A process for the catalytic alternating copolymerization of an epoxide with a cyclic anhydride

Abstract

The application discloses a method for catalyzing the alternating copolymerization reaction of an epoxide and a cyclic anhydride, and utilizes a composite zinc dicarboxylate catalyst to catalyze the alternating copolymerization reaction of the epoxide and the cyclic anhydride, wherein the catalyst comprises the following components in a molar ratio: a) a zinc compound; and b) a metal hydride compound, wherein the molar ratio of the zinc compound to the metal hydride compound is 1:0.1-12. The zinc compound is a Zn-R(COO)2 general formula compound, wherein R is a C1-C8 hydrocarbon group; and the metal hydride compound is XH Y A general formula compound, wherein X is Li, Na, Mg, K, Ca, Be, Sr, Ba, Ra, Fr, Rb or Cs, and Y is 1, 2 or 3. The composite catalyst prepared by the method has the characteristics of high catalytic activity and low polyether content when applied to catalyze the alternating copolymerization reaction of an epoxide and a cyclic anhydride.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of catalytic preparation of polyester materials, and relates to a method for catalyzing the alternating copolymerization of epoxide and cyclic anhydride. BACKGROUND

[0002] Traditional polyester materials are mainly divided into semi-aromatic polyesters and aliphatic polyesters. Semi-aromatic polyesters such as polyester like terylene have excellent mechanical properties, barrier properties and other properties, and are widely used in the fields of fibers, packaging materials and liquid crystal materials. The monomers used to synthesize aliphatic polyesters are derived from a large number of renewable resources, and aliphatic polyesters are also an excellent degradable material, so they are highly concerned and can replace traditional petroleum-based polymers. There are mainly two methods for synthesizing polyesters, one is step polymerization represented by diols and diacids or diesters, and the other is chain polymerization including alternating polymerization of epoxide and cyclic anhydride. Since step polymerization has the problem of small molecule by-products, high temperature and low pressure are often required to remove small molecule by-products during polymerization to improve the reaction degree, so this method has the problems of high energy consumption and difficult control of polymer molecular weight and its distribution. Chain polymerization can use the selectivity of catalysts to control the structure and molecular weight and its distribution of polymers. Nowadays, the alternating copolymerization of epoxide and cyclic anhydride is a new way to prepare new polyesters, and the range of monomers involved is very wide, including a large number of renewable monomers. Among them, bio-based epoxide includes limonene epoxide, furfuryl epoxide and epoxide from plant oil, which can be obtained from plant oil, and non-food plant resources such as corn cob or straw. At the same time, through post-polymerization modification, these polyesters are functionalized to become new materials with different functions.

[0003] At present, a variety of metal complexes have been used to catalyze the alternating copolymerization of epoxide and cyclic anhydride, including zinc, magnesium, iron, chromium, manganese, aluminum, nickel and cobalt complexes. Meng et al. (RSC Advances, 2014, 4, 9503) synthesized the alternating copolymer of propylene oxide and phthalic anhydride using zinc glutarate as catalyst, and the yield of polymerization reached 18.1 g polymer / g catalyst (about equivalent to 9.65 g polymer / g catalyst / 8 hours), and the polyether content was 51%. The zinc dicarboxylate catalyst prepared by this method has low preparation cost, but has the problems of low catalytic activity and poor selectivity.

[0004] The present application found that by mixing zinc dicarboxylate catalyst with metal hydride compound at a certain molar ratio and grinding, a composite catalyst was prepared, which was applied to the alternating copolymerization of epoxide and cyclic anhydride, and the catalytic activity and selectivity could be significantly improved, and the polyether content could be reduced. SUMMARY

[0005] The application aims to provide a preparation method of a complex zinc dicarboxylate catalyst, which is applied to catalyze the alternating copolymerization reaction of epoxide and cyclic anhydride, and has the characteristics of high catalytic activity and low polyether content.

