A process for the preparation of polyesters by the ring-opening polymerization of cyclic monomers catalyzed by a urea-amino acid based sodium salt catalyst
By using sodium salt catalysts of urea-amino acids to catalyze the ring-opening polymerization of cyclic monomers, the problems of high energy consumption and catalyst deactivation in traditional polyester preparation have been solved, realizing a highly efficient and environmentally friendly polyester preparation method suitable for industrial production.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- NANJING TECH UNIV
- Filing Date
- 2024-06-20
- Publication Date
- 2026-07-03
Smart Images
Figure CN118791720B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of organic catalysis and polymer synthesis technology, specifically relating to a method for preparing polyester by ring-opening polymerization of cyclic monomers catalyzed by a sodium salt catalyst based on urea-amino acids. Background Technology
[0002] Among numerous synthetic polymer materials, aliphatic polyesters occupy an important position due to their excellent biodegradability, bioabsorbability, and biocompatibility. As an environmentally friendly new material, this type of polyester material has attracted much research attention in the field of polymer chemistry and is gradually being applied in the fields of biomedicine and microelectronics.
[0003] Traditional polyester preparation methods mainly involve polycondensation, which typically requires high temperatures, consumes a lot of energy, has an uncontrollable reaction process, and often involves side reactions, resulting in polyesters with low molecular weight and a wide molecular weight distribution. In contrast, polyesters prepared using ring-opening polymerization have high molecular weight and a narrow molecular weight distribution. This not only allows for precise control of the chemical composition of the polymerization product but also improves the stability of material properties, making the material's properties and applications more moderate and broadening the application areas of aliphatic polyesters.
[0004] Catalysts used for the preparation of aliphatic polyesters via ROP mainly fall into three categories: (1) organometallic complexes; (2) organic catalysts, including organic protic acids (sulfonic acids and phosphonic acids, etc.) and organic superbases (organoamidine bases, phosphononitrile bases and N-heterocyclic carbenes, etc.); and (3) bifunctional catalysts, mainly including (thio)urea (hydrogen bond donor) / organic base synergistic systems. Metal catalysts are complex to prepare, costly, and the residual toxic metals can harm the body or pollute the environment and are difficult to separate and recover from the product, which is detrimental to industrial applications and has adverse environmental impacts.
[0005] Ring-opening polymerization catalyzed by organic catalysts is characterized by its mildness, high efficiency, and minimal impact from side reactions. It also avoids the problem of metal residues in the product, resulting in polyesters with well-defined structures and low molecular weight distributions. In industrial production, the production of polyesters and related polymers such as polycarbonates generally employs bulk polymerization methods at relatively high temperatures. However, many high-performance organic catalysts in existing technologies suffer from low thermal stability and are prone to deactivation or degradation at industrial production temperatures, limiting their application range. Therefore, exploring a cheap, readily available, and high-temperature-resistant organic molecular catalyst and utilizing it to catalyze the ring-opening polymerization of cyclic monomers to prepare polyesters has significant commercial application value. Summary of the Invention
[0006] The technical problem to be solved by this invention is a method for preparing polyester by ring-opening polymerization of cyclic monomers based on sodium salt catalyst of urea-amino acids. The method adopts bulk polymerization and does not require the introduction of additional reaction solvents into the reaction system. The high reaction temperature greatly reduces the sensitivity of the reaction system to air and water, which is beneficial to industrial production.
[0007] To address the aforementioned technical problems, embodiments of the present invention provide a method for preparing polyester by ring-opening polymerization of cyclic monomers catalyzed by a sodium salt catalyst of urea-amino acids. In the presence of an initiator, the cyclic monomers undergo ring-opening polymerization under the catalysis of a sodium salt catalyst of urea-amino acids as shown in Formula I. After the polymerization reaction is completed, a good solvent is added to the mixture obtained from the reaction, the mixture is filtered to obtain a filtrate, the filtrate is slowly added to a precipitation solvent, centrifuged, and dried to obtain polyester.
[0008] The initiator is an alcohol initiator;
[0009] The sodium salt catalyst of the urea-amino acid is prepared from isocyanate and sodium salt of amino acid, and its structural formula is as follows. :
[0010] Mode ;
[0011] Among them, R 1 The alkyl, phenyl, benzyl, monosubstituted or polysubstituted phenyl, monosubstituted or polysubstituted benzyl groups with 1 to 6 carbon atoms are selected; the substituents of the monosubstituted or polysubstituted phenyl or benzyl groups are tert-butyl, methoxy, or halogen substituents.
[0012] R 2 Selected from amino acids and their side chain groups;
[0013] M is selected from Na.
[0014] The cyclic monomer is selected from lactone monomers, lactide monomers, and carbonate monomers;
[0015] The structural formula of the lactone monomer is as follows: :
[0016] Mode ;
[0017] Where A is [—(CR 3 R 4 )—] N N is an integer from 2 to 10; R 3 R 4 Selected from H, halogen atoms, alkyl groups having 1 to 5 carbon atoms, and alkyl groups having 1 to 5 carbon atoms substituted with halogen atoms or hydroxyl groups;
[0018] The structural formula of the lactone monomer is as follows: :
[0019] Mode ;
[0020] Where D and B are the same or different [—(CR 5 R 6 )—] N N is an integer from 1 to 10; R 5 R 6 Selected from H, halogen atoms, alkyl groups having 1 to 5 carbon atoms, and alkyl groups having 1 to 5 carbon atoms substituted with halogen atoms or hydroxyl groups;
[0021] The structural formula of the carbonate monomer is as follows: :
[0022] Mode ;
[0023] Among them, R 7 R 8 Selected from H, halogen atom, hydroxyl group, alkyl group having 1 to 5 carbon atoms, and alkyl group having 1 to 5 carbon atoms substituted by halogen atom or hydroxyl group.
