Process for the catalytic preparation of polycarbonates using a protic ionic liquid

Abstract

The application discloses a method for preparing polycarbonate by using a protonic ionic liquid catalyst. The cation of the protonic ionic liquid catalyst is an organic base compound, and the anion of the protonic ionic liquid catalyst is an imidazole derivative. The protonic ionic liquid catalyst is characterized in that dimethyl carbonate and diol monomers are efficiently activated through hydrogen bonding, and efficient conversion of the diol monomers is promoted by selecting anions and cations with different acidity coefficients, so that polycarbonate with high molecular weight is synthesized. The protonic ionic liquid catalyst synthesized in the application has the advantages of simple preparation method, green environmental protection, no residue and the like, and has extremely high application prospect in the preparation of polycarbonate.

Description

Technical Field

[0001] This application belongs to the field of polycarbonate synthesis technology, specifically relating to a proton-type ionic liquid catalyst for catalytic preparation of polycarbonate and a method for catalytic preparation of polycarbonate. Background Technology

[0002] Polycarbonate (PC) possesses excellent optical, thermal, and mechanical properties, making it widely used in food packaging, electronic devices, medical equipment, and aerospace. It has become the fastest-growing general-purpose material in terms of demand among the five major engineering plastics. Currently, the main methods for preparing polycarbonate are the phosgene process and the melt transesterification polycondensation process. The phosgene process requires large amounts of dichloromethane and toxic phosgene, posing significant environmental problems, resulting in high production costs and poor product quality; therefore, it has been phased out. In contrast, the melt transesterification polycondensation process eliminates the use of toxic phosgene and organic solvents, and excess raw materials and byproducts can be recycled, making it the primary method for polycarbonate production at present.

[0003] In the melt transesterification polycondensation process for preparing polycarbonate, diol monomers react with diphenyl carbonate or dimethyl carbonate through two reaction stages: transesterification and polycondensation. Diphenyl carbonate, prepared by transesterification of dimethyl carbonate and phenol, is currently the most commonly used monomer for preparing isosorbide-based polycarbonates. However, the preparation of polycarbonate using diphenyl carbonate also has some drawbacks. Firstly, it requires high purity of diphenyl carbonate, increasing product costs. Secondly, the increased viscosity of the reaction system during the polycondensation stage makes it difficult to remove the byproduct phenol, resulting in phenol residue that affects product quality. In comparison, the synthesis of polycarbonate using dimethyl carbonate has greater development potential. This is mainly because dimethyl carbonate can be synthesized from CO2, making it a green and environmentally friendly renewable chemical product, and its price is much lower than that of diphenyl carbonate. Furthermore, the byproduct of transesterification of dimethyl carbonate with diol monomers is methanol, which is easier to remove from the reaction system than phenol. Therefore, the synthesis of polycarbonate using dimethyl carbonate reduces the process steps, lowers energy consumption, saves costs, and aligns with the requirements of sustainable development. However, dimethyl carbonate contains two reaction sites: an alkyl carbon and a carbonyl carbon. Under the action of a basic catalyst, diol monomers can selectively generate methylated and methylated products with dimethyl carbonate. Among these, the methylated products are not conducive to the preparation of high molecular weight polycarbonates. Therefore, developing highly active and selective catalysts to effectively target and activate the active sites of dimethyl carbonate is key to the preparation of high molecular weight polycarbonates from dimethyl carbonate.

