A dimethylene pyridine bridged aminobisphenoxide alkali metal complex, its preparation method and use

Abstract

The application discloses a kind of dimethylene pyridine bridged double aminophenol alkali metal complex and its preparation method and application in high activity catalytic lactone ring-opening polymerization.The preparation method includes the following steps: dimethylene pyridine bridged double aminophenol ligand is reacted with metal hydride in organic medium, then is filtered, concentrated, and the target dimethylene pyridine bridged double aminophenol alkali metal complex is obtained by recrystallization step.The dimethylene pyridine bridged double aminophenol alkali metal complex of the application is a kind of high-efficiency lactone ring-opening polymerization catalyst, and can be used for the polymerization reaction of high activity catalytic lactide etc.The dimethylene pyridine bridged double aminophenol alkali metal complex of the application has very obvious advantages: raw material is easy to obtain, synthesis route is simple, has high catalytic activity, can obtain high molecular weight polyester material, meets the needs of industrial department.The structural formula is as shown below:

Description

Technical Field

[0001] This invention relates to a class of dimethylenepyridine-bridged bisaminophenoxy alkali metal complexes, and the application of such complexes in lactone polymerization. Background Technology

[0002] To address the shortage of fossil fuels, there is a growing demand for suitable alternatives to petroleum-derived plastics. Polylactide (PLA), also known as polylactic acid, has been widely researched and applied in various fields, including biomedicine, over the past two decades due to its excellent biodegradability and biocompatibility, and its similar physical and mechanical properties to some polyolefin products. Used PLA products can be remelted, recycled, or composted, where they are naturally degraded into non-toxic and harmless carbon dioxide and water. Compared to petroleum-based polyolefin products, PLA offers significant advantages in sustainable production and post-processing.

[0003] The properties of polylactide (PL) are determined by its microstructure. By utilizing metal complexes to catalyze the ring-opening polymerization of different types of lactide monomers, such as L-lactide (L-LA), D-lactide (D-LA), meso-lactide (meso-LA), and racemic lactide (rac-LA), PLAs with various microstructures can be obtained. Random PLAs are amorphous, brittle, lack stretchability, and degrade rapidly; isotactic PLAs or isotactic block PLAs are semi-crystalline materials with high melting points, good thermodynamic properties, and stretchability. Therefore, developing novel metal complex catalysts to achieve highly active and controllable synthesis of PLAs with different microstructures has become a major research direction in this field.

[0004] Among the metal complex catalysts studied to date, alkali metal complexes have attracted attention due to their high catalytic activity for lactide polymerization. In 2011, the Mountford group synthesized a [OOO]-type tridentate bisphenol oxy potassium complex, which exhibited high activity and controllability for the ring-opening polymerization of rac-LA. Under conditions of room temperature, dichloromethane, and the addition of 1 equivalent of benzyl alcohol, it could completely convert the monomer in 5 minutes to catalyze the polymerization of 300 equivalents of rac-LA (Inorg. Chem., 2011, 50, 3589–3595). In 2015, the Francesca group synthesized a tetranuclear alkali metal complex, which could completely convert the monomer in 3 minutes to catalyze the polymerization of 250 equivalents of rac-LA under conditions of room temperature, tetrahydrofuran, and the addition of 1 equivalent of benzyl alcohol, demonstrating good polymerization controllability (Dalton Trans., 2015, 44, 20216-20231). In 2015, Cano's group synthesized iminophenoxy alkali metal complexes. The potassium complex exhibited high catalytic activity for the ring-opening polymerization of rac-LA. At room temperature, with the addition of 1 equivalent of benzyl alcohol as an initiator, the monomer conversion of 100 equivalents of rac-LA reached 99% in 30 seconds. Under the same conditions, the lithium complex showed lower activity, requiring 45 minutes to completely convert 100 equivalents of monomer (Organometallics, 2015, 34, 477–487). In 2014, Wu's group synthesized purine monophenoloxy sodium and potassium complexes containing crown ether structures. These complexes exhibited high catalytic activity for the polymerization of racemic lactide. At room temperature, with the addition of 10 equivalents of benzyl alcohol, the polymerization of 500 equivalents of rac-LA was completely converted in only 2 minutes (Macromolecules, 2014, 47, 7789-7796). In 2015, Wu's group synthesized a potassium phenoxy complex with a crown ether structure as an auxiliary ligand and substituted with triphenylmethyl groups. This complex exhibited high catalytic activity for rac-LA polymerization. In toluene at room temperature, the addition of 10 equivalents of benzyl alcohol catalyzed the complete conversion of 1000 equivalents of rac-LA in just 1 minute, with good polymerization controllability (Catal. Sci. Technol., 2016, 6, 515–520). In 2017, Wang's group synthesized an iminophenoxy crown ether potassium complex. This type of complex exhibited high catalytic activity at room temperature. In toluene at room temperature, the addition of 1 equivalent of benzyl alcohol catalyzed the complete conversion of 100 equivalents of rac-LA in just 1 minute (RSC Adv., 2017, 7, 24055–24063).

[0005] Significant breakthroughs have been achieved in the research of lactide polymerization, with polylactide exhibiting a certain degree of regularity obtained through the effective design of metal complex catalyst structures. Most alkali metal complexes with high activity for lactide ring-opening polymerization contain crown ethers as auxiliary ligands; however, crown ethers are toxic and unsuitable for industrial production. Therefore, the development of highly active and biocompatible alkali metal complexes is of great significance for the industrial application of lactide ring-opening polymerization. Summary of the Invention

[0006] One of the objectives of this invention is to disclose a class of dimethylenepyridine-bridged bisaminophenoxy alkali metal complexes.

[0007] The second objective of this invention is to disclose a method for preparing a class of dimethylenepyridine-bridged bisaminophenoxy alkali metal complexes.

[0008] The third objective of this invention is to disclose the application of a class of dimethylenepyridine-bridged bisaminophenoxy alkali metal complexes in lactone polymerization.