[0024] Preferably, in formula I, R 1 Selected from methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, tolyl, p-methoxyphenyl, p-chlorophenyl; R 2 The amino acids and their side chain groups are selected from glycine, methyl of alanine, isopropyl of valine, isobutyl of leucine, and benzyl of phenylalanine; M is selected from Na.
[0025] Preferably, the 13 sodium salt catalysts of urea-amino acids, 1-13, correspond to the following structural formulas:
[0026] .
[0027] The alcohol initiator is selected from one or more of methanol, ethanol, n-propanol, isopropanol, n-butanol, tert-butanol, benzyl alcohol, phenethyl alcohol, and phenylpropanol.
[0028] The cyclic monomer is selected from one of β-propiolactone, γ-butyrolactone, δ-valerolactone, γ-chloro-δ-valerolactone, ε-caprolactone, 2-chloro-ε-caprolactone, glycolide, l-lactide, d-lactide, trimethylene carbonate, hydroxytrimethylene carbonate, and chlorotrimethylene carbonate.
[0029] The good solvent is selected from one of dichloromethane, trichloromethane, toluene, benzene, acetone or tetrahydrofuran;
[0030] The precipitation solvent is selected from methanol or ethanol.
[0031] The reaction conditions for ring-opening polymerization are as follows: reaction temperature is 40~200℃, reaction time is 0.1~90h; the molar ratio of sodium urea-amino acid catalyst to cyclic monomer is 10~800:1; and the molar ratio of sodium urea-amino acid catalyst to alcohol initiator is 1~2:1.
[0032] This invention also provides a method for preparing a sodium salt catalyst of urea-amino acids, wherein the sodium salt catalyst of urea-amino acids has the structural formula shown in the figure below. :
[0033] Mode ;
[0034] Among them, R 1 The alkyl, phenyl, benzyl, monosubstituted or polysubstituted phenyl, monosubstituted or polysubstituted benzyl groups with 1 to 6 carbon atoms are selected; the substituents of the monosubstituted or polysubstituted phenyl or benzyl groups are tert-butyl, methoxy, or halogen substituents.
[0035] R 2 Selected from amino acids and their side chain groups;
[0036] M is selected from Na;
[0037] The preparation method of the sodium salt catalyst of urea-amino acid includes the following steps:
[0038] S1. At room temperature, amino acids (0.022 mol) were added to a stirred aqueous hydroxide solution (8%, 5.06 mL, 0.022 mol) and stirred for 24-72 h. The resulting reaction mixture was the sodium salt of the amino acid.
[0039] S2. Place the sodium salt of the amino acid obtained in step S1 in an ice bath, and slowly add 10 mL of acetone containing 0.022 mol of isocyanate, stirring overnight.
[0040] S3. Filter the mixture obtained in step S2 to remove the solids, and concentrate and dry the liquid under vacuum to obtain a sodium salt catalyst of urea-amino acids derived from amino acids and isocyanates.
[0041] In step S1, the amino acid is selected from one or more of glycine, alanine, valine, leucine, isoleucine and phenylalanine.
[0042] The hydroxide is selected from one or more of lithium hydroxide, sodium hydroxide, potassium hydroxide, and cesium hydroxide;
[0043] In step S2, the isocyanate is selected from one of p-methoxyphenyl isocyanate, p-toluene isocyanate, and p-chlorophenyl isocyanate.
[0044] The beneficial effects of the above technical solution of the present invention are as follows:
[0045] 1. This invention provides a sodium salt catalyst for urea-amino acids, used to catalyze the ring-opening polymerization of cyclic monomers to prepare polyester. The raw material amino acid in this sodium salt catalyst is derived from natural sources, making it a sodium salt catalyst for urea-amino acids that is inexpensive, readily available, and can be mass-produced industrially.
[0046] 2. This invention provides a method for preparing polyester by ring-opening polymerization of cyclic monomers catalyzed by a sodium salt catalyst of urea-amino acids. This bulk polymerization method eliminates the need for introducing additional reaction solvents into the reaction system. Furthermore, the high reaction temperature significantly reduces the sensitivity of the reaction system to air and water, which is beneficial for industrial production. This preparation method has significant advantages such as high efficiency, simple operation, and wide applicability. It allows for the controlled synthesis of polyester products with target molecular weights, yielding products with high yields, no monomer residue, and clean appearance. Attached Figure Description
[0047] Figure 1 The polylactic acid obtained in Example 10 is a polylactic acid. 1 H NMR spectrum;
[0048] Figure 2 The spectrum of polyl-lactide prepared in Example 10 is obtained by size exclusion chromatography.
[0049] Figure 3 The polytrimethylene carbonate prepared in Example 11 1 H NMR spectrum;
[0050] Figure 4 This is a size exclusion chromatogram of the polytrimethylene carbonate prepared in Example 11;
[0051] Figure 5 The spectrum of polyl-lactide prepared in Example 12 is obtained by size exclusion chromatography.
[0052] Figure 6 The spectrum of polyl-lactide prepared in Example 13 is obtained by size exclusion chromatography.
