Pyridine-phenol compound, polyester prepared from pyridine-phenol compound, and preparation method and application of pyridine-phenol compound

Abstract

The invention discloses a pyridine-phenol compound, polyester prepared from the pyridine-phenol compound as well as a preparation method and application of the pyridine-phenol compound. The pyridine-phenol compound has a structure as shown in a formula (I), wherein in the formula (I), R1 is selected from amino, dimethylamino or pyrrolidinyl; r2 is selected from nitro, fluorine or trifluoromethyl; r3 is selected from hydrogen, methoxyl, methyl, isopropyl, tert-butyl or fluorine; and R4 is selected from hydrogen, methoxyl, methyl, ethyl, isopropyl, tert-butyl or fluorine. The pyridine-phenol compound is an efficient organic catalyst and can catalyze ring-opening polymerization of a cyclic monomer to prepare aliphatic polyester, the conversion rate of the cyclic monomer is high, and the dispersion coefficient (PDI) of the synthesized polyester is low. The catalyst is insensitive to the environment (stable to air and water), does not contain metal, and is mild in reaction condition, high in reaction selectivity and high in polymerization speed. # imgabs0 #

Description

Technical Field

[0001] The invention relates to the technical field of polyester preparation, in particular to a pyridine-phenol compound, a polyester prepared therefrom, and a preparation method and application thereof. Background Art

[0002] Aliphatic polyester polymers, such as polyvalerolactone (PVL) and polylactide (PLA), have been increasingly used in the field of environmentally friendly materials due to their good biocompatibility and biodegradability. These polyesters can be modified to obtain materials with special functions, which can be used as alternative materials for drug carriers, tissue engineering, medical sutures, and medical screws. In addition, the small molecule compounds obtained by depolymerization of these polyester materials can be recycled and reused to alleviate the increasingly serious environmental and energy crises.

[0003] At present, the preparation methods of aliphatic polyesters mainly include polycondensation and ring-opening polymerization. Compared with the polycondensation of chain monomers, the polyester prepared by ring-opening polymerization of cyclic monomers has a narrow molecular weight distribution, mild reaction conditions, and no by-products are generated. In ring-opening polymerization, metal-containing catalysts such as stannous octoate, antimony trioxide and alkoxyaluminum are commonly used. However, the use of such metal catalysts is very likely to lead to metal residues, thereby limiting their application in biology, medicine, microelectronics, etc. Organic catalysts have gradually become a substitute for metal catalysts due to their advantages such as easy availability, easy preparation, safety and non-toxicity. After Hedrick first reported the ring-opening polymerization of lactide catalyzed by 4-dimethylaminopyridine (DMAP) as an organic catalyst in 2001, the types of ring-opening polymerization of lactones catalyzed by organic catalysts have become larger and larger, and common ones are carbene, phosphazene, bifunctional thioureaamine, guanidine, Bronsted acid, etc. (Macromolecules, 2000, 33, 4316-4320; Polymer Chemistry, 2014, 5, 3098-3106). However, some of these catalysts have expensive raw materials, some are extremely sensitive to air and water, and some have poor activity. Considering industrial applications, it is of great significance to prepare efficient organic catalysts using natural products or cheap industrial products (with mature industrial preparation technology) as raw materials in the field of catalytic preparation of aliphatic polyesters. Summary of the invention

[0004] The purpose of the present invention is to overcome the problems of expensive raw materials, instability and poor activity of polyester organic catalysts in the prior art, and to provide a pyridine-phenol compound, a polyester prepared therefrom, and a preparation method and application thereof. The pyridine-phenol compound of the present invention has cheap raw materials, is easily available, and is simple to prepare. It can be used as a catalyst for preparing polyester by ring-opening polymerization, has the characteristics of high catalytic activity, stability to air and water, no metal, mild reaction conditions, etc., high conversion rate of cyclic monomers, and the obtained polymer has the characteristics of high yield and narrow molecular weight distribution, etc.

[0005] In order to achieve the above object, the first aspect of the present invention provides a pyridine-phenol compound, wherein the pyridine-phenol compound has a structure shown in formula (I):

[0006]

[0007] In formula (I), R 1 is selected from amino, dimethylamino or pyrrolidinyl; R 2 is selected from nitro, fluoro or trifluoromethyl; R 3 is selected from hydrogen, methoxy, methyl, isopropyl, tert-butyl or halogen; R 4 is selected from hydrogen, methoxy, methyl, ethyl, isopropyl, tert-butyl or halogen.

