Polymerization method of 1,3-dioxolan-4-one compounds

Abstract

The present invention provides a polymerization method of 1,3-dioxolan-4-one compounds, comprising the following steps: carrying out a polymerization reaction on the 1,3-dioxolan-4-one compounds under the catalysis of an imidazole-substituted aminophenoxy zinc complex catalyst. The imidazole-substituted aminophenoxy zinc complex catalyst has the structure shown in formula (I), and its preparation method comprises the following steps: directly reacting a neutral ligand with a metal raw material compound in an organic medium, and then obtaining the target compound through filtration, concentration, and recrystallization steps. The 1,3-dioxolan-4-one compounds have the structure shown in formula (II). Compared with the prior art, the polymerization method provided by the present invention enables the 1,3-dioxolan-4-one compounds to efficiently achieve homopolymerization and random copolymerization with lactide.

Description

Technical Field

[0001] The present invention relates to the technical field of polymers, and particularly relates to a method for polymerizing 1,3-dioxolan-4-one compounds. Background Art

[0002] Since the birth of plastics, synthetic plastics mainly based on polyolefins have been widely used. Made from petrochemical products and being difficult to degrade, the energy and environmental problems brought about by the widespread use of polyolefin materials have become increasingly prominent. To eliminate white pollution and alleviate the dependence on petroleum resources, the research and development of degradable polymer materials have emerged as the times require. Among the many known degradable materials, polyester materials have the best biocompatibility, and most of their raw materials are derived from recyclable biomass. Moreover, their waste can ultimately be naturally degraded into water and carbon dioxide, returning to the entire ecological cycle without additional pollution, making them green and environmentally friendly materials with great development prospects. For example, the polylactic acid material, which is a research hotspot in the current academic and industrial circles, can not only be completely degraded, but also has heat resistance, tensile resistance, is easy to process, and is suitable for industrial production. The research on its synthesis is also relatively mature. The current mainstream method is to synthesize polylactic acid by ring-opening polymerization of lactide dimer under the catalysis of a catalyst. The catalysts used in the polymerization reaction are mainly various metal organic catalysts to achieve the catalytic syndiotactic selective polymerization or highly active polymerization of racemic lactide. Generally, the polylactic acid polymer chain structure is relatively single and post-modification is very difficult, resulting in limited application scenarios. Therefore, the research on synthesizing polyesters by ring-opening polymerization of other suitable monomers or copolymerizing with lactide to synthesize polyester copolymers has become a current research hotspot.

[0003] As a polymerization monomer, 1,3-dioxolan-4-one compounds have not been around for a long time. They are a very special type of polymerization monomer independent of hydroxy acids, lactones, lactides, and oxocarboxylic anhydrides. The relevant research literature is very limited, but their advantages are very prominent. Belonging to emerging polymerization monomers, the high reactivity of oxocarboxylic anhydrides brings the disadvantages of instability, difficulty in monomer purification and storage. In addition, their synthesis also relies on toxic chemicals. Compared with oxocarboxylic anhydrides, 1,3-dioxolan-4-one monomers are simpler, safer, and faster to synthesize. The raw materials only require α-hydroxy acids and any aldehyde or ketone, and the corresponding monomers can be prepared by dehydration under acid catalysis. It is a polymerization monomer type with great research prospects.

[0004] In 2014, Martin and his colleagues first used 1,3-dioxolan-4-one monomers in a polymerization reaction. When the feed ratio of lactide, 1,3-dioxolan-4-one (DOX), catalyst, and initiator was 250:250:1:1, copolymerization was carried out at 100 °C for 24 hours, and the resulting polymer M n= 10000, PDI = 1.40, the insertion rate of DOX reached 36%, and the glass transition temperature of the polymer was 42 °C. This polymer is more easily degradable than ordinary PLA (Green Chem., 2014, 16, 1768).

[0005] In 2017, Cairns and his colleagues synthesized a series of 1,3-dioxolan-4-one monomers and attempted the homopolymerization and copolymerization of some monomers. When the feed ratio of two 1,3-dioxolan-4-one monomers, catalyst, and initiator was 50:50:1:1, at 40 °C, the conversion rates of both monomers reached over 90%, and the M of the polymer n = 11100, PDI = 2.2. In addition, the authors also attempted the homopolymerization of 5-methyl-1,3-dioxolan-4-one (MeDOX). Under the catalysis of Salen-Al complex, when the feed ratio was 100:1:1 and polymerized for 24 hours, the monomer conversion rate reached 81%. The polymerization activities of the remaining monomers were far worse than that of MeDOX. Among them, 500 equivalents of (R)-5-phenyl-1,3-dioxolan-4-one (R-PhDOX) only reached a conversion rate of 55% after melt polymerization at 180 °C for 72 h under the catalysis of Salen-Al. The polymerization activity of the monomer is greatly affected by the substituents on the five-membered ring (Polym.Chem., 2017, 8, 2990).

[0006] In 2020, Gazzotti and his colleagues synthesized two 1,3-dioxolan-4-one monomers with different substituents starting from carvacrol and cardanol in biomass. These monomers and lactide can achieve solvent-free copolymerization under the catalysis of various zinc salts and tin salts, but often only a low insertion rate of 1,3-dioxolan-4-one monomers (<21%) can be achieved during copolymerization. Moreover, with the insertion of 1,3-dioxolan-4-one monomers, the molecular weight of the copolymer decreased to varying degrees, and the glass transition temperature of the copolymer also decreased (Macromolecules, 2020, 53, 6420).

[0007] Although 1,3-dioxolan-4-one compounds have many advantages in synthesis, judging from the results reported in the current literature, their polymerization results are not ideal. The reason may be that the types of catalysts involved in polymerization research are limited to Salen-Al complexes, zinc salts, tin salts, etc., and the catalytic activity is poor. In addition, the structure of this type of compound will also affect the polymerization activity. Therefore, in the field of polymerization of 1,3-dioxolan-4-one compounds, it is necessary to further explore new catalysts and monomer structures with high activity, and both homopolymerization and copolymerization with other monomers such as lactide need to be further studied in depth. Summary of the Invention

[0008] The object of the present invention is to provide a polymerization method of 1,3-dioxolan-4-one compounds.