[0009] The technical concept of this invention: Salan-type aminobisphenol ligands are characterized by readily available raw materials, simple synthesis, and tunable structure. By changing substituents to adjust electronic and steric effects, the catalytic activity and stereoselectivity of metal complexes can be effectively controlled. However, they only have four coordination sites, which is insufficient for stabilizing the metal center in alkali metal catalysts. This invention proposes to introduce a pyridine group into the Salan ligand, utilizing its five chelating coordination sites to stabilize the alkali metal center and apply it to lactide polymerization. By changing the substituents in the ligand, the Lewis acidity of the metal center and the steric hindrance around the metal center can be adjusted, aiming to achieve highly active and controllable catalytic ring-opening polymerization of racemic lactide using alkali metal complexes.

[0010] The present invention provides a dimethylenepyridine-bridged bisaminophenol ligand (I) and its alkali metal complex (II), characterized in that they have the following general formula:

[0011]

[0012] In equations (I) and (II):

[0013] R 1 ~R 2 Representing C1 to C respectively 20 Alkyl groups with straight, branched, or cyclic structures, C7–C6 30 Mono- or polyaryl substituted alkyl groups, or halogens;

[0014] R 3 Representing C1 to C 20 Alkyl groups with straight, branched, or cyclic structures, C7–C630 Mono- or polyaryl substituted alkyl groups, C6-C 18 aryl;

[0015] n is 0 or 1;

[0016] M represents Na and K.

[0017] More characteristically, in equations (I) and (II), R 1 ~R 2 Preferably, they are C1-C8 straight-chain, branched, or cyclic alkyl groups, C7-C8... 20 Mono- or polyaryl substituted alkyl groups, or halogens; R 3 Preferably, it is an alkyl group with a C1-C8 straight chain, branched chain, or cyclic structure, and a C7-C8 alkyl group. 20 Mono- or polyaryl substituted alkyl groups, C6-C 12 Aryl groups.

[0018] Preferably, in formulas (I) and (II), R 1 ~R 2 They are methyl, isopropyl, tert-butyl, cumyl, and triphenylmethyl, respectively; R 3 The compounds are methyl, ethyl, tert-butyl, n-butyl, cyclopentyl, cyclohexyl, benzyl, and phenyl.

[0019] The preferred structure of the dimethylenepyridine-bridged bisaminophenol ligand is as follows:

[0020]

[0021]

[0022] The preferred structure of the dimethylenepyridine-bridged bisaminophenoxy alkali metal complex is as follows:

[0023]

[0024]

[0025] The preparation method of the dimethylenepyridine-bridged bisaminophenol ligand (I) and its alkali metal complex (II) of the present invention includes the following steps:

[0026]

[0027] The 2-bromomethyl-4,6-disubstituted phenol of formula (III) and the 2,6-di(substituted aminomethyl)pyridine of formula (IV) were reacted in an organic medium in the presence of an alkylamine at a temperature of 0–90 °C for a time of 2–72 hours. Then, the dimethylenepyridine-bridged diaminophenol ligand compound (I) was collected from the reaction product.

[0028] Optionally, the dimethylpyridine-bridged bisaminophenol ligand compound shown in formula (I) is reacted with a metal hydride in an organic medium at a temperature of 0–100 °C for 2–24 hours, and then the dimethylpyridine-bridged bisaminophenol oxyalkali metal complex (II) is collected from the reaction product.

[0029] In the above preparation method, the substituent R 1 ~R 3 It is consistent with the corresponding groups of the dimethylenepyridine-bridged bisaminophenol ligand (I) and its alkali metal complex (II) as described in this invention;

[0030] The alkylamine is triethylamine, tributylamine, or triisopropylamine;

[0031] The metal hydride MH is NaH or KH;

[0032] The molar ratio of dimethylpyridine-bridged bisaminophenol ligand compound (I) to the metal hydride is 1:2.0 to 4.0; preferably 1:2.2 to 2.5.

[0033] The organic medium is selected from one or more of tetrahydrofuran, diethyl ether, toluene, benzene, petroleum ether, and n-hexane.

[0034] In the preparation method of the dimethylenepyridine-bridged bisaminophenol ligand (I) of the present invention, the synthesis of 2-bromomethyl-4,6-disubstituted phenol as shown in formula (III) can be obtained by reacting 2,4-substituted phenol with paraformaldehyde in a 33% hydrogen bromide acetic acid solution according to the following route (Inorg. Chem., 2002, 41, 3656; J. Org. Chem., 1994, 59, 1939):

[0035]

[0036] In the preparation method of the dimethylenepyridine-bridged bisaminophenol ligand (I) of the present invention, the synthesis of 2,6-bis(substituted aminomethyl)pyridine as shown in formula (IV) can be carried out according to the following route (Chem.-Eur.J., 2005, 11(8), 2385-2394), that is, 2,6-pyridinedimethylethanol is oxidized to obtain 2,6-pyridinedicarboxaldehyde, and then reacted with primary amine R 3 The reaction of NH2 followed by reduction with a reducing agent yields:

[0037]

[0038] The synthesis of 2,6-bis(substituted aminomethyl)pyridine as shown in formula (IV) can also be carried out via the following route, referring to the method in the literature (Nat. Commun., 2021, 12, 1572): reacting 2,6-pyridinediethanol with hydrogen bromide to give 2,6-dibromomethylpyridine, followed by reaction with a primary amine R. 3 The reaction of NH2 followed by reduction with a reducing agent yields:

[0039]

[0040] In the above preparation method, the reducing agent is a common reducing agent in organic reactions, such as sodium borohydride or lithium aluminum hydride.

[0041] The dimethylenepyridine-bridged bisaminophenoloxy alkali metal complex described in this invention is a highly efficient lactone polymerization catalyst that can be used for the polymerization of L-lactide, D-lactide, rac-lactide, and meso-lactide, in the form of solution polymerization and melt polymerization.

[0042] Using the dimethylenepyridine-bridged bisaminophenoxy alkali metal complex of the present invention as a catalyst, lactide is polymerized at -70 to 250°C, preferably -70 to 180°C, and most preferably -70 to 140°C; the molar ratio of catalyst to monomer during polymerization is 1:1 to 10000, preferably 1:20 to 5000, and most preferably 1:100 to 3000.