[0006] The technical scheme of the application is:

[0007] The application relates to a method for catalyzing the alternating copolymerization reaction of epoxide and cyclic anhydride, which is specifically a method for catalyzing the alternating copolymerization reaction of epoxide and cyclic anhydride by using a complex zinc dicarboxylate catalyst. and cyclic anhydride wherein n is 1, 2 or 3; R1 and R2 are substituents of the epoxide; R3 and R4 are substituents of the anhydride; the complex zinc dicarboxylate catalyst comprises a main catalyst and a cocatalyst, the main catalyst is a zinc compound with Zn-R(COO)2 as the main body, and the cocatalyst is a metal hydride compound XH Y wherein R is a C1-C8 hydrocarbon group, X is Li, Na, Mg, K, Ca, Be, Sr, Ba, Ra, Fr, Rb or Cs, and Y is 1, 2 or 3.

[0008] Further, R1 and R2 are H, CH2Cl, CH2OBn, methyl, a benzene ring, cyclohexene, cyclopentene, naphthalene or a cyclohexyl group, and R1 and R2 are the same or different; R3 and R4 are H, =CH2, a benzene ring, cyclohexene or a norbornene ring, and R3 and R4 are the same or different.

[0009] Further, the epoxide is propylene oxide, ethylene oxide, cyclohexene oxide, butylene oxide, chloropropylene oxide, phenyl glycidyl ether, allyl glycidyl ether, 2-(oxiranylmethoxy)tetrahydro-2H-pyran, tetrahydrofuran or oxystyrene; and the cyclic anhydride is succinic anhydride, phthalic anhydride, cyclopentane-1,2-dicarboxylic anhydride, cyclopropane-1,2-dicarboxylic anhydride, itaconic anhydride, citraconic anhydride, maleic anhydride or norbornene diacid anhydride.

[0010] Further, the preparation method of the complex zinc dicarboxylate catalyst comprises the following steps: first, the zinc compound and the metal hydride compound are mixed according to the molar ratio, and then the mixture is ground and crushed by a planetary ball mill at a high speed for 5-40 hours under an inert atmosphere, and the grinding speed is 100-400 revolutions per minute, so that the complex catalyst is prepared.

[0011] Further, the molar ratio of the zinc compound to the metal hydride compound is 1:0.1-12.

[0012] Further, the copolymerization reaction temperature is 20-120 DEG C, and the reaction time is 2-100 hours.

[0013] Further, the preparation method of the zinc compound comprises the following steps:

[0014] The dicarboxylic acid and zinc source are mixed in a molar ratio of 100:20-100, and then an appropriate amount of reaction medium (such as dibutyl ether, toluene, tetrahydrofuran and ethanol, etc.) is added, and the mixture is stirred vigorously at 0-80°C for 1-24h. Then, the mixture is subjected to rotary evaporation, washing, filtration and drying in sequence, and finally a white powdery product is obtained. The zinc source is one or more of zinc oxide, zinc acetate, zinc nitrate, zinc hydroxide, zinc stearate and dialkyl zinc, and the acid source is a dicarboxylic acid R(COOH)2, wherein R is a C1-C8 hydrocarbon group;

[0015] The preferred preparation method is as follows: a dialkyl zinc solution is added to a dicarboxylic acid solution, and the reaction is carried out under a specific temperature rising procedure, a crude zinc dicarboxylate catalyst is synthesized by a precipitation method, and finally the zinc dicarboxylate catalyst is obtained by washing, filtering and drying, and the purity of the zinc dicarboxylate catalyst is ≥99%; the specific temperature rising procedure refers to that the dialkyl zinc solution and the dicarboxylic acid solution are prepared at low temperature, and after mixing, the initial temperature is -5-10°C, and the temperature is raised to room temperature at a temperature rising rate of 0.1-1°C / min.

[0016] Further, the dialkyl zinc is (C x H 2x+1 )2Zn; the good solvent for the reaction system of the dialkyl zinc and the dicarboxylic acid R(COOH)2 is one or a mixture of two or more of C x H 2x+1 OH, C x H 2x+2 , C x H 2x+1 COC x H 2x+1 , C x H 2x+1 OC x H 2x+1 and C x H 2x O y , wherein R is a C1-C8 hydrocarbon group, x≥1 and y≥1; the dicarboxylic acid is one of succinic acid, glutaric acid, adipic acid, pimelic acid or suberic acid.

