A method for preparing 9,9-bis(3,4-dicarboxyphenyl)fluorene anhydride

Abstract

The invention provides a method for preparing 9,9-bis(3,4-dicarboxyphenyl)fluorene anhydride, comprising the following steps: S1: mixing fluorene, phthalic anhydride, an inorganic salt and a solvent to obtain a mixed solution A; S2: heating the mixed solution to a certain temperature, reacting for a period of time, cooling, filtering, treating the filtrate, and precipitating 9,9-bis(3,4-dicarboxyphenyl)fluorene anhydride. The method for preparing 9,9-bis(3,4-dicarboxyphenyl)fluorene anhydride of the present invention has the advantages of short reaction steps, easy purchase of raw materials and low cost, simple post-processing operation, high yield, high product purity and less environmental pollution.

Description

Technical Field

[0001] The invention belongs to the technical field of material raw material preparation, and in particular relates to a method for preparing 9,9-bis(3,4-dicarboxyphenyl)fluorene anhydride. Background Art

[0002] Polyimide (PI) is a rigid polymer with an imide ring in the main chain and a highly regular chemical structure. It is a polymer material obtained by the reaction of dianhydride and diamine through melt polycondensation or solution polycondensation to form polyamic acid (PAA), and then imidization. PI has the advantages of good light transmittance and strong resistance to heat and oxygen aging. It is widely used in high-tech fields such as aerospace, electronic power, and precision machinery, including special plastics, composite materials, films, adhesives, fibers, liquid crystal orientation agents, separation membranes, photoresists, etc., and has become an irreplaceable high-performance polymer material. As a new type of dianhydride monomer, 9,9-bis(3,4-dicarboxyphenyl)fluorene dianhydride has good application prospects.

[0003] At present, there are few literatures on the synthesis of 9,9-bis(3,4-dicarboxyphenyl)fluorene anhydride, and even fewer methods suitable for production:

[0004] 1)Xu Z, Zhao C, Sun W, et al. An efficient and general method for thesynthesis of stable isotope deuterium labeled phthalate esters[J]. Journal of Labeled Compounds and Radiopharmaceuticals, 2021, 64.

[0005] This article discloses that o-xylene is oxidized by a large amount of potassium permanganate under alkaline conditions to generate phthalic acid. This method has a relatively violent reaction when potassium permanganate is added, and can produce a large amount of waste solid and waste liquid, and the treatment cost is relatively high, so it is not suitable for mass production.

[0006] 2) Angus RO, Yacoub K. 9,9-bis-(3,4-dicarboxyphenyl)fluorenedianhydrides: US, US5061809 A.

[0007] This article discloses that 9,9-bis(3,4-dicarboxyphenyl)fluorene anhydride is obtained by a three-step reaction using 9-fluorenone and o-xylene as starting materials, wherein the second step of the synthesis of 4,4'-(9H-fluorene-9,9-diyl)diphthalic acid has a long reaction time, requires expensive metal salts, and has a high cost.

[0008] 3)Cao X, Yang W, Liu C, et al. Palladium-Catalyzed Direct Arylation of C–HBond To Construct Quaternary Carbon Centers: The Synthesis of Diarylfluorene[J]. Organic Letters, 2013, 15(12): 3102-3105.

[0009] These two articles disclose that fluorene compounds and aromatic halides are used as starting materials to obtain double coupling target products through a one-step reaction with palladium catalysts and different ligands. However, the required palladium catalysts are expensive and the used ligands are difficult to separate and remove, which is not suitable for mass production.

[0010] In the existing BPAF synthesis process, the oxidation of methyl to carboxylic acid takes a long time, has a low yield, and requires a large amount of precious metal catalyst, which is not suitable for mass production. These methods have different degrees of limitations in the application of industrial production. Therefore, it is urgent to find a suitable method for preparing BPAF industrially. Summary of the invention

[0011] In view of this, the present invention aims to propose a method for preparing 9,9-bis(3,4-dicarboxyphenyl)fluorene anhydride to solve the problems of long reaction time, low yield, and the need for a large amount of precious metal catalyst, which is not suitable for mass production.

[0012] To achieve the above object, the technical solution of the present invention is achieved as follows:

[0013] A method for preparing 9,9-bis(3,4-dicarboxyphenyl)fluorene anhydride comprises the following steps:

[0014] S1: mixing fluorene, phthalic anhydride, an inorganic salt and a solvent to obtain a mixed solution A;

[0015] S2: heating the mixed solution to a certain temperature, reacting for a period of time, cooling, filtering, treating the filtrate, and precipitating 9,9-bis(3,4-dicarboxyphenyl)fluorene anhydride.

[0016] The reaction structure is as follows:

[0017]

[0018] Furthermore, the molar ratio of fluorene, phthalic anhydride, inorganic salt and solvent is 1:2.05:(0.6-1.3):(5-13). Preferably, the molar ratio of fluorene, phthalic anhydride, metal salt and solvent is 1:2.05:1.1:5.2.