[0053] Figure 7 Catalyst 2 prepared in Example 1 1 H NMR spectrum;
[0054] Figure 8 Catalyst 2 prepared in Example 1 13 C NMR spectrum;
[0055] Figure 9 The catalyst 3 prepared in Example 2 1 H NMR spectrum;
[0056] Figure 10 The catalyst 3 prepared in Example 2 13 C NMR spectrum;
[0057] Figure 11 Catalyst 4 prepared in Example 3 1 H NMR spectrum;
[0058] Figure 12 Catalyst 4 prepared in Example 3 13 C NMR spectrum;
[0059] Figure 13 Catalyst 5 prepared in Example 4 1 H NMR spectrum;
[0060] Figure 14 Catalyst 5 prepared in Example 4 13 C NMR spectrum;
[0061] Figure 15 The catalyst 6 prepared in Example 5 1 H NMR spectrum;
[0062] Figure 16 The catalyst 6 prepared in Example 5 13 C NMR spectrum;
[0063] Figure 17 The catalyst 7 prepared in Example 6 1 H NMR spectrum;
[0064] Figure 18 The catalyst 7 prepared in Example 6 13 C NMR spectrum;
[0065] Figure 19 The catalyst 8 prepared in Example 7 1 H NMR spectrum;
[0066] Figure 20 The catalyst 8 prepared in Example 7 13 C NMR spectrum;
[0067] Figure 21 The catalyst 10 prepared in Example 81 H NMR spectrum;
[0068] Figure 22 The catalyst 10 prepared in Example 8 13 C NMR spectrum;
[0069] Figure 23 The catalyst 11 prepared in Example 9 1 H NMR spectrum;
[0070] Figure 24 The catalyst 11 prepared in Example 9 13 C10 NMR spectrum. Detailed Implementation
[0071] The present invention can be further illustrated by the following embodiments, which are for illustrative purposes only and not for limiting the invention. Any person skilled in the art will understand that these embodiments do not limit the invention in any way, and that appropriate modifications and data transformations can be made thereto without departing from the spirit and scope of the invention.
[0072] The concept of this invention is as follows:
[0073] (1) Under the reaction conditions, the sodium salt catalyst based on urea-amino acids performs dual activation on the cyclic monomer and the initiator;
[0074] (2) In the presence of an alcohol initiator, a cyclic monomer is catalyzed by sodium salt of urea-amino acid to obtain polyester.
[0075] Based on the above ideas, this invention provides a method for preparing polyester by ring-opening polymerization of cyclic monomers catalyzed by a sodium salt catalyst of urea-amino acids. In the presence of an initiator, the cyclic monomers undergo ring-opening polymerization under the catalysis of a sodium salt catalyst of urea-amino acids as shown in Formula I. After the polymerization reaction is complete, a good solvent is added to the resulting mixture, and the mixture is filtered to obtain a filtrate. The filtrate is slowly added to a precipitation solvent, centrifuged, and dried to obtain the polyester. The polyester obtained by this invention has controllable terminal structure and molecular weight distribution. For example, a narrow molecular weight distribution can be achieved by adding a compound containing active hydrogen (ROH) as an initiator to the ring-opening polymerization reaction. The monomer terminal structures initiated by this initiator are RO- and -OH, respectively, and the ratio of lactone monomer to initiator determines the target molecular weight of the obtained polyester. Under the condition of an initiator, the ring-opening polymerization reaction catalyzed by this catalyst yields polymers with controllable molecular weight and terminal structure and a narrow molecular weight distribution.
[0076] The initiator is an alcohol initiator, selected from one or more of methanol, ethanol, n-propanol, isopropanol, n-butanol, tert-butanol, benzyl alcohol, phenethyl alcohol, and phenylpropanol.
[0077] The good solvent is selected from one of dichloromethane, trichloromethane, toluene, benzene, acetone or tetrahydrofuran; the precipitation solvent is selected from methanol or ethanol.
[0078] The reaction conditions for ring-opening polymerization are as follows: reaction temperature of 40–200 °C, reaction time of 0.1–90 h; molar ratio of sodium urea-amino acid catalyst to cyclic monomer of 10–800:1; molar ratio of sodium urea-amino acid catalyst to alcohol initiator of 1–2:1. Preferably, the reaction temperature for ring-opening polymerization is 60–140 °C, reaction time of 0.2–36 h; molar ratio of sodium urea-amino acid catalyst to cyclic monomer of 25–400:1.
[0079] The sodium salt catalyst of the urea-amino acid is prepared from isocyanate and sodium salt of amino acid, and its structural formula is as follows. :
[0080] Mode ;
[0081] Among them, R 1 It is selected from one of the following: alkyl, phenyl, benzyl, monosubstituted or polysubstituted phenyl, monosubstituted or polysubstituted benzyl with 1 to 6 carbon atoms, with or without branches; wherein the substituent of the monosubstituted or polysubstituted phenyl or benzyl is tert-butyl, methoxy, or halogen substituent.
[0082] R 2 Selected from amino acids and their side chain groups;
[0083] M is selected from Na.
[0084] Preferably, in formula I, R 1 Selected from methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, tolyl, p-methoxyphenyl, p-chlorophenyl; R 2 The group is selected from amino acids and their side chain groups, namely glycine, methyl of alanine, isopropyl of valine, isobutyl of leucine, and benzyl of phenylalanine; M is selected from Li, Na, K and Cs.
[0085] The cyclic monomer is selected from one of lactone monomers, lactide monomers, and carbonate monomers;
[0086] The structural formula of the lactone monomer is as follows: :
[0087] Mode ;
[0088] Where A is [—(CR 3 R 4 )—] NN is an integer from 2 to 10; R 3 R 4 Selected from H, halogen atoms, alkyl groups having 1 to 5 carbon atoms, and alkyl groups having 1 to 5 carbon atoms substituted with halogen atoms or hydroxyl groups; preferably, A is [—(CR 3 R 4 )—] N N is an integer from 2 to 5; R 3 R 4 Selected from H or halogen atoms.
[0089] The structural formula of the lactone monomer is as follows: :
[0090] Mode ;
[0091] Where D and B are the same or different [—(CR 5 R 6 )—] N N is an integer from 1 to 10; R 5 R 6 Selected from H, halogen atoms, alkyl groups having 1 to 5 carbon atoms, and alkyl groups having 1 to 5 carbon atoms substituted with halogen atoms or hydroxyl groups; preferably, D and B are the same or different [—(CR 5 R 6 )—] N N is an integer from 1 to 6; R 5 R 6 It is selected from H, methyl and halogen atoms.