[0009] To achieve the above object of the invention, the present invention provides the following technical solutions:

[0010] The present invention provides a polymerization method of 1,3-dioxolan-4-one compounds, comprising the following steps:

[0011] Polymerize the 1,3-dioxolan-4-one compound under the condition catalyzed by an imidazole-substituted aminophenoxy zinc complex catalyst;

[0012] The imidazole-substituted aminophenoxy zinc complex catalyst has the structure shown in formula (I), and its ligand has the structure shown in formula (II):

[0013]

[0014] In the formulas (I) and (II):

[0015] The R 1 、R 2 are independently selected from one of hydrogen, C1-C 12 alkyl with a straight-chain, branched-chain or cyclic structure, C7-C 20 alkyl substituted with a single or multiple aryl groups, and halogen;

[0016] The R 3 、R 4 are independently selected from C1-C6 alkyl with a straight-chain, branched-chain or cyclic structure, C7-C 20 alkyl substituted with a single or multiple aryl groups, C6-C 18 aryl;

[0017] The X represents an amino group NR 5 R 6 wherein R 5 、R 6 are independently selected from C1-C6 alkyl with a straight-chain, branched-chain or cyclic structure, trimethylsilyl, triethylsilyl, dimethylhydrogensilyl, and R 5 and R 6 may be the same or different.

[0018] Preferably, in the formulas (I) and (II), the R 1 、R 2 are independently selected from one of hydrogen, methyl, tert-butyl, isopropylphenyl, and trityl;

[0019] The R 3 is one of n-butyl, n-hexyl, cyclohexyl, benzyl or phenyl;

[0020] The R 4 is one of methyl, benzyl or phenyl;

[0021] The X is bis(trimethylsilyl)amino.

[0022] Preferably, the imidazole-substituted aminophenoxy zinc complex catalyst has one of the following structures:

[0023]

[0024] The polymerization method of the present invention is characterized in that the preparation method of the imidazole-substituted aminophenoxy zinc complex of formula (I) comprises the following steps:

[0025]

[0026] After deprotonating the N-substituted imidazole compound shown in formula (III) with n-butyllithium in an organic medium, reacting it with N,N-dimethylformamide, the reaction temperature is -78 to 30 °C, the reaction time is 2 to 72 hours, and collecting 2-formyl-N-substituted imidazole shown in formula (IV) from the reaction product;

[0027] Optionally, reacting the 2-formyl-N-substituted imidazole shown in formula (IV) with a primary amine compound in an organic medium to obtain an imine compound shown in formula (V), the reaction temperature is 60 to 150 °C, the reaction time is 2 to 72 hours; and then reducing the imine compound with sodium borohydride to obtain a secondary amine compound shown in formula (VI), the reaction temperature is -20 to 50 °C, the reaction time is 8 to 72 hours;

[0028] Optionally, reacting the secondary amine compound shown in formula (VI) with 2-bromomethyl-4,6-disubstituted phenol shown in formula (VII) in an organic medium in the presence of a base scavenger triethylamine, the reaction temperature is -20 to 50 °C, the reaction time is 12 to 72 hours, and then collecting the imidazole-substituted aminophenol ligand compound (II) from the reaction product;

[0029] Optionally, further reacting the imidazole-substituted aminophenol ligand compound shown in formula (II) with a zinc metal raw material compound in an organic medium, the reaction temperature is 0 to 100 °C, the reaction time is 12 to 96 hours, and then collecting the target imidazole-substituted aminophenoxy zinc complex (I) from the reaction product;

[0030] In the above preparation method, the substituents R 1 ~R 4 are consistent with the corresponding groups of the imidazole-substituted aminophenol ligand (II) and its metal zinc complex (I) satisfying the present invention;

[0031] The zinc metal raw material compound has the general formula ZnX2, where X is the same as the corresponding group of the imidazole-substituted aminophenoxy zinc complex (I) described in the present invention; the zinc metal raw material compound is preferably bis{bis(trimethylsilyl)amino}zinc;

[0032] The molar ratio of the imidazole-substituted aminophenol ligand compound to the zinc metal raw material compound is 1:1 to 1.5;

[0033] In the above preparation method, the organic medium is selected from one or two of methanol, tetrahydrofuran, ether, toluene, benzene, petroleum ether, and n-hexane.

[0034] The polymerization method described in the present invention is characterized in that the 1,3-dioxolane-4-one compound has the structure shown in formula (VIII):

[0035]

[0036] In the formula (VIII):

[0037] The R 7 independently selected from C1-C 12 alkyl with a straight-chain, branched-chain or cyclic structure, C7-C 20 alkyl mono- or poly-aryl-substituted, C6-C 18 aryl;

[0038] The R 8 、R 9 independently selected from C1-C6 alkyl with a straight-chain, branched-chain or cyclic structure, or the two are connected to form a ring; R 8 and R 9 may be the same or different;

[0039] The configuration of the carbon atom marked with * is R-, S-, or racemic structure.

[0040] Preferably, in the formula (VIII), the R 7 independently selected from C1-C6 alkyl with a straight-chain, branched-chain or cyclic structure, phenyl, benzyl;

[0041] The R 8 、R 9 independently selected from methyl, ethyl, propyl, or the two are connected to form a five-membered or six-membered ring.

[0042] More preferably, the 1,3-dioxolane-4-one compound has the structures shown in formulas (IX) to (XII):

[0043]

[0044] The polymerization method according to the present invention is characterized in that the preparation method of the 1,3-dioxolan-4-one compound represented by formula (VIII) comprises the following steps:

[0045]

[0046] The substituted α-hydroxycarboxylic acid and the ketone compound are dehydrated and cyclized in the presence of a dehydrating agent, the reaction temperature is -25 to 160 °C, the reaction time is 1 to 72 hours, and the 1,3-dioxolan-4-one compound represented by formula (VIII) is collected from the reaction product;

[0047] In the above preparation method, the substituents R 7 ~R 9 are consistent with the corresponding groups of the 1,3-dioxolan-4-one compound (VIII) satisfying the present invention.

[0048] The polymerization method according to the present invention is characterized in that the raw material of the polymerization reaction further comprises lactide as a comonomer;

[0049] Preferably, the lactide is one or more of L-lactide, D-lactide, rac-lactide, and meso-lactide.

[0050] The polymerization method according to the present invention is further characterized in that the molar ratio of the imidazole-substituted aminophenoxy zinc complex catalyst to the 1,3-dioxolan-4-one compound is preferably 1:(50 to 1000); the molar ratio of the imidazole-substituted aminophenoxy zinc complex catalyst to lactide is preferably 1:(0 to 1000);

[0051] Preferably, the temperature of the polymerization reaction is 25 to 160 °C;

[0052] The time of the polymerization reaction is 0.1 to 200 hours;

[0053] The polymerization reaction is carried out in an inert atmosphere.