[0008] The second aspect of the present invention provides a method for preparing a pyridine-phenol compound, the method comprising: reacting a pyridine derivative with a phenol derivative to obtain a pyridine-phenol compound; wherein the pyridine-phenol compound has a structure as shown in formula (I); the pyridine derivative has a structure as shown in formula (II); and the phenol derivative has a structure as shown in formula (III);

[0009]

[0010] Among them, R 1 is selected from amino, dimethylamino or pyrrolidinyl; R 2 is selected from nitro, fluoro or trifluoromethyl; R 3 is selected from hydrogen, methoxy, methyl, isopropyl, tert-butyl or halogen; R 4 is selected from hydrogen, methoxy, methyl, ethyl, isopropyl, tert-butyl or halogen.

[0011] The third aspect of the present invention provides a pyridine-phenol compound prepared by the aforementioned preparation method.

[0012] The fourth aspect of the present invention provides the use of the aforementioned pyridine-phenol compound in the preparation of polyester.

[0013] The fifth aspect of the present invention provides a method for preparing the aforementioned polyester, the method comprising: subjecting a cyclic monomer to a ring-opening polymerization reaction in the presence of a catalyst to obtain a polyester; wherein the catalyst is the aforementioned pyridine-phenol compound.

[0014] Through the above technical solution, the beneficial technical effects achieved by the present invention are as follows:

[0015] (1) The pyridine-phenol compound of the present invention uses industrially available organic base and weak acid phenol as raw materials, and the catalyst is prepared in one step through a simple acid-base reaction. The preparation method is simple, easy to operate, the raw materials are cheap and readily available, and there are no by-products.

[0016] (2) The pyridine-phenol compound of the present invention is a highly efficient organic catalyst that can catalyze the ring-opening polymerization of cyclic monomers to prepare aliphatic polyesters, with a high conversion rate of cyclic monomers and a low polydispersity index (PDI) of the synthesized polyester. The catalyst is not sensitive to the environment (stable to air and water), does not contain metals, has mild reaction conditions, high reaction selectivity and fast polymerization speed, which greatly enhances the process feasibility of the reaction and reduces industrial production costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 4-dimethylaminopyridine p-nitrophenolate (catalyst 1a) obtained in Preparation Example 1 of the present invention 1 HNMR spectrum;

[0018] Figure 2 The polyvalerolactone obtained in Example 1 of the present invention 1 HNMR spectrum;

[0019] Figure 3 The polylactide obtained in Example 2 of the present invention 1 HNMR spectrum;

[0020] Figure 4 This is the spectrum of the polyvalerolactone obtained in Example 1 of the present invention in size exclusion chromatography analysis. DETAILED DESCRIPTION

[0021] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0022] The first aspect of the present invention provides a pyridine-phenol compound, wherein the pyridine-phenol compound has a structure shown in formula (I):

[0023]

[0024] In formula (I), R 1 is selected from amino, dimethylamino or pyrrolidinyl; R 2 is selected from nitro, fluoro or trifluoromethyl; R 3 is selected from hydrogen, methoxy, methyl, isopropyl, tert-butyl or halogen; R 4 is selected from hydrogen, methoxy, methyl, ethyl, isopropyl, tert-butyl or halogen.

[0025] In the present invention, the halogen is selected from fluorine, chlorine, bromine or iodine.

[0026] In some embodiments of the present invention, R 1 is selected from amino, dimethylamino or pyrrolidinyl; R 2 is selected from nitro, fluoro or trifluoromethyl; R 3 is selected from hydrogen, methoxy, methyl, isopropyl, tert-butyl or fluorine; R 4 is selected from hydrogen, methoxy, methyl, ethyl, isopropyl, tert-butyl or fluorine.

