihydrate, a first solvent, and a catalyst are mixed and heated until the reaction is complete to obtain a first intermediate; the first intermediate and nitric acid are mixed and heated until the reaction is complete to obtain a tetracarboxylic acid intermediate; the tetracarboxylic acid intermediate is mixed and heated with a second solvent for dehydration to obtain a desired product. The method for preparing 9,9-bis(trifluoromethyl)-2,3,6,7-oxanthene tetracarboxylic dianhydride of the present invention overcomes the disadvantage of low yield of existing routes, and has the advantages of mild reaction conditions, simple post-processing operation, solvent recyclability, good quality, etc.

Description

Technical Field

[0001] The invention belongs to the field of chemical synthesis, and in particular relates to a method for preparing 9,9-bis(trifluoromethyl)-2,3,6,7-oxanthene tetracarboxylic dianhydride. Background Art

[0002] 9,9-Bis(trifluoromethyl)-2,3,6,7-oxanthene tetracarboxylic dianhydride (hereinafter referred to as 6FCDA) is a polyimide dianhydride monomer. It is a material obtained by polymerizing with diamine monomers of different structures. After processing, it can be used in aerospace, microelectronics, liquid crystal, laser, separation membrane and other fields.

[0003] The preparation of 9,9-bis(trifluoromethyl)-2,3,6,7-oxanthene tetracarboxylic dianhydride is difficult, and the prior art literature reports are as follows:

[0004] 1) The invention patent with publication number CN112424261A discloses a method for preparing 6FCDA: using hexafluoroacetone trihydrate as a raw material and 3,4-dimethylphenol as a raw material, the product is prepared through three steps of reaction, the first step yield is 48%, the second step yield is 82%, the third step yield is 82%, and the total yield is 32.27%.

[0005] 2) Patent No. US5051520 uses hexafluoroacetone as a raw material, reacts with 3,4-dimethylphenol or 3,3',4,4'-tetramethyl diphenyl ether in hydrofluoric acid to obtain 6FCDA tetramethyl, which is then oxidized and dehydrated to obtain 6FCDA. The first step yield is 17%, the second step yield is 61%, and the third step yield is not mentioned.

[0006] The index methods disclosed in the above literature are basically similar and have low yields. Therefore, it is of great significance to develop a new method for preparing 6FCDA. Summary of the invention

[0007] In view of this, the present invention aims to provide a method for preparing 9,9-bis(trifluoromethyl)-2,3,6,7-oxanthene tetracarboxylic dianhydride to improve the conversion rate and product purity of the reaction process.

[0008] To achieve the above object, the technical solution of the present invention is achieved as follows:

[0009] A method for preparing 9,9-bis(trifluoromethyl)-2,3,6,7-oxanthene tetracarboxylic dianhydride comprises the following steps:

[0010] Step S1, mixing 5-indanol, hexafluoroacetone trihydrate, a first solvent and a catalyst and heating them until the reaction is complete to obtain a first intermediate 6FCDM;

[0011] Step S2, mixing the first intermediate and nitric acid and heating until the reaction is complete to obtain a tetracarboxylic acid intermediate 6FCDC;

[0012] Step S3, mixing the tetracarboxylic acid intermediate 6FCDC with the second solvent and heating and dehydrating the mixture to obtain the desired product 6FCDA.

[0013] Furthermore, in step S1, the molar ratio of 5-indanol, hexafluoroacetone trihydrate and catalyst is (2-3):1:(1.5-3); preferably 2.5:1:2.

[0014] Furthermore, the catalyst is methyl trifluoromethanesulfonate.

[0015] Further, the first solvent is a mixture of one or two of NMP, DMSO, DMAC, DMF, toluene, dichloromethane, dichloroethane, and chloroform; preferably, it is a mixture of toluene and dichloroethane; further preferably, the volume ratio of toluene to dichloroethane is 3:1; further preferably, the mass ratio of hexafluoroacetone trihydrate to the mixture of toluene and dichloroethane is 1:(4-8).

[0016] Furthermore, the reaction temperature in step S1 is 70-100°C; preferably 90°C.

[0017] Furthermore, in step S2, the mass ratio of the first intermediate to nitric acid is 1:(10-30); preferably 1:15.

[0018] Furthermore, the mass fraction of nitric acid in step S2 is 5%-30%, preferably 10%.

[0019] Furthermore, in step S2, the reaction temperature is 100-150° C., and the reaction pressure is 0.5-5 MPa; preferably, the reaction temperature is 130° C., and the reaction pressure is 3 MPa.

[0020] Furthermore, in step S3, the mass ratio of the tetracarboxylic acid intermediate to the second solvent is 1:(20-40), and the reaction temperature is 100-200°C; preferably, the mass ratio of the tetracarboxylic acid intermediate to the second solvent is 1:30, and the reaction temperature is 140°C.