[0054] Preferably, the raw material of the polymerization reaction further comprises an alcohol compound;

[0055] The molar ratio of the imidazole-substituted aminophenoxy zinc complex catalyst to the alcohol compound is 1:(0 to 10);

[0056] The alcohol compound is a C1-C 10 linear, branched or cyclic alkyl alcohol, or a C7-C 20 monoaryl-substituted or polyaryl-substituted alkyl alcohol.

[0057] The present invention provides a method for polymerizing 1,3-dioxolan-4-one compounds, comprising the following steps: subjecting 1,3-dioxolan-4-one compounds to a polymerization reaction under the catalysis of an imidazole-substituted amino-phenoxy zinc complex catalyst. Compared with the prior art, the polymerization method provided by the present invention enables 1,3-dioxolan-4-one compounds to undergo homopolymerization and random copolymerization with lactide with higher efficiency. Detailed Description of the Invention

[0058] The present invention provides a method for polymerizing 1,3-dioxolan-4-one compounds, comprising the following steps:

[0059] Subjecting 1,3-dioxolan-4-one compounds to a polymerization reaction under the catalysis of an imidazole-substituted amino-phenoxy zinc complex catalyst;

[0060] The imidazole-substituted amino-phenoxy zinc complex catalyst has the structure shown in formula (I), and its ligand has the structure shown in formula (II):

[0061]

[0062] In formula (I) and (II):

[0063] The R 1 、R 2 are independently selected from one of hydrogen, C1-C 12 alkyl with a straight-chain, branched-chain or cyclic structure, C7-C 20 alkyl substituted with a mono- or poly-aryl group, and halogen;

[0064] The R 3 、R 4 are independently selected from C1-C6 alkyl with a straight-chain, branched-chain or cyclic structure, C7-C 20 alkyl substituted with a mono- or poly-aryl group, C6-C 18 aryl group;

[0065] The X represents an amino group NR 5 R 6 wherein R 5 、R 6 are independently selected from C1-C6 alkyl with a straight-chain, branched-chain or cyclic structure, trimethylsilyl group, triethylsilyl group, dimethylhydrogensilyl group, and R 5 and R 6 can be the same or different.

[0066] Preferably, in formula (I) and (II), the R 1 、R 2 are independently selected from one of hydrogen, methyl, tert-butyl, isopropylphenyl, and trityl;

[0067] The R 3 is one of n-butyl, n-hexyl, cyclohexyl, benzyl or phenyl;

[0068] The R 4 is one of methyl, benzyl or phenyl;

[0069] The X is bis(trimethylsilyl)amino.

[0070] Preferably, the imidazole-substituted aminophenoxy zinc complex catalyst has one of the following structures:

[0071]

[0072] The polymerization method of the present invention is characterized in that the preparation method of the imidazole-substituted aminophenoxy zinc complex of formula (I) includes the following steps:

[0073]

[0074] The N-substituted imidazole compound shown in formula (III) is deprotonated with n-butyllithium in an organic medium and then reacted with N,N-dimethylformamide at a reaction temperature of -78 to 30 °C for a reaction time of 2 to 72 hours, and 2-formyl-N-substituted imidazole shown in formula (IV) is collected from the reaction product;

[0075] Optionally, the 2-formyl-N-substituted imidazole shown in formula (IV) is reacted with a primary amine compound in an organic medium to obtain an imine compound shown in formula (V) at a reaction temperature of 60 to 150 °C for a reaction time of 2 to 72 hours; the imine compound is then reduced with sodium borohydride to obtain a secondary amine compound shown in formula (VI) at a reaction temperature of -20 to 50 °C for a reaction time of 8 to 72 hours;

[0076] Optionally, the secondary amine compound shown in formula (VI) is reacted with 2-bromomethyl-4,6-disubstituted phenol shown in formula (VII) in an organic medium in the presence of a base scavenger triethylamine at a reaction temperature of -20 to 50 °C for a reaction time of 12 to 72 hours, and then the imidazole-substituted aminophenol ligand compound (II) is collected from the reaction product;

[0077] Optionally, the imidazole-substituted aminophenol ligand compound shown in formula (II) is reacted with a zinc metal raw material compound in an organic medium at a reaction temperature of 0 to 100 °C for a reaction time of 12 to 96 hours, and then the target imidazole-substituted aminophenoxy zinc complex (I) is collected from the reaction product;

[0078] In the above preparation method, the substituents R 1 ~R 4Consistent with the respective groups of the imidazole-substituted aminophenol ligands (II) and their metal zinc complexes (I) according to the present invention;

[0079] The zinc metal raw material compound has the general formula ZnX2, and X is consistent with the corresponding group of the imidazole-substituted aminophenoxy zinc complex (I) according to the present invention; the zinc metal raw material compound is preferably bis{bis(trimethylsilyl)amino}zinc;

[0080] The molar ratio of the imidazole-substituted aminophenol ligand compound to the zinc metal raw material compound is 1:1 to 1.5;

[0081] In the above preparation method, the organic medium is selected from one or two of methanol, tetrahydrofuran, diethyl ether, toluene, benzene, petroleum ether and n-hexane.

[0082] The polymerization method according to the present invention is characterized in that the 1,3-dioxolane-4-one compound has a structure as shown in formula (VIII):

[0083]

[0084] In the formula (VIII):

[0085] The R 7 is independently selected from C1-C 12 alkyl with a straight-chain, branched-chain or cyclic structure, C7-C 20 alkyl mono- or poly-aryl-substituted, C6-C 18 aryl;

[0086] The R 8 , R 9 are independently selected from C1-C6 alkyl with a straight-chain, branched-chain or cyclic structure, or the two are connected to form a ring; R 8 and R 9 can be the same or different;

[0087] The configuration of the carbon atom marked with * is R-, S- or racemic structure.

[0088] Preferably, in the formula (VIII), the R 7 is independently selected from C1-C6 alkyl with a straight-chain, branched-chain or cyclic structure, phenyl, benzyl;

[0089] The R 8 , R 9 are independently selected from methyl, ethyl, propyl, or the two are connected to form a five-membered or six-membered ring.