[0017] Further, the molar ratio of the dialkyl zinc to the dicarboxylic acid is 20:20-22; the mass concentration of the dialkyl zinc solution is 10%-20%; the mass concentration of the dicarboxylic acid solution is 5%-15%; the reaction time under the specific temperature rising procedure is 1-12h, and mechanical stirring is carried out at a rotation speed of 0-3000rpm during the reaction.

[0018] Further, the XRD spectrum of the prepared zinc compound has diffraction peaks at 2θ angles of 12.90±0.5, 22.80±0.4 and 23.10±0.4, the full width at half maximum is higher than 0.4 and the crystallinity is 40-70%, the specific surface area of the zinc dicarboxylate catalyst is 30-100 m 2 / g.

[0019] Further, the alternating copolymerization of the epoxide and the cyclic anhydride: the complex catalyst is dissolved in a solvent, then the epoxide and the cyclic anhydride are added respectively, and the reaction temperature and the reaction time are set. After the reaction, the solvent is removed by rotary evaporation, the viscous product is taken out, dichloromethane is added to stir and dissolve, 5% hydrochloric acid is added to remove the residual zinc compound catalyst, the anhydride and the metal hydride, then methanol is added for washing, and finally the alternating copolymerization product is obtained after drying. The molar ratio of the zinc compound, the epoxide and the cyclic anhydride is 1:100-600:1-100. The beneficial effects of the present application are:

[0020] The complex catalyst prepared by the method has the characteristics of high catalytic activity and low polyether content when applied to the alternating copolymerization of the epoxide and the cyclic anhydride. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 The H NMR spectrum of the copolymer prepared for Comparative Example 1 1 H NMR spectrum;

[0022] Figure 2 The H NMR spectrum of the copolymer prepared for Example 1 1 H NMR spectrum;

[0023] Figure 3 The H NMR spectrum of the copolymer prepared for Example 2 1 H NMR spectrum;

[0024] Figure 4 The H NMR spectrum of the copolymer prepared for Example 3 1 H NMR spectrum;

[0025] Figure 5 The yield and the columnar analysis of the H NMR spectrum of the copolymer prepared for Comparative Example 1, Example 1, Example 2 and Example 3 1 H NMR spectrum; DETAILED DESCRIPTION

[0026] The present application will be described in detail below with reference to the examples.

[0027] Example 1:

[0028] Take 20 mmol glutaric acid to configure into a mass concentration of about 15% tetrahydrofuran solution, then add 100 ml round bottom flask, the speed is set to 1000 rpm, slowly add the mass concentration of 20% n-hexane solution dissolved with 20 mmol diethyl zinc at 0 ℃ nitrogen environment, after adding, by 0 ℃ to room temperature at the heating rate of 0.2 ℃ / min, reaction 6 hours. After the reaction, the unreacted diethyl zinc and glutaric acid are removed with n-hexane and tetrahydrofuran respectively, and the zinc glutarate catalyst is obtained after drying. Under the nitrogen atmosphere, the zinc glutarate is premixed with sodium hydride at a molar ratio of 1:0.5, and then ground by a planetary ball mill for 30 h at a speed of 300 rpm to prepare a composite catalyst. Add the corresponding composite catalyst (the main catalyst is 0.92 mmol) into a 100 ml round bottom flask, then add appropriate amount of toluene, and then add propylene oxide and phthalic anhydride into the bottle (the molar ratio of zinc glutarate, propylene oxide and phthalic anhydride is 1:311:39), set the reaction temperature to 75 ℃, and react for 8 hours. After the reaction, the solvent is removed by rotary evaporation, the viscous product is taken out from the reaction bottle, dichloromethane is added to stir and dissolve, 5% hydrochloric acid is added to remove the residual catalyst, acid anhydride and metal hydride, then methanol is added for washing, and finally the copolymer is obtained after drying. Figure 2 The copolymer prepared in Example 1 is 1 H NMR spectrum.