[0043] Using the dimethylenepyridine-bridged bisaminophenoxy alkali metal complex described in this invention as a catalyst, a certain amount of alcohol can be added as a chain transfer agent to control the molecular weight of the resulting polymer during the catalytic polymerization of lactones. The molar ratio of catalyst to alcohol and lactide monomer during polymerization is 1:1–50:1–10000, preferably 1:1–20:20–5000, and most preferably 1:1–10:100–3000; the alcohol is C1–C6. 10 Alkyl alcohols with straight-chain, branched, or cyclic structures, C7–C6 20 Mono- or polyaryl substituted alkyl alcohols, preferably isopropanol or benzyl alcohol.

[0044] Using the dimethylenepyridine-bridged bisaminophenoxy alkali metal complex of the present invention as a catalyst, a solvent may also be included in the catalytic polymerization of lactones. The solvent is preferably one or more of toluene, tetrahydrofuran, dichloromethane, n-hexane, petroleum ether, m-xylene, o-xylene, mesitylene, and trichlorobenzene. Specifically, it may be one, two, three, four, or five kinds of solvents.

[0045] The catalyst provided by this invention is easy to prepare and has stable properties. Furthermore, the catalyst exhibits high catalytic activity and controllability in the ring-opening polymerization of lactide, and highly controllable polymerization can be achieved by adjusting the ligand structure and polymerization conditions. The invention is further illustrated below with specific embodiments, but is not limited thereto. Detailed Implementation

[0046] Example 1

[0047] ligand L 1 Synthesis of H2

[0048] (1) Synthesis of 2,6-pyridinedicarboxaldehyde

[0049]

[0050] Under argon protection, 2,6-pyridinediethanol (5.40 g, 38.8 mmol), 40 mL of 1,4-dioxane, and selenium dioxide (4.44 g, 43.5 mmol) were added sequentially to a flask, and the mixture was heated to 110 °C for 5 h. The reaction mixture was filtered to obtain a yellow solution, which was concentrated until slightly turbid, and 15 mL of petroleum ether was slowly added. The mixture was then placed in a refrigerator for crystallization. The obtained solid was dried under vacuum to remove the solvent, yielding a light brown solid of 2,6-pyridinedicarboxaldehyde (4.83 g, 90%).

[0051] 1 H NMR (400MHz, CDCl3): δ10.15(s,2H,-CHO),8.17(d, 3 J = 7.6 Hz, 2H, PyH), 8.08 (t, 3 J = 7.6 Hz, 1H, PyH.

[0052] (2) Synthesis of 2,6-bis(benzylaminomethyl)pyridine

[0053]

[0054] 2,6-pyridinedicarboxaldehyde (1.35 g, 10.0 mmol) and 30 mL of methanol were added to a 100 mL round-bottom flask, followed by benzylamine (2.2 mL, 20 mmol). The mixture was heated under reflux for 12 hours. After cooling, NaBH4 (1.51 g, 40.0 mmol) was slowly added. The mixture was heated to 70 °C and reacted for 12 hours. Methanol was removed under vacuum, and the reaction was quenched with a saturated potassium carbonate solution. The mixture was poured into a separatory funnel, extracted with dichloromethane, dried over anhydrous sodium sulfate, filtered, and the solvent was removed from the filtrate to obtain 2,6-bis(benzylaminomethyl)pyridine (3.11 g, 98%).

[0055] 1H NMR (400MHz, CDCl3): δ 7.61 (t, 3 J=7.6Hz,1H,Py-H),7.40–7.30(m,8H,Ar-Hand Ph-H),7.25(tt, 3 J = 7.0 Hz 4 J = 1.5 Hz, 2H, Ar-H), 7.19 (d, 3 J=7.6Hz,2H,Py-H),3.93(s,4H,Py-CH2-),3.86(s,4H,Ph-CH2-),2.39(br s,2H,-NH-).

[0056] (3) Ligand L 1 Synthesis of H2

[0057]

[0058] 2,6-Bis(benzylaminomethyl)pyridine (3.11 g, approximately 9.82 mmol) and 60 mL of dichloromethane were added to a 100 mL round-bottom flask, followed by 11 mL of triethylamine. Then, 2-bromomethyl-4,6-di-tert-butylphenol (6.00 g, 20.0 mmol) was added, resulting in a yellow reaction solution. The reaction was allowed to proceed for 24 h. After completion, the reaction solution was poured into 50 mL of water, shaken, and separated. The solution was extracted with dichloromethane, and the combined organic phases were washed with water. The mixture was dried over anhydrous sodium sulfate, filtered, and dried under vacuum to obtain a yellow oily substance. Recrystallization from dichloromethane / methanol yielded 5.89 g of a pale yellow solid, with a yield of 78%.

[0059] 1 H NMR(400MHz, CDCl3): δ10.77(br s,2H,ArOH),7.60(t, 3 J = 7.7 Hz, 1H, Py-H), 7.35 (d, 3 J = 7.3 Hz, 4H, Ph-H), 7.29 (t, 3 J = 7.3 Hz, 4H, Ph-H), 7.23 (t, 3 J = 7.3 Hz, 2H, Ph-H), 7.21 (d, 4 J = 2.3 Hz, 2H, Ar-H), 7.18 (d, 3 J = 7.7 Hz, 2H, Py-H), 6.87 (d, 4 J=2.3Hz,2H,Ar-H),3.84(s,4H,Py-CH2-),3.79(s,4H,Ar-CH2-),3.72(s,4H,Ph-CH2-),1.48(s,18H,-C(CH3)3),1.28(s,18H,-C(CH3)3).13 C{ 1 H}NMR (100MHz, CDCl3, 298K): δ157.62,153.99,140.61,137.53,137.30,137.08,135.63,129.96,12 9.66,128.68,128.36,127.63,127.28,124.43,124.19,123.24,122.94,122.24,121.94,121.67(All Ar-C),58.92(Py-CH2),58.51(Ar-CH2),58.10(Ph-CH2),35.09(C(CH3)3),34.26(C(CH3)3),31.89,31.77,29.80(all C(CH3)3).ESI-HRMS calcd.for C 51 H 67 N3O2+H + [M+H]:754.5307; found:754.5309.