[0027] In some embodiments of the present invention, the pyridine-phenol compound has at least one of the structures shown in Formula I-1 to Formula I-3:

[0028]

[0029] The second aspect of the present invention provides a method for preparing a pyridine-phenol compound, the method comprising: reacting a pyridine derivative with a phenol derivative to obtain a pyridine-phenol compound; wherein the pyridine-phenol compound has a structure as shown in formula (I); the pyridine derivative has a structure as shown in formula (II); and the phenol derivative has a structure as shown in formula (III);

[0030]

[0031] Among them, R 1 is selected from amino, dimethylamino or pyrrolidinyl; R 2 is selected from nitro, fluoro or trifluoromethyl; R 3 is selected from hydrogen, methoxy, methyl, isopropyl, tert-butyl or halogen; R 4 is selected from hydrogen, methoxy, methyl, ethyl, isopropyl, tert-butyl or halogen.

[0032] In the present invention, the halogen is selected from fluorine, chlorine, bromine or iodine.

[0033] In some embodiments of the present invention, R 1 is selected from amino, dimethylamino or pyrrolidinyl; R 2 is selected from nitro, fluoro or trifluoromethyl; R 3 is selected from hydrogen, methoxy, methyl, isopropyl, tert-butyl or fluorine; R 4 is selected from hydrogen, methoxy, methyl, ethyl, isopropyl, tert-butyl or fluorine.

[0034] The method of the invention uses an industrially easily prepared organic base (such as 4-pyrrolidinopyridine or 4-dimethylaminopyridine) and weak acid phenol as raw materials, and prepares a pyridine-phenol compound in one step through a simple acid-base reaction.

[0035] The pyridine base and substituted phenols selected in the present invention are raw materials with relatively mature industrial synthesis technology. The organic base pyridine and the weak acid phenol can react in one step to obtain a pyridine-phenol compound. The preparation method of the present invention is simple, easy to operate, the raw materials are cheap and easy to obtain, and there is no by-product.

[0036] In some embodiments of the present invention, the molar ratio of the pyridine derivative to the phenol derivative is 0.5-2:1.

[0037] In some embodiments of the present invention, the reaction temperature is 25-80°C and the reaction time is 6-24h.

[0038] In some embodiments of the present invention, the reaction is carried out in a solvent selected from one or more of tetrahydrofuran, dichloromethane, chloroform and toluene.

[0039] The third aspect of the present invention provides a pyridine-phenol compound prepared by the aforementioned preparation method.

[0040] In some embodiments of the present invention, the pyridine-phenol compound has one of the structures shown in Formula I-1 to Formula I-3:

[0041]

[0042] The pyridine-phenol compound of the invention is a highly efficient organic catalyst, which is stable to air and water, does not contain metal, has mild reaction conditions, and can catalyze the ring-opening polymerization of cyclic monomers to prepare aliphatic polyesters.

[0043] The fourth aspect of the present invention provides the use of the aforementioned pyridine-phenol compound in the preparation of polyester.

[0044] The fifth aspect of the present invention provides a method for preparing the aforementioned polyester, the method comprising: subjecting a cyclic monomer to a ring-opening polymerization reaction in the presence of a catalyst to obtain a polyester; wherein the catalyst is the aforementioned pyridine-phenol compound.

[0045] The pyridine-phenol compound of the present invention is a highly efficient organic catalyst, which can catalyze the ring-opening polymerization of cyclic monomers to prepare aliphatic polyesters. In the pyridine-phenol compound, protonated pyridine can be used as a hydrogen bond donor to activate the carbonyl group of the cyclic monomer, and the phenol oxide anion can be used as a hydrogen bond acceptor to activate the initiator alcohol, thereby promoting its nucleophilic attack on the carbonyl group of the cyclic monomer, and the protonated pyridine base and the phenol oxide anion constitute a bifunctional catalyst.

[0046] The present invention uses a cheap, easily available and easily prepared catalyst to catalyze the ring-opening polymerization of cyclic monomers to synthesize polyester. Pyridine-phenol is used as a catalyst for the ring-opening polymerization reaction, and the reaction conditions are mild, the reaction selectivity is high and the polymerization rate is fast, and the obtained polymer product has an accurate molecular weight and low dispersibility. In this process, the prepared pyridine-phenol is not sensitive to the environment, and the process feasibility of the reaction is greatly enhanced. As a low-priced and easily prepared catalyst, the cost in industrial production can be reduced.

