CN115947936A - Preparation method of polyetherimide - Google Patents

Abstract

The invention relates to the technical field of polyetherimide synthesis, in particular to a preparation method of polyetherimide, which comprises the following steps: under the protection of inert gas, carrying out nucleophilic substitution reaction etherification condensation on dihalo phthalimide, dihydric phenol and inorganic base in a non-polar organic solvent in the presence of a copper salt catalyst and a phenanthroline ligand, and after the reaction is finished, carrying out reaction post-treatment to finally obtain the polyetherimide product. The preparation method of the polyetherimide takes halogenated phthalic anhydride, organic diamine and the like as initial raw materials, and the target product is prepared through two steps of reactions of imidization and etherification condensation, and the polyetherimide is a chemical product with a very large use demand.

Description

A kind of preparation method of polyetherimide

Technical Field

The invention relates to a method for preparing polyetherimide, and belongs to the technical field of polyetherimide synthesis.

Background Art

Polyetherimide is a non-crystalline thermoplastic polyimide with excellent properties such as high temperature resistance, high strength, high modulus, high insulation, corrosion resistance, good dimensional stability and easy processing. It is an engineering plastic with excellent comprehensive performance and is widely used in electronics, machinery, automobiles, aircraft, food, medical care, aerospace and other fields.

The traditional preparation method of polyetherimide is an alkaline hydrolysis and acidification route, as described in US patent applications US3879428A, US5068353A and US3957862A: using halogenated or nitro-substituted phthalic anhydride as a starting material, halogenated or nitro-substituted phthalimide is obtained by imidization protection, and then the halogenated or nitro-substituted phthalimide is reacted with a dialkali metal salt of bisphenol A in a polar aprotic solvent such as dimethyl sulfoxide, dimethylformamide, dimethylacetamide, etc. to prepare an etherified bisimide, wherein the disodium salt of bisphenol A is prepared by refluxing and separating water of bisphenol A and sodium hydroxide in water/benzene or toluene, and the etherified bisimide obtained above is further subjected to a strong alkaline hydrolysis, acidification and dehydration process to finally obtain a dianhydride monomer, and the dianhydride monomer is polymerized with a diamine to obtain the target polyetherimide, and the reaction process is as follows:

；

;

wherein X represents a nitro group or a halogen (F, Cl, Br, I); M represents an alkali metal; R represents an aromatic C _6-20 monocyclic or polycyclic portion optionally substituted by 1 to 6 C _1-8 alkyl groups, 1 to 8 halogen atoms, or a combination comprising at least one of the foregoing; R ¹ represents a monovalent C _1-13 organic group, a phenyl group, a biphenyl group, etc.; R ² represents a C _6-30 aromatic hydrocarbon group and its halogenated derivatives.

The above-mentioned traditional methods have the problems of long synthesis route, complicated steps and high cost: firstly, the raw materials 4-nitrophthalic anhydride or 4-halogenated phthalic anhydride are not easy to prepare, and the isomers (3-nitrophthalic anhydride or 3-halogenated phthalic anhydride) and disubstituted products (3, 4 positions) are difficult to separate, resulting in high raw material costs; secondly, the preparation process of bisphenol A dialkali metal salt is prone to salt agglomeration and wall formation to form "salt cakes", which are not easy to disperse, resulting in low yield and poor reaction stability in the etherified bisimide preparation step; and the alkaline hydrolysis and acidification step involves the use of a large amount of acid and alkali, which ultimately produces a large amount of acidic wastewater, high cost for waste treatment, and environmental pollution.

In the US patent applications US4318857A and US7268237A, the preparation method of polyetherimide is improved in view of the defects of the traditional method: the dianhydride monomer is prepared by using the imide-anhydride exchange reaction, thereby avoiding the large amount of acid-base byproducts caused by the alkali hydrolysis of the bisimide and the subsequent cumbersome washing process. The reaction process is as follows:

；

;

wherein X, R, R ¹ and R ² are as defined above.

Although this method avoids the alkaline hydrolysis and acidification steps of the traditional method, its disadvantages are that the reaction equipment is relatively complex and unconventional, the reaction conditions are harsh (the reaction temperature is high, at least 170~200℃; the reaction process requires the use of triethylamine catalysis), and the reaction conversion rate is low. The separation of the main and by-products is difficult, and it is not suitable for large-scale production.

The above methods all use a series of steps to synthesize the dianhydride monomer, and then the dianhydride and diamine are subjected to imidization polymerization to prepare the target polyetherimide. In addition, there is another method that uses a one-step etherification polymerization of bis(halogenated or nitro-substituted phthalimide) and a dialkali metal salt of bisphenol A to prepare polyetherimide. For example, in U.S. patent applications US3838097A and US3852242A, nitro-substituted phthalic anhydride and diamine are used to prepare bis(nitro-substituted phthalimide), and then Etherification polymerization is carried out with bisphenol A dialkali metal salt in a non-protonic solvent (such as N,N-dimethylformamide/DMF) at a reaction temperature of 40°C to finally obtain the target polyetherimide; Chinese patent applications CN103958569A and CN104039867A are based on the above technology, replacing the starting material with halogenated phthalic anhydride (especially chlorinated), and the etherification polymerization solvent is replaced with o-dichlorobenzene (o-DCB), and polyetherimide is prepared at a reaction temperature of 200°C. The reaction process is as follows:

；

;

wherein X represents a nitro group, a halogen (F, Cl, Br, I); R represents a C6-30 aromatic hydrocarbon group and a halogenated derivative thereof; R1 represents an aromatic _C6-20 monocyclic or polycyclic moiety optionally substituted by 1 to 6 _C1-8 alkyl groups, 1 to 8 halogen atoms or a combination comprising at least one of the foregoing; and M represents an alkali metal.

Compared with the traditional method of anhydride amine polymerization, this method uses halogenated or nitro-substituted phthalic anhydride as the starting material, and prepares the target polyetherimide through two steps of imidization and etherification polymerization, thereby avoiding the tedious steps and a large amount of high-salt wastewater in the synthesis of dianhydride monomers, and has significant advantages in process advancement and comprehensive cost. However, compared with the traditional polymerization of anhydride amine polymerization, the etherification polymerization involved in this method has a relatively low reaction activity, resulting in a low weight-average molecular weight (Mw) and glass transition temperature (Tg) of the final polymer, and due to the incomplete etherification reaction, the yield of the final polymer is low, and the comprehensive material performance cannot meet commercial requirements. Therefore, this etherification polymerization method is currently only in the literature reporting stage and has not yet been realized in large-scale production.

Based on the above analysis, it is very important to seek a low-cost, high-yield method for preparing polyetherimide with satisfactory performance.

Summary of the invention

The present invention aims at the deficiencies in the prior art and provides a method for preparing polyetherimide. Under the catalytic action of copper salt and phenanthroline ligands, the etherification condensation reaction activity of halogenated phthalimide and dihydric phenol is significantly improved, so that polyetherimide that meets commercial standards can be prepared by etherification condensation, that is, having a high molecular weight and a high glass transition temperature. At the same time, this method is suitable for large-scale production.