[0060] Example 2

[0061] ligand L 2 Synthesis of H2

[0062] (1) Synthesis of 2,6-bis(cyclohexylaminomethyl)pyridine

[0063]

[0064] Except for the use of cyclohexylamine (4.00 g, 40.3 mmol), 2,6-pyridinedicarboxaldehyde (2.70 g, 20.0 mmol), and NaBH4 (3.20 g, 80.0 mmol) as raw materials, the process was the same as that used in the synthesis of 2,6-bis(benzylaminomethyl)pyridine, yielding 2,6-bis(cyclohexylaminomethyl)pyridine (4.49 g, 75%).

[0065] 1 H NMR (400MHz, CDCl3): δ 7.53 (t, 3 J = 7.7 Hz, 1H, Py-H), 7.10 (d, 3 J=7.7Hz,2H,Py-H),3.87(s,4H,-CH2-),2.45(tt, 3 J=10.1,3.8Hz,2H,CH of cyclohexyl),2.32(br s,2H,-NH-),1.90(br d, 3J=11.5Hz,4H,CH2 of cyclohexyl),1.74–1.65(m,4H,CH2 ofcyclohexyl),1.62–1.53(m,2H,CH2 of cyclohexyl),1.28-1.04(m,10H,CH2 ofcyclohexyl).

[0066] (2) Ligand L 2 Synthesis of H2

[0067]

[0068] Except for the use of 2,6-bis(cyclohexylaminomethyl)pyridine (3.01 g, 10.0 mmol) and 2-bromomethyl-4,6-di-tert-butylphenol (6.00 g, 20.0 mmol) as raw materials, the reaction procedure was the same as that of L. 1 With the same H2, a yellow solid (4.52 g, 61%) was finally obtained.

[0069] 1 H NMR (400MHz, CDCl3): δ11.17(br s,2H,Ar-OH),7.56(t, 3 J=7.7Hz,1H,Py-H),7.21-7.16(m,4H,Ar-H&Py-H),6.84(d, 4 J=2.4Hz,2H,Ar-H),3.85(s,4H,Py-CH2),3.81(s,4H,Ar-CH2),2.63(tt, 3 J=11.5,3.0Hz,2H,CH2 of cyclohexyl),1.94(br d, 3 J=11.5Hz,4H,CH2of cyclohexyl),1.77(br d, 3 J=12.0Hz,4H,CH2 of cyclohexyl),1.59(br d, 3 J=10.6Hz,2H,CH of cyclohexyl),1.42(s,18H,Ar-C(CH3)3)1.46-1.38(m,2H,CH2 ofcyclohexyl),1.27(s,Ar-C(CH3)3),1.31-1.22(m,2H,CH2 of cyclohexyl),1.19-1.01(m,6H,CH2 of cyclohexyl). 13 C{ 1H}NMR (100MHz, CDCl3, 298K): δ158.47,154.47,140.39,137.27,136.99,136.47,124.05,123.81,122.90,122.60,121.89,121.70,121.40 (all Ar-C),58.88,58.68(Py-CH2N-),55.72(-NCH2Ar),54.48(-NCH-),34.97,34.24(C(CH3)3),31.91,31.77,29.75,29.69(all C(CH3)3),28.22,28.11,26.05(all-CH2-of cyclohexyl).ESI-HRMS calcd.for C 49 H 75 N3O2+H + [M+H]:738.5933; found:738.5940.

[0070] Example 3

[0071] ligand L 3 Synthesis of H2

[0072] (1) Synthesis of 2,6-di(bromomethyl)pyridine

[0073]

[0074] Add 6.4 mL of 33 wt% acetic acid solution of hydrogen bromide and 26 mL of glacial acetic acid to a 100 mL round-bottom flask. While stirring, add 1.82 g (13.1 mmol) of 2,6-pyridinediethanol and heat under reflux for 8 h. After the reaction is complete, cool. Under ice-water bath cooling, slowly add sodium hydroxide solution to adjust the pH to 9. A grayish-white solid precipitates out; filter to obtain 2,6-bis(bromomethyl)pyridine as a white solid (2.20 g, 63%).

[0075] 1 H NMR (400MHz, CDCl3): δ 7.71 (t, 3 J = 7.8 Hz, 1H, Py-H), 7.38 (d, 3 J=7.8Hz,2H,Py-H),4.54(s,4H,Py-CH2-).

[0076] (2) Synthesis of 2,6-bis(tert-butylaminomethyl)pyridine

[0077]

[0078] Add 12.7 mL of tert-butylamine (120 mmol) and 3.317 g of potassium carbonate (240 mmol) to a 100 mL round-bottom flask and set aside. Dissolve 2,6-di(bromomethyl)pyridine (2.65 g, 10.0 mmol) in 20 mL of DMF and slowly add it dropwise to the aforementioned round-bottom flask, reacting for 8 h. Quench the reaction with 50 mL of water, extract with 100 mL of DCM, and dry with anhydrous sodium sulfate. After filtering to remove the desiccant, remove the solvent from the filtrate under vacuum to obtain a pale yellow transparent liquid (2.02 g, 80%).

[0079] 1 H NMR (400MHz, CDCl3): δ 7.51 (t, 3 J = 2.7 Hz, 1H, Py-H), 7.12 (d, 3 J=2.7Hz,2H,Py-H),5.25(s,2H,-NH-),3.81(s,4H,Py-CH2-),1.14(s,18H,-C(CH3)3).

[0080] (3) Ligand L 3 Synthesis of H2

[0081]

[0082] Except for the use of 2,6-bis(tert-butylaminomethyl)pyridine (2.02 g, 8.10 mmol) and 2-bromomethyl-4,6-di-tert-butylphenol (4.85 g, 16.2 mmol) as raw materials, the other procedures were the same as those for ligand L. 1 The synthesis of H2 was the same. Recrystallization from dichloromethane / petroleum ether gave a white solid (3.84 g, yield 56%).