[0047] In some embodiments of the present invention, the cyclic monomer is selected from cyclic lactones, cyclic lactides or cyclic carbonates.

[0048] Further, the cyclic lactone has a structure shown in formula (IV), the cyclic lactide has a structure shown in formula (V), and the cyclic carbonate has a structure shown in formula (VI);

[0049]

[0050] In formula (IV), A is a general formula [-(CR 7 R 8 )-] n The structure shown, wherein n is an integer of 2-10; R 7 and R 8 Each is independently selected from hydrogen, C1-C5 substituted or unsubstituted straight or branched chain alkyl;

[0051] In formula (V), A and B are each independently a general formula [-(CR 7 R 8 ))-] m The structure shown, wherein, m is an integer of 1-10, A and B are the same or different; R 7 and R 8 Selected from hydrogen, C1-C5 substituted or unsubstituted straight or branched chain alkyl;

[0052] In formula (VI), R 5 and R 6 Each is independently selected from hydrogen, C1-C5 substituted or unsubstituted straight or branched chain alkyl, hydroxyl or halogen.

[0053] R 7 and R 8 are selected from the same or different groups. 5 and R 6 are selected from the same or different groups.

[0054] In some embodiments of the present invention, the cyclic monomer is valerolactone, caprolactone, octalactone, decanolactone, nonanolactone, dodecalactone, 3-methyl-5-valerolactone, lactide, glycolide or a six-membered ring carbonate.

[0055] Preferably, the cyclic monomer is δ-valerolactone, ε-caprolactone or L-lactide.

[0056] In the present invention, the conversion rate of the cyclic monomer is 80-99%, preferably 90-98%.

[0057] In some embodiments of the present invention, the molar ratio of the cyclic monomer to the catalyst is 100-1000:1.

[0058] In some embodiments of the present invention, the temperature of the ring-opening polymerization reaction is 80-300° C., and the time is 0.5-24 h.

[0059] In the present invention, the polyester includes, but is not limited to, polyvalerolactone, polycaprolactone, polyoctalactone, polydecanolactone, polynonanolactone, polydodecalactone, poly3-methyl-5-valerolactone, polylactide, polyglycolide or polyhexamethylene carbonate.

[0060] In the present invention, the ring-opening polymerization reaction is carried out in the presence of a solvent or in the absence of a solvent; when the polymerization is carried out in the presence of a solvent, the solvent includes but is not limited to: one or more of acetone, cyclohexanone, dioxane, tetrahydrofuran, benzene, toluene, xylene, dichloromethane, chloroform, tetrachloromethane, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide and acetonitrile; preferably tetrahydrofuran, toluene, dichloromethane, chloroform or N,N-dimethylformamide.

[0061] In the present invention, the ring-opening polymerization reaction can be carried out in the presence of an initiator or in the absence of an initiator; when the ring-opening polymerization reaction is carried out in the presence of an initiator, the initiator includes but is not limited to one or more of methanol, ethanol, n-propanol, isopropanol, n-butanol, benzyl alcohol, phenylethyl alcohol, ethylene glycol, 5-hexen-1-ol and water. Preferably, the molar ratio of the initiator to the catalyst is 0.01-10:1.

[0062] In the present invention, the ring-opening polymerization reaction is carried out under vacuum with a vacuum degree of 1-500 Pa; or is completed under protective gas (inert gas, such as Ar) with a protective gas pressure of 100-101325 Pa.

[0063] In the solution before the ring-opening polymerization reaction, the initial reaction concentration of the cyclic monomer is 0.1 mol / L-100 mol / L; after the ring-opening polymerization reaction is completed, a terminator is added, and the terminator is triethylamine. After the terminator is added, a precipitation solvent is added or the precipitation solvent is directly added, and the precipitation solvent is methanol, ethanol, ether or n-hexane.

[0064] The sixth aspect of the present invention provides the polyester obtained by the aforementioned preparation method, wherein the number average molecular weight of the polyester is 1000-100000 g / mol, the molecular weight distribution coefficient is 1-2, and the metal content is 0.

[0065] With the pyridine-phenol compound of the present invention as a catalyst, the conversion rate of the cyclic monomer is high (80-99%), and the corresponding polyester prepared has a low dispersion index (PDI).