[0004] Currently reported catalysts for the synthesis of polycarbonate from dimethyl carbonate and glycol monomers are mostly metal oxides, organoalkali metals, and organic bases. Examples include lithium acetylacetonate catalyst (CN114957640A; Polymer Chemistry, 2013, 51, 1387-1397), sodium tert-butoxide catalyst (ACS Sustainable Chemistry & Engineering, 2020, 8, 9968-9979), 1,5,7-triazidobicyclo(4.4.0)dec-5-ene organic base catalyst (Green Chemistry, 2020, 22, 4550), and sodium bicarbonate and tetraisopropyl titanate composite catalyst (CN104031249A). These catalysts have single active sites and poor selectivity, easily causing dimethyl carbonate to undergo simultaneous methyl esterification as a side reaction, resulting in a lower molecular weight of the obtained polycarbonate. Furthermore, metal oxides or organoalkali metal catalysts can easily leave metal residues, affecting the quality of the polycarbonate. In addition, relevant literature has reported the applications of bis(triethylenediamine) ionic liquids (New Journal of Chemistry, 2024, 48, 3221), quaternary phosphorus ionic liquids (Catalysis Science & Technology, 2022, 12, 1756-1765), and quaternary ammonium ionic liquids (GreenChem., 2021, 23, 447) in the synthesis of polycarbonate. However, these ionic liquid catalysts have low catalytic activity, resulting in polycarbonate with low molecular weight, which is insufficient for industrial applications. Therefore, developing a highly efficient catalyst is of great practical significance for the synthesis of high molecular weight polycarbonate. Summary of the Invention

[0005] The purpose of this invention is to provide a system and method that enable the system to have high security, stability and reliability.

[0006] To address the shortcomings of existing technologies, this application aims to provide a method for preparing polycarbonate using a proton-type ionic liquid catalyst. The proton-type ionic liquid catalyst is prepared by neutralization reaction of equimolar amounts of Brønsted base and Brønsted acid. In the catalytic process of preparing polycarbonate from dimethyl carbonate and glycol monomers, the protonated hydrogen of the proton-type ionic liquid cation forms hydrogen bonds with the carbonyl group of dimethyl carbonate, and the negatively charged anion forms hydrogen bonds with the hydroxyl group of the glycol monomer. The synergistic effect of the cation and anion through hydrogen bonding effectively activates the reaction substrate for transesterification and polycondensation reactions. Simultaneously, by adjusting the acidity coefficients of the cation and anion, the conversion rate and selectivity of the glycol monomer are improved, and high molecular weight polycarbonate is synthesized. Furthermore, the method described in this application uses dimethyl carbonate to synthesize polycarbonate, which is green and pollution-free, reduces process steps, lowers energy consumption, saves costs, and meets the requirements of sustainable development.

[0007] To achieve this objective, the present invention adopts the following technical solution:

[0008] A method for preparing polycarbonate using proton-type ionic liquid catalysis involves using glycol monomers and dimethyl carbonate as raw materials, and a proton-type ionic liquid as a catalyst, to synthesize polycarbonate through transesterification and polycondensation reactions.

[0009] Transesterification reaction: Using a proton-type ionic liquid as a catalyst, diol monomers and dimethyl carbonate undergo transesterification reaction under normal pressure and nitrogen atmosphere.

[0010] Polycondensation reaction: Polycarbonate is prepared by polycondensation of the transesterification product under negative pressure.

[0011] The proton-type ionic liquid catalyst has an organic base compound as its cation and an imidazole derivative as its anion. The structural formula of the proton-type ionic liquid is as follows:

[0012]

[0013] In this compound, cation X is an organic base compound, and the anions R1, R2, and R3 are -C. n H 2n+1 (0≦n≦4), -NO2, at least one of the following: benzene ring.

[0014] Optionally, the anion of the proton-type ionic liquid catalyst is any one of imidazole, 2-methylimidazolium, 2-ethylimidazolium, 2-propylimidazolium, 2-ethyl-4-methylimidazolium, benzimidazole, 2-phenylimidazolium, 4-phenylimidazolium, and 2-nitroimidazolium.