[0029] Example 2:

[0030] Take 20 mmol glutaric acid to configure into a mass concentration of about 15% tetrahydrofuran solution, then add 100 ml round bottom flask, the speed is set to 1000 rpm, slowly add the mass concentration of 20% n-hexane solution dissolved with 20 mmol diethyl zinc at 0 ℃ nitrogen environment, after adding, by 0 ℃ to room temperature at the heating rate of 0.2 ℃ / min, reaction 6 hours. After the reaction, the unreacted diethyl zinc and glutaric acid are removed with n-hexane and tetrahydrofuran respectively, and the zinc glutarate catalyst is obtained after drying. Under the nitrogen atmosphere, the zinc glutarate is premixed with sodium hydride at a molar ratio of 1:0.5, and then ground by a planetary ball mill for 30 h at a speed of 300 rpm to prepare a composite catalyst. Add the corresponding composite catalyst (the main catalyst is 0.92 mmol) into a 100 ml round bottom flask, then add appropriate amount of toluene, and then add propylene oxide and phthalic anhydride into the bottle (the molar ratio of zinc glutarate, propylene oxide and phthalic anhydride is 1:311:39), set the reaction temperature to 75 ℃, and react for 8 hours. After the reaction, the solvent is removed by rotary evaporation, the viscous product is taken out from the reaction bottle, dichloromethane is added to stir and dissolve, 5% hydrochloric acid is added to remove the residual catalyst, acid anhydride and metal hydride, then methanol is added for washing, and finally the copolymer is obtained after drying. Figure 3H NMR spectrum of the copolymer prepared in Example 2. 1 H NMR spectrum of the copolymer prepared in Example 2.

[0031] Example 3:

[0032] Take 20 mmol glutaric acid to prepare a tetrahydrofuran solution with a mass concentration of about 15%, then add it into a 100 ml round bottom flask, set the rotation speed to 1000 rpm, slowly add a 20% mass concentration n-hexane solution containing 20 mmol diethyl zinc under a nitrogen atmosphere at 0°C, after adding, heat it from 0°C to room temperature at a rate of 0.2°C / min, and react for 6 hours. After the reaction is completed, remove the unreacted diethyl zinc and glutaric acid with n-hexane and tetrahydrofuran respectively, and dry to obtain a zinc glutarate catalyst. Under a nitrogen atmosphere, premix the zinc glutarate and sodium hydride at a molar ratio of 1:6, then use a planetary ball mill to grind for 30 hours at a rotation speed of 300 rpm, and a composite catalyst is prepared. Add the corresponding composite catalyst (the main catalyst is 0.92 mmol) into a 100 ml round bottom flask, then add an appropriate amount of toluene, and then add propylene oxide and phthalic anhydride into the flask (the molar ratio of zinc glutarate, propylene oxide and phthalic anhydride is 1:311:39), set the reaction temperature to 75°C, and react for 8 hours. After the reaction is completed, remove the solvent by rotary evaporation, take out the viscous product from the reaction flask, add dichloromethane to stir and dissolve it, add 5% hydrochloric acid to remove the residual catalyst, acid anhydride and metal hydride, then add methanol for washing, and finally dry to obtain the copolymer. Figure 4 H NMR spectrum of the copolymer prepared in Example 2. 1 H NMR spectrum of the copolymer prepared in Example 2.

[0033] Example 3:

[0034] Take 20 mmol adipic acid to configure into a mass concentration of about 5% tetrahydrofuran solution, then add 100 ml round bottom flask, the speed is set to 1000 rpm, slowly add the mass concentration of 10% n-hexane solution dissolved with 20 mmol diisopropyl zinc under the condition of 10 ℃ nitrogen environment, after adding, from 10 ℃ to room temperature by the heating rate 0.9 ℃ / min, reaction 1 hour. After the reaction is completed, the unreacted diisopropyl zinc and adipic acid are removed with n-hexane and tetrahydrofuran respectively, and the zinc adipate catalyst is obtained after drying. Under the environment of nitrogen atmosphere, the zinc adipate and potassium hydride are premixed according to the molar ratio of 1:10, and then ground by a planetary ball mill for 5 h, and the rotation speed of the ball mill is 100 r / min. The composite catalyst is prepared. In a 100 ml round bottom flask, add the corresponding composite catalyst (the main catalyst is 0.86 mmol), then add appropriate amount of toluene, then add propylene oxide and maleic anhydride into the bottle (the molar ratio of zinc adipate, propylene oxide and maleic anhydride is 1:333:42), and set the reaction temperature to 75 ℃. The reaction is carried out for 8 hours. After the reaction is completed, the solvent is removed by rotary evaporation, the viscous product is taken out from the reaction bottle, dichloromethane is added to stir and dissolve, 5% hydrochloric acid is added to remove the residual catalyst, anhydride and metal hydride, then methanol is added for washing, and finally the copolymer is obtained after drying.