[0066] The present invention can efficiently synthesize polyester by using the aforementioned pyridine-phenol compound as a catalyst. Compared with polyester synthesized using a metal-containing catalyst, the polyester obtained by the method of the present invention has no metal residue, a narrow molecular weight distribution, and no chain transesterification reaction, and has broad application prospects, and has great commercial application potential in the fields of biomedicine and microelectronics.

[0067] A seventh aspect of the present invention provides use of the aforementioned polyester in biomedical materials or plastic packaging materials.

[0068] The polyester prepared by the method of the present invention can be used as a biomedical material or a plastic packaging material, especially a degradable food packaging material. For example, polycaprolactone (PCL) and polylactide (PLA) can be used as degradable surgical sutures, polycaprolactone can also be used for medical surgical splints, and polylactide can also be used as food packaging bags, straws, lunch boxes, etc.

[0069] The present invention is described in detail below by way of examples, but the protection scope of the present invention is not limited to the following description.

[0070] In the following examples and comparative examples, if no specific conditions are specified, the experiments were carried out under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used, if no manufacturer is specified, are all conventional products that can be obtained through commercial channels.

[0071] The nuclear magnetic resonance hydrogen spectra involved in the following examples were measured using a Bruker AscendTM-400 nuclear magnetic resonance hydrogen spectrometer produced by Bruker Corporation, and the deuterated reagents used were deuterated chloroform (CDCl3) and deuterated dimethyl sulfoxide (DMSO-d6).

[0072] Preparation Example 1

[0073] 4-Dimethylaminopyridine (1.22 g, 10 mmol, 1.0 equiv) and 4-nitrophenol (1.39 g, 10 mmol, 1.0 equiv) were added to a 50 mL reaction bottle, and tetrahydrofuran (20 mL) was used as solvent. The mixture was stirred at room temperature for 2 hours to obtain a white precipitate, which was filtered, washed with tetrahydrofuran (20 mL) for 3 times, and vacuum dried for 6 hours to obtain a catalyst 1a (2.4 g, 91% yield) of the structure shown in Formula I-1.1 H NMR spectrum Figure 1 As shown, 1 H NMR(400MHz,Chloroform-d)δ8.14(s,4H),6.89(s,4H),6.60(s,1H),3.14(s,6H). By Figure 1 It can be seen that there are hydrogen signals from the aromatic region of the pyridinium salt, as well as methyl hydrogen signals and phenol oxide anion aromatic hydrogen signal groups, indicating that catalyst 1a with the structure shown in formula I-1 is obtained.

[0074] Preparation Example 2

[0075] 4-Dimethylaminopyridine (1.22 g, 10 mmol, 1.0 equiv) and 4-nitrophenol (1.39 g, 10 mmol, 1.0 equiv) were added to a 50 mL reaction bottle, and tetrahydrofuran (20 mL) was used as solvent. The mixture was stirred at room temperature for 2 hours to obtain a white precipitate. The precipitate was filtered, washed with tetrahydrofuran (20 mL) 3 times, and vacuum dried for 6 hours to obtain catalyst 1b (2.4 g, 91% yield) with the structure shown in Formula I-2.

[0076] Preparation Example 3

[0077] 4-Dimethylaminopyridine (1.22 g, 10 mmol, 1.0 equiv) and 4-nitrophenol (1.39 g, 10 mmol, 1.0 equiv) were added to a 50 mL reaction bottle, and tetrahydrofuran (20 mL) was used as solvent. The mixture was stirred at room temperature for 2 hours to obtain a white precipitate. The precipitate was filtered, washed with tetrahydrofuran (20 mL) 3 times, and vacuum dried for 6 hours to obtain catalyst 1c (2.4 g, 91% yield) with the structure shown in Formula I-3.

[0078] Preparation Comparative Example 1

[0079] Catalyst D1 was obtained by following the method of Preparation Example 1, except that 4-dimethylaminopyridine was replaced by chloropyridine.