[0090] More preferably, the 1,3-dioxolane-4-one compound has a structure as shown in formulas (IX)-(XII):

[0091]

[0092] The polymerization method described in the present invention is characterized in that the preparation method of the 1,3-dioxolan-4-one compound represented by formula (VIII) includes the following steps:

[0093]

[0094] The substituted α-hydroxycarboxylic acid and the ketone compound are dehydrated and cyclized in the presence of a dehydrating agent, the reaction temperature is -25 to 160 °C, the reaction time is 1 to 72 hours, and the 1,3-dioxolan-4-one compound shown in formula (VIII) is collected from the reaction product;

[0095] In the above preparation method, the substituents R 7 ~R 9 are consistent with the corresponding groups of the 1,3-dioxolan-4-one compound (VIII) described in the present invention.

[0096] For the convenience of description and understanding of the present invention, the four 1,3-dioxolan-4-one compounds shown in the above formulas (IX) to (XII) are specifically named as (R)-3-phenyl-1,4-dioxaspiro[4.5]decane-2-one, (R)-3-phenyl-1,4-dioxaspiro[4.4]nonane-2-one, (R)-2,2-dimethyl-5-phenyl-1,3-dioxolan-4-one, (S)-5-benzyl-2,2-dimethyl-1,3-dioxolan-4-one, and are abbreviated as NDOX-1, NDOX-2, NDOX-3, and NDOX-4 respectively. Among them, the synthesis of NDOX-1 is prepared by dehydrating D-mandelic acid and cyclohexanone under high temperature and acid catalysis (J. Am. Chem. Soc., 1981, 103(18):5414). The synthesis of NDOX-2 is prepared by dehydrating D-mandelic acid and cyclopentanone under high temperature and acid catalysis (Recueil des Travaux Chimiques des Pays-Bas, 1992, 111(3):129). NDOX-3 is prepared by dehydrating D-mandelic acid and acetone under low temperature and acid catalysis (J Organomet Chem., 1993, 451(1):133). The synthesis of NDOX-4 requires diazotization of L-phenylalanine first and then preparation with acetone under low temperature and acid catalysis (Org. Lett., 2012, 14(16):4246-4249).

[0097] The polymerization method described in the present invention is characterized in that the raw materials of the polymerization reaction further include lactide as a comonomer;

[0098] The lactide is preferably one or more of L-lactide, D-lactide, rac-lactide and meso-lactide.

[0099] The present invention has no special requirements on the mixing order of the 1,3-dioxolan-4-one compound, lactide and the imidazole-substituted amino phenoxy zinc complex catalyst. The 1,3-dioxolan-4-one compound, lactide and the imidazole-substituted amino phenoxy zinc complex catalyst can be mixed in any order.

[0100] In the present invention, the molar ratio of the imidazole-substituted amino phenoxy zinc complex catalyst to the 1,3-dioxolan-4-one compound is preferably 1:(50 - 1000), more preferably 1:(100 - 500), and most preferably 1:(100 - 200); the molar ratio of the imidazole-substituted amino phenoxy zinc complex catalyst to the lactide is preferably 1:(0 - 1000), more preferably 1:(0 - 500), and most preferably 1:(0 - 200). The present invention has no special requirements on the molar ratio of the 1,3-dioxolan-4-one compound to the lactide, and it is only necessary to meet the requirements of the molar ratio of the catalyst to the 1,3-dioxolan-4-one monomer and the molar ratio of the catalyst to the lactide. In the present invention, the molar ratio of the 1,3-dioxolan-4-one compound to the lactide can be any value.

[0101] In the present invention, the temperature of the polymerization reaction is preferably 25 - 160 °C, more preferably 25 - 70 °C. In the present invention, the time of the copolymerization reaction is preferably 0.1 - 200 hours, more preferably 1 - 80 hours, and most preferably 4 - 24 hours. The present invention has no special requirements on the heating method of the polymerization reaction, and any heating method well-known to those skilled in the art can be used for heating.

[0102] In the present invention, the copolymerization reaction is preferably carried out under an inert atmosphere. The present invention has no special requirements on the inert atmosphere, and any inert atmosphere well-known to those skilled in the art can be used, specifically it can be argon.

[0103] In the present invention, the raw materials of the copolymerization reaction preferably further include an alcohol compound. In the present invention, the alcohol compound is preferably a C1 - C 10 linear, branched or cyclic alkyl alcohol, or a C7 - C 20Mono- or poly-aryl substituted alkyl alcohols; more preferably isopropanol and benzyl alcohol. In the present invention, the molar ratio of the imidazole-substituted aminophenoxy zinc complex catalyst to the alcohol compound is preferably 1:(0-10), more preferably 1:(0-5), and most preferably 1:(0-2). The present invention has no special requirements for the addition order of the alcohol compound, and it can be mixed with the 1,3-dioxolane-4-one compound, lactide, and catalyst in any order. In the present invention, the alcohol compound is used as a co-initiator, which can accelerate the polymerization rate, make the molecular weights of the homopolymer and copolymer closer to the theoretical values, and have a narrower molecular weight distribution. It is used to react with the catalyst to in-situ generate an alkoxy zinc complex, further catalyzing the homopolymerization and copolymerization reactions.

[0104] In the present invention, the raw materials for the polymerization reaction preferably further include a solvent, and the solvent is preferably one or more of toluene, m-xylene, o-xylene, mesitylene, and trichlorobenzene. Specifically, it can be one, two, three, four, or five. The present invention has no special requirements for the addition order of the solvent, and it can be mixed with the alcohol, lactide, 1,3-dioxolane-4-one compound, and catalyst in any order. The present invention preferably dissolves the catalyst in the solvent to prepare a catalyst solvent to make the addition amount of the catalyst more controllable. In the present invention, the addition amount of the solvent is preferably based on the concentration of the catalyst. In the present invention, the molar concentration of the imidazole-substituted aminophenoxy zinc complex catalyst in the solvent is preferably 0.020-0.030 M; more preferably 0.023-0.028 M, and most preferably 0.025 M.

[0105] The present invention has no special requirements for the device used in the polymerization reaction, and any device well-known to those skilled in the art that can meet the technical requirements of this application can be used. In the present invention, the polymerization reaction is preferably carried out in a polymerization flask.

[0106] The present invention preferably adds a chain terminator to terminate the polymerization reaction after reaching the polymerization reaction time. The present invention has no special requirements for the type of the chain terminator, and any chain terminator well-known to those skilled in the art that can terminate the polymerization reaction of the 1,3-dioxolane-4-one compound can be used. Specifically, it can be a commercially available aprotic solvent, such as petroleum ether, dichloromethane, n-hexane, tetrahydrofuran, etc. The present invention has no special requirements for the dosage of the chain terminator, and it can be added according to the conventional technical content in the art.