[0035] Example 5:

[0036] Take 100 mmol of zinc oxide (99.9%), 100 mmol of glutaric acid (99.0%), and 250 ml of toluene, and add them into a 500 ml three-necked flask. Stir vigorously at 55 ℃ for 24 h. After the reaction is completed, remove the toluene by rotary evaporation, and wash with acetone several times. Dry finally to obtain the zinc glutarate catalyst. Under the environment of nitrogen atmosphere, the zinc glutarate and calcium hydride are premixed according to the molar ratio of 1:4, and then ground by a planetary ball mill for 30 h, and the rotation speed of the ball mill is 300 r / min. The composite catalyst is prepared. In a 100 ml round bottom flask, add the corresponding composite catalyst (the main catalyst is 0.92 mmol), then add appropriate amount of toluene, then add ethylene oxide and phthalic anhydride into the bottle (the molar ratio of zinc glutarate, ethylene oxide and phthalic anhydride is 1:435:54), and set the reaction temperature to 50 ℃. The reaction is carried out for 8 hours. After the reaction is completed, the solvent is removed by rotary evaporation, the viscous product is taken out from the reaction bottle, dichloromethane is added to stir and dissolve, 5% hydrochloric acid is added to remove the residual catalyst, anhydride and metal hydride, then methanol is added for washing, and finally the copolymer is obtained after drying.

[0037] Example 6:

[0038] Take zinc oxide (99.9%) 100 mmol, adipic acid (99.0%) 100 mmol, toluene 250 ml, add 500 ml three-necked flask, under the condition of 55℃ and intense stirring, react for 24 h, after the reaction, remove toluene by rotary evaporation, and wash with acetone for several times, dry finally to obtain zinc adipate catalyst. Under the nitrogen atmosphere, premix zinc adipate with sodium hydride according to the molar ratio of 1:6, then grind by using planetary ball mill for 30 h, the rotation speed of the ball mill is 300 rpm / min, to prepare the composite catalyst. Add the corresponding composite catalyst (the main catalyst is 0.86 mmol) into 100 ml round-bottom flask, then add appropriate amount of toluene, and then add propylene oxide and succinic anhydride into the flask (the molar ratio of zinc adipate, propylene oxide and succinic anhydride is 1:333:42), set the reaction temperature to 75℃, and react for 8 hours. After the reaction, remove the solvent by rotary evaporation, take out the viscous product from the reaction flask, add dichloromethane to stir and dissolve, and then add 5% hydrochloric acid to remove the residual catalyst, acid anhydride and metal hydride, then add methanol for washing, and finally dry to obtain the copolymer.

[0039] Comparative Example 1 (compared with Examples 1, 2, 3):

[0040] Take 20 mmol glutaric acid to configure a tetrahydrofuran solution with a mass concentration of about 15%, then add it into a 100 ml round-bottom flask, set the rotation speed to 1000 rpm, and slowly add a n-hexane solution with a mass concentration of 20% containing 20 mmol diethyl zinc under the nitrogen atmosphere at 0℃, then increase the temperature to room temperature at a rate of 0.2℃ / min from 0℃, and react for 6 hours. After the reaction, remove the unreacted diethyl zinc and glutaric acid by using n-hexane and tetrahydrofuran respectively, and dry to obtain zinc glutarate catalyst. Under the nitrogen atmosphere, grind the zinc glutarate catalyst by using planetary ball mill for 30 h, and the rotation speed of the ball mill is 300 rpm / min. Add 0.92 mmol of the ground zinc glutarate catalyst into a 100 ml round-bottom flask, then add appropriate amount of toluene, and then add propylene oxide and phthalic anhydride into the flask (the molar ratio of zinc glutarate, propylene oxide and phthalic anhydride is 1:311:39), set the reaction temperature to 75℃, and react for 8 hours. After the reaction, remove the solvent by rotary evaporation, take out the viscous product from the reaction flask, add dichloromethane to stir and dissolve, and then add 5% hydrochloric acid to remove the residual catalyst and acid anhydride, then add methanol for washing, and finally dry to obtain the copolymer. Figure 1 The properties of the copolymer prepared for Comparative Example 1 1 H NMR spectrum.