[0015] Optionally, the organic base compound is selected from 1,8-diazabicycloundec-7-ene, 1,5-diazabicyclo[4.3.0]non-5-ene, 1,5,7-triazabicyclo(4.4.0)dec-5-ene, 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene, tetramethylguanidine, 1,3-diphenylguanidine, 3,7-diazabicyclo[3.3.1]nonane, 1,4-di-di-benzene, etc. Any one of the following: azabicyclo[2.2.2]octane, 1-azabicyclo[2.2.2]octane, tetrahydropyrrole, hexahydropyridine, piperazine, imino-tris(dimethylamino)phosphine, pyridine, 4-dimethylaminopyridine, dimethylamine, diethylamine, di-n-propylamine, di-n-butylamine, trimethylamine, triethylamine, tri-n-propylamine, tri-n-butylamine, N,N-dimethylethylamine, N,N-diethylmethylamine, and N,N-diethyl-1-propylamine;

[0016] Optionally, the organic base compound is any one of 1,8-diazabicycloundec-7-ene, 1,5-diazabicyclo[4.3.0]non-5-ene, 1,5,7-triazidobicyclo(4.4.0)dec-5-ene, 7-methyl-1,5,7-trizabicyclo[4.4.0]dec-5-ene, tetramethylguanidine, 1,3-diphenylguanidine, 3,7-diazabicyclo[3.3.1]nonane, 1,4-diazabicyclo[2.2.2]octane, and 1-azabicyclo[2.2.2]octane.

[0017] The applicant discovered that the proton-type ionic liquid catalyst obtained using the above-mentioned anion and cation configuration has the characteristic of efficiently activating dimethyl carbonate and diol monomers for transesterification and polycondensation reactions through the synergistic effect of hydrogen bonds. At the same time, by adjusting the acidity coefficients of the anion and cation, the conversion rate and selectivity of the diol monomers are improved, and high molecular weight polycarbonate is synthesized by catalysis.

[0018] Optionally, the diol monomer is selected from at least one of isosorbide, iso-idyl alcohol, isomannitol, 2,5-furandiethanol, 2,5-tetrahydrofurandiethanol, 4,4'-diphenolvalerate, 2,2-bis(4'-hydroxyphenyl)propane, 2,2-bis(4'-hydroxyphenyl)butane, 4,4'-dihydroxydiphenylmethane, 4,4'-dihydroxydiphenylcyclohexane, 1,4-benzenedimethanol, 1,3-benzenedimethanol, and 1,4-cyclohexanediethanol.

[0019] Optionally, the diol monomer is any one of isosorbide, iso-idyl alcohol, isomannitol, 4,4'-diphenolvalerate, 2,2-bis(4'-hydroxyphenyl)propane, 2,2-bis(4'-hydroxyphenyl)butane, 4,4'-dihydroxydiphenylmethane, 4,4'-dihydroxydiphenylcyclohexane, 1,4-benzenedimethanol, 1,3-benzenedimethanol, and 1,4-cyclohexanediethanol.

[0020] Optionally, the molar ratio of dimethyl carbonate to diol monomer is any value or any two values ​​within the range of 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, 11:1, 12:1, 13:1, 14:1, 15:1, 16:1, 17:1, 18:1, 19:1, and 20:1.

[0021] Optionally, the molar ratio of dimethyl carbonate to diol monomer is any value or a range of any two values ​​from 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1.

[0022] Optionally, the amount of the proton-type ionic liquid catalyst is any value or any two values ​​within the range of 0.1‰, 0.2‰, 0.3‰, 0.4‰, 0.5‰, 0.6‰, 0.7‰, 0.8‰, 0.9‰, 1‰, 1.1‰, 1.2‰, 1.3‰, 1.4‰, 1.5‰, 1.6‰, 1.7‰, 1.8‰, 1.9‰, and 2‰ of the molar amount of the diol monomer.

[0023] Optionally, the amount of the proton-type ionic liquid catalyst is any value or any two values ​​within the range of 0.1‰, 0.2‰, 0.3‰, 0.4‰, 0.5‰, 0.6‰, 0.7‰, 0.8‰, 0.9‰, and 1‰ of the molar amount of the diol monomer.