[0092] The structural formula of the carbonate monomer is as follows: :
[0093] Mode ;
[0094] Among them, R 7 R 8 It is selected from H, halogen atom, hydroxyl group, alkyl group having 1 to 5 carbon atoms, and alkyl group having 1 to 5 carbon atoms substituted with halogen atom or hydroxyl group. Preferably, R 7 R 8 It is selected from H, halogen atom and hydroxyl group.
[0095] Preferably, the cyclic monomer is selected from one of β-propiolactone, γ-butyrolactone, δ-valerolactone, γ-chloro-δ-valerolactone, ε-caprolactone, 2-chloro-ε-caprolactone, glycolide, l-lactide, d-lactide, trimethylene carbonate, hydroxytrimethylene carbonate, and chlorotrimethylene carbonate.
[0096] The sodium salt catalysts of 13 urea-amino acids, 1-13, correspond to the following structural formulas:
[0097] .
[0098] This invention also provides a method for preparing a sodium salt catalyst of urea-amino acids, comprising the following steps:
[0099] S1. At room temperature, amino acids (0.022 mol) were added to a stirred aqueous hydroxide solution (8%, 5.06 mL, 0.022 mol) and stirred for 24-72 h. The resulting reaction mixture was the sodium salt of the amino acid.
[0100] The amino acid is selected from one or more of glycine, alanine, valine, leucine, isoleucine, and phenylalanine; the hydroxide is selected from one or more of lithium hydroxide, sodium hydroxide, potassium hydroxide, and cesium hydroxide.
[0101] S2. Place the sodium salt of the amino acid obtained in step S1 in an ice bath, and slowly add 10 mL of acetone containing 0.022 mol of isocyanate, stirring overnight.
[0102] The isocyanate is selected from one of p-methoxyphenyl isocyanate, p-toluene isocyanate, and p-chlorophenyl isocyanate.
[0103] S3. Filter the mixture obtained in step S2 to remove the solids, and concentrate and dry the liquid under vacuum to obtain a sodium salt catalyst of urea-amino acids derived from amino acids and isocyanates.
[0104] To make the technical problems, technical solutions and advantages of the present invention clearer, a detailed description will be given below in conjunction with the accompanying drawings and specific embodiments.
[0105] Example 1
[0106] The preparation method of urea-amino acid sodium salt catalyst 2 is as follows: At room temperature, 0.957 g (7.62 mmol, 1 eq) of glycine methyl ester hydrochloride and 0.736 g (7.62 mmol, 1.15 eq) of sodium bicarbonate solid were weighed into a 250 mL round-bottom flask, and 0.987 mL (7.62 mmol, 1 eq) of p-methoxyphenyl isocyanate dissolved in 100 mL of dichloromethane was added. Then, the mixture was stirred on a magnetic stirrer for 24 h. The resulting mixture was filtered to obtain a liquid, which was concentrated and dried under vacuum to constant weight to obtain urea-glycine methyl ester hydrochloride as a white solid (1.62 g, 89%). Finally, the product obtained in the previous step was subjected to an esterification reaction. 0.332 g (8.30 mmol, 1.2 eq) of sodium hydroxide solid was added to 40 mL of tetrahydrofuran aqueous solution (THF:H2O = 3:1), and the reaction was carried out for 36 h. The resulting liquid was concentrated under vacuum to remove the solvent and dried to constant weight to obtain sodium salt catalyst 2 of urea-amino acid, which was a white powder (1.34 g, 80%).
[0107] Figure 7 Catalyst 2 prepared in Example 1 1 H NMR spectrum; Figure 8 Catalyst 2 prepared in Example 1 13 CNMR spectrum.
[0108] Example 2
[0109] The preparation method of urea-amino acid sodium salt catalyst 3 is as follows: At room temperature, prepare 5.5 mL of 8% sodium hydroxide aqueous solution (8%, 0.011 mol), weigh alanine (0.98 g, 0.011 mol) into a 50 mL round-bottom flask, add the prepared sodium hydroxide aqueous solution, add a rotor and stir at room temperature for 72 h. Then, place the above-obtained reaction mixture, i.e., sodium alanine, in an ice bath, slowly add 10 mL of acetone solution of p-methoxyphenyl isocyanate (1.43 mL, 0.011 mol) and stir overnight. Finally, filter out the solid in the obtained mixture, concentrate and dry the liquid under vacuum to constant weight to obtain urea-amino acid sodium salt catalyst 3, which is a white powder (1.92 g, 67%).
[0110] Figure 9 The catalyst 3 prepared in Example 2 1 H NMR spectrum; Figure 10 The catalyst 3 prepared in Example 2 13 CNMR spectrum.
[0111] Example 3
[0112] The preparation method of urea-amino acid sodium salt catalyst 4 is as follows: At room temperature, prepare 5.5 mL of 8% sodium hydroxide aqueous solution (8%, 0.011 mol), weigh valine (1.29 g, 0.011 mol) into a 50 mL round-bottom flask, add the prepared sodium hydroxide aqueous solution, add a rotor and stir at room temperature for 48 h. Then, place the above-obtained reaction mixture, i.e., valine sodium salt, in an ice bath, and slowly add 10 mL of acetone solution of p-methoxyphenyl isocyanate (1.43 mL, 0.011 mol) and stir overnight. Finally, filter out the solid in the obtained mixture, and concentrate and dry the liquid under vacuum to constant weight to obtain urea-amino acid sodium salt catalyst 4, which is a white powder (2.70 g, 85%).
[0113] Figure 11 Catalyst 4 prepared in Example 3 1 H NMR spectrum; Figure 12 Catalyst 4 prepared in Example 3 13 CNMR spectrum.