[0107] After the reaction is terminated, the present invention preferably dissolves the reactants with dichloromethane or other large-polarity low-boiling-point solvents such as chloroform. The present invention has no special requirements for the dosage of the dichloromethane, as long as it can completely dissolve all the reactants.

[0108] After adding the dichloromethane and concentrating, the present invention preferably adds an alcohol such as methanol, ethanol, isopropanol or benzyl alcohol to precipitate the copolymer product. The present invention has no special requirements for the addition amount of the methanol, until the precipitate no longer increases.

[0109] After the polymerization product is precipitated, the present invention preferably dries the polymerization product at 60 °C to obtain the target product. The present invention has no special requirements for the specific implementation manner of the drying, and the drying can be carried out by using the drying methods of solid substances well-known to those skilled in the art, specifically, it can be vacuum drying (less than 0.1 mmHg). In the present invention, the drying time is preferably 16 to 28 hours, more preferably 20 to 26 hours, and most preferably 24 hours.

[0110] The present invention provides a polymerization method of 1,3-dioxolan-4-one compounds, comprising the following steps: polymerizing 1,3-dioxolan-4-one monomers under the catalytic condition of an imidazole-substituted aminophenoxy zinc catalyst. Compared with the prior art, the polymerization method provided by the present invention enables 1,3-dioxolan-4-one compounds to carry out homopolymerization and random copolymerization with lactide with higher efficiency.

[0111] The polymerization method provided by the present invention is simple and efficient, the catalyst has high catalytic activity, wide application range, and has broad application prospects. The following further illustrates the present invention through examples, but the present invention is not limited thereto. The following combines examples to detail the polymerization method of 1,3-dioxolan-4-one compounds provided by the present invention, but they cannot be understood as limiting the protection scope of the present invention.

[0112] Example 1

[0113] Synthesis of N-methylimidazole-substituted secondary amine

[0114]

[0115] Under argon protection, add N-methylimidazole (8.21 g, 0.100 mol) to a Schlenk flask, dissolve it with 30 mL of anhydrous tetrahydrofuran, cool it to -78 °C, add 40 mL of n-butyllithium (0.10 mol, 2.50 M), stir for 5-10 min, dropwise add 15 mL of N,N-dimethylformamide (about 0.21 mol), keep the temperature for reaction for 1 h and then raise the temperature to room temperature for reaction for more than 1 h. Add 50 mL of 12 M hydrochloric acid to quench, neutralize the excess acid with 40% sodium hydroxide solution, adjust the pH to 10, extract with dichloromethane, wash the organic phase once with saturated sodium chloride aqueous solution, dry with anhydrous sodium sulfate and then spin-dry the solvent to obtain 1-methyl-1H-2-formylimidazole, in the form of an orange-yellow liquid (7.20 g, yield 52%, purity 80%).

[0116] Take 1-methyl-1H-2-formylimidazole (1.25 g, purity 80%, about 10 mmol) in a 100 mL eggplant-shaped flask, dissolve it with 30 mL of methanol, add benzylamine dropwise (1.07 g, 10.0 mmol), then add a spatula of anhydrous magnesium sulfate as a dehydrating agent, control the oil bath temperature at 80 °C, reflux for 24 h to obtain a mixture containing H1. After cooling the above reaction device to room temperature, place it in an ice bath and add sodium borohydride (0.56 g, 15 mmol). After no bubbles are generated, react overnight at room temperature. Place the reaction device in an ice bath, add 6M dilute hydrochloric acid dropwise to quench until no more bubbles are generated, add dichloromethane for extraction, dry the organic phase with anhydrous sodium sulfate and then rotary evaporate to obtain 1.69 g of a yellowish-brown viscous liquid, which is the crude product of the target product Z1, with a purity of about 85% and a yield of 71%.

[0117] The synthesis steps of Z2 are exactly the same as those of Z1, except that the raw materials 1-methyl-1H-2-formyl-imidazole (1.25 g, purity 80%, about 10 mmol) and cyclohexylamine (0.99 g, 10 mmol) are used. The same operations and the feeding amounts of other drugs are used to obtain 1.74 g of a yellowish-brown viscous liquid, which is the crude product of the target product Z2, with a purity of about 89% and a yield of 80%.

[0118] Example 2

[0119] Ligand L 1 Synthesis of H

[0120]

[0121] Add secondary amine Z1 (0.85 g, purity 85%, about 5.3 mmol) and 2 mL of triethylamine (about 15 mmol) to a 100 mL eggplant-shaped flask, dissolve with 30 mL of dichloromethane, and add 2-(bromomethyl)-4,6-di-tert-butylphenol (1.59 g, 5.30 mmol). React overnight. Wash with saturated saline solution, dry the organic phase with anhydrous sodium sulfate and then rotary evaporate the solvent to obtain an orange viscous liquid. Add methanol to precipitate a large amount of white solid, wash with methanol, and remove methanol under reduced pressure to obtain 1.28 g of product, with a yield of 57%. 1 H NMR(CDCl3,400MHz,298K):δ10.24(br s,1H),7.40–7.23(m,5H),7.21(d, 4 J=2.4Hz,1H),6.95(d, 3 J=1.2Hz,1H),6.87(d, 4 J=2.4Hz,1H),6.79(d, 3J = 1.3 Hz, 1H), 3.81 (s, 2H), 3.69 (s, 4H), 3.35 (s, 3H), 1.43 (s, 9H), 1.27 (s, 9H).

[0122] Example 3

[0123] Ligand L 2 Synthesis of H

[0124]

[0125] Secondary amine Z1 (0.85 g, purity 85%, about 5.30 mmol) and 2 mL of triethylamine (about 15 mmol) were added to a 100 mL eggplant-shaped flask, dissolved in 30 mL of dichloromethane, and 2-bromomethyl-4-methyl-6-tritylphenol (1.68 g, 5.30 mmol) was added. The reaction was carried out overnight. After washing with saturated saline solution and drying, the solvent was evaporated to dryness to obtain an orange viscous liquid. A large amount of white solid was precipitated by adding methanol, and it was washed with methanol. After removing methanol, 1.67 g of the product was obtained with a yield of 56%. 1 H NMR (CDCl3, 400 MHz, 298 K): δ 10.02 (br s, 1H), 7.25–7.03 (m, 18H), 6.97–6.85 (m, 4H), 6.82 (d, 4 J = 2.1 Hz, 1H), 6.68 (d, 3 J = 1.3 Hz, 1H), 3.80 (s, 2H), 3.47 (s, 2H), 3.44 (s, 2H), 2.92 (s, 3H), 2.17 (s, 3H). 13 C NMR (CDCl3, 100 MHz, 298 K): δ 153.51, 146.11 (NC=N), 143.42, 136.75, 133.63, 131.29, 131.23, 131.18, 131.00, 130.86, 130.03, 129.89, 129.22, 129.06, 128.46, 127.52, 127.34, 127.01, 126.97, 125.38, 121.90, 121.75, 121.57, 63.23, 58.04, 57.73, 48.29, 32.49, 20.99. Anal. Calcd. for C 39 H 37 N3O: C, 83.09; H, 6.62; N, 7.45. Found: C, 83.17; H, 6.34; N, 7.71%.