[0080] Example 1

[0081] Catalyst 1a (0.0261 g, 0.1 mmol, 1.0 equiv), δ-valerolactone (0.91 mL, 10.0 mmol, 100 equiv) and benzyl alcohol (1.03 μL, 0.1 mmol, 1.0 equiv) were added to a reaction flask without adding a solvent. Under argon protection, the reaction mixture was stirred and reacted at 100°C for 6 hours. The reactant was concentrated and poured into methanol. The precipitate was filtered and dried to constant weight to obtain a white polyvalerolactone product. The conversion rate of δ-valerolactone was 91%, the number average molecular weight Mn of polyvalerolactone was 6600 g / mol, and the dispersion PDI was 1.04 (molecular exclusion chromatography, Waterscolumn: 5 mm, 300×7.8 mm, tetrahydrofuran as the mobile phase, 0.7 mL·min -1 , polystyrene as standard). 1 H NMR Figure 2 The size exclusion chromatogram obtained is shown in Figure 4 As shown by Figure 2 It can be seen that the polymer has high purity and low monomer residue. Figure 4 It can be seen that the number average molecular weight is 6.6 kg / mol and the molecular weight distribution coefficient is 1.04.

[0082] Example 2

[0083] Catalyst 1b (0.0287 g, 0.1 mmol, 1.0 equiv), lactide (4.32 mL, 30.0 mmol, 300 equiv) and n-butanol (9.1 mg, 0.1 mmol, 1.0 equiv) were added to a reaction flask, dissolved with 2.0 mL of tetrahydrofuran, stirred at 25 ° C for 48 hours under argon protection, and then the reactants were concentrated and poured into ether. The precipitate was filtered and dried to constant weight to obtain a white polylactide product. The conversion rate of lactide was 97%, the number average molecular weight Mn of the polylactide was 43200 g / mol, and the dispersion PDI was 1.34. The obtained polylactide 1 H NMR Figure 3 As shown by Figure 3 It can be seen that the polymer has high purity and low monomer residue.

[0084] Example 3

[0085] Catalyst 1c (0.0291 g, 0.1 mmol, 1.0 equiv), ε-caprolactone (0.33 mL, 3.0 mmol, 30 equiv) and propargyl alcohol (5.8 μL, 0.1 mmol, 1.0 equiv) were added to a reaction bottle and dissolved with 1.0 mL of toluene. Under argon protection, the mixture was stirred at 25°C for 24 hours. The reactants were concentrated and poured into ethanol. The precipitate was filtered and dried to constant weight to obtain a white polycaprolactone product. The conversion rate of ε-caprolactone was 95%, the number average molecular weight Mn of polyvalerolactone was 4720 g / mol, and the dispersion degree PDI was 1.17.

[0086] Example 4

[0087] Catalyst 1c (0.0145 g, 0.05 mmol, 1.0 equiv), lactide (720 mg, 5 mmol, 100 equiv) and methanol (2.05 μL, 0.05 mmol, 1.0 equiv) were added to a reaction bottle, and the bulk was polymerized without solvent at 150°C, and stirred at 25°C for 1 hour under argon protection. Triethylamine was added to terminate the reaction, and the reactant was concentrated and poured into ether, and the precipitate was filtered and dried to constant weight to obtain a white polylactide product, with a lactide conversion rate of 99%, a number average molecular weight Mn of polylactic acid of 14500 g / mol, and a dispersion degree PDI of 1.04.

[0088] Example 5

[0089] Catalyst 1c (0.0145 g, 0.05 mmol, 1.0 equiv), valerolactone (150 mg, 1.5 mmol, 30 equiv) and benzyl alcohol (5.2 μL, 0.05 mmol, 1.0 equiv) were added to a reaction bottle, dissolved with 1.5 mL of dichloromethane, and stirred at 200° C. for 2 hours under argon protection. Triethylamine was added to terminate the reaction, the reactant was concentrated and poured into methanol, the precipitate was filtered and dried to constant weight, and 0.102 g of white polyvalerolactone product was obtained. The conversion rate of valerolactone was 95%, the number average molecular weight Mn of polyvalerolactone was 4300 g / mol, and the dispersion degree PDI was 1.16.