The technical solution of the present invention to solve the above technical problems is as follows: a method for preparing polyetherimide, the preparation method comprising: under the protection of inert gas, in the presence of a copper salt catalyst and a phenanthroline ligand, a dihalogenated phthalimide, a dihydric phenol and an inorganic base are subjected to nucleophilic substitution reaction etherification condensation in a non-polar organic solvent, after the reaction is completed, the polyetherimide product is finally obtained by post-reaction treatment;

The structural formula of the bishalogenated phthalimide is:

；

;

The structural formula of the dihydric phenol is:

；

;

The structural formula of the polyetherimide is:

；

;

Wherein, n is an integer between 1 and 300; ^R1 represents a C6-C30 aromatic hydrocarbon group; ^R2 represents an aromatic C6-C20 monocyclic or polycyclic ring substituted by at least one of 1 to 6 C1-C8 alkyl groups or 1 to 8 halogen atoms; X represents a halogen, such as F, Cl, Br, I.

。Preferably, n is an integer between 140 and 160, X is preferably Cl, ^R1 is a benzene ring, and ^R2 is

.

The preparation principle of the polyetherimide is:

。

.

Furthermore, the polyetherimide is any one of the following structural formulas:

。

.

Further, the copper salt catalyst is selected from any one or a combination of CuCl, CuBr and CuI; the phenanthroline ligand is selected from any one or a combination of the following structural formulas L1-L4:

。

.

（1,10-菲咯啉）。Preferably, the copper salt catalyst is CuI, and the phenanthroline ligand is

(1,10-phenanthroline).

Furthermore, the preparation method of the dihalogenated phthalimide is as follows: under the protection of an inert gas, 4-halogenated phthalic anhydride and an organic diamine are subjected to an imidization reaction in a non-polar organic solvent to obtain a dihalogenated phthalimide crude product, and then subjected to post-reaction treatment to obtain a dihalogenated phthalimide product;

The structural formula of the 4-halogenated phthalic anhydride is:

；

;

The structural formula of the organic diamine is:

；

;

The molar ratio of the organic diamine to 4-halogenated phthalic anhydride is 1.00:1.80-2.20, the reaction temperature of the imidization reaction is 40-160°C, and the reaction time is 1-8 hours; the amount of the non-polar organic solvent added in the imidization reaction is 1.0-6.0 times the theoretical mass of the product dihalogenated phthalimide.

The principle of preparing dihalogenated phthalimide by imidization reaction is:

。

.

Furthermore, the organic diamine is any one of m-phenylenediamine, p-phenylenediamine, 3-methyl-1,4-phenylenediamine, 4,4'-biphenylenediamine, 3,3'-dimethyl-4,4'-biphenylenediamine, 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylmethane or 3,3'-dimethyl-4,4'-diaminodiphenylmethane, but is not limited to these.

Preferably, the organic diamine is m-phenylenediamine or p-phenylenediamine; more preferably, the organic diamine is m-phenylenediamine.

Preferably, the molar ratio of the organic diamine to 4-halogenated phthalic anhydride is 1.00:1.95-2.05, the reaction temperature of the imidization reaction is 130-150°C, and the reaction time is 3-5 hours; the amount of the non-polar organic solvent added in the imidization reaction is 3.0-4.0 times the theoretical mass of the product dihalogenated phthalimide.

Furthermore, the post-reaction treatment of the imidization reaction includes filtering, washing, and drying to obtain the dihalogenated phthalimide product; the filtering method includes but is not limited to pressure filtration, vacuum filtration, centrifugal filtration, preferably vacuum filtration; the washing solvent includes but is not limited to methanol, ethanol, isopropanol, etc., preferably ethanol; the drying method is atmospheric pressure drying or negative pressure drying, preferably atmospheric pressure drying; the drying time is 1 to 10 hours, preferably 4 to 7 hours; the drying temperature is 50 to 150°C, preferably 90 to 110°C.

Furthermore, the non-polar organic solvent is selected from any one or a combination of cyclohexane, n-heptane, petroleum ether, benzene, toluene, o-xylene, p-xylene, mesitylene and mixed xylenes, but is not limited to these.

Preferably, the polar organic solvent is mixed xylene.

Furthermore, the inorganic base is any one or a combination of monobasic alkali metal hydroxides and alkali metal carbonates.

Furthermore, the inorganic base is one or a combination of potassium hydroxide, sodium hydroxide, potassium carbonate, sodium carbonate and cesium carbonate, but is not limited to these.

Preferably, the inorganic base is potassium hydroxide.

Furthermore, a capping agent is added during the nucleophilic substitution reaction etherification condensation process, and the reaction temperature of the nucleophilic substitution reaction etherification condensation is 40-160° C., and the reaction time is 1-10 hours. The addition of the capping agent can make the nucleophilic substitution reaction etherification condensation process more stable.

Preferably, the end-capping agent is chlorobenzene, and the reaction temperature of the nucleophilic substitution reaction etherification condensation is 130-150° C., and the reaction time is 4-6 hours.

Furthermore, the molar ratio of the dihalogenated phthalimide to the dihydric phenol is 1.00:0.80~1.20; the molar ratio of the alkali metal ions in the inorganic base to the phenolic hydroxyl groups in the dihydric phenol is 1.00:1.00~1.10; the molar amount of the copper salt catalyst is 1~10% of the molar amount of the dihalogenated phthalimide; the molar amount of the phenanthroline ligand is 1~20% of the molar amount of the dihalogenated phthalimide; in the nucleophilic substitution reaction etherification condensation reaction, the amount of the non-polar organic solvent is 1.0~8.0 times the theoretical mass of the product polyetherimide.

Preferably, the molar ratio of the dihalogenated phthalimide to the dihydric phenol is 1.00:0.95~1.05; the molar ratio of the alkali metal ions in the inorganic base to the phenolic hydroxyl groups in the dihydric phenol is 1.00:1.00~1.05; the molar amount of the copper salt catalyst is 4~6% of the molar amount of the dihalogenated phthalimide; the molar amount of the phenanthroline ligand is 8~12% of the molar amount of the dihalogenated phthalimide; in the nucleophilic substitution reaction etherification condensation reaction, the amount of the non-polar organic solvent is 4.0~5.0 times the theoretical mass of the product polyetherimide.

Furthermore, the post-reaction treatment process of the nucleophilic substitution reaction etherification condensation includes filtering, crushing, washing, and drying to obtain a powdery finished polyetherimide, and then melt extruding, air cooling, and pelletizing to obtain a granular finished polyetherimide.

The filtering method includes but is not limited to pressure filtration, vacuum filtration, centrifugal filtration, preferably pressure filtration; the washing solvent includes but is not limited to methanol, ethanol, isopropanol, etc., preferably ethanol; the drying method is normal pressure drying or negative pressure drying, preferably normal pressure drying; the drying time is 3 to 15 hours, preferably 8 to 10 hours; the drying temperature is 80 to 200°C, preferably 130 to 150°C.

The beneficial effects of the present invention are:

(1) Compared with the conventional method, the preparation method of polyetherimide of the present invention avoids the problems of complicated steps, large amount of wastewater, high cost and the like involved in the synthesis process of dianhydride. In the method of the present invention, halogenated phthalic anhydride, organic diamine and the like are used as starting materials, and the target product is prepared through two steps of imidization and etherification condensation. Polyetherimide itself is a chemical product with a very large demand for use. The preparation method of the present invention has simple preparation steps and simple post-treatment, reduces wastewater production and reduces production costs. Therefore, the preparation method of the present invention is more conducive to industrial production.