[0126] Example 4

[0127] Ligand L 3Synthesis of H

[0128]

[0129] Add secondary amine Z2 (2.25 g, purity 89%, about 10.40 mmol), 3.04 g of triethylamine (30.00 mmol) into a 100 mL eggplant-shaped flask, dissolve with 30 mL of dichloromethane, add 2-(bromomethyl)-4-methyl-6-tritylphenol (3.35 g, 10.40 mmol), and react at room temperature overnight. Wash with saturated brine solution, dry the organic phase and then rotary evaporate the solvent to obtain an orange viscous liquid. Add methanol to precipitate a large amount of white solid, and wash with methanol. Remove methanol to obtain 3.00 g of product, with a yield of 67%. 1 H NMR(CDCl3,400MHz,298K):δ10.36(br s,1H),7.18–7.07(m,15H),6.87–6.84(m,2H),6.73(d, 4 J=2.1Hz,1H),6.67(d, 3 J=1.3Hz,1H),3.76(s,2H),3.61(s,2H),3.03(s,3H),2.35(tt,J=11.9,3.4Hz,1H),2.15(s,3H),1.79–1.71(br d,2H),1.70–1.63(br d,2H),1.63–1.54(brd,1H),1.30–1.16(m,2H),1.15–0.99(m,3H). 13 C NMR(CDCl3,100MHz,298K):δ154.02,146.10,143.85,133.28,131.23,131.17,130.52,130.37,128.72,128.56,127.42,127.23,126.92,126.86,126.62,125.24,121.98,121.74,63.13,58.53,53.60,45.64,32.67,27.34,25.99,21.02.Anal.Calcd.for C 38 H 41 N3O:C,82.12;H,7.44;N,7.56.Found:C,82.27;H,7.17;N,7.71%.

[0130] Example 5

[0131] Synthesis of zinc complex Zn1

[0132]

[0133] In a 50 mL Schlenk flask, zinc bis{bis(trimethylsilyl)amide} (386 mg, 1.00 mmol) was added and dissolved in 10 mL of toluene. Ligand L 2 H (563 mg, 1.00 mmol) was added thereto, and the reaction was carried out overnight. Toluene and free silylamine were removed by vacuum pumping. A small amount of tetrahydrofuran was added for dissolution, followed by filtration. Recrystallization with a proper amount of n-hexane gave 495 mg of a white solid with a yield of 63%. 1 1H NMR (C6D6, 400 MHz, 298 K): δ 7.73 (d, 3 J = 7.5 Hz, 6H), 7.28 (d, 4 J = 2.3 Hz, 1H), 7.24 (t, 4 J = 7.8 Hz, 6H), 7.17 - 7.14 (m, 2H), 7.03 (t, 3 J = 7.3 Hz, 3H), 7.01–6.94 (m, 3H), 6.02 (d, 4 J = 2.3 Hz, 1H), 5.28 (d, 3 J = 1.5 Hz, 1H), 5.24 (d, 3 J = 1.5 Hz, 1H), 4.30–3.99 (m, 3H), 3.30 (d, 2 J = 15.6 Hz, 1H), 2.89 (d, 2 J = 11.3 Hz, 1H), 2.64 (d, 2 J = 15.5 Hz, 1H), 1.97 (s, 3H), 1.80 (s, 3H), 0.39 (s, 18H). 13 13C NMR (CDCl3, 100 MHz, 298 K): 13 13C NMR (101 MHz, C6D6) δ 165.17 (NC=N), 147.87, 145.57, 134.55, 133.11, 132.53, 132.43, 131.58, 128.26, 128.15, 128.02, 127.91, 127.78, 127.67, 125.59, 124.67, 121.93, 120.74, 119.45, 63.91, 62.89, 60.85, 48.09, 30.63, 20.70, 6.22. Anal. Calcd. for C 45 H 54 N4OSi2Zn: C, 68.55; H, 6.90; N, 7.11. Found: C, 68.40; H, 7.08; N, 7.06%.

[0134] Example 6

[0135] Synthesis of Zinc Complex Zn2

[0136]

[0137] In a 50 mL Schlenk flask, zinc bis{bis(trimethylsilyl)amide} (386 mg, 1.00 mmol) was added and dissolved in 10 mL of toluene. Ligand L 3 H (555 mg, 1.00 mmol) was added thereto, and the reaction was carried out overnight. After removing toluene and free silylamine under reduced pressure, a small amount of tetrahydrofuran was added to dissolve the residue, followed by filtration. Recrystallization with a proper amount of n-hexane gave 512 mg of a white solid with a yield of 66%. 1 1H NMR (400 MHz, C6D6) δ 7.72 (d, 3 J = 7.5 Hz, 6H), 7.30 (d, 4 J = 2.4 Hz, 1H), 7.23 (t, 3 J = 7.7 Hz, 6H), 7.01 (t, 3 J = 7.3 Hz, 3H), 6.29 (d, 4 J = 2.4 Hz, 1H), 5.30 (d, 3 J = 1.5 Hz, 1H), 5.10 (d, 3 J = 1.5 Hz, 1H), 3.99 (d, 2 J = 11.1 Hz), 2.88 (d, 2 J = 15.6 Hz, 1H), 2.86 (d, 2 J = 11.1 Hz, 1H), 2.78 (tt, 3 J = 11.8 Hz, 8H), 2.70 (d, 2 J = 15.6 Hz, 1H), 2.43 (br d, 3 J = 11.8 Hz, 1H), 2.18 (br d, 3 J = 12.0 Hz, 1H), 2.08 (s, 3H), 2.06 (s, 3H), 1.71 (pesudo t, 3 J = 13.2 Hz, 2H), 1.52 (br d, 3 J = 13.0 Hz, 1H), 1.30–1.05 (m, 2H), 1.01–0.78 (m, 3H), 0.34 (s, 18H). 1313C NMR(100MHz, C6D6) δ 165.38, 148.07, 146.02, 134.38, 132.61, 132.48, 131.71, 128.43, 128.30, 128.06, 127.82, 125.66, 125.41, 124.92, 124.73, 122.29, 120.74, 120.48, 119.32, 65.73, 63.98, 58.19, 46.44, 30.91, 30.85, 29.28, 27.51, 26.14, 21.04, 20.99, 6.23. Anal. Calcd. for C 44 H 58 N4OSi2Zn: C, 67.71; H, 7.49; N, 7.18. Found: C, 67.33; H, 7.49; N, 7.15%.