[0090] Example 6

[0091] Catalyst 1a (0.0261 g, 0.1 mmol, 1.0 equiv), valerolactone (0.45 ml, 5 mmol, 50 equiv) and 1-propanol (7.5 μL, 0.1 mmol, 1.0 equiv) were added to a 10 mL polymerization tube and heated to 80° C. under an argon atmosphere. After reacting for 40 minutes, triethylamine was added to terminate the reaction. 1The conversion rate of valerolactone measured by H NMR spectrum was 98%. The polymer was dissolved in dichloromethane in an amount that was sufficient to dissolve the polymer, and the solution was poured into cold methanol. The precipitate was filtered and placed in a vacuum drying oven to dry to constant weight to obtain 0.38 g of polyvalerolactone with a number average molecular weight Mn of 5120 g / mol and a dispersity of 1.08.

[0092] Example 7

[0093] Catalyst 1a (2.61 g, 10.0 mmol, 100.0 equiv), butyl dodecalactone (5.949 g, 30.0 mmol, 300 equiv) and 5-hexen-1-ol (12.0 μL, 0.1 mmol, 1.0 equiv) were added to a reaction bottle, dissolved with 3.0 ml of chloroform, stirred at 25° C. for 16 hours under argon protection, and then triethylamine was added to terminate the reaction. The reactants were concentrated and poured into n-hexane, the precipitate was filtered and dried to constant weight to obtain a white polyvalerolactone product, the conversion rate of butyl dodecalactone was 80%, the number average molecular weight Mn of polybutyl dodecalactone was 46700 g / mol, and the dispersion degree PDI was 1.12.

[0094] Example 8

[0095] Catalyst 1b (2.87 g, 10 mmol, 1.0 equiv), six-membered ring carbonate (3.06 g, 30.0 mmol, 300 equiv) and phenylethanol (11.9 μL, 0.1 mmol, 1.0 equiv) were added to a reaction bottle, dissolved with 5.0 ml of dichloromethane, stirred at room temperature for 12 hours under argon protection, and then triethylamine was added to terminate the reaction. The reactants were concentrated and poured into n-hexane, the precipitate was filtered and dried to constant weight to obtain a white polyvalerolactone product, the conversion rate of the six-membered ring carbonate was 91%, the number average molecular weight Mn of the polybutylene dodecalactone was 92900 g / mol, and the dispersion PDI was 1.21.

[0096] Example 9

[0097] Catalyst 1c (0.0145 g, 0.05 mmol, 1.0 equiv) and valerolactone (150 mg, 1.5 mmol, 30 equiv) were added to a reaction bottle without adding an initiator, dissolved in 5 mL of dichloromethane, and stirred at 0°C for 24 hours under argon protection. Triethylamine was added to terminate the reaction, the reactant was concentrated and poured into methanol, the precipitate was filtered and dried to constant weight to obtain a white polyvalerolactone product, the conversion rate of valerolactone was 87%, the number average molecular weight Mn of polyvalerolactone was 3800 g / mol, and the dispersion degree PDI was 1.09.

[0098] Comparative Example 1

[0099] The method of Preparation Example 1 was followed, except that the catalyst 1a was replaced by the catalyst D1 obtained in Comparative Preparation Example 1. The conversion rate of δ-valerolactone was 46%, the number average molecular weight was 1560 g / mol, and the dispersion degree PDI was 1.34.

[0100] The results of the above examples and comparative examples are listed in Table 1.

[0101] Table 1

[0102]

[0103] It can be seen from the results in Table 1 that the monomer conversion rate using the catalyst of the present invention is higher than 80%, which is higher than the monomer conversion rate of Comparative Example 1. Compared with Comparative Example 1, the present application has significantly better effects.

[0104] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A pyridine-phenol compound, characterized in that The pyridine-phenol compound has a structure shown in formula (I): In formula (I), R 1 is selected from amino, dimethylamino or pyrrolidinyl; R 2 is selected from nitro, fluoro or trifluoromethyl; R 3 is selected from hydrogen, methoxy, methyl, isopropyl, tert-butyl or halogen; R 4 is selected from hydrogen, methoxy, methyl, ethyl, isopropyl, tert-butyl or halogen.

2. The pyridine-phenol compound according to claim 1, wherein R 3 is selected from hydrogen, methoxy, methyl, isopropyl, tert-butyl or fluorine; R 4 is selected from hydrogen, methoxy, methyl, ethyl, isopropyl, tert-butyl or fluorine.