[0019] Furthermore, in step S1, the inorganic salt is selected from at least one of aluminum chloride, aluminum bromide, and aluminum iodide. Preferably, the inorganic salt is aluminum chloride.

[0020] Furthermore, the solvent is a protic solvent.

[0021] Furthermore, the solvent is one of acetic anhydride, acetonitrile, dioxane, DMF, and DMAC solution. Preferably, the solvent is acetic anhydride.

[0022] Furthermore, in step S2, the mixed solution is heated to 80-160°C, preferably 140-145°C.

[0023] Furthermore, the reaction time in step S2 is 4-8 hours.

[0024] Furthermore, the treatment of the filtrate in step S1 includes concentrating and distilling the filtrate to obtain the finished product, or adding acetic anhydride to the filtrate to precipitate the finished product.

[0025] Compared with the prior art, the method for preparing 9,9-bis(3,4-dicarboxyphenyl)fluorene anhydride according to the present invention has the following beneficial effects:

[0026] The invention has the advantages of short reaction steps, easy purchase of raw materials with low cost, simple post-processing operation, high yield, high product purity and less environmental pollution. 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 embodiments.

[0029] Example 1

[0030] Add 320.00 g (3.13 mol) of acetic anhydride, 100 g (0.60 mol) of fluorene, 182.67 g (1.23 mol) of phthalic anhydride, and 88.23 g (0.66 mol) of aluminum chloride to a sealed reaction bottle, raise the temperature to 140-145°C, react for 5 hours, turn off the heating, cool, filter, dissolve the filter cake with acetonitrile, filter with suction, and concentrate the filtrate to obtain 248.79 g of white solid with a yield of 90.21% and a purity of 99.55%.

[0031] Example 2

[0032] Add 400 g (9.7 mol) of acetonitrile, 120 g (0.72 mol) of fluorene, 219.20 g (1.48 mol) of phthalic anhydride, and 211.79 g (0.79 mol) of aluminum bromide to a sealed reaction bottle, raise the temperature to 80-85°C, react for 7 hours, turn off the heating, cool, filter, and concentrate the filtrate to obtain 289.98 g of a white solid with a yield of 87.62% and a purity of 99.31%.

[0033] Example 3

[0034] To a sealed reaction bottle, add 710 g (9.71 mol) of DMF, 170 g (1.02 mol) of fluorene, 310.54 g (2.10 mol) of phthalic anhydride, and 437.81 g (1.07 mol) of aluminum iodide. Heat to 150-160°C, react for 5 h, turn off the heating, cool, filter, add acetic anhydride to the filtrate, precipitate a large amount of solid, filter 386.84 g of white solid, with a yield of 82.51% and a purity of 98.93%.

Claims

1. A method for preparing 9,9-bis(3,4-dicarboxyphenyl)fluorene anhydride, characterized in that: The steps include: S1: mixing fluorene, phthalic anhydride, an inorganic salt and a solvent to obtain a mixed solution A; S2: heating the mixed solution to a certain temperature, reacting for a period of time, cooling, filtering, and treating the filtrate to precipitate 9,9-bis(3,4-dicarboxyphenyl)fluorene anhydride; In step S1, the inorganic salt is selected from at least one of aluminum chloride, aluminum bromide, and aluminum iodide; The solvent is one of acetic anhydride, acetonitrile, dioxane, DMF, and DMAC solution; In step S2, the mixed solution is heated to 80-160° C.; The reaction time in step S2 is 4-8 hours.

2. A method for preparing 9,9-bis(3,4-dicarboxyphenyl)fluorene anhydride according to claim 1, characterized in that: The molar ratio of fluorene, phthalic anhydride, inorganic salt and solvent is 1:2.05:(0.6-1.3):(5-13).

3. A method for preparing 9,9-bis(3,4-dicarboxyphenyl)fluorene anhydride according to claim 1 or 2, characterized in that: The molar ratio of fluorene, phthalic anhydride, inorganic salt and solvent is 1:2.05:1.1:5.

2.

4. A method for preparing 9,9-bis(3,4-dicarboxyphenyl)fluorene anhydride according to claim 1, characterized in that: The inorganic salt in step S1 is aluminum chloride.

5. A method for preparing 9,9-bis(3,4-dicarboxyphenyl)fluorene anhydride according to claim 1, characterized in that: The solvent is acetic anhydride.

6. A method for preparing 9,9-bis(3,4-dicarboxyphenyl)fluorene anhydride according to claim 1, characterized in that: In step S2, the mixed solution is heated to 140-145°C.

7. A method for preparing 9,9-bis(3,4-dicarboxyphenyl)fluorene anhydride according to claim 1, characterized in that: The treatment of the filtrate in step S2 includes concentrating and distilling the filtrate to obtain the finished product, or adding acetic anhydride to the filtrate to precipitate the finished product.

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