[0021] Furthermore, the second solvent is a mixture of one or two of toluene, acetic anhydride, propionic anhydride, xylene, trimethylbenzene, and dichlorobenzene; preferably xylene.

[0022] Compared with the prior art, the preparation method of the present invention has the following advantages:

[0023] The preparation method of 9,9-bis(trifluoromethyl)-2,3,6,7-oxanthene tetracarboxylic dianhydride of the present invention overcomes the disadvantage of low yield of the existing route and has the advantages of mild reaction conditions, simple post-treatment operation, solvent recovery and reuse, good quality, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings:

[0025] Figure 1 A schematic diagram of the synthetic route of the preparation method described in an embodiment of the present invention;

[0026] Figure 2 This is a schematic diagram of liquid chromatography of 9,9-bis(trifluoromethyl)-2,3,6,7-oxanthene tetracarboxylic dianhydride prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0027] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0028] The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with embodiments.

[0029] The synthetic route of the preparation method of 9,9-bis(trifluoromethyl)-2,3,6,7-oxanthene tetracarboxylic dianhydride in the present invention is as follows: Figure 1 shown.

[0030] Example 1

[0031] Step S1: Add 67g (0.5mol) of 5-indanol, 65.6g (0.4mol) of methyl trifluoromethanesulfonate, 264g of a mixed solution of toluene and dichloroethane to a reaction flask, heat to 50°C, add 44g (0.2mol) of hexafluoroacetone trihydrate in batches, then heat to 90°C, and after the raw materials react completely, gradually cool the reaction solution to room temperature, then cool with ice water until a large amount of solid precipitates, filter, wash the filter cake with the mixed solution, and distill the filtrate under reduced pressure to recover the solvent, which can be reused. The filter cake is vacuum dried to obtain an off-white solid 6FCDM, 57.2g, with a yield of 71.77%.

[0032] Step S2: 39.8 g (0.1 mol) of 6FCDM and 597 g of 10% nitric acid were added to a reactor, and the temperature was slowly raised to 130° C., while the pressure in the reactor was controlled not to exceed 3 MPa. The reaction was carried out for 2 hours, and then the temperature was lowered to room temperature, filtered, washed with water, and dried to obtain 42.6 g of white solid 6FCDC with a yield of 86.23%.

[0033] Step S3, 42g (0.085mol) 6FCDC was added to 294g o-xylene, and the temperature was raised to 140°C, and refluxed at this temperature to separate water until it was dry. After the reaction solution was cooled to 0°C, stirred for 2 hours, filtered, the filtrate was decompressed to recover the solvent, and the filter cake was vacuum dried to obtain 6FCDA, 36.7g, with a yield of 94.2% and a content of 99.94%. Its liquid chromatogram is shown as follows Figure 2 shown.

[0034] Example 2

[0035] Step S1: Add 53.6g (0.4mol) of 5-indanol, 49g (0.3mol) of methyl trifluoromethanesulfonate, 176g of a mixed solution of toluene and dichloroethane to a reaction flask, heat to 50°C, add 44g (0.2mol) of hexafluoroacetone trihydrate in batches, then heat to 70°C, and after the raw materials react completely, gradually cool the reaction solution to room temperature, then cool with ice water until a large amount of solid precipitates, filter, wash the filter cake with the mixed solution, and distill the filtrate under reduced pressure to recover the solvent, which can be reused. The filter cake is vacuum dried to obtain an off-white solid 6FCDM, 30.4g, with a yield of 38.14%.

[0036] Step S2: 39.8 g (0.1 mol) of 6FCDM and 398 g of 10% nitric acid were added to a reactor, and the temperature was slowly raised to 100° C., while the pressure in the reactor was controlled not to exceed 5 MPa. The reaction was carried out for 5 hours, and then the temperature was lowered to room temperature, filtered, washed with water, and dried to obtain 21.9 g of a white solid 6FCDC with a yield of 44.33%.

[0037] Step S3, 42g (0.085mol) 6FCDC was added to 210g o-xylene, and the temperature was raised to 140°C, and refluxed at this temperature to separate water until it was dry. The reaction solution was cooled to 0°C, stirred for 2 hours, filtered, the filtrate was decompressed to recover the solvent, and the filter cake was vacuum dried to obtain 6FCDA, 28.5g, with a yield of 73.15% and a content of 98.35%.

[0038] Example 3

[0039] Step S1: Add 80.4g (0.6mol) of 5-indanol, 98g (0.6mol) of methyl trifluoromethanesulfonate, 352g of a mixed solution of toluene and dichloroethane to a reaction flask, heat to 50°C, add 44g (0.2mol) of hexafluoroacetone trihydrate in batches, then heat to 100°C, and after the raw materials react completely, gradually cool the reaction solution to room temperature, then cool with ice water until a large amount of solid precipitates, filter, wash the filter cake with the mixed solution, and distill the filtrate under reduced pressure to recover the solvent, which can be reused. The filter cake is vacuum dried to obtain an off-white solid 6FCDM, 57.5g, with a yield of 72.15%.