[0024] Optionally, the transesterification reaction temperature is any value or any range of two values ​​from 80℃, 90℃, 100℃, 110℃, 120℃, 130℃, 140℃, 150℃, 160℃, 170℃, 180℃, 190℃, and 200℃, and the transesterification reaction time is any value from 1h, 2h, 3h, 4h, 5h, 6h, 7h, 8h, 9h, 10h, 11h, 12h, 13h, 14h, and 15h. The range of any two values, the polycondensation reaction temperature being any value or a range of any two values ​​from 200℃, 220℃, 230℃, 240℃, 250℃, 260℃, 270℃, 280℃, 290℃, 300℃, and the polycondensation reaction time being any value or a range of any two values ​​from 0.5h, 1h, 1.5h, 2h, 2.5h, 3h, 3.5h, 4h, 4.5h, 5h, 5.5h, 6h.

[0025] Optionally, the transesterification reaction temperature is any value or any two of the following: 100℃, 110℃, 120℃, 130℃, 140℃, 150℃, 160℃, 170℃, and 180℃; the transesterification reaction time is any value or any two of the following: 1h, 2h, 3h, 4h, 5h, 6h, 7h, 8h, 9h, and 10h; the polycondensation reaction temperature is any value or any two of the following: 220℃, 230℃, 240℃, 250℃, 260℃, 270℃, and 280℃; and the polycondensation reaction time is any value or any two of the following: 0.5h, 1h, 1.5h, 2h, 2.5h, 3h, 3.5h, and 4h.

[0026] This application has the following beneficial effects:

[0027] (1) This application uses a proton-type ionic liquid as a catalyst to catalyze the reaction of dimethyl carbonate and glycol monomers to prepare polycarbonate. Compared with existing organic base, alkali metal and non-proton-type ionic liquid catalysts, the proton-type ionic liquid catalyst described in this application can activate the reaction substrate through strong hydrogen bonding. At the same time, the strength of hydrogen bonding between the proton-type ionic liquid and the reaction substrate can be adjusted by selecting anions and cations with different acidity coefficients, which can effectively activate the polymerization monomer and promote the synthesis of high molecular weight polycarbonate.

[0028] (2) The proton-type ionic liquid used in this application is simple to prepare, obtained through an equimolar Brønsted acid-base neutralization reaction without any further processing. Furthermore, the proton-type ionic liquid exhibits good stability during the transesterification stage and is removed under vacuum during the polycondensation stage, leaving no residue in polycarbonate. The proton-type ionic liquid possesses high catalytic activity and selectivity, and its preparation method is simple, using inexpensive raw materials. It is environmentally friendly and residue-free, showing promising prospects for industrial application. Attached Figure Description

[0029] Figure 1 The image shows the 1H NMR spectrum of the product from Example 1 of this application, indicating that the chemical structure of the obtained product is consistent with the structure of the target product.

[0030] Figure 2 This describes the interaction mechanism between protonated and aprotonated ionic liquids and the reaction substrate.

[0031] Figure 3 This is a schematic diagram of the polymerization mechanism of isosorbide and dimethyl carbonate catalyzed by [DBUH][Im]. Detailed Implementation

[0032] The technical solution of the present invention will be further illustrated below through specific embodiments.

[0033] The following are examples of proton-type ionic liquid synthesis used in this application:

[0034] (1) Synthesis of 1,8-diazabicycloundec-7-enimidazolium ([DBUH][Im])

[0035]

[0036] Imidazole (0.01 mol, 0.68 g) was placed in a 25 mL single-necked flask, which was then placed in an ice bath. 1,8-diazabicycloundec-7-ene (0.01 mol, 1.52 g) was slowly added dropwise to the flask under magnetic stirring. After the addition was complete, the reaction mixture was stirred at room temperature for 12 h, yielding 2.16 g of the product (98% yield).

[0037] (2) Synthesis of 1,8-diazabicycloundec-7-ene-2-methylimidazolium ([DBUH][2-MeIm])

[0038]

[0039] 2-Methylimidazole (0.01 mol, 0.82 g) was placed in a 25 mL single-necked flask, which was then placed in an ice bath. 1,8-diazabicycloundec-7-ene (0.01 mol, 1.52 g) was slowly added dropwise to the flask under magnetic stirring. After the addition was complete, the reaction mixture was stirred at room temperature for 12 h, yielding 2.33 g of the product (99% yield).