[0083] 1 H NMR (400MHz, CDCl3): δ10.91(br s,2H,Ar-OH),7.31(t, 3 J = 7.7 Hz, 1H, Py-H), 7.12 (d, 4 J = 2.4 Hz, 2H, Ar-H), 7.09 (d, 3 J = 7.7 Hz, 2H, Py-H), 6.81 (d, 4 J=2.4Hz,2H,Ar-H),3.91(s,4H,Py-CH2-),3.81(s,4H,Ar-CH2-),1.38(s,18H,Ar-C(CH3)3),1.25(s,18H,Ar-C(CH3)3),1.19(s,18H,NC(CH3)3). 13 C{ 1H}NMR (100MHz, CDCl3, 298K): δδ159.69,154.18,140.61,136.52,136.20,135.57,123.67,123.45,123.01,122.80,122.52,121.37,121.03 (all Ar-C),56.99(Py-CH2N-),56.24(-NCH2Ar),54.77(NC(CH3)3),34.87,34.22(C(CH3)3),31.90,31.76,29.73,29.65(all C(CH3)3),27.12,26.96(NC(CH3)3).ESI-HRMS calcd.forC 45 H 71 N3O2+H + [M+H]:686.5620; found:686.5626.

[0084] Example 4

[0085] Synthesis of alkali metal complex Na1

[0086]

[0087] Weigh L 1 H2 (377 mg, 0.500 mmol) was dissolved in 200 nmol of tetrahydrofuran in a 50 mL Schlenk flask. NaH (36 mg, 1.5 mmol) was then added, and the mixture was stirred for 8 h. After the reaction was complete, the remaining NaH and a small amount of solid impurities were removed by filtration. The supernatant was concentrated under vacuum until the solution became slightly viscous. Hexane was added until slight turbidity was achieved, and recrystallization yielded a pale yellow solid (212 mg, 56%).

[0088] 1 H NMR (400MHz, C6D6): δ 7.61 (d, 4 J = 2.3 Hz, 2H, Ar-H), 7.19 (d, 4 J = 2.3 Hz, 2H, Ar-H), 6.91 (d, 3 J=7.1Hz,4H,Ph-H),6.85–6.75(m,6H,Ph-H),6.58(t, 3 J = 7.6 Hz, 1H, Py-H), 6.04 (d, 3 J = 7.6 Hz, 2H, Py-H), 4.68 (d, 2 J = 9.8 Hz, 2H, Py-CH2-), 4.13 (d, 2J=16.1Hz,2H,Ar-CH2-),3.86(d, 2 J=12.3Hz,2H,Ph-CH2-),3.56-3.47(m,10H,2THF and 2H of Ph-CH2-),3.40(d, 2 J = 9.8 Hz, 2H, Py-CH2-), 3.02 (d, 2 J=16.1Hz,2H,Ar-CH2-),1.75(s,18H,Ar-C(CH3)3),1.48(s,18H,Ar-C(CH3)3),1.38–1.24(m,8H,2THF). 13 C{ 1 H}NMR (100MHz, C6D6): δ167.64,159.32,136.33,136.15,135.99,131.18,13 0.75,128.96,128.85,127.07,124.56,124.09,123.99,119.28,119.16(All Ar-C of),68.19(THF),61.68(-NCH2Py),55.06(-NCH2Ar),54.92(-NCH2Ph),35.73(C(CH3)3),34.09 (C(CH3)3),32.59(C(CH3)3),30.73(C(CH3)3),30.66(C(CH3)3),25.57(THF).Anal.Calcd.for C 59 H 81 N3Na2O4: C, 75.20; H, 8.66; N, 4.46%. Found: C, 74.92; H, 8.69; N, 4.54%.

[0089] Example 5

[0090] Synthesis of alkali metal complex Na2

[0091]

[0092] Except for raw materials using L 2 Except for H2 (369 mg, 0.599 mmol) and NaH (36 mg, 1.5 mmol), the operation steps were the same as for Na1. A white solid (495 mg, 50% yield) was finally obtained.

[0093] 1 H NMR (400MHz, C6D6): δ7.52(br s,2H,Ar-H),7.19(br s,2H,Ar-H),6.83(t,3 J = 7.6 Hz, 1H, Py-H), 6.38 (d, 3 J=7.7Hz,2H,Py-H),4.30(br s,2H,Py-CH2N-),3.99(br s,2H,Ar-CH2N-),3.75-3.28(m,12H,2THF,2H of Ar-CH2N-&2H of Py-CH2N-),2.58(t, 3 J=11.2Hz,2H,CH2 of cyclohexyl),2.00(br s,2H,CH2 of cyclohexyl),1.68(br s,20H,CH2 of cyclohexyl and Ar-C(CH3)3),1.49(br s,22H,4H of CH2 of cyclohexyl and 18H ofAr-C(CH3)3),1.37-1.26(m,12H,CH2 of cyclohexyl and 2THF),1.01(br s,4H,CH2 of cyclohexyl),0.88(br s,4H,CH2 of cyclohexyl). 13 C{ 1 H}NMR (100MHz, C6D6): δ167.07,161.31,137.06,136.49,135.89,130.82,128.70,124.57,123.44,119.96(All Ar-C),68.04(THF),61.91(Py-CH2N-),57.52(-NCH2Ar),53.36(-NCH-),35.41(C(CH3)3),34.02(C(CH3)3),3 2.60(C(CH3)3),30.70(C(CH3)3),27.93(-CH2-),27.00(-CH2-),26.67(-CH2-),25.57(THF).Anal.Calcd.for C 57 H 89 N3Na2O4: C, 73.91; H, 9.68; N, 4.54%. Found: C, 74.13; H, 9.85; N, 4.41%.

[0094] Example 6

[0095] Synthesis of alkali metal complex Na3

[0096]

[0097] Except for raw materials using L3 Except for H2 (343 mg, 0.500 mmol) and NaH (36 mg, 1.5 mmol), the operation steps were the same as for Na1. A pale yellow solid (579 mg, yield 66%) was finally obtained.