(2) The preparation method of the present invention greatly improves the activity of the etherification condensation reaction by introducing a copper salt catalyst and a phenanthroline ligand during the etherification process, so that the etherification reaction can be completed at a lower temperature (40-160°C, preferably 130-150°C) and a shorter reaction time (1-10 hours, preferably 4-6 hours), thereby reducing production energy consumption, lowering production equipment requirements, and improving production efficiency.

(3) In the traditional preparation method of polyetherimide, it is necessary to use non-protonic polar solvents (such as DMF) or high-boiling point chlorinated solvents (such as o-dichlorobenzene), because the dispersion effect of the reaction raw materials in these solvents is better, which is more conducive to the reaction process. However, these solvents are relatively expensive and have high miscibility with water, resulting in high solvent recovery costs. In the preparation method described in the present invention, by introducing copper salt catalysts and phenanthroline ligands, the reaction process can also be carried out well in non-polar solvents, overcoming the conventional technical prejudice. In addition, the price and cost of non-polar solvents themselves are relatively lower, and non-polar solvents have poor miscibility with water. Good separation can be achieved by stratification, and the solvent is easy to recover and reuse, which is more conducive to industrial production.

(4) The preparation method of the present invention can directly use dihydric phenol and dihalogenated phthalimide to complete the etherification polymerization reaction, eliminating the step of preparing sodium phenol salt, and finally successfully prepares a polyetherimide product with high molecular weight and high glass transition temperature. The material performance evaluation shows that it meets commercial standards. In addition, the method involves conventional unit reactions and equipment, which is suitable for large-scale production.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a ¹ H NMR spectrum of the polyetherimide prepared in Example 1;

FIG2 is a ¹ H NMR spectrum of the chemical shift portion of 6.7-8.3 in FIG1 ;

FIG3 is an IR spectrum of the polyetherimide prepared in Example 1.

DETAILED DESCRIPTION

The specific implementation of the present invention is described in detail below. The present invention can be implemented in many other ways than those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present invention, so the present invention is not limited by the specific embodiments disclosed.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which the present invention belongs. The terms used are only for describing specific embodiments and are not intended to limit the present invention.

A preparation method of polyetherimide, the preparation method comprising: under the protection of inert gas, in the presence of a copper salt catalyst and a phenanthroline ligand, dihalogenated phthalimide, dihydric phenol and an inorganic base are subjected to nucleophilic substitution reaction etherification condensation in a non-polar organic solvent, after the reaction is completed, post-reaction treatment is performed to finally obtain the polyetherimide product;

The preparation principle of the polyetherimide is:

；

;

Wherein, n is an integer between 1 and 300; ^R1 represents a C6-C30 aromatic hydrocarbon group or a C6-C30 aromatic hydrocarbon group substituted by a halogen; ^R2 represents an aromatic C6-C20 monocyclic or polycyclic ring substituted by at least one of 1 to 6 C1-C8 alkyl groups or 1 to 8 halogen atoms; and X represents a halogen.

In the embodiment of the present invention, the copper salt catalyst is selected from any one or a combination of CuCl, CuBr and CuI; the phenanthroline ligand is selected from any one or a combination of the following structural formulas L1-L4:

。

.

In an embodiment of the present invention, the preparation method of the dihalogenated phthalimide is as follows: under the protection of an inert gas, 4-halogenated phthalic anhydride and an organic diamine are subjected to an imidization reaction in a non-polar organic solvent to obtain a dihalogenated phthalimide crude product, and then subjected to post-reaction treatment to obtain a dihalogenated phthalimide product;

The principle of preparing dihalogenated phthalimide by imidization reaction is:

。

.

In the embodiment of the present invention, the molar ratio of the organic diamine to 4-halogenated phthalic anhydride is 1.00:1.80-2.20, the reaction temperature of the imidization reaction is 40-160°C, the reaction time is 1-8 hours, the specific reaction time is determined according to the tracking sampling during the reaction process, the specific measure for the final control of the reaction is sampling every 1 hour, and the high performance liquid chromatography (HPLC) test shows that the content of the target dihalogenated phthalimide is greater than 99.0%, and the content of raw materials and intermediates is less than 0.1%.

The organic diamine is any one of m-phenylenediamine, p-phenylenediamine, 3-methyl-1,4-phenylenediamine, 4,4'-biphenylenediamine, 3,3'-dimethyl-4,4'-biphenylenediamine, 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylmethane or 3,3'-dimethyl-4,4'-diaminodiphenylmethane.

The post-reaction treatment of the imidization reaction includes filtering, washing, and drying to obtain the dihalogenated phthalimide product; the filtering method includes but is not limited to pressure filtration, vacuum filtration, and centrifugal filtration; the washing solvent is selected from methanol, ethanol, isopropanol, etc.; the drying method is atmospheric pressure drying or negative pressure drying; the drying time is 1 to 10 hours; and the drying temperature is 50 to 150°C.

In the embodiment of the present invention, the non-polar organic solvent is selected from any one or a combination of cyclohexane, n-heptane, petroleum ether, benzene, toluene, o-xylene, p-xylene, mesitylene and mixed xylenes;

In the embodiment of the present invention, the inorganic base is any one or a combination of monobasic alkali metal hydroxides and alkali metal carbonates. The inorganic base is one or a combination of potassium hydroxide, sodium hydroxide, potassium carbonate, sodium carbonate and cesium carbonate.

In the embodiment of the present invention, the reaction temperature of the nucleophilic substitution reaction etherification condensation is 40-160° C., and the reaction time is 1-10 hours. The specific reaction time is determined according to the tracking sampling during the reaction process. The final control measure of the reaction is to sample every 1 hour, and test Mw by GPC and Tg by DSC-TGA until it is stable and no longer increases.

In the embodiment of the present invention, chlorobenzene is added as a capping agent during the etherification condensation of the nucleophilic substitution reaction.

In an embodiment of the present invention, in the nucleophilic substitution reaction etherification condensation process, the molar ratio of the dihalogenated phthalimide to the dihydric phenol is 1.00:0.80~1.20; the molar ratio of the alkali metal ion in the inorganic base to the phenolic hydroxyl group in the dihydric phenol is 1.00:1.00~1.10; the molar amount of the copper salt catalyst is 1~10% of the molar amount of the dihalogenated phthalimide; and the molar amount of the phenanthroline ligand is 1~20% of the molar amount of the dihalogenated phthalimide.

The post-reaction treatment process of the nucleophilic substitution reaction etherification condensation comprises filtering, crushing, washing and drying to obtain a powdery finished polyetherimide, and then melt extruding, air cooling and pelletizing to obtain a granular finished polyetherimide.

The filtering method includes but is not limited to pressure filtration, vacuum filtration, and centrifugal filtration; the washing solvent includes but is not limited to methanol, ethanol, isopropanol, etc.; the drying method is normal pressure drying or negative pressure drying; the drying time is 3 to 15 hours, and the drying temperature is 80 to 200°C.

The inert gas includes but is not limited to one or more of nitrogen, helium, neon, argon, etc., preferably nitrogen.