[0040] In this embodiment, gas chromatography equipped with a flame ionization detector was used to analyze the conversion rate of diol monomers after transesterification.

[0041] In the embodiments of this application, the conversion rate of the diol monomer is calculated based on the following formula.

[0042]

[0043] In this embodiment, the molecular weight of polycarbonate was determined using gel permeation chromatography with N,N-dimethylformamide as the eluent and polystyrene as the standard.

[0044] Example 1

[0045] The reaction formula for synthesizing polycarbonate using dimethyl carbonate and isosorbide as raw materials in this embodiment is as follows:

[0046]

[0047] Transesterification stage: 63.0 g (0.7 mol) of dimethyl carbonate and 14.6 g (0.1 mol) of isosorbide were added to a 250 mL four-necked flask equipped with a mechanical stirrer and a reflux condenser. The mixture was heated to 140 °C in an oil bath and 44 mg (2 × 10⁻⁶) of isosorbide was added. -4 The transesterification reaction was carried out under a nitrogen atmosphere for 4 hours using 1,8-diazabicycloundec-7-enimidazole ([DBUH][Im]) catalyst. The circulating condensate was then shut off, and the reaction temperature was slowly increased to 180℃ and maintained for 1 hour to remove byproducts such as methanol and unreacted dimethyl carbonate. In the polycondensation stage, the temperature was gradually increased to 240℃, and the vacuum was gradually reduced to 100 Pa for 1 hour, ultimately yielding a polycarbonate product. The isosorbide conversion rate was measured to be 95.4%, and the weight-average molecular weight of the polycarbonate was 58500 g / mol.

[0048] Example 2

[0049] The difference from Example 1 is that 44mg (2×10) was used. -4 The catalyst 1,8-diazabicycloundec-7-enimidazole ([DBUH][Im]) was replaced with 59.2 mg (2 × 10⁻⁶) mol. -4 A 1,8-diazabicycloundec-7-ene-4-phenylimidazolium ([DBUH][4-PhIm]) catalyst was used, with other conditions remaining constant. The conversion rate of isosorbide was measured to be 90.1%, and the weight-average molecular weight of polycarbonate was 55800 g / mol.

[0050] Example 3

[0051] The difference from Example 1 is that 44mg (2×10) was used. -4 The 1,8-diazabicycloundec-7-enimidazole ([DBUH][Im]) catalyst was replaced with 59.2 mg (2 × 10⁻⁶) mol. -4 A 1,8-diazabicycloundec-7-ene-2-phenylimidazolium ([DBUH][2-PhIm]) catalyst was used, with other conditions remaining constant. The conversion rate of isosorbide was measured to be 92.1%, and the weight-average molecular weight of polycarbonate was 57700 g / mol.

[0052] Example 4

[0053] The difference from Example 1 is that 44mg (2×10) was used. -4 The 1,8-diazabicycloundec-7-enimidazole ([DBUH][Im]) catalyst was replaced with 49.6 mg (2 × 10⁻⁶) mol. -4 A 1,8-diazabicycloundec-7-ene-2-ethylimidazolium ([DBUH][2-EtIm]) catalyst was used, with other conditions remaining constant. The conversion rate of isosorbide was measured to be 88.3%, and the weight-average molecular weight of polycarbonate was 55400 g / mol.

[0054] Example 5

[0055] The difference from Example 1 is that 44mg (2×10) was used. -4 The catalyst 1,8-diazabicycloundec-7-enimidazole ([DBUH][Im]) was replaced with 46.8 mg (2 × 10⁻⁶) -4 A 1,8-diazabicycloundec-7-ene-2-methylimidazolium ([DBUH][2-MeIm]) catalyst was used, with other conditions remaining constant. The conversion rate of isosorbide was measured to be 88.1%, and the weight-average molecular weight of polycarbonate was 50600 g / mol.