[0114] Example 4
[0115] The preparation method of urea-amino acid sodium salt catalyst 5 is as follows: At room temperature, prepare 5.5 mL of 8% sodium hydroxide aqueous solution (8%, 0.011 mol), weigh leucine (1.44 g, 0.011 mol) into a 50 mL round-bottom flask, add the prepared sodium hydroxide aqueous solution, add a rotor and stir at room temperature for 72 h. Then, place the above-obtained reaction mixture, i.e., sodium leucine, in an ice bath, slowly add 10 mL of acetone solution of p-methoxyphenyl isocyanate (1.43 mL, 0.011 mol) and stir overnight. Finally, filter out the solid in the obtained mixture, concentrate and dry the liquid under vacuum to constant weight to obtain urea-amino acid sodium salt catalyst 5, which is a white powder (2.33 g, 70%).
[0116] Figure 13 Catalyst 5 prepared in Example 4 1 H NMR spectrum; Figure 14 Catalyst 5 prepared in Example 4 13 CNMR spectrum.
[0117] Example 5
[0118] The preparation method of urea-amino acid sodium salt catalyst 6 is as follows: At room temperature, prepare 5.5 mL of 8% sodium hydroxide aqueous solution (8%, 0.011 mol), weigh phenylalanine (1.82 g, 0.011 mol) into a 50 mL round-bottom flask, add the prepared sodium hydroxide aqueous solution, add a rotor and stir at room temperature for 72 h. Then, place the above-obtained reaction mixture, i.e., sodium phenylalanine, in an ice bath, slowly add 10 mL of acetone solution of p-methoxyphenyl isocyanate (1.43 mL, 0.011 mol) and stir overnight. Finally, filter out the solid in the obtained mixture, concentrate and dry the liquid under vacuum to constant weight to obtain urea-amino acid sodium salt catalyst 6, which is a white powder (2.96 g, 80%).
[0119] Figure 15 The catalyst 6 prepared in Example 5 1 H NMR spectrum; Figure 16 The catalyst 6 prepared in Example 5 13 CNMR spectrum.
[0120] Example 6
[0121] The preparation method of urea-amino acid sodium salt catalyst 7 is as follows: At room temperature, prepare 5.5 mL of 8% sodium hydroxide aqueous solution (8%, 0.011 mol), weigh valine (1.29 g, 0.011 mol) into a 50 mL round-bottom flask, add the prepared sodium hydroxide aqueous solution, add a rotor and stir at room temperature for 48 h. Then, place the above-obtained reaction mixture, i.e., valine sodium salt, in an ice bath, slowly add 10 mL of acetone solution of p-toluene isocyanate (1.39 mL, 0.011 mol) and stir overnight. Finally, filter out the solid in the obtained mixture, concentrate and dry the liquid under vacuum to constant weight to obtain urea-amino acid sodium salt catalyst 7, which is a white powder (1.95 g, 65%).
[0122] Figure 17 The catalyst 7 prepared in Example 6 1 H NMR spectrum; Figure 18 The catalyst 7 prepared in Example 6 13 CNMR spectrum.
[0123] Example 7
[0124] The preparation method of urea-amino acid sodium salt catalyst 8 is as follows: At room temperature, prepare 5.5 mL of 8% sodium hydroxide aqueous solution (8%, 0.011 mol), weigh valine (1.29 g, 0.011 mol) into a 50 mL round-bottom flask, add the prepared sodium hydroxide aqueous solution, add a rotor and stir at room temperature for 48 h. Then, place the above-obtained reaction mixture, i.e., valine sodium salt, in an ice bath, slowly add 10 mL of acetone solution of p-chlorophenyl isocyanate (1.41 mL, 0.011 mol) and stir overnight. Finally, filter out the solid in the obtained mixture, concentrate and dry the liquid under vacuum to constant weight to obtain urea-amino acid sodium salt catalyst 8, which is a white powder (2.35 g, 73%).
[0125] Figure 19 The catalyst 8 prepared in Example 7 1 H NMR spectrum; Figure 20 The catalyst 8 prepared in Example 7 13 CNMR spectrum.
[0126] Example 8
[0127] The preparation method of urea-amino acid sodium salt catalyst 10 is as follows: At room temperature, prepare 7.7 mL of 8% potassium hydroxide aqueous solution (8%, 0.011 mol), weigh valine (1.29 g, 0.011 mol) into a 50 mL round-bottom flask, add the prepared potassium hydroxide aqueous solution, add a rotor and stir at room temperature for 72 h. Then, place the above-obtained reaction mixture, i.e., valine sodium salt, in an ice bath, and slowly add 10 mL of acetone solution of p-methoxyphenyl isocyanate (1.43 mL, 0.011 mol) and stir overnight. Finally, concentrate and dry the obtained liquid under vacuum to constant weight to obtain urea-amino acid sodium salt catalyst 10, which is a white powder (3.01 g, 90%).
[0128] Figure 21 The catalyst 10 prepared in Example 8 1 H NMR spectrum; Figure 22 The catalyst 10 prepared in Example 8 13 C10 NMR spectrum.
[0129] Example 9
[0130] The preparation method of urea-amino acid sodium salt catalyst 11 is as follows: At room temperature, 3.3 g of 50% CsOH aqueous solution was added to 17.325 g of water to obtain an 8% cesium hydroxide aqueous solution (8%, 0.011 mol). Valine (1.29 g, 0.011 mol) was weighed into a 50 mL round-bottom flask, and the prepared sodium hydroxide aqueous solution was added. After adding a rotor, the mixture was stirred at room temperature for 48 h. Then, the above-obtained reaction mixture, i.e., valine sodium salt, was placed in an ice bath, and an acetone solution (10 mL) of p-methoxyphenyl isocyanate (1.43 mL, 0.011 mol) was slowly added dropwise and stirred overnight. Finally, the solid in the obtained mixture was filtered off, and the liquid was concentrated and dried under vacuum to constant weight to obtain urea-amino acid sodium salt catalyst 11, which is a pale yellow powder (3.37 g, 77%).