[0041] Comparative Example 2 (compared with Examples 1, 2, 3):

[0042] Take 20 mmol glutaric acid to configure into a mass concentration of about 15% tetrahydrofuran solution, then add 100 ml round bottom flask, the speed is set to 1000 rpm, slowly add the mass concentration of 20% n-hexane solution dissolved with 20 mmol diethyl zinc at 0 ℃ under nitrogen atmosphere, after adding, from 0 ℃ to room temperature at the rate of 0.2 ℃ / min, reaction for 6 hours. After the reaction is completed, the unreacted diethyl zinc and glutaric acid are removed with n-hexane and tetrahydrofuran respectively, and the zinc glutarate catalyst is obtained after drying. Under the nitrogen atmosphere, the zinc glutarate is premixed with sodium hydride at a molar ratio of 1:15, and then ground by a planetary ball mill for 30 h at a speed of 300 rpm to prepare a composite catalyst. Add the corresponding composite catalyst (0.92 mmol of main catalyst) into a 100 ml round bottom flask, add appropriate amount of toluene, then add propylene oxide and phthalic anhydride into the bottle (the molar ratio of zinc glutarate, propylene oxide and phthalic anhydride is 1:311:39), and set the reaction temperature to 75 ℃, reaction for 8 hours. After the reaction is completed, the solvent is removed by rotary evaporation, the viscous product is taken out from the reaction bottle, stirred and dissolved in dichloromethane, 5% hydrochloric acid is added to remove the residual catalyst, acid anhydride and metal hydride, then methanol is added for washing, and finally dried to obtain the copolymer.

[0043] Comparative Example 3 (compared with Example 5):

[0044] Take 100 mmol of zinc oxide (99.9%), 100 mmol of glutaric acid (99.0%), and 250 ml of toluene, add them into a 500 ml three-necked flask, and react at 55 ℃ under the condition of vigorous stirring for 24 h. After the reaction is completed, the toluene is removed by rotary evaporation, and the zinc glutarate catalyst is obtained after washing with acetone several times and drying. Under the nitrogen atmosphere, the zinc glutarate catalyst is ground by a planetary ball mill for 30 h at a speed of 300 rpm. Add 0.92 mmol of the ground zinc glutarate catalyst into a 100 ml round bottom flask, add appropriate amount of toluene, then add ethylene oxide and phthalic anhydride into the bottle (the molar ratio of zinc glutarate, ethylene oxide and phthalic anhydride is 1:435:54), and set the reaction temperature to 50 ℃, reaction for 8 hours. After the reaction is completed, the solvent is removed by rotary evaporation, the viscous product is taken out from the reaction bottle, stirred and dissolved in dichloromethane, 5% hydrochloric acid is added to remove the residual catalyst and acid anhydride, then methanol is added for washing, and finally dried to obtain the copolymer.

[0045] Comparative Example 4 (compared with Example 6):

[0046] Zinc oxide (99.9%) 100 mmol, adipic acid (99.0%) 100 mmol, toluene 250 ml, were added into a 500 ml three-necked flask, and the mixture was stirred vigorously at 55°C for 24 h. After the reaction, the toluene was removed by rotary evaporation, and the product was washed with acetone several times and dried to obtain the zinc adipate catalyst. The zinc adipate catalyst was ground in a planetary ball mill for 30 h at 300 rpm under nitrogen atmosphere. The ground zinc adipate catalyst 0.86 mmol was added into a 100 ml round bottom flask, and then an appropriate amount of toluene was added. Propylene oxide and succinic anhydride were added into the flask (molar ratio of zinc adipate:propylene oxide: succinic anhydride = 1:333:42), and the reaction was carried out at 75°C for 8 h. After the reaction, the solvent was removed by rotary evaporation, and the viscous product was taken out of the flask, dissolved in dichloromethane, and washed with 5% hydrochloric acid to remove the residual catalyst and anhydride, and then washed with methanol. Finally, the copolymer was obtained by drying.