[0056] Example 6

[0057] The difference from Example 1 is that 44mg (2×10) was used. -4 The catalyst 1,8-diazabicycloundec-7-enimidazole ([DBUH][Im]) was replaced with 46.8 mg (2 × 10⁻⁶) -4 A 1,8-diazabicycloundec-7-ene-4-methylimidazolium ([DBUH][4-MeIm]) catalyst was used, with other conditions remaining constant. The conversion rate of isosorbide was measured to be 87.2%, and the weight-average molecular weight of polycarbonate was 52800 g / mol.

[0058] Example 7

[0059] The difference from Example 1 is that 44mg (2×10) was used. -4 The 1,8-diazabicycloundec-7-enimidazole ([DBUH][Im]) catalyst was replaced with 52.4 mg (2 × 10⁻⁶) mol. -4 A 1,8-diazabicycloundec-7-ene 2-ethyl-4-methylimidazolium ([DBUH][2-Et-4-MeIm]) catalyst was used, with other conditions remaining constant. The conversion rate of isosorbide was measured to be 86.6%, and the weight-average molecular weight of polycarbonate was 46500 g / mol.

[0060] Example 8

[0061] The difference from Example 1 is that 44mg (2×10) was used. -4 The catalyst 1,8-diazabicycloundec-7-enimidazole ([DBUH][Im]) was replaced with 53 mg (2 × 10⁻⁶) mol. -4 A 1,8-diazabicycloundec-7-ene 2-nitroimidazole ([DBUH][2-NitrIm]) catalyst was used, with other conditions remaining constant. The conversion rate of isosorbide was measured to be 81.2%, and the weight-average molecular weight of polycarbonate was 48300 g / mol.

[0062] Example 9

[0063] The difference from Example 1 is that 44mg (2×10) was used. -4 The 1,8-diazabicycloundec-7-ene ([DBUH][Im]) catalyst was replaced with 38.4 mg (2 × 10⁻⁶) mol. -4 A 1,5-diazabicyclo[4.3.0]non-5-enimidazole ([DBNH][Im]) catalyst was used, with other conditions remaining unchanged. The conversion rate of isosorbide was measured to be 91.6%, and the weight-average molecular weight of polycarbonate was 58200 g / mol.

[0064] Example 10

[0065] The difference from Example 1 is that 44mg (2×10) was used. -4 The 1,8-diazabicycloundec-7-ene ([DBUH][Im]) catalyst was replaced with 44.2 mg (2 × 10⁻⁶) mol. -4 A 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-enimidazole ([MTBDH][Im]) catalyst was used, with other conditions remaining unchanged. The conversion rate of isosorbide was measured to be 94.2%, and the weight-average molecular weight of polycarbonate was 59800 g / mol.

[0066] Example 11

[0067] The difference from Example 1 is that the transesterification reaction temperature was changed from 140°C to 100°C, while other conditions remained unchanged. The conversion rate of isosorbide was measured to be 56.5%, and the weight-average molecular weight of polycarbonate was 44600 g / mol.

[0068] Example 12

[0069] The difference from Example 1 is that the transesterification reaction temperature was changed from 140°C to 120°C, while other conditions remained unchanged. The conversion rate of isosorbide was measured to be 88.3%, and the weight-average molecular weight of polycarbonate was 54300 g / mol.

[0070] Example 13

[0071] The difference from Example 1 is that the transesterification reaction temperature was changed from 140°C to 160°C, while other conditions remained unchanged. The conversion rate of isosorbide was measured to be 94.5%, and the weight-average molecular weight of polycarbonate was 62,800 g / mol.

[0072] Example 14

[0073] The difference from Example 1 is that the transesterification reaction temperature was changed from 140°C to 180°C, while other conditions remained unchanged. The conversion rate of isosorbide was measured to be 93.8%, and the weight-average molecular weight of polycarbonate was 54900 g / mol.

[0074] Example 15

[0075] The difference from Example 1 is that the transesterification reaction temperature was changed from 140°C to 200°C, while other conditions remained unchanged. The conversion rate of isosorbide was measured to be 94.2%, and the weight-average molecular weight of polycarbonate was 49600 g / mol.