[0131] Figure 23 The catalyst 11 prepared in Example 9 1 H NMR spectrum; Figure 24 The catalyst 11 prepared in Example 9 13 C10 NMR spectrum.
[0132] Example 10
[0133] In a 10 mL polymerization tube, L-lactide (0.24 g, 1.67 mmol), sodium urea-amino acid catalyst 4 (0.0096 g, 0.0332 mmol), and phenylpropanol (4.5 μL, 0.0332 mmol) were added. The mixture was magnetically stirred at 140 °C for 2 hours. The reaction was then stopped, and a small amount of dichloromethane was added dropwise to dissolve the mixture. The resulting solution was then slowly added dropwise to cold methanol, resulting in the precipitation of a white polymer. After centrifugation and vacuum drying, 0.14 g of the product was obtained, with a conversion rate of 95%. The number-average molecular weight (Mn) of the poly-L-lactide was 6000 g / mol, and the molecular weight distribution (PDI) was 1.10.
[0134] Figure 1 The polylactic acid obtained in Example 10 is a polylactic acid. 1 H NMR spectrum; Figure 2 The spectrum of polyl-lactide prepared in Example 10 is obtained by size exclusion chromatography.
[0135] Example 11
[0136] In a 10 mL polymerization tube, trimethylene carbonate (0.0847 g, 0.83 mmol), sodium urea-amino acid catalyst 4 (0.0096 g, 0.0332 mmol), and phenylpropanol (4.5 μL, 0.0332 mmol) were added. The mixture was magnetically stirred at 60 °C for 4 hours. The reaction was then stopped, and a small amount of dichloromethane was added dropwise to dissolve the mixture. The resulting solution was then slowly added dropwise to cold methanol, resulting in the precipitation of a white polymer. After centrifugation and vacuum drying, 0.05 g of the product was obtained, with a conversion rate of 98%. The number-average molecular weight (Mn) of the polyhydroxytrimethylene carbonate was 2900 g / mol, and the molecular weight distribution (PDI) was 1.10.
[0137] Figure 3 The polytrimethylene carbonate prepared in Example 11 1 H NMR spectrum; Figure 4 The spectrum is from the size exclusion chromatography analysis of the polytrimethylene carbonate prepared in Example 11.
[0138] Example 12
[0139] In a 10 mL polymerization tube, L-lactide (0.24 g, 1.67 mmol), sodium urea-amino acid catalyst 10 (0.0101 g, 0.0332 mmol), and benzyl alcohol (4.5 μL, 0.0332 mmol) were added. The mixture was magnetically stirred at 140 °C for 70 minutes. The reaction was then stopped, and a small amount of dichloromethane was added dropwise to dissolve the mixture. The resulting solution was then slowly added dropwise to cold methanol, resulting in the precipitation of a white polymer. After centrifugation and vacuum drying, 0.21 g of the product was obtained, with a conversion rate of 92%. The number-average molecular weight (Mn) of the poly-L-lactide was 5400 g / mol, and the molecular weight distribution (PDI) was 1.16.
[0140] Figure 5 The spectrum of polyl-lactide prepared in Example 12 is obtained by size exclusion chromatography.
[0141] Example 13
[0142] In a 10 mL polymerization tube, L-lactide (0.24 g, 1.67 mmol), sodium salt catalyst 11 of urea-amino acids (0.0132 g, 0.0332 mmol), and phenylpropanol (9.0 μL, 0.0332 mmol) were added. The mixture was magnetically stirred at 140 °C for 70 minutes. The reaction was then stopped, and a small amount of dichloromethane was added dropwise to dissolve the mixture. The resulting solution was then slowly added dropwise to cold methanol, resulting in the precipitation of a white polymer. After centrifugation and vacuum drying, 0.22 g of the product was obtained, with a conversion rate of 96%. The number-average molecular weight (Mn) of poly-L-lactide was 6100 g / mol, and the molecular weight distribution (PDI) was 1.18.
[0143] Figure 6 The spectrum of polyl-lactide prepared in Example 13 is obtained by size exclusion chromatography.
[0144] Example 14
[0145] In a 10 mL polymerization tube, L-lactide (0.24 g, 1.67 mmol), sodium urea-amino acid catalyst 2 (0.0082 g, 0.0332 mmol), and phenylpropanol (4.5 μL, 0.0332 mmol) were added. The mixture was magnetically stirred at 140 °C for 2 hours. The reaction was then stopped, and a small amount of dichloromethane was added dropwise to dissolve the mixture. The resulting solution was then slowly added dropwise to cold methanol, resulting in the precipitation of a white polymer. After centrifugation and vacuum drying, 0.16 g of the product was obtained, with a conversion rate of 80%. The number-average molecular weight (Mn) of the poly-L-lactide was 5500 g / mol, and the molecular weight distribution (PDI) was 1.05.
[0146] Example 15
[0147] In a 10 mL polymerization tube, L-lactide (0.24 g, 1.67 mmol), sodium urea-amino acid catalyst 3 (0.0086 g, 0.0332 mmol), and phenylpropanol (4.5 μL, 0.0332 mmol) were added. The mixture was magnetically stirred at 140 °C for 2 hours. The reaction was then stopped, and a small amount of dichloromethane was added dropwise to dissolve the mixture. The resulting solution was then slowly added dropwise to cold methanol, resulting in the precipitation of a white polymer. After centrifugation and vacuum drying, 0.20 g of the product was obtained, with a conversion rate of 89%. The number-average molecular weight (Mn) of the poly-L-lactide was 6400 g / mol, and the molecular weight distribution (PDI) was 1.08.