[0047] The catalysts of the above examples and comparative examples were used to catalyze the preparation of alternating copolymers, and the polymerization results are shown in Table 1.

[0048] Table 1

[0049]

[0050]

[0051] Examples 1-6 and Comparative Examples 1-4 are the results of the application of composite zinc dicarboxylate catalysts to the alternating copolymerization of propylene oxide or ethylene oxide and itaconic anhydride, phthalic anhydride, succinic anhydride, or maleic anhydride.

[0052] As shown in Table 1, the zinc compound catalysts of Examples 1, 2, 3, and 4 and Comparative Examples 1 and 2 are derived from a preferred preparation method, the zinc compound catalysts of Examples 5 and 6 and Comparative Examples 3 and 4 are derived from a general preparation method, and the composite catalysts prepared by compounding the zinc compound catalysts prepared by the two methods with metal hydride compounds are used to catalyze the alternating copolymerization of epoxide and cyclic anhydride, and the activity and selectivity of the composite catalysts are higher than those of the single catalysts prepared by the respective methods. As compared with Comparative Examples 1 and 2, the same zinc compound catalyst and metal hydride compound are compounded in different molar ratios, which has a great influence on the activity and selectivity. When an appropriate amount of metal hydride compound is compounded with the zinc compound catalyst, the activity and selectivity are obviously improved. As compared with Comparative Example 1, the activity of Examples 1, 2, and 3 is increased by 19.4%, 59.7%, and 71.8%, respectively, and the polyester content is increased by 3.2%, 6.9%, and 11%, respectively. However, when an excessive amount of metal hydride compound is compounded, the activity and selectivity are obviously decreased. Therefore, the appropriate molar ratio is particularly important for the activity and selectivity. The reason why Examples 5 and 6 are better than Comparative Examples 1 and 2 is that the zinc compound catalyst prepared by the preferred preparation method is much better than the zinc compound catalyst prepared by the general preparation method.

[0053] The application discloses a method for catalyzing the alternating copolymerization of epoxide and cyclic anhydride, which uses a composite catalyst prepared by ball-milling a zinc compound catalyst and a metal hydride compound to catalyze the alternating copolymerization, and the preparation method is simple. The zinc compound catalyst is of a general formula Zn-R(COO)2 (R is a C1-C8 hydrocarbon group), and the metal hydride compound is of a general formula XH Y (X is Li, Na, Mg, K, Ca, Be, Sr, Ba, Ra, Fr, Rb, or Cs, and Y is 1, 2, or 3), which are used together as catalysts, and the yield and polyester content are obviously improved.

[0054] It should be noted that the above description of the embodiments is used to help understand the application, but does not constitute a limitation on the application. Furthermore, the technical features involved in the above-described various embodiments of the application can be combined with each other as long as there is no conflict. In addition, the above only describes some embodiments of the application, but not all embodiments. Based on the embodiments of the application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of the application.

Claims

1. A process for the catalytic alternating copolymerization of an epoxide with a cyclic anhydride characterized in that, Catalysis of epoxide with complex zinc dicarboxylate catalyst and cyclic anhydride alternating copolymerization reaction, wherein n is 1, 2 or 3; R1, R2 are substituents of the epoxide; R3, R4 are substituents of the anhydride; said complex zinc dicarboxylate catalyst comprises a main catalyst and a cocatalyst, said main catalyst is a zinc compound with Zn-R(COO)2 as the main body, and said cocatalyst is a metal hydride compound XH Y , wherein R is a C1-C8 hydrocarbon group, X is Li, Na, Mg, K, Ca, Be, Sr, Ba, Ra, Fr, Rb or Cs, and Y is 1, 2 or 3.

2. A process for the catalytic epoxide and cyclic anhydride alternating copolymerization reaction according to claim 1, characterized in that, R1, R2 are H, CH2Cl, CH2OBn, methyl, phenyl ring, cyclohexene, cyclopentene, naphthalene or cyclohexyl, R1, R2 are the same or different; R3, R4 are H, =CH2, phenyl ring, cyclohexene or norbornene ring, R3, R4 are the same or different.