[0076] Example 16

[0077] The difference from Example 1 was that the transesterification time was changed from 4 hours to 2 hours, while other conditions remained the same. The conversion rate of isosorbide was measured to be 68.6%, and the weight-average molecular weight of polycarbonate was 41,500 g / mol.

[0078] Example 17

[0079] The difference from Example 1 was that the transesterification time was changed from 4 hours to 3 hours, while other conditions remained the same. The conversion rate of isosorbide was measured to be 87.3%, and the weight-average molecular weight of polycarbonate was 54,300 g / mol.

[0080] Example 18

[0081] The difference from Example 1 was that the transesterification time was changed from 4 hours to 5 hours, while other conditions remained the same. The conversion rate of isosorbide was measured to be 95.7%, and the weight-average molecular weight of polycarbonate was 62,700 g / mol.

[0082] Example 19

[0083] The difference from Example 1 was that the transesterification time was changed from 4 hours to 6 hours, while other conditions remained the same. The conversion rate of isosorbide was measured to be 96.2%, and the weight-average molecular weight of polycarbonate was 60,200 g / mol.

[0084] Example 20

[0085] The difference from Example 1 is that the transesterification reaction temperature was changed from 140℃ to 160℃, and the polycondensation reaction temperature was changed from 240℃ to 220℃, while other conditions remained unchanged. The weight-average molecular weight of the polycarbonate was measured to be 54400 g / mol.

[0086] Example 21

[0087] The difference from Example 1 is that the transesterification reaction temperature was changed from 140℃ to 160℃, and the polycondensation reaction temperature was changed from 240℃ to 230℃, while other conditions remained unchanged. The weight-average molecular weight of the polycarbonate was measured to be 59700 g / mol.

[0088] Example 22

[0089] The difference from Example 1 is that the transesterification reaction temperature was changed from 140°C to 160°C, and the polycondensation reaction temperature was changed from 240°C to 250°C, while other conditions remained unchanged. The weight-average molecular weight of the polycarbonate was measured to be 62400 g / mol.

[0090] Example 23

[0091] The difference from Example 1 is that the transesterification reaction temperature was changed from 140°C to 160°C, and the polycondensation reaction temperature was changed from 240°C to 260°C, while other conditions remained unchanged. The weight-average molecular weight of the polycarbonate was measured to be 63,600 g / mol.

[0092] Example 24

[0093] The difference from Example 1 is that the transesterification reaction temperature was changed from 140℃ to 160℃, and the polycondensation reaction temperature was changed from 240℃ to 270℃, while other conditions remained unchanged. The weight-average molecular weight of the polycarbonate was measured to be 58900 g / mol.

[0094] Example 25

[0095] The difference from Example 1 is that the transesterification reaction temperature was changed from 140℃ to 160℃, and the polycondensation reaction time was changed from 1h to 0.5h, while other conditions remained unchanged. The weight-average molecular weight of the polycarbonate was measured to be 46900 g / mol.

[0096] Example 26

[0097] The difference from Example 1 is that the transesterification reaction temperature was changed from 140℃ to 160℃, and the polycondensation reaction time was changed from 1h to 1.5h, while other conditions remained unchanged. The weight-average molecular weight of the polycarbonate was measured to be 65700 g / mol.

[0098] Example 27

[0099] The difference from Example 1 is that the transesterification reaction temperature was changed from 140℃ to 160℃, and the polycondensation reaction time was changed from 1h to 2h, while other conditions remained unchanged. The weight-average molecular weight of the polycarbonate was measured to be 62400 g / mol.

[0100] Example 28

[0101] The difference from Example 1 is that the transesterification reaction temperature was changed from 140℃ to 160℃, and the polycondensation reaction time was changed from 1h to 2.5h, while other conditions remained unchanged. The weight-average molecular weight of the polycarbonate was measured to be 60600 g / mol.

[0102] Example 29

[0103] The difference from Example 1 is that 63.0 g (0.7 mol) of dimethyl carbonate was replaced with 27.0 g (0.3 mol), while other conditions remained unchanged. The conversion rate of isosorbide was measured to be 82.5%, and the weight-average molecular weight of polycarbonate was 47,500 g / mol.