[0098] 1 H NMR(400MHz,C6D6)::δ7.53(br s,1H,Ar-H),7.26(br s,1H,Ar-H),7.11(br s,2H,Ar-H),6.83(t, 3 J = 7.5 Hz, 1H, Py-H), 6.25 (d, 3 J=7.5Hz,2H,Py-H),4.67(br s,1H,PyCH2N-),4.35(br s,1H,PyCH2N-),3.91-3.44(m,5H,PyCH2N-),3.43-3.33(m,8H,THF),3.24(br s,1H,ArCH2N-),1.75(s,9H,Ar-C(CH3)3),1.54(s,9H,Ar-C(CH3)3),1.48(s,18H,Ar-C(CH3)3),1.35-1.22(m,17H,THF and NC(CH3)3),0.98(s,9H,NC(CH3)3). 13 C{ 1 H}NMR (100MHz, C6D6): δ166.63,160.18,136.15,135.90,131.18,130.18,128.39,124.55,122.87,118.68,116.81(All Ar-C),68.01(THF),62.21(Py-CH2N-),58.49(-NCH2Ar),56.75(Py-CH2N-),55.67(-NCH2Ar),54.42(NC(CH3)3),53.67(NC(CH3)3),35.65(C(C H3)3),35.30(C(CH3)3),34.03(C(CH3)3),32.69(C(CH3)3),30.94(C(CH3)3),27.45(C(CH3)3),27.09(C(CH3)3),25.48(THF).Anal.Calcd.for C 53 H 85 N3Na2O4: C, 72.81; H, 9.80; N, 4.81%. Found: C, 72.64; H, 9.68; N, 4.70%.

[0099] Example 7

[0100] Synthesis of alkali metal complex K1

[0101]

[0102] Except for raw materials using L 1 Except for H2 (377 mg, 0.500 mmol) and KH (60 mg, 1.5 mmol), the procedure was the same as for Na1. A pale yellow solid (533 mg, 64% yield) was finally obtained.

[0103] 1 H NMR (400MHz, C6D6): δ 7.60 (d, 4 J = 2.8 Hz, 4H, Ar-H), 7.26 (d, 4 J=2.8Hz,4H,Ar-H),7.00-6.80(m,18H,Ph-H and Py-H),6.74(t, 3 J = 7.0 Hz, 4H, Ph-H), 6.61 (d, 3 J=7.8Hz,4H,Py-H),3.65(br s,8H,NCH2Py),3.44(br s,8H,NCH2Ar),3.27(br s,8H,NCH2Ph),1.73(s,36H,C(CH3)3),1.52(s,36H,C(CH3)3). 13 C{ 1 H}NMR (100MHz, C6D6): δ167.34,159.62,140.36,136.73,136.25,130.37,129.77,128.97,128.80,128.35,127.03,123.90,123.72,122.25(All Ar-C),67.83(THF),62.39(Py-CH2N-),61.14(Ar-CH2N-),59.27(-NCH2Ph),35.51(C(CH 3)3),34.06(C(CH3)3),32.63(C(CH3)3),30.55(C(CH3)3),25.81(THF).Anal.Calcd.for C 102 H 130 K4N6O4·C4H8O: C, 73.48; H, 8.03; N, 4.85%. Found: C 73.23; H7.99; N 5.00%.

[0104] Example 8

[0105] Under argon protection, racemic lactide (0.144 g, 1.0 mmol) was added to a polymerization flask and dissolved in 0.3 mL of toluene, followed by 0.2 mL of a benzyl alcohol toluene solution. 0.5 mL of a Na3 catalyst toluene solution was added to the polymerization flask. The reaction mixture was: [rac-LA]0 = 1.0 M, [Na]0 = 0.002 M, [BnOH]0 = 0.004 M, [rac-LA]0:[Na]0:[BnOH]0 = 500:1:2. The reaction temperature was controlled at 25 ± 1 °C, and the reaction was allowed to proceed for 1 min. Petroleum ether was then added to terminate the reaction. The solvent was removed, and the residue was dissolved in dichloromethane. Methanol was added to precipitate the polymer. The mixture was then vacuum dried for 24 h. The conversion rate was 94%. n =4.56×10 4 g / mol, molecular weight distribution PDI = 1.43, isotacticity P m =0.56.

[0106] Example 9

[0107] Under argon protection, racemic lactide (0.144 g, 1.0 mmol) was added to a polymerization flask and dissolved in 0.1 mL of toluene, followed by 0.4 mL of benzyl alcohol in toluene solution. 0.5 mL of Na3 catalyst in toluene solution was added to the polymerization flask. [rac-LA]0 = 1.0 M, [Na]0 = 0.002 M, [BnOH]0 = 0.008 M, [rac-LA]0:[Na]0:[BnOH]0 = 500:1:4. The reaction temperature was controlled at 25 ± 1 °C, and the reaction was carried out for 35 seconds. Petroleum ether was added to terminate the reaction. The solvent was removed, and the residue was dissolved in dichloromethane. Methanol was added to precipitate the polymer. The mixture was then vacuum dried for 24 h. The conversion rate was 90%, M n =1.96×10 4 g / mol, molecular weight distribution PDI = 1.41, isotacticity P m =0.54.

[0108] Example 10

[0109] Except for the temperature being changed to -50±1℃, the other operations were the same as in Example 8. After reacting for 29 minutes, the conversion rate was 85%. n =2.33×10 4 g / mol, molecular weight distribution PDI = 1.26, isotacticity P m =0.62.

[0110] Example 11

[0111] Under argon protection, racemic lactide (0.144 g, 1.0 mmol) was added to a polymerization flask and dissolved in 0.4 mL of toluene, followed by 0.1 mL of benzyl alcohol in toluene solution. 0.5 mL of catalyst Na1 in toluene solution was added to the polymerization flask. [rac-LA]0 = 1.0 M, [Na]0 = 0.002 M, [BnOH]0 = 0.002 M, [rac-LA]0:[Na]0:[BnOH]0 = 500:1:1. The reaction temperature was controlled at 25 ± 1 °C, and the reaction was carried out for 150 seconds. Petroleum ether was added to terminate the reaction. The solvent was removed, and the residue was dissolved in dichloromethane. Methanol was added to precipitate the polymer. The mixture was vacuum dried for 24 h. The conversion rate was 90%, M n =4.31×10 4 g / mol, molecular weight distribution PDI = 1.64, isotacticity P m =0.54.