In the embodiment, the comprehensive material performance evaluation method and standard for the finished polyetherimide are as follows:

(1) The weight average molecular weight (Mw) and the polydispersity index (PDI) of the polyetherimide are obtained by gel permeation chromatography (GPC) test, with the Mw range being ≥30,000 Daltons, preferably ≥60,000 Daltons, more preferably ≥90,000 Daltons, and the PDI range being ≤2.00, preferably ≤1.80, more preferably ≤1.60;

(2) The glass transition temperature (Tg) of the polyetherimide is tested using a differential scanning calorimeter (DSC) according to standard ASTM D3418, and the Tg range is ≥100.0°C, preferably ≥200.0°C, and more preferably ≥220.0°C;

(3) The tensile strength, tensile modulus and elongation after break of the polyetherimide are tested using a universal material tester according to standard ASTM D638, with a tensile strength range of ≥70.0 MPa, preferably ≥90.0 MPa, and more preferably ≥110.0 MPa; a tensile modulus range of ≥3000.0 MPa, preferably ≥3200.0 MPa, and more preferably ≥3500.0 MPa; and an elongation after break of ≥1.0%, preferably ≥30.0%, and more preferably ≥60.0%;

(4) The melt flow index of the polyetherimide is tested according to standard ASTM D1238 using a melt flow meter under conditions of a weight of 6.7 kilograms (kg) and a temperature of 337° C. The melt flow index range is 3.0 to 30.0 g/10 min, preferably 5.0 to 25.0 g/10 min, and more preferably 8.0 to 15.0 g/10 min.

The key raw material information involved in the examples is as follows (the remaining raw materials are common commercially available industrial products):

(1) 4-Chlorophthalic anhydride, HPLC＞99%, purchased from Sinopharm Chemical Reagent Co., Ltd., or prepared by known methods (DE2236875C3, DE2257643A1, etc.).

(2) m-phenylenediamine, GC>99.9%, purchased from Henan Alpha Chemical Co., Ltd.

(3) Bisphenol A, GC>99.9%, purchased from Shanghai Haiqu Chemical Co., Ltd.

(4) Cuprous iodide, purity 99.95%, purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.

(5) Phenanthroline ligand L1, HPLC>98%, purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.

(6) Phenanthroline ligand L2, purity >98%, purchased from Hubei Hengjingrui Chemical Co., Ltd.

(7) Phenanthroline ligand L3, purity >98%, purchased from Shaoxing Shunbang Pharmaceutical Technology Co., Ltd.

(8) Phenanthroline ligand L4, purity >98%, purchased from Henan Weitixi Chemical Technology Co., Ltd.

Example 1

Synthesis of 1,3-bis[N-(4-chlorophthalimide)]benzene, wherein the structural formula of the 1,3-bis[N-(4-chlorophthalimide)]benzene is as follows:

；

;

Under nitrogen atmosphere, add mixed xylene (655.85 g Shandong Tongxin Chemical, the same below), 4-chlorophthalic anhydride (182.56g, 1.0mol), after stirring evenly, m-phenylenediamine (54.07g, 0.5mol) was added, and the temperature was raised to reflux of the system. During the process, water droplets were continuously separated from the water separator. The reaction temperature was 135℃-140℃. The reaction process was detected and tracked. After the reaction was completed, the system was cooled to room temperature, and powder solid precipitated. After filtration, the filter cake was rinsed with ethanol (218.62g) and dried to obtain a white powder solid, weighing 203.31g, with a yield of 93.00%, HPLC test purity of 99.83%, test melting point: 325.26℃~326.38℃~328.05℃ (DSC test), and the structure was identified by HPLC-MS (m/z: 436.08, 100%), confirming that the obtained compound was 1,3-di[N-(4-chlorophthalimide)]benzene.

Synthesis of polyetherimide (PEI-1), the structural formula of the polyetherimide (PEI-1) is as follows:

；

;

Under nitrogen atmosphere, mixed xylene (1354.11 g) was added to a three-necked flask, and then 1,3-di[N-(4-chlorophthalimido)]benzene (195.82 g, 0.45 mol), bisphenol A (104.43 g, 0.46 mol), potassium hydroxide (51.18 g, 0.91 mol), cuprous iodide (4.52 g, 0.024 mol), phenanthroline ligand L1 (8.24 g, 0.042 mol), and chlorobenzene (2.06 g, 0.018 mol) were added in sequence. Stirring was started and the temperature was raised to reflux. During the process, water droplets were continuously separated from the water separator. The reaction temperature was 135°C-140°C. The reaction process was monitored. After the reaction is completed, the system is filtered at 90-100°C, and then the system is cooled to room temperature and filtered. The filter cake is added to a tissue grinder and pulverized and washed with ethanol (541.64 g). After completion, it is filtered again. The filter cake is dried to obtain an off-white powder solid, weighing 257.50 g, with a yield of 95.08%. The structure is identified by H-NMR and IR (see Figures 1-2 for H-NMR and Figure 3 for IR), where H-NMR (deuterated chloroform, 500 MHz): 8.03 (arom-O-arom), 7.65 (N-arom-N), 7.60 (arom-O-arom), 7.51 (N-arom-N), 7.48 (arom-C(CH ₃ ) ₂ ), 7.25~7.30 (N-arom-N), 7.13 (arom-O-arom), 1.73 (CH ₃ ), confirming that the obtained compound is polyetherimide, recorded as PEI-1, and then the material properties thereof are tested, and the results are shown in Table 1 .

Example 2

Synthesis of 1,3-bis[N-(4-chlorophthalimido)]benzene:

Under nitrogen atmosphere, petroleum ether (874.48 g, boiling point 60-90 ° C) and 4-chlorophthalic anhydride (164.30 g, 0.9 mol) were added to a three-necked flask. After stirring evenly, m-phenylenediamine (54.07 g, 0.5 mol) was added. The temperature was raised to 40 ° C ~ 45 ° C, and the reaction was continued. The reaction process was monitored and tracked. After the reaction was completed, the system was cooled to room temperature. Powder solid precipitated, filtered, and the filter cake was washed with ethanol (218.6 2g) was washed and dried to obtain a white powder solid, weighing 174.15g, with a yield of 79.66%, a purity of 99.78% as determined by HPLC, and a melting point of 325.26°C~326.32°C~328.04°C (DSC test). The structure was identified by HPLC-MS (m/z: 436.08, 100%), confirming that the obtained compound was 1,3-di[N-(4-chlorophthalimido)]benzene.

Synthesis of polyetherimide (PEI-2):

Under nitrogen atmosphere, petroleum ether (1354.11 g, boiling point 60-90 °C) was added to a three-necked flask, followed by 1,3-di[N-(4-chlorophthalimido)]benzene (195.82 g, 0.45 mol), bisphenol A (82.18 g, 0.36 mol), potassium hydroxide (36.72 g, 0.65 mol), CuCl (4.45 g, 0.045 mol), phenanthroline ligand L2 (21.27 g, 0.0 9mol), chlorobenzene (2.06g), stirring was started and the temperature was raised to 40-45℃ for reaction, the reaction process was detected and tracked, and the reaction was filtered after completion. Then the system was cooled to room temperature and filtered. The filter cake was added to a tissue grinder and pulverized and washed with ethanol (541.64g). After completion, it was filtered again. After drying the filter cake, an off-white powder solid was obtained, weighing 221.03g, with a yield of 81.62%, recorded as PEI-2, and then the material properties were tested. The results are shown in Table 1.