[0138] Example 7

[0139] (R)-3-Phenyl-1,4-dioxaspiro[4.5]decan-2-one (NDOX-1) Synthesis

[0140]

[0141] 15.20 g of D-mandelic acid (100.00 mmol), 12 mL of cyclohexanone (116 mmol) and 1.91 g of p-toluenesulfonic acid monohydrate (10.00 mmol) were mixed and 100 mL of toluene was added as a water-carrying agent. The mixture was refluxed with water separation at 140 °C until no more water was distilled off. The reaction was stopped, cooled to room temperature, washed three times with saturated aqueous sodium bicarbonate solution, the toluene was evaporated, and a brownish-yellow solid was obtained. After recrystallization from petroleum ether three times, 11.2 g of a colorless solid was obtained with a yield of 48%. 1 1H NMR(400MHz, CDCl3): δ 7.51–7.32(m, 5H), 5.39(s, 1H), 2.03–1.84(m, 4H), 1.81–1.66(m, 4H), 1.61–1.40(m, 2H).

[0142] Example 8

[0143] (R)-3-Phenyl-1,4-dioxaspiro[4.4]nonan-2-one (NDOX-2) Synthesis

[0144]

[0145] 15.20 g of D-mandelic acid (100.0 mmol), 18 mL of cyclopentanone (204.0 mmol) and 1.91 g (10.00 mmol) of p-toluenesulfonic acid monohydrate were mixed and 100 mL of toluene was added as a water-carrying agent. The mixture was refluxed and water was separated at 140 °C until no more water was distilled off. After cooling to room temperature, it was washed three times with saturated aqueous sodium bicarbonate solution, the toluene was distilled off, and a brownish-yellow solid was obtained. Recrystallization from ethanol gave 10.0 g of a colorless solid with a yield of 46%. 1 H NMR (400 MHz, CDCl3): δ 7.56 - 7.31 (m, 5H), 5.34 (s, 1H), 2.25 - 1.97 (m, 4H), 1.95 - 1.70 (m, 4H). 13 C NMR (CDCl3, 100 MHz, 298K): δ 171.56, 134.37, 129.08, 128.81, 126.59, 120.90, 76.26, 37.16, 36.85, 23.44, 21.12. Anal. Calcd. for C 13 H 14 O3: C, 71.54%; H, 6.47%. Found: C, 71.61%; H, 6.57%. [α] 25 D = -62.29 (C = 0.0142 mol / L, DCM).

[0146] Example 9

[0147] (R)-2,2-Dimethyl-5-phenyl-1,3-dioxolan-4-one (NDOX-3) synthesis

[0148]

[0149] 6.30 g of concentrated sulfuric acid (about 64.60 mmol) was cooled to -10 °C, 10.00 g of D-mandelic acid (65.72 mmol) was dissolved in 30 mL of acetone, and it was added dropwise to the concentrated sulfuric acid, and the reaction was carried out at a constant temperature for 1 h. 16.70 g of sodium carbonate (157.60 mmol) was dissolved in 60 mL of water. After the reaction was completed, the mixed solution was slowly poured into this sodium carbonate solution, and it was continuously stirred until no bubbles were generated and then filtered by suction. A white solid was obtained, redissolved in dichloromethane, dried with anhydrous sodium sulfate and filtered. After most of the dichloromethane was distilled off, a small amount of petroleum ether was added for recrystallization to obtain 6.9 g of colorless crystals with a yield of 55%. 1 H NMR (400 MHz, CDCl3): δ 7.53 - 7.32 (m, 5H), 5.40 (s, 1H), 1.73 (s, 3H, CH3), 1.68 (s, 3H, CH3).

[0150] Example 10

[0151] Synthesis of (S)-5-benzyl-2,2-dimethyl-1,3-dioxolan-4-one (NDOX-4)

[0152]

[0153] 11.90 g of concentrated sulfuric acid (about 121.40 mmol) was dissolved in 100 mL of water. After cooling to 0 °C, 10.00 g of L-phenylalanine (60.54 mmol) was added and stirred until dissolved. 25.00 g of sodium nitrite (362.35 mmol) was dissolved in 60 mL of water and added dropwise to the aqueous solution of phenylalanine above. The reaction was carried out at 0 °C for 2 h and then transferred to room temperature for 20 h. After the reaction was completed, it was extracted three times with ethyl acetate, and the solvent was evaporated to obtain a yellow solid, which was washed with dichloromethane to obtain 7.3 g of white solid L-3-phenyllactic acid, with a yield of 72.6%.

[0154] 16.70 g of sodium carbonate (157.60 mmol) was dissolved in 60 mL of water. 6.30 g of concentrated sulfuric acid (about 64.60 mmol) was cooled to minus 10 °C, and 10.90 g of L-3-phenyllactic acid (about 65.60 mmol) was dissolved in 50 mL of acetone and added dropwise to the concentrated sulfuric acid. The reaction was carried out at a constant temperature for 1 h. After the reaction was completed, the mixed solution was slowly poured into the pre-prepared sodium carbonate solution, stirred continuously until there were no bubbles, and then filtered by suction to obtain a white solid. It was redissolved in dichloromethane, dried with anhydrous sodium sulfate, and recrystallized with a small amount of petroleum ether to obtain 5.6 g of colorless crystals, with a yield of 45%. 1 H NMR (400 MHz, CDCl3): δ 7.48 - 7.08 (m, 5H), 4.67 - 4.64 (dd, 3 J = 6.5, 4.1 Hz, 1H), 3.25–3.00 (m, 2H), 1.50 (s, 3H), 1.36 (s, 3H).