[0040] Step S2: 39.8 g (0.1 mol) of 6FCDM and 1194 g of 10% nitric acid were added to a reactor, and the temperature was slowly raised to 150° C., while the pressure in the reactor was controlled not to exceed 3 MPa. The reaction was carried out for 1 hour, and then the temperature was lowered to room temperature, filtered, washed with water, and dried to obtain 41.8 g of white solid 6FCDC with a yield of 84.61%.

[0041] Step S3, 42g (0.085mol) 6FCDC was added to 420g o-xylene, and the temperature was raised to 140°C, and refluxed at this temperature to separate water until it was dry. The reaction solution was cooled to 0°C, stirred for 2 hours, filtered, the filtrate was decompressed to recover the solvent, and the filter cake was vacuum dried to obtain 6FCDA, 36.5g, with a yield of 93.67% and a content of 99.93%.

[0042] Example 4

[0043] Step S1: Add 75g (0.56mol) of 5-indanol, 59g (0.36mol) of methyl trifluoromethanesulfonate, and 220g of a mixed solution of recovered toluene and dichloroethane to a reaction flask, heat to 50°C, add 44g (0.2mol) of hexafluoroacetone trihydrate in batches, and then heat to 90°C. After the raw materials react completely, gradually cool the reaction solution to room temperature, then cool with ice water until a large amount of solid precipitates, filter, and wash the filter cake with the mixed solution. The filter cake is vacuum dried to obtain an off-white solid 6FCDM, 56.1g, with a yield of 70.38%.

[0044] Step S2: 39.8 g (0.1 mol) of 6FCDM and 478 g of 15% nitric acid were added to a reactor, and the temperature was slowly raised to 120° C., while the pressure in the reactor was controlled not to exceed 3 MPa. The reaction was carried out for 1 hour, and then the temperature was lowered to room temperature, filtered, washed with water, and dried to obtain 39.7 g of white solid 6FCDC with a yield of 80.36%.

[0045] Step S3, 42g (0.085mol) 6FCDC was added to 420g o-xylene, and the temperature was raised to 140°C, and refluxed at this temperature to separate water until it was dry. The reaction solution was cooled to 0°C, stirred for 2 hours, filtered, and vacuum dried to obtain 6FCDA, 34.8g, with a yield of 89.32% and a content of 99.91%.

Claims

1. A method for preparing 9,9-bis(trifluoromethyl)-2,3,6,7-oxanthene tetracarboxylic dianhydride, characterized in that: The following steps are involved: Step S1, mixing 5-indanol, hexafluoroacetone trihydrate, a first solvent, and a catalyst and heating them until the reaction is complete to obtain a first intermediate 6FCDM; Step S2, mixing the first intermediate and nitric acid and heating until the reaction is complete to obtain a tetracarboxylic acid intermediate 6FCDC; Step S3, mixing the tetracarboxylic acid intermediate with the second solvent and heating and dehydrating to obtain the desired product 6FCDA; the step S1 also includes the following steps: after the raw materials react completely, gradually cooling the reaction solution to room temperature, then cooling with ice water until a large amount of solid precipitates, filtering, washing the filter cake with the mixed solution, and distilling the filtrate under reduced pressure to recover the solvent, and the solvent can be reused; In step S1, the molar ratio of 5-indanol, hexafluoroacetone trihydrate, and catalyst is (2-3):1:(1.5-3); The catalyst in step S1 is methyl trifluoromethanesulfonate; In step S2, the mass ratio of the first intermediate to nitric acid is 1:(10-30); The synthetic route of the product 6FCDA is:

2. The preparation method according to claim 1, characterized in that: The first solvent is one or a mixture of two of NMP, DMSO, DMAC, DMF, toluene, dichloromethane, dichloroethane, and chloroform.

3. The preparation method according to claim 1, characterized in that: The reaction temperature in step S1 is 70-100°C.

4. The preparation method according to claim 1, characterized in that: The mass fraction of nitric acid in step S2 is 5%-30%.

5. The preparation method according to claim 1, characterized in that: In step S2, the reaction temperature is 100-150° C., and the reaction pressure is 0.5-5 MPa.

6. The preparation method according to claim 1, characterized in that: In step S3, the mass ratio of the tetracarboxylic acid intermediate to the second solvent is 1:(20-40), and the reaction temperature is 100-200°C.

7. The preparation method according to claim 1, characterized in that: The second solvent is one or a mixture of two of toluene, acetic anhydride, propionic anhydride, xylene, trimethylbenzene and dichlorobenzene.

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