[0112] Example 12

[0113] Except for replacing the catalyst with Na1, the other operations were the same as in Example 8. After 66 seconds of reaction, the conversion rate was 85%, M n =3.50×10 4 g / mol, molecular weight distribution PDI = 1.44, isotacticity P m =0.57.

[0114] Example 13

[0115] Under argon protection, racemic lactide (0.144 g, 1.0 mmol) was added to a polymerization flask and dissolved in 0.2 mL of toluene, followed by 0.3 mL of benzyl alcohol in toluene solution. 0.5 mL of catalyst Na1 in toluene solution was added to the polymerization flask. [rac-LA]0 = 1.0 M, [Na]0 = 0.002 M, [BnOH]0 = 0.002 M, [rac-LA]0:[Na]0:[BnOH]0 = 500:1:3. The reaction temperature was controlled at 25 ± 1 °C, and the reaction was carried out for 50 seconds. Petroleum ether was added to terminate the reaction. The solvent was removed, and the residue was dissolved in dichloromethane. Methanol was added to precipitate the polymer. The mixture was vacuum dried for 24 h. The conversion rate was 92%, M n =2.67×10 4 g / mol, molecular weight distribution PDI = 1.41, isotacticity P m =0.57.

[0116] Example 14

[0117] Except for replacing the catalyst with Na1, the other operations were the same as in Example 9. After reacting for 250 seconds, the conversion rate was 90%, M n =1.91×10 4g / mol, molecular weight distribution PDI = 1.39, isotacticity P m =0.53.

[0118] Example 15

[0119] Except for replacing the catalyst with Na1 and changing the temperature to -50±1℃, the other operations were the same as in Example 8. After reacting for 28 minutes, the conversion rate was 61%, M n =2.21×10 4 g / mol, molecular weight distribution PDI = 1.21, isotacticity P m =0.65.

[0120] Example 16

[0121] Except for the temperature being changed to -50±1℃, the other operations were the same as in Example 13. After reacting for 25 minutes, the conversion rate was 75%. n =1.48×10 4 g / mol, molecular weight distribution PDI = 1.13, isotacticity P m =0.63.

[0122] Example 17

[0123] Under argon protection, racemic lactide (0.144 g, 1.0 mmol) was added to a polymerization flask and dissolved in 0.3 mL of tetrahydrofuran, followed by 0.2 mL of a tetrahydrofuran solution of benzyl alcohol. 0.5 mL of a tetrahydrofuran solution of catalyst Na1 was added to the polymerization flask. The concentrations were: [rac-LA]0 = 1.0 M, [Na]0 = 0.002 M, [BnOH]0 = 0.004 M, and [rac-LA]0:[Na]0:[BnOH]0 = 500:1:2. The reaction temperature was controlled at 25 ± 1 °C, and the reaction was carried out for 18 min. Petroleum ether was added to terminate the reaction. The solvent was removed, and the residue was dissolved in dichloromethane. Methanol was added to precipitate the polymer. The product was then vacuum dried for 24 h. The conversion rate was 97%. n =3.89×10 4 g / mol, molecular weight distribution PDI = 1.62, isotacticity P m =0.62.

[0124] Example 18

[0125] Under argon protection, racemic lactide (0.576 g, 4.0 mmol) was added to a polymerization flask and dissolved in 0.3 mL of toluene, followed by 0.2 mL of a benzyl alcohol toluene solution. 0.5 mL of a Na1 catalyst toluene solution was added to the polymerization flask. The reaction mixture was prepared with [rac-LA]0 = 1.0 M, [Na]0 = 0.002 M, [BnOH]0 = 0.004 M, and [rac-LA]0:[Na]0:[BnOH]0 = 2000:1:2. The reaction was carried out at -50 ± 1 °C for 47 minutes, and then petroleum ether was added to terminate the reaction. The solvent was removed, and the residue was dissolved in dichloromethane. Methanol was added to precipitate the polymer. The mixture was then vacuum dried for 24 h. The conversion rate was 37%. n =4.81×10 5 g / mol, molecular weight distribution PDI = 1.48, isotacticity P m =0.63.

[0126] Example 19

[0127] Except for replacing the catalyst with Na2, the other operations are the same as in Example 8. After 90 seconds of reaction, the conversion rate is 90%, M n =5.21×10 4 g / mol, molecular weight distribution PDI = 1.36, isotacticity P m =0.52.

[0128] Example 20

[0129] Except for replacing the catalyst with Na2, the other operations are the same as in Example 9. After 50 seconds of reaction, the conversion rate is 95%, M n =2.74×10 4 g / mol, molecular weight distribution PDI = 1.53, isotacticity P m =0.51.

[0130] Example 21

[0131] Except for replacing the catalyst with Na2 and changing the temperature to -50±1℃, the other operations were the same as in Example 8. After reacting for 136 minutes, the conversion rate was 90%, M n =6.66×10 4 g / mol, molecular weight distribution PDI = 1.45, isotacticity P m =0.63.

[0132] Example 22

[0133] Except for replacing the catalyst with K1, the other operations are the same as in Example 8. After 78 seconds of reaction, the conversion rate is 95%, M n =6.31×10 4 g / mol, molecular weight distribution PDI = 1.49, isotacticity P m =0.54.

[0134] Example 23

[0135] Except for replacing the catalyst with K1, the other operations are the same as in Example 9. After 54 seconds of reaction, the conversion rate is 90%, M n =2.79×10 4 g / mol, molecular weight distribution PDI = 1.47, isotacticity P m =0.53.

[0136] Example 24

[0137] Except for replacing the catalyst with K1 and changing the temperature to -50±1℃, the other operations were the same as in Example 8. After reacting for 46 minutes, the conversion rate was 91%, M n =4.11×10 4 g / mol, molecular weight distribution PDI = 1.51, isotacticity P m =0.62.