Example 3

Synthesis of 1,3-bis[N-(4-chlorophthalimido)]benzene:

Under nitrogen atmosphere, mesitylene (874.48 g) and 4-chlorophthalic anhydride (200.816 g, 1.1 mol) were added to a three-necked flask. After stirring evenly, m-phenylenediamine (54.07 g, 0.5 mol) was added. The temperature was raised to a system reaction temperature of 155°C-160°C. During the heating reaction, water droplets were continuously separated from the water separator. The reaction was continued at a constant temperature. After completion, the system was cooled to room temperature. Powder solid precipitated and was filtered. The filter cake was washed with ethanol (218 .62g) was eluted and dried to obtain a white powder solid, weighing 210.33g, with a yield of 96.21%, a purity of 99.89% as determined by HPLC, and a melting point of 325.27°C~326.32°C~328.03°C (DSC test). The structure was identified by HPLC-MS (m/z: 436.08, 100%), confirming that the obtained compound was 1,3-di[N-(4-chlorophthalimido)]benzene.

Synthesis of polyetherimide (PEI-3):

Under nitrogen atmosphere, mesitylene (1354.11 g) was added to a three-necked flask, followed by 1,3-di[N-(4-chlorophthalimido)]benzene (195.82 g, 0.45 mol), bisphenol A (123.28 g, 0.54 mol), potassium carbonate (74.63 g, 0.54 mol), CuBr (0.65 g, 0.0045 mol), phenanthroline ligand L3 (1.12 g, 0.0045 mol), and chlorobenzene (2.06 g). Stirring was started and the temperature was raised to 155°C-160°C. During the reaction, water droplets were continuously separated from the water separator. The reaction process was detected and tracked. After the reaction was completed, the system was filtered at 90-100°C, and then the system was cooled to room temperature and filtered. The filter cake was added to a tissue grinder and crushed and washed with ethanol (541.64 g). After completion, it was filtered again. After the filter cake was dried, an off-white powder solid was obtained, weighing 256.63 g, with a yield of 94.76%, recorded as PEI-3, and then the material properties were tested. The results are shown in Table 1.

Example 4

Synthesis of 1,3-bis[N-(4-chlorophthalimido)]benzene:

Under nitrogen atmosphere, cyclohexane (655.85 g) and 4-chlorophthalic anhydride (182.56 g, 1 mol) were added to a three-necked flask. After stirring, m-phenylenediamine (54.07 g, 0.5 mol) was added, and the temperature was raised to a system reaction temperature of 78°C-81°C. The reaction process was detected and tracked. After the reaction was completed, the system was cooled to room temperature, and a powder solid was precipitated. The filter cake was filtered, and the filter cake was rinsed with ethanol (218.62 g) and dried to obtain a white powder solid, weighing 199.99 g, with a yield of 91.48%, a purity of 99.84% tested by HPLC, and a melting point of 325.26°C~326.37°C~328.05°C (DSC test). At the same time, the structure was identified by HPLC-MS (m/z: 436.08, 100%), confirming that the obtained compound was 1,3-di[N-(4-chlorophthalimide)]benzene.

Synthesis of polyetherimide (PEI-4):

Under nitrogen atmosphere, benzene (1354.11 g) was added to a three-necked flask, followed by the 1,3-di[N-(4-chlorophthalimido)]benzene (195.82 g, 0.45 mol) obtained in the previous step, bisphenol A (104.43 g, 0.46 mol), cesium carbonate (149.88 g, 0.46 mol), cuprous iodide (4.52 g, 0.024 mol), phenanthroline ligand L4 (10.09 g, 0.042 mol), chlorobenzene ( 2.06g, 0.018mol), stirring was started and the temperature was raised to 78℃~81℃, the reaction process was monitored and tracked, and the reaction was filtered after completion. Then the system was cooled to room temperature and filtered. The filter cake was added to a tissue grinder and pulverized and washed with ethanol (541.64g). After completion, it was filtered again. After drying, an off-white powder solid was obtained, weighing 237.50g, with a yield of 87.79%, recorded as PEI-4, and then the material properties were tested. The results are shown in Table 1.

Example 5

Synthesis of 1,4-bis[N-(4-chlorophthalimide)]benzene, wherein the structural formula of the 1,4-bis[N-(4-chlorophthalimide)]benzene is as follows:

；

;

Under nitrogen atmosphere, mixed xylene (655.85 g) and 4-chlorophthalic anhydride (182.56, 1 mol) were added to a three-necked flask. After stirring, p-phenylenediamine (54.07 g, 0.5 mol) was added and the temperature was raised to reflux. During the process, water droplets were continuously separated from the water separator. The reaction temperature was 135°C-140°C. The reaction process was tracked by detection. After the reaction was completed, the system was cooled to room temperature. Powder solid precipitated and filtered. The filter cake was rinsed with ethanol (218.62 g) and dried to obtain a white powder solid, weighing 204.81 g, with a yield of 93.69%, and a purity of 99.62% tested by HPLC. The structure was identified by HPLC-MS (m/z: 436.32, 100%), confirming that the obtained compound was 1,4-di[N-(4-chlorophthalimide)]benzene.

Synthesis of polyetherimide (PEI-5), the structural formula of the polyetherimide (PEI-5) is as follows:

；

;

Under nitrogen atmosphere, add mixed xylene (1354.11 g) into a three-necked flask, and then add 1,4-di[N-(4-chlorophthalimido)]benzene (195.82 g, 0.45 mol), bisphenol A (104.43 g, 0.46 mol), potassium hydroxide (51.18 g, 0.91 mol), cuprous iodide (4.52 g, 0.024 mol), phenanthroline ligand L1 (8.24 g, 0.042 mol), and chlorobenzene (2.06 g) obtained in the previous step in sequence, and start stirring. The temperature was raised to the reflux of the system, during which water droplets were continuously separated from the water separator. The reaction temperature in the system was 135°C-140°C. The reaction process was monitored and tracked. After the reaction was completed, the system was filtered at 90-100°C, and then the system was cooled to room temperature and filtered. The filter cake was added to a tissue grinder and crushed and washed with ethanol (541.64 g). After completion, it was filtered again. After drying the filter cake, an off-white powder solid was obtained, weighing 255.19 g, with a yield of 94.23%, recorded as PEI-5, and then the material properties were tested. The results are shown in Table 1.

Example 6

Synthesis of 1,4-bis[N-(4-chlorophthalimido)]benzene:

Under nitrogen atmosphere, mixed xylene (355.85 g), o-xylene (300 g), and 4-chlorophthalic anhydride (182.56, 1 mol) were added to a three-necked flask. After stirring evenly, p-phenylenediamine (54.07 g, 0.5 mol) was added and the temperature was raised to reflux. During the process, water droplets were continuously separated from the water separator. The reaction temperature was 135°C-140°C. The reaction process was detected and tracked. After the reaction was completed, the system was cooled to room temperature, and a powder solid was precipitated. The filter cake was filtered and rinsed with ethanol (218.62 g). After drying, a white powder solid was obtained, weighing 203.36 g, with a yield of 93.02%, and a purity of 99.51% tested by HPLC. The structure was identified by HPLC-MS (m/z: 436.32, 100%), confirming that the obtained compound was 1,4-di[N-(4-chlorophthalimide)]benzene.