[0148] Example 16
[0149] In a 10 mL polymerization tube, L-lactide (0.24 g, 1.67 mmol), sodium urea-amino acid catalyst 5 (0.0100 g, 0.0332 mmol), and phenylpropanol (4.5 μL, 0.0332 mmol) were added. The mixture was magnetically stirred at 140 °C for 2 hours. The reaction was then stopped, and a small amount of dichloromethane was added dropwise to dissolve the resulting mixture. The solution was then slowly added dropwise to cold methanol, resulting in the precipitation of a white polymer. After centrifugation and vacuum drying, 0.19 g of the product was obtained, with a conversion rate of 81%. The number-average molecular weight (Mn) of the poly-L-lactide was 5900 g / mol, and the molecular weight distribution (PDI) was 1.10.
[0150] Example 17
[0151] In a 10 mL polymerization tube, L-lactide (0.24 g, 1.67 mmol), sodium urea-amino acid catalyst 6 (0.0112 g, 0.0332 mmol), and phenylpropanol (4.5 μL, 0.0332 mmol) were added. The mixture was magnetically stirred at 140 °C for 2 hours. The reaction was then stopped, and a small amount of dichloromethane was added dropwise to dissolve the resulting mixture. The solution was then slowly added dropwise to cold methanol, resulting in the precipitation of a white polymer. After centrifugation and vacuum drying, 0.17 g of the product was obtained, with a conversion rate of 77%. The number-average molecular weight (Mn) of the poly-L-lactide was 5600 g / mol, and the molecular weight distribution (PDI) was 1.10.
[0152] Example 18
[0153] In a 10 mL polymerization tube, L-lactide (0.24 g, 1.67 mmol), sodium salt catalyst 7 of urea-amino acids (0.0090 g, 0.0332 mmol), and phenylpropanol (4.5 μL, 0.0332 mmol) were added. The mixture was magnetically stirred at 140 °C for 2 hours. The reaction was then stopped, and a small amount of dichloromethane was added dropwise to dissolve the mixture. The resulting solution was then slowly added dropwise to cold methanol, resulting in the precipitation of a white polymer. After centrifugation and vacuum drying, 0.20 g of the product was obtained, with a conversion rate of 86%. The number-average molecular weight (Mn) of poly-L-lactide was 6200 g / mol, and the molecular weight distribution (PDI) was 1.08.
[0154] Example 19
[0155] In a 10 mL polymerization tube, L-lactide (0.24 g, 1.67 mmol), sodium urea-amino acid catalyst 8 (0.0097 g, 0.0332 mmol), and phenylpropanol (4.5 μL, 0.0332 mmol) were added. The mixture was magnetically stirred at 140 °C for 2 hours. The reaction was then stopped, and a small amount of dichloromethane was added dropwise to dissolve the mixture. The resulting solution was then slowly added dropwise to cold methanol, resulting in the precipitation of a white polymer. After centrifugation and vacuum drying, 0.19 g of the product was obtained, with a conversion rate of 85%. The number-average molecular weight (Mn) of the poly-L-lactide was 6100 g / mol, and the molecular weight distribution (PDI) was 1.09.
[0156] Example 20
[0157] In a 10 mL polymerization tube, L-lactide (0.24 g, 1.67 mmol), sodium urea-amino acid catalyst 10 (0.0101 g, 0.0332 mmol), and phenylpropanol (4.5 μL, 0.0332 mmol) were added. The mixture was magnetically stirred at 140 °C for 2 hours. The reaction was then stopped, and a small amount of dichloromethane was added dropwise to dissolve the resulting mixture. The solution was then slowly added dropwise to cold methanol, resulting in the precipitation of a white polymer. After centrifugation and vacuum drying, 0.23 g of the product was obtained, with a conversion rate of 98%. The number-average molecular weight (Mn) of the poly-L-lactide was 7100 g / mol, and the molecular weight distribution (PDI) was 1.10.
[0158] Example 21
[0159] In a 10 mL polymerization tube, L-lactide (0.24 g, 1.67 mmol), sodium urea-amino acid catalyst 11 (0.0132 g, 0.0332 mmol), and phenylpropanol (4.5 μL, 0.0332 mmol) were added. The mixture was magnetically stirred at 140 °C for 2 hours. The reaction was then stopped, and a small amount of dichloromethane was added dropwise to dissolve the resulting mixture. The solution was then slowly added dropwise to cold methanol, resulting in the precipitation of a white polymer. After centrifugation and vacuum drying, 0.22 g of the product was obtained, with a conversion rate of 95%. The number-average molecular weight (Mn) of the poly-L-lactide was 6900 g / mol, and the molecular weight distribution (PDI) was 1.10.
[0160] This invention provides a method for preparing polyester by ring-opening polymerization of cyclic monomers catalyzed by a sodium salt catalyst of urea-amino acids. This bulk polymerization method eliminates the need for introducing additional reaction solvents into the reaction system. Furthermore, the high reaction temperature significantly reduces the sensitivity of the reaction system to air and water, which is beneficial for industrial production. This preparation method offers significant advantages such as high efficiency, simple operation, and wide applicability. It allows for the controlled synthesis of polyesters with target molecular weights, yielding products with high yields, no monomer residue, and clean appearance.
[0161] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.