[0138] Example 25

[0139] Under argon protection, L-lactide (0.144 g, 1.0 mmol) was added to a polymerization flask and dissolved in 0.3 mL of tetrahydrofuran, followed by 0.2 mL of a tetrahydrofuran solution of benzyl alcohol. 0.5 mL of a tetrahydrofuran solution of catalyst Na1 was added to the polymerization flask. The concentrations were: [rac-LA]0 = 1.0 M, [Na]0 = 0.002 M, [BnOH]0 = 0.004 M, and [rac-LA]0:[Na]0:[BnOH]0 = 500:1:2. The reaction temperature was controlled at 25 ± 1 °C, and the reaction was allowed to proceed for 42 s. Petroleum ether was added to terminate the reaction. The solvent was removed, and the residue was dissolved in dichloromethane. Methanol was added to precipitate the polymer. The product was then vacuum dried for 24 h. The conversion rate was 95%. n =4.89×10 4 g / mol, molecular weight distribution PDI = 1.46, isotacticity P m =1.

[0140] Example 26

[0141] Under argon protection, racemic lactide (0.144 g, 1.0 mmol) was added to a polymerization flask and dissolved in 0.5 mL of toluene. 0.5 mL of a toluene solution of catalyst Na1 was added to the polymerization flask. [rac-LA]0 = 1.0 M, [Na]0 = 0.002 M, [rac-LA]0:[Na]0 = 500:1. The reaction temperature was controlled at 25 ± 1 °C, and the reaction was carried out for 120 min. Petroleum ether was added to terminate the reaction. The solvent was removed, and the residue was dissolved in dichloromethane. Methanol was added to precipitate the polymer. The mixture was then vacuum dried for 24 h. The conversion rate was 90%, M n =1.13×104 g / mol, molecular weight distribution PDI = 1.38.

Claims

1. A dimethylenepyridine-bridged bisaminophenol ligand (I) and a corresponding dimethylenepyridine-bridged bisaminophenol alkali metal complex (II), characterized in that, It has the following general formula: In equations (I) and (II): R 1 -R 2 Representing C1-C8 straight-chain, branched, or cyclic alkyl groups, respectively, C7-C 20 Mono- or polyaryl substituted alkyl groups; R 3 Represents C1-C8 straight-chain, branched, or cyclic alkyl groups, C7-C 20 Mono- or polyaryl substituted alkyl groups; n is 0 or 1; M represents Na and K.

2. The dimethylenepyridine-bridged bisaminophenol ligand (I) and the corresponding dimethylenepyridine-bridged bisaminophenol alkali metal complex (II) according to claim 1, characterized in that, R 1 -R 2 Methyl, isopropyl, tert-butyl, cumyl, triphenylmethyl; R 3 The compounds are methyl, ethyl, tert-butyl, n-butyl, cyclopentyl, cyclohexyl, and benzyl.

3. The method for preparing the dimethylenepyridine-bridged bisaminophenol ligand (I) and the corresponding dimethylenepyridine-bridged bisaminophenol alkali metal complex (II) according to any one of claims 1-2, comprising the following steps: The 2-bromomethyl-4,6-disubstituted phenol of formula (III) and the 2,6-bis(substituted aminomethyl)pyridine of formula (IV) were reacted in an organic medium in the presence of an alkylamine at a temperature of 0-90 ºC for 2-72 hours. The dimethylpyridine-bridged bisaminophenol ligand compound (I) was then collected from the reaction product. The dimethylpyridine-bridged bisaminophenol ligand compound shown in formula (I) was reacted with a metal hydride in tetrahydrofuran at a temperature of 0-100 ºC for 2-24 hours. The dimethylpyridine-bridged bisaminophenol oxyalkali metal complex (II) was then collected from the reaction product. In the above preparation method, the substituent R 1 -R 3 It is consistent with the respective groups of the dimethylenepyridine-bridged bisaminophenol ligand (I) and the corresponding dimethylenepyridine-bridged bisaminophenol oxyalkali metal complex (II) as described in any one of claims 1-2; The alkylamine is triethylamine, tributylamine, or triisopropylamine; The metal hydride MH is NaH or KH.

4. According to claim 3, the molar ratio of dimethylpyridine-bridged bisaminophenol ligand compound (I) to the metal hydride is 1:2.0-4.0; the organic medium is selected from one or more of tetrahydrofuran, diethyl ether, toluene, benzene, petroleum ether and n-hexane.

5. The application of the dimethylenepyridine-bridged bisaminophenoxy alkali metal complex (II) according to any one of claims 1-2, characterized in that, Used for the ring-opening polymerization of L-lactide, D-lactide, rac-lactide, and meso-lactide.

6. The application according to claim 5, characterized in that, Using the dimethylenepyridine-bridged bisaminophenoloxy alkali metal complex (II) according to any one of claims 1-2 as a catalyst, lactide is polymerized, wherein the molar ratio of catalyst to monomer during polymerization is 1:1-10000.

7. The application according to claim 5, characterized in that, Using the dimethylenepyridine-bridged bisaminophenoxy alkali metal complex (II) according to any one of claims 1-2 as a catalyst, lactide is polymerized in the presence of an alcohol, wherein the molar ratio of catalyst to alcohol and lactide during polymerization is 1:1-50:1-10000; wherein the alcohol is C1-C 10 Alkyl alcohols with straight-chain, branched, or cyclic structures, C7-C 20 Mono- or polyaryl-substituted alkyl alcohols.

8. The application according to claim 5, characterized in that, Using the dimethylenepyridine-bridged bisaminophenoxy alkali metal complex (II) according to any one of claims 1-2 as a catalyst, lactide is polymerized at -70-250ºC in the presence of an alcohol, wherein the molar ratio of catalyst to alcohol and lactide during polymerization is 1:1-50:1-10000; wherein the alcohol is C1-C 10 Alkyl alcohols with straight-chain, branched, or cyclic structures, C7-C 20 Mono- or polyaryl-substituted alkyl alcohols.

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