Synthesis of polyetherimide (PEI-6):

Under nitrogen atmosphere, mixed xylene (1000 g) and o-xylene (354.11 g) were added to a three-necked flask, and then 1,4-di[N-(4-chlorophthalimido)]benzene (195.82 g, 0.45 mol), bisphenol A (104.43 g, 0.46 mol), potassium hydroxide (51.18 g, 0.91 mol), cuprous iodide (4.52 g, 0.024 mol), phenanthroline ligand L1 (4.36 g, 0.022 mol), phenanthroline ligand L3 (4.98 g, 0.02 mol) were added in sequence. ol), chlorobenzene (2.06g), stirring was started and the temperature was raised to reflux of the system. During the process, water droplets were continuously separated from the water separator. The reaction temperature in the system was 135℃-140℃. The reaction process was detected and tracked. After the reaction was completed, the system was filtered at 90-100℃, and then the system was cooled to room temperature and filtered. The filter cake was added to a tissue grinder and pulverized and washed with ethanol (541.64g). After completion, it was filtered again. After drying the filter cake, an off-white powder solid was obtained, weighing 253.75g, with a yield of 93.7%, recorded as PEI-6, and then the material properties were tested. The results are shown in Table 1.

Example 7

Synthesis of 1,4-bis[N-(4-chlorophthalimido)]benzene:

Under nitrogen atmosphere, mixed xylene (355.85 g), p-xylene (300 g), and 4-chlorophthalic anhydride (182.56, 1 mol) were added to a three-necked flask. After stirring evenly, p-phenylenediamine (54.07 g, 0.5 mol) was added and the temperature was raised to reflux. During the process, water droplets were continuously separated from the water separator. The reaction temperature was 135°C-140°C. The reaction process was detected and tracked. After the reaction was completed, the system was cooled to room temperature, and a powder solid was precipitated. The filter cake was filtered and rinsed with ethanol (218.62 g) and dried to obtain a white powder solid, weighing 203.71 g, with a yield of 93.18%, and a purity of 99.64% tested by HPLC. The structure was identified by HPLC-MS (m/z: 436.32, 100%), confirming that the obtained compound was 1,4-di[N-(4-chlorophthalimide)]benzene.

Synthesis of polyetherimide (PEI-7):

Under nitrogen atmosphere, mixed xylene (1000 g) and p-xylene (354.11 g) were added to a three-necked flask, and then 1,4-di[N-(4-chlorophthalimido)]benzene (195.82 g, 0.45 mol), bisphenol A (104.43 g, 0.46 mol), potassium hydroxide (51.18 g, 0.91 mol), cuprous iodide (2.29 g, 0.012 mol), CuCl (1.19 g, 0.012 mol), phenanthroline ligand L1 (8.24 g, 0.042 mol) were added in sequence. l), chlorobenzene (2.06g), stirring was started and the temperature was raised to the reflux of the system. During the process, water droplets were continuously separated from the water separator. The reaction temperature in the system was 135℃-140℃. The reaction process was detected and tracked. After the reaction was completed, the system was filtered at 90~100℃, and then the system was cooled to room temperature and filtered. The filter cake was added to a tissue grinder and pulverized and washed with ethanol (541.64g). After completion, it was filtered again. After the filter cake was dried, an off-white powder solid was obtained, weighing 252.40g, with a yield of 93.2%, recorded as PEI-7, and then the material properties were tested. The results are shown in Table 1.

Comparative Example 1

Synthesis of 1,3-bis[N-(4-chlorophthalimido)]benzene: Same as Example 1.

Synthesis of polyetherimide (PEI-1*):

The same method as in Example 1 is adopted, except that no phenanthroline ligand is added, and the specific steps are as follows:

Under nitrogen atmosphere, mixed xylene (1354.11 g) was added to a three-necked flask, followed by 1,3-di[N-(4-chlorophthalimido)]benzene (195.82 g, 0.45 mol), bisphenol A (104.43 g, 0.46 mol), potassium hydroxide (51.18 g, 0.91 mol), cuprous iodide (4.52 g, 0.024 mol), and chlorobenzene (2.06 g). Stirring was started and the temperature was raised to reflux. Water droplets are continuously separated from the water separator, the reaction temperature is 135℃-140℃, the reaction process is detected and tracked, and after the reaction is completed, the system is filtered at 90~100℃, and then the system is cooled to room temperature and filtered. The filter cake is added to a tissue grinder and crushed and washed with ethanol (541.64g). After completion, it is filtered again. After the filter cake is dried, a white powder solid is obtained, weighing 256.63g, with a yield of 94.76%, recorded as PEI-1*, and then the material properties are tested. The results are shown in Table 1.

Comparative Example 2

Synthesis of 1,3-bis[N-(4-chlorophthalimido)]benzene: Same as Example 1

Synthesis of polyetherimide (PEI-1**):

The same method as in Example 1 is adopted, except that no phenanthroline ligand and copper salt catalyst are added, and the specific steps are as follows:

Under nitrogen atmosphere, mixed xylene (1354.11 g) was added to a three-necked flask, and then 1,3-di[N-(4-chlorophthalimide)]benzene (195.82 g, 0.45 mol), bisphenol A (104.43 g, 0.46 mol), potassium hydroxide (51.18 g, 0.91 mol), and chlorobenzene (2.06 g) were added in sequence. Stirring was started and the temperature was raised to reflux of the system. During the process, water droplets were continuously separated from the water separator. The reaction temperature was 135°C-140°C. The reaction process was detected and tracked. After the reaction was completed, the system was filtered at 90-100°C, and then the system was cooled to room temperature and filtered. The filter cake was added to a tissue grinder and pulverized and washed with ethanol (541.64 g). After completion, it was filtered again. After drying, the filter cake was obtained to obtain an off-white powder solid, weighing 208.15 g, with a yield of 76.86%, recorded as PEI-1**, and then the material properties were tested. The results are shown in Table 1.

Comparative Example 3

Synthesis of 1,3-bis[N-(4-chlorophthalimido)]benzene: Same as Example 1

Synthesis of polyetherimide (PEI-1***):

The same method as in Example 1 was used, except that the mixed xylene was replaced with dimethyl sulfoxide and the reaction temperature was 188°C-190°C.

The yield was 92.1%, recorded as PEI-1***, and then the material properties were tested. The results are shown in Table 1.

Comparative Example 4

Preparation of polyetherimide using polar solvent dimethyl sulfoxide:

Synthesis of 1,3-bis[N-(4-chlorophthalimido)]benzene:

A 2000ml three-necked flask was equipped with a mechanical stirrer, a 0-300℃ thermometer, a nitrogen conduit, a water separator and a reflux condenser. After nitrogen replacement for 15 minutes, dimethyl sulfoxide (DMSO) (655.85g) and 4-chlorophthalic anhydride (182.56g) were added to the system. The system was stirred at an internal temperature of 60℃ for 30 minutes until the system was evenly dispersed and in a grayish white turbid state. Metaphenylenediamine (54.07g) was added. After completion, the temperature was raised to an internal temperature of 140-145℃. The system gradually changed from colorless and transparent to light yellow and transparent. The reaction was continued at this temperature for 4 hours. After completion, the system was cooled to Methanol (655.85 g) was added at room temperature with stirring, and a large amount of solid was gradually precipitated. After the addition was complete, it was filtered, and the filter cake was rinsed with ethanol (218.62 g) and dried to obtain a white powder solid weighing 189.67 g, with a yield of 86.76%. The purity tested by HPLC was 99.70%, and the tested melting point was 326.16°C~327.44°C~328.82°C (DSC test). The structure was identified by HPLC-MS (m/z: 436.08, 100%), confirming that the obtained compound was 1,3-di[N-(4-chlorophthalimido)]benzene.