3. The pyridine-phenol compound according to claim 1, wherein The pyridine-phenol compound has one or more structures shown in Formula I-1 to Formula I-3:

4. A method for preparing a pyridine-phenol compound, characterized in that: The preparation method comprises: A pyridine derivative is reacted with a phenol derivative to obtain a pyridine-phenol compound; wherein the pyridine-phenol compound has a structure shown in formula (I); the pyridine derivative has a structure shown in formula (II); and the phenol derivative has a structure shown in formula (III); Among them, R 1 is selected from amino, dimethylamino or pyrrolidinyl; R 2 is selected from nitro, fluoro or trifluoromethyl; R 3 is selected from hydrogen, methoxy, methyl, isopropyl, tert-butyl or halogen; R 4 is selected from hydrogen, methoxy, methyl, ethyl, isopropyl, tert-butyl or halogen.

5. The preparation method according to claim 4, wherein The molar ratio of the pyridine derivative to the phenol derivative is 0.5-2:

1.

6. The preparation method according to claim 4 or 5, wherein: The reaction temperature is 25-80°C and the reaction time is 6-24h; And / or, the reaction is carried out in a solvent, and the solvent is selected from one or more of tetrahydrofuran, dichloromethane, chloroform and toluene.

7. A pyridine-phenol compound obtained by the preparation method according to any one of claims 4 to 6.

8. The pyridine-phenol compound according to claim 7, wherein The pyridine-phenol compound has one of the structures shown in Formula I-1 to Formula I-3:

9. Use of the pyridine-phenol compound according to any one of claims 1 to 3 and 7 to 8 in the preparation of polyester.

10. A method for preparing polyester, characterized in that: The preparation method comprises: in the presence of a catalyst, subjecting a cyclic monomer to a ring-opening polymerization reaction to obtain a polyester; wherein the catalyst is the pyridine-phenol compound described in any one of claims 1-3 and 7-8.

11. The preparation method according to claim 10, wherein: The cyclic monomer is selected from cyclic lactone, cyclic lactide or cyclic carbonate; Preferably, the cyclic lactone has a structure shown in formula (IV), the cyclic lactide has a structure shown in formula (V), and the cyclic carbonate has a structure shown in formula (VI); In formula (IV), A is a general formula [-(CR 7 R 8 )-] n The structure shown, wherein n is an integer of 2-10; R 7 and R 8 Each is independently selected from hydrogen, C1-C5 substituted or unsubstituted straight or branched chain alkyl; In formula (V), A and B are each independently a general formula [-(CR 7 R 8 ))-] m The structure shown, wherein m is an integer of 1-10, A and B are the same or different; R 7 and R 8 Selected from hydrogen, C1-C5 substituted or unsubstituted straight or branched chain alkyl; In formula (VI), R 5 and R 6 Each is independently selected from hydrogen, C1-C5 substituted or unsubstituted straight or branched chain alkyl, hydroxyl or halogen.

12. The preparation method according to claim 10 or 11, wherein: The cyclic monomer is valerolactone, caprolactone, octanolactone, decanolactone, nonanolactone, dodecanolactone, 3-methyl-5-valerolactone, lactide, glycolide or a six-membered ring carbonate; Preferably, the cyclic monomer is δ-valerolactone, ε-caprolactone or L-lactide.

13. The preparation method according to any one of claims 10 to 12, wherein: The molar ratio of the cyclic monomer to the catalyst is 100-1000:1; And / or, the ring-opening polymerization reaction is carried out at a temperature of 80-300° C. and a time of 0.5-24 h; And / or, the ring-opening polymerization reaction is carried out in the presence of an initiator, and the initiator is selected from one or more of methanol, ethanol, n-propanol, isopropanol, n-butanol, benzyl alcohol, phenylethyl alcohol, ethylene glycol, 5-hexen-1-ol and water; preferably, the molar ratio of the initiator to the catalyst is 0.01-10:

1.

14. The polyester obtained by the preparation method according to any one of claims 10 to 13, wherein: The polyester has a number average molecular weight of 1000-100000 g / mol, a molecular weight distribution coefficient of 1-2, and a metal content of 0.

15. Use of the polyester according to claim 14 in biomedical materials or plastic packaging materials.

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