[0155] Example 11

[0156] Under argon protection, rac-lactide (72 mg, 0.5 mmol) and NDOX-1 (116 mg, 0.5 mmol) were added to a polymerization flask, and 0.5 mL of benzyl alcohol toluene solution was added. 0.5 mL of the toluene solution of Zn1 was measured and added to the polymerization flask. So that [Cat.]0 = 0.005 M, [rac-LA]:[NDOX-1]:[Cat.]:[BnOH] = 100:100:1:1. The reaction temperature was controlled at 25 °C, and the reaction was carried out for 6 h. Petroleum ether was added to terminate the reaction. It was dissolved with dichloromethane, and the conversion rate was measured by sampling. After the remaining solution was concentrated, methanol was added to precipitate the polymer, and it was dried in vacuo for 24 h. Through calculation and detection, the conversion rate of lactide was 99%, and the conversion rate of NDOX-1 was 15%; the content of lactide linkages in the polymer was 93%, and the content of NDOX-1 linkages was 7%; M n = 1.34×10 4 g / mol, and the molecular weight distribution PDI = 1.61.

[0157] The above M n and PDI were both detected by GPC.

[0158] Example 12

[0159] Under argon protection, rac-lactide (72 mg, 0.5 mmol) and NDOX-1 (116 mg, 0.5 mmol) were added to a polymerization flask, and 0.5 mL of benzyl alcohol toluene solution was added. 0.5 mL of the toluene solution of Zn1 was measured and added to the polymerization flask. So that [Cat.]0 = 0.005 M, [rac-LA]:[NDOX-1]:[Cat.]:[BnOH] = 100:100:1:1. The reaction temperature was controlled at 45 °C, and the reaction was carried out for 6 h. Petroleum ether was added to terminate the reaction. Other treatments were the same as in Example 11. The conversion rate of lactide was 99%, and the conversion rate of NDOX-1 was 28%; the content of lactide linkages in the polymer was 86%, and the content of NDOX-1 linkages was 14%; M n = 8.28×10 3 g / mol, and the molecular weight distribution PDI = 1.72.

[0160] Example 13

[0161] Under argon protection, rac-lactide (72 mg, 0.5 mmol) and NDOX-1 (116 mg, 0.5 mmol) were added to a polymerization flask, and 0.5 mL of toluene solution was added. 0.5 mL of the toluene solution of Zn1 was measured and added to the polymerization flask. So that [Cat.]0 = 0.005 M, [rac-LA]:[NDOX-1]:[Cat.]:[BnOH] = 100:100:1:0. The reaction temperature was controlled at 45 °C, and the reaction was carried out for 6 h. Petroleum ether was added to terminate the reaction. Other treatments were the same as in Example 11. The conversion rate of lactide was 99%, and the conversion rate of NDOX-1 was 21%; the content of lactide linkages in the polymer was 90%, and the content of NDOX-1 linkages was 10%; M n = 1.27×10 4 g / mol, and the molecular weight distribution PDI = 2.05.

[0162] Example 14

[0163] Under argon protection, rac-lactide (72 mg, 0.5 mmol) and NDOX-1 (116 mg, 0.5 mmol) were added to a polymerization flask, and 0.5 mL of toluene solution was added. 0.5 mL of the toluene solution of Zn1 was measured and added to the polymerization flask. So that [Cat.]0 = 0.005 M, [rac-LA]:[NDOX-1]:[Cat.]:[BnOH] = 100:100:1:1. The reaction temperature was controlled at 70 °C, and the reaction was carried out for 6 h. Petroleum ether was added to terminate the reaction. Other treatments were the same as in Example 11. The conversion rate of lactide was 99%, and the conversion rate of NDOX-1 was 42%; the content of lactide linkages in the polymer was 78%, and the content of NDOX-1 linkages was 22%; M n = 6.89×10 3 g / mol, and the molecular weight distribution PDI = 1.81.

[0164] Example 15

[0165] Under argon protection, rac-lactide (72 mg, 0.5 mmol) and NDOX-1 (116 mg, 0.5 mmol) were added to a polymerization flask, and 0.5 mL of toluene solution of benzyl alcohol was added. 0.5 mL of the toluene solution of Zn2 was measured and added to the polymerization flask. So that [Cat.]0 = 0.005 M, [rac-LA]:[NDOX-1]:[Cat.]:[BnOH] = 100:100:1:1. The reaction temperature was controlled at 25 °C, and the reaction was carried out for 6 h. Petroleum ether was added to terminate the reaction. Other treatments were the same as in Example 11. The conversion rate of lactide was 99%, and the conversion rate of NDOX-1 was 9%; the content of lactide linkages in the polymer was 96%, and the content of NDOX-1 linkages was 4%; M n = 1.35×10 4g / mol, the polydispersity index (PDI) of the molecular weight distribution is 1.86.

[0166] Example 16

[0167] Under argon protection, rac-lactide (72 mg, 0.5 mmol) and NDOX-1 (116 mg, 0.5 mmol) were added to a polymerization flask, and a toluene solution of 0.5 mL of benzyl alcohol was added. 0.5 mL of a toluene solution of Zn2 was measured and added to the polymerization flask. So that [Cat.]0 = 0.005 M, [rac-LA]:[NDOX-1]:[Cat.]:[BnOH] = 100:100:1:1. The reaction temperature was controlled at 45 °C, and the reaction was carried out for 6 h. Petroleum ether was added to terminate the reaction. Other treatments were the same as in Example 11. The conversion rate of lactide was 99%, and the conversion rate of NDOX-1 was 17%; the content of lactide linkages in the polymer was 91%, and the content of NDOX-1 linkages was 9%; M n = 9.06×10 3 g / mol, the polydispersity index (PDI) of the molecular weight distribution is 2.05.

[0168] Example 17

[0169] Under argon protection, rac-lactide (72 mg, 0.5 mmol) and NDOX-1 (116 mg, 0.5 mmol) were added to a polymerization flask, and a toluene solution of 0.5 mL of benzyl alcohol was added. 0.5 mL of a toluene solution of Zn2 was measured and added to the polymerization flask. So that [Cat.]0 = 0.005 M, [rac-LA]:[NDOX-1]:[Cat.]:[BnOH] = 100:100:1:1. The reaction temperature was controlled at 70 °C, and the reaction was carried out for 6 h. Petroleum ether was added to terminate the reaction. Other treatments were the same as in Example 11. The conversion rate of lactide was 99%, and the conversion rate of NDOX-1 was 25%; the content of lactide linkages in the polymer was 87%, and the content of NDOX-1 linkages was 13%; M n = 5.12×10 3 g / mol, the polydispersity index (PDI) of the molecular weight distribution is 2.50.

[0170] Example 18

[0171] Under argon protection, rac-lactide (108 mg, 0.75 mmol) and NDOX-1 