Synthesis of polyetherimide (PEI-1****):

A 2000ml three-necked flask was equipped with a mechanical stirrer, a 0-300℃ thermometer, a nitrogen conduit and a reflux condenser. After nitrogen replacement for 15 minutes, water (74.67g), bisphenol A (91.32g) and sodium hydroxide (32.00g) were added to the system under stirring. After stirring, dimethyl sulfoxide (547.92g) and benzene (273.96g) were added. After completion, the temperature was raised to reflux. The reaction temperature was 80-85℃ and kept warm for 6 hours. During this period, the water generated by the reaction was separated and most of the benzene was finally evaporated. The residue became a white solid-liquid mixture. It was cooled to 30-40℃ and the 1,3-di[ N-(4-chlorophthalimide)]benzene (171.39 g), chlorobenzene (1.80 g), after completion, the system continued to keep the reaction at an internal temperature of 188-190 ° C for 5 hours, after completion, the system was cooled to room temperature, methanol (1500 ml) was added under stirring, and a large amount of off-white powder solid was gradually precipitated. After filtration, the filter cake was washed once with water (547.92 g) and three times with methanol (1500 ml each time). After washing, the solid obtained was dried to obtain an off-white powder solid, weighing 224.53 g, with a yield of 94.72%, recorded as PEI-1****, and then the material properties were tested. The results are shown in Table 1.

Comparative Example 5

Synthesis of 1,4-bis[N-(4-chlorophthalimido)]benzene: Same as Example 5

Synthesis of polyetherimide (PEI-5*):

The same method as in Example 5 is adopted, except that no phenanthroline ligand is added, and the specific steps are as follows:

Under nitrogen atmosphere, mixed xylene (1354.11 g) was added to a three-necked flask, followed by 1,4-di[N-(4-chlorophthalimido)]benzene (195.82, 0.45 mol), bisphenol A (104.43 g, 0.46 mol), potassium hydroxide (51.18 g, 0.91 mol), cuprous iodide (4.52 g, 0.024 mol), and chlorobenzene (2.06 g). Stirring was started and the temperature was raised to reflux. Water droplets are continuously separated from the water separator, the reaction temperature is 135℃-140℃, the reaction process is detected and tracked, and after the reaction is completed, the system is filtered at 90~100℃, and then the system is cooled to room temperature and filtered. The filter cake is added to a tissue grinder and crushed and washed with ethanol (541.64g). After completion, it is filtered again. After the filter cake is dried, a white powder solid is obtained, weighing 254.35g, with a yield of 93.92%, recorded as PEI-5*, and then the material properties are tested. The results are shown in Table 1.

Comparative Example 6

Synthesis of 1,4-bis[N-(4-chlorophthalimido)]benzene: Same as Example 5

Synthesis of polyetherimide (PEI-5**):

The same method as in Example 5 is adopted, except that no phenanthroline ligand and copper salt catalyst are added, and the specific steps are as follows:

Under nitrogen atmosphere, mixed xylene (1354.11 g) was added to a three-necked flask, and then 1,4-di[N-(4-chlorophthalimide)]benzene (195.82 g, 0.45 mol), bisphenol A (104.43 g, 0.46 mol), potassium hydroxide (51.18 g, 0.91 mol), and chlorobenzene (2.06 g) were added in sequence. Stirring was started and the temperature was raised to reflux of the system. During the process, water droplets were continuously separated from the water separator. The reaction temperature was 135°C-140°C. The reaction process was detected and tracked. After the reaction was completed, the system was filtered at 90-100°C, and then the system was cooled to room temperature and filtered. The filter cake was added to a tissue grinder and pulverized and washed with ethanol (541.64 g). After completion, it was filtered again. After drying, the filter cake was obtained to obtain an off-white powder solid, weighing 199.40 g, with a yield of 73.63%, recorded as PEI-5**, and then the material properties were tested. The results are shown in Table 1.

Comparative Example 7

Synthesis of 1,4-bis[N-(4-chlorophthalimido)]benzene: Same as Example 5

Synthesis of polyetherimide (PEI-5***):

The same method as in Example 5 was used, except that the mixed xylene was replaced with dimethyl sulfoxide and the reaction temperature was 188°C-190°C.

The yield was 91.2%, recorded as PEI-5***, and then the material properties were tested. The results are shown in Table 1.

Comparative Example 8

Preparation of polyetherimide using polar solvent dimethyl sulfoxide:

Synthesis of 1,4-bis[N-(4-chlorophthalimido)]benzene:

A 2000ml three-necked flask was equipped with a mechanical stirrer, a 0-300℃ thermometer, a nitrogen conduit, a water separator and a reflux condenser. After nitrogen replacement for 15 minutes, dimethyl sulfoxide (655.85g) and 4-chlorophthalic anhydride (182.56g) were added to the system. The system was stirred at an internal temperature of 60℃ for 30 minutes until the system was evenly dispersed and in a grayish white turbid state. p-phenylenediamine (54.07g) was added. After completion, the temperature was raised to an internal temperature of 140-145℃. The system gradually changed from colorless and transparent to light yellow and transparent. The system was kept at this temperature. The reaction was carried out at room temperature for 4 hours. After completion, the system was cooled to room temperature, and methanol (655.85 g) was added under stirring. A large amount of solid was gradually precipitated. After the addition was completed, it was filtered, and the filter cake was rinsed with ethanol (218.62 g) and dried to obtain a white powder solid, weighing 195.14 g, with a yield of 89.26%. The purity tested by HPLC was 99.50%. The structure was identified by HPLC-MS (m/z: 436.32, 100%), confirming that the obtained compound was 1,4-di[N-(4-chlorophthalimido)]benzene.

Synthesis of polyetherimide (PEI-5****)

A 2000ml three-necked flask was equipped with a mechanical stirrer, a 0-300℃ thermometer, a nitrogen conduit and a reflux condenser. After nitrogen replacement for 15 minutes, water (74.67g), bisphenol A (91.32g, 0.400mol), and sodium hydroxide (32.00g, 0.800mol) were added to the system under stirring. After stirring, dimethyl sulfoxide (547.92g) and benzene (273.96g) were added. After completion, the temperature was raised to reflux and kept warm for 6 hours. During this period, the water generated by the reaction was separated and most of the benzene was finally evaporated. The residue became a white solid-liquid mixture, which was cooled to 30-40℃ and the 1,4-di[N-(4-chlorophthalic acid)] obtained in the previous step was added in sequence. The system was heated to room temperature for 5 hours, and methanol (1500 ml) was added under stirring to gradually precipitate a large amount of off-white powder solid. After filtration, the filter cake was washed once with water (547.92 g) and three times with methanol (1500 ml each time). After washing, the solid was dried to obtain an off-white powder solid, weighing 225.62 g, with a yield of 95.18%. The obtained compound was confirmed to be polyetherimide, recorded as PEI-5****, and then the material properties were tested. The results are shown in Table 1.