[0104] Example 30

[0105] The difference from Example 1 is that 63.0 g (0.7 mol) of dimethyl carbonate was replaced with 45.0 g (0.5 mol), while other conditions remained unchanged. The conversion rate of isosorbide was measured to be 87.1%, and the weight-average molecular weight of polycarbonate was 53,500 g / mol.

[0106] Example 31

[0107] The difference from Example 1 is that 63.0 g (0.7 mol) of dimethyl carbonate was replaced with 81.0 g (0.9 mol), while other conditions remained unchanged. The conversion rate of isosorbide was measured to be 95.9%, and the weight-average molecular weight of polycarbonate was 62100 g / mol.

[0108] Comparative Example 1

[0109] This comparative example uses dimethyl carbonate and isosorbide as raw materials to synthesize polycarbonate.

[0110] Transesterification stage: 67.5 g (0.75 mol) of dimethyl carbonate and 14.6 g (0.1 mol) of isosorbide were added to a 250 mL four-necked flask equipped with a mechanical stirrer and a reflux condenser. The mixture was heated to 98 °C in an oil bath, and 10.6 mg (2 × 10⁻⁶) of [unspecified ingredient] was added. -4 The transesterification reaction was carried out under a nitrogen atmosphere for 6 hours using lithium acetylacetone catalyst (mol). The circulating condensate was then shut off, and the reaction temperature was slowly increased to 180℃ and maintained for 1 hour to remove byproducts such as methanol and unreacted dimethyl carbonate. In the polycondensation stage, the temperature was gradually increased to 240℃, and the vacuum was gradually reduced to 10 Pa for 5 hours, ultimately yielding a polycarbonate product. The isosorbide conversion rate was measured to be 95.1%, and the weight-average molecular weight of the polycarbonate was 45900 g / mol.

[0111] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for preparing polycarbonate using proton-type ionic liquid catalysis, characterized in that, Polycarbonate was synthesized from isosorbide and dimethyl carbonate as raw materials, and proton-type ionic liquid as catalyst, via transesterification and polycondensation reaction. The structural formula of the proton-type ionic liquid is as follows: Among them, cation X is derived from 1,8-diazabicycloundec-7-ene, 1,5-diazabicyclo[4.3.0]non-5-ene, 1,5,7-triazabicyclo(4.4.0)dec-5-ene, 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene, tetramethylguanidine, 1,3-diphenylguanidine, 3,7-diazabicyclo[3.3.1]nonane, 1,4-diazabicyclo[4.3.0]nonane, and 1,8-diazabicyclo[4.3.0]nonane. Any one of the following: bicyclo[2.2.2]octane, 1-azabicyclo[2.2.2]octane, tetrahydropyrrole, hexahydropyridine, piperazine, imino-tris(dimethylamino)phosphine, pyridine, 4-dimethylaminopyridine, dimethylamine, diethylamine, di-n-propylamine, di-n-butylamine, trimethylamine, triethylamine, tri-n-propylamine, tri-n-butylamine, N,N-dimethylethylamine, N,N-diethylmethylamine, and N,N-diethyl-1-propylamine; The anion is derived from any one of imidazole, 2-methylimidazolium, 2-ethylimidazolium, 2-propylimidazolium, 2-ethyl-4-methylimidazolium, benzimidazole, 2-phenylimidazolium, 4-phenylimidazolium, and 2-nitroimidazolium.

2. The method according to claim 1, characterized in that, The molar ratio of dimethyl carbonate to isosorbide monomer is 1-20:

1.

3. The method according to claim 1, characterized in that, The amount of the proton-type ionic liquid catalyst used is 0.1‰-2‰ of the molar amount of isosorbide monomer.

4. The method according to claim 1, characterized in that, The transesterification reaction temperature is 80-200 ℃ and the transesterification reaction time is 1-15 h. The polycondensation reaction temperature is 200-300 ℃ and the polycondensation reaction time is 0.5-6 h.

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