Claims
1. A method for preparing polyester by ring-opening polymerization of cyclic monomers catalyzed by a sodium salt catalyst of urea-amino acids, characterized in that, In the presence of an initiator, cyclic monomers undergo ring-opening polymerization under the catalysis of a sodium salt catalyst of urea-amino acid as shown in Formula I; after the polymerization reaction is completed, a good solvent is added to the mixture obtained from the reaction, the mixture is filtered to obtain a filtrate, the filtrate is slowly added to a precipitation solvent, centrifuged and dried to obtain a polyester. The initiator is an alcohol-based initiator; The sodium salt catalyst of the urea-amino acid is prepared from isocyanate and sodium salt of amino acid, and its structural formula is as follows. : Mode ; Among them, R 1 The alkyl, phenyl, benzyl, monosubstituted or polysubstituted phenyl, monosubstituted or polysubstituted benzyl groups with 1 to 6 carbon atoms are selected; the substituents of the monosubstituted or polysubstituted phenyl or benzyl groups are tert-butyl, methoxy, or halogen substituents. R 2 Selected from amino acids and their side chain groups; M is selected from Na; The cyclic monomer is selected from lactone monomers, lactide monomers, and carbonate monomers; The structural formula of the lactone monomer is as follows: : Mode ; Where A is [—(CR 3 R 4 )—] N N is an integer from 2 to 10; R 3 R 4 Selected from H, halogen atoms, alkyl groups having 1 to 5 carbon atoms, and alkyl groups having 1 to 5 carbon atoms substituted with halogen atoms or hydroxyl groups; The structural formula of the lactone monomer is as follows: : Mode ; Where D and B are the same or different [—(CR 5 R 6 )—] N N is an integer from 1 to 10; R 5 R 6 Selected from H, halogen atoms, alkyl groups having 1 to 5 carbon atoms, and alkyl groups having 1 to 5 carbon atoms substituted with halogen atoms or hydroxyl groups; The structural formula of the carbonate monomer is as follows: : Mode ; Among them, R 7 R 8 Selected from H, halogen atom, hydroxyl group, alkyl group having 1 to 5 carbon atoms, and alkyl group having 1 to 5 carbon atoms substituted by halogen atom or hydroxyl group.
2. The method for preparing polyester by ring-opening polymerization of cyclic monomers catalyzed by a sodium salt catalyst based on urea-amino acids according to claim 1, characterized in that, In formula I, R 1 Selected from methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, tolyl, p-methoxyphenyl, p-chlorophenyl; R 2 The amino acids are selected from their side chain groups, namely glycine, methyl of alanine, isopropyl of valine, isobutyl of leucine, and benzyl of phenylalanine.
3. The method for preparing polyester by ring-opening polymerization of cyclic monomers catalyzed by a sodium salt catalyst based on urea-amino acids according to claim 1, characterized in that, The sodium salt catalysts of 13 urea-amino acids, 1-13, correspond to the following structural formulas: 。 4. The method for preparing polyester by ring-opening polymerization of cyclic monomers catalyzed by a sodium salt catalyst based on urea-amino acids according to claim 1, characterized in that, The alcohol initiator is selected from one or more of methanol, ethanol, n-propanol, isopropanol, n-butanol, tert-butanol, benzyl alcohol, phenethyl alcohol, and phenylpropanol.
5. The method for preparing polyester by ring-opening polymerization of cyclic monomers catalyzed by a sodium salt catalyst based on urea-amino acids according to claim 1, characterized in that, The cyclic monomer is selected from one of β-propiolactone, γ-butyrolactone, δ-valerolactone, γ-chloro-δ-valerolactone, ε-caprolactone, 2-chloro-ε-caprolactone, glycolide, l-lactide, d-lactide, trimethylene carbonate, hydroxytrimethylene carbonate, and chlorotrimethylene carbonate.
6. The method for preparing polyester by ring-opening polymerization of cyclic monomers catalyzed by a sodium salt catalyst based on urea-amino acids according to claim 1, characterized in that, The good solvent is selected from one of dichloromethane, trichloromethane, toluene, benzene, acetone or tetrahydrofuran; The precipitation solvent is selected from methanol or ethanol.
7. The method for preparing polyester by ring-opening polymerization of cyclic monomers catalyzed by a sodium salt catalyst based on urea-amino acids according to claim 1, characterized in that, The reaction conditions for ring-opening polymerization are as follows: reaction temperature is 40~200℃, reaction time is 0.1~90h; the molar ratio of sodium urea-amino acid catalyst to cyclic monomer is 10~800:1; and the molar ratio of sodium urea-amino acid catalyst to alcohol initiator is 1~2:
1.
8. A method for preparing a sodium salt catalyst of urea-amino acids, characterized in that, The structural formula of the sodium salt catalyst of urea-amino acid is as follows: : Mode ; Among them, R 1 The alkyl, phenyl, benzyl, monosubstituted or polysubstituted phenyl, monosubstituted or polysubstituted benzyl groups with 1 to 6 carbon atoms are selected; the substituents of the monosubstituted or polysubstituted phenyl or benzyl groups are tert-butyl, methoxy, or halogen substituents. R 2 Selected from amino acids and their side chain groups; M is selected from Na; The preparation method of the sodium salt catalyst of urea-amino acid includes the following steps: S1. At room temperature, amino acids are added to a stirred aqueous hydroxide solution and stirred for 24-72 h. The resulting reaction mixture is the sodium salt of the amino acid. S2. Place the sodium salt of the amino acid obtained in step S1 in an ice bath and slowly add acetone of isocyanate while stirring overnight. S3. Filter the mixture obtained in step S2 to remove the solids, and concentrate and dry the liquid under vacuum to obtain a sodium salt catalyst of urea-amino acids derived from amino acids and isocyanates.
9. The method for preparing the sodium salt catalyst of urea-amino acids according to claim 8, characterized in that, In step S1, the amino acid is selected from one or more of glycine, alanine, valine, leucine, isoleucine, and phenylalanine. The hydroxide is selected from one or more of lithium hydroxide, sodium hydroxide, potassium hydroxide, and cesium hydroxide; In step S2, the isocyanate is selected from one of p-methoxyphenyl isocyanate, p-toluene isocyanate, and p-chlorophenyl isocyanate.