Table 1 Comparison of polyetherimide material performance test data

As can be seen from Table 1 above, the polyetherimide materials PEI-1~PEI-7 prepared by the preparation method of the present invention in Examples 1-7 have high molecular weight and high glass transition temperature, and have good mechanical properties. At the same time, the material has ideal processing performance (melt flow index 8.0~15.0g/10min). The preparation method of the present invention greatly improves the activity of the etherification condensation reaction by introducing a copper salt catalyst and a phenanthroline ligand during the etherification condensation reaction, and obtains a high-quality polyetherimide material that meets commercial standards. In addition, the etherification reaction in the preparation method of the present invention can be completely carried out under lower temperature conditions and shorter reaction time, and a more inexpensive and easily recyclable non-polar organic solvent can be used during the reaction.

By comparing the data of PEI-1 and PEI-1*, and the data of PEI-5 and PEI-5*, it can be seen that if phenanthroline ligands are not added during the etherification condensation reaction, the molecular weight, glass transition temperature, mechanical properties and processing properties of the obtained polyetherimide material are relatively poor. This is because the synergistic effect of phenanthroline ligands and copper salt catalysts can help improve the activity of the etherification condensation reaction and enhance the quality of polyetherimide products.

By comparing the data of PEI-1 and PEI-1** and the data of PEI-5 and PEI-5**, it can be seen that if phenanthroline ligands and copper salt catalysts are not added during the etherification condensation reaction, the molecular weight, glass transition temperature, mechanical properties and processing properties of the obtained polyetherimide material will be worse. This shows that if phenanthroline ligands and copper salt catalysts are not added, the etherification condensation reaction is incomplete. Phenanthroline ligands and copper salt catalysts can greatly improve the activity of the etherification condensation reaction and obtain high-quality polyetherimide products.

By comparing the performance data of PEI-1 with PEI-1***, PEI-1**** and PEI-5 with PEI-5***, PEI-5****, it can be seen that if conventional non-protonic polar solvents are used in the preparation process of polyetherimide and the reaction temperature is increased, the molecular weight, glass transition temperature and mechanical properties of the obtained polyetherimide product are all reduced, because increasing the reaction temperature will cause a more violent reaction, some cracking reactions will occur, and ultimately the quality of the polyetherimide product will be reduced. In addition, polar solvents have high miscibility with water, which makes it difficult to recover the solvent. In the preparation method of the present invention, the non-polar solvent used is separated from the water layer, which is more conducive to the recovery of the solvent. The preparation method of the present invention greatly improves the activity of the etherification condensation reaction by introducing a copper salt catalyst and a phenanthroline ligand, and broadens the range of solvent selection in the reaction process.

The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are exhaustively listed. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

For those skilled in the art, several modifications and improvements may be made without departing from the concept of the present invention, all of which belong to the protection scope of the present invention. The protection scope of the present invention shall be based on the attached claims.

Claims (10)

1. The preparation method of the polyetherimide is characterized by comprising the following steps: carrying out nucleophilic substitution reaction etherification condensation on dihalo phthalimide, dihydric phenol and inorganic base in a non-polar organic solvent in the presence of a copper salt catalyst and a phenanthroline ligand under the protection of inert gas, and after the reaction is finished, carrying out reaction post-treatment to finally obtain the polyetherimide product;

the structural formula of the bihalophthalimide is as follows:

；

the structural formula of the dihydric phenol is as follows:

；

the structural formula of the polyetherimide is as follows:

；

wherein n is an integer between 1 and 300; r ¹ An aromatic hydrocarbon group representing C6-C30; r ² Represents an aromatic C6-C2 group substituted with at least one of 1 to 6C 1-C8 alkyl groups or 1 to 8 halogen atoms0 is monocyclic or polycyclic; x represents halogen.

2. The method for preparing the polyetherimide according to claim 1, wherein n is an integer from 140 to 160, X represents Cl, and R is ¹ Is a benzene ring, R ² Is composed of

。

3. The method of claim 1, wherein the polyetherimide is represented by any one of the following structural formulas:

；

。

4. the preparation method of the polyetherimide according to claim 1, wherein the copper salt catalyst is selected from any one or a combination of CuCl, cuBr and CuI; the phenanthroline ligand is selected from any one or a combination of more of the following structural formulas L1-L4:

；

；

；

。

5. the method of claim 1, wherein the bis-halophthalimide is prepared by: under the protection of inert gas, 4-halogenated phthalic anhydride and organic diamine are subjected to imidization reaction in a non-polar organic solvent to prepare a crude product of the dihalogenated phthalimide, and then the crude product of the dihalogenated phthalimide is obtained after the reaction and the treatment;

the structural formula of the 4-halogenated phthalic anhydride is as follows:

；

the structural formula of the organic diamine is as follows:

；

the molar ratio of the organic diamine to the 4-halogenated phthalic anhydride is 1.00:1.80 to 2.20, wherein the reaction temperature of the imidization reaction is 40 to 160 ℃.

6. The method of claim 5, wherein the organic diamine is any one of m-phenylenediamine, p-phenylenediamine, 3-methyl-1, 4-phenylenediamine, 4' -biphenyldiamine, 3' -dimethyl-4, 4' -biphenyldiamine, 4' -diaminodiphenyl ether, 4' -diaminodiphenylmethane, or 3,3' -dimethyl-4, 4' -diaminodiphenylmethane;

the molar ratio of the organic diamine to the 4-halogenated phthalic anhydride is 1.00:1.95 to 2.05, wherein the reaction temperature of the imidization reaction is 130 to 150 ℃.

7. The method according to any one of claims 1 to 6, wherein the non-polar organic solvent is selected from any one or a combination of cyclohexane, n-heptane, petroleum ether, benzene, toluene, o-xylene, p-xylene, mesitylene, and mixed xylenes;

the inorganic base is any one or combination of more of monobasic alkali metal hydroxide and alkali metal carbonate.

8. The method of claim 7, wherein the inorganic base is one or more selected from the group consisting of potassium hydroxide, sodium hydroxide, potassium carbonate, sodium carbonate, and cesium carbonate.

9. The method for preparing the polyetherimide according to claim 1, wherein an end-capping agent is added during the nucleophilic substitution etherification condensation, and the reaction temperature of the nucleophilic substitution etherification condensation is 40 to 160 ℃.

10. The method for preparing the polyetherimide according to claim 1, wherein in the nucleophilic substitution etherification condensation process, the molar ratio of the bis-halophthalimide to the dihydric phenol is 1.00:0.80 to 1.20; the molar ratio of alkali metal ions in the inorganic base to phenolic hydroxyl groups in the dihydric phenol is 1.00:1.00 to 1.10; the molar usage of the copper salt catalyst is 1 to 10 percent of the molar usage of the bi-halophthalimide; the molar amount of the phenanthroline ligand is 1-20% of the molar amount of the dihalogen phthalimide, and the reaction temperature of the nucleophilic substitution reaction etherification condensation is 130-150 ℃.

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