3. A process for the catalytic epoxide and cyclic anhydride alternating copolymerization reaction according to claim 1, characterized in that, The epoxide is propylene oxide, ethylene oxide, cyclohexene oxide, butylene oxide, epichlorohydrin, phenyl glycidyl ether, allyl glycidyl ether, 2-(oxiranylmethoxy)tetrahydro-2H-pyran, tetrahydrofuran or styrene oxide; the cyclic anhydride is succinic anhydride, phthalic anhydride, cyclopentane-1,2-dicarboxylic anhydride, cyclopropane-1,2-dicarboxylic anhydride, itaconic anhydride, citraconic anhydride, maleic anhydride or norbornene diacid anhydride.

4. A process for the catalytic epoxide and cyclic anhydride alternating copolymerization reaction according to claim 1, characterized in that, The preparation method of the composite zinc dicarboxylate catalyst comprises the following steps: firstly, mixing the zinc compound and the metal hydride compound according to a molar ratio, and then performing high-speed grinding and milling for 5-40 hours under an inert atmosphere by using a planetary ball mill at a grinding speed of 100-400 rpm to obtain the composite catalyst.

5. The process for the catalytic epoxide and cyclic anhydride alternating copolymerization reaction according to claim 1, characterized in that, The molar ratio of the zinc compound to the metal hydride compound is 1:0.1-12.

6. A process for the catalytic epoxide and cyclic anhydride alternating copolymerization reaction according to claim 1, characterized in that, The copolymerization temperature is 20-120℃, and the reaction time is 2-100 hours.

7. A process for the catalytic alternating copolymerization of an epoxide and a cyclic anhydride according to any one of claims 1 to 6, characterized in that, The preparation method of the zinc compound comprises the following steps: adding a dialkyl zinc solution into a dicarboxylic acid solution, performing a reaction under a specific temperature rising procedure, synthesizing a crude zinc dicarboxylate catalyst by a precipitation method, and finally washing, filtering and drying to obtain the zinc dicarboxylate catalyst, wherein the purity of the zinc dicarboxylate catalyst is greater than or equal to 99%; the specific temperature rising procedure refers to that the dialkyl zinc solution and the dicarboxylic acid solution are prepared at a low temperature, and the initial temperature of the mixture is-5-10℃ after mixing, and the temperature is raised to room temperature at a temperature rising rate of 0.1-1℃ / min.

8. A process for the catalytic epoxide and cyclic anhydride alternating copolymerization reaction according to claim 7, characterized in that, dialkylzinc is (C x H 2x+1 )2Zn; a good solvent for the reaction system of dialkylzinc and dicarboxylic acid R(COOH)2 is C x H 2x+1 OH, C x H 2x+2 , C x H 2x+1 COC x H 2x+1 , C x H 2x+1 OC x H 2x+1 and C x H 2x O y , or a mixture of two or more thereof, wherein R is C1-C8 hydrocarbon group, x≥1, y≥1; the dicarboxylic acid is one of succinic acid, glutaric acid, adipic acid, pimelic acid or suberic acid.

9. A process for the catalytic epoxide and cyclic anhydride alternating copolymerization reaction according to claim 7, characterized in that, The molar ratio of the dialkyl zinc to the dicarboxylic acid is 20:20-22; the mass concentration of the dialkyl zinc solution is 10%-20%; the mass concentration of the dicarboxylic acid solution is 5%-15%; and the reaction time for the reaction under the specific temperature rising procedure is 1-12 hours, and the mechanical stirring speed during the reaction is 0-3000 rpm.

10. A process for the catalytic alternating copolymerization of an epoxide and a cyclic anhydride according to claim 7, characterized in that, The XRD spectrum of the prepared zinc compound has diffraction peaks at 2θ angles of 12.90±0.5, 22.80±0.4, and 23.10±0.4, the full width at half maximum is higher than 0.4, the crystallinity is 40-70%, and the specific surface area of the zinc dicarboxylate catalyst is 30-100 m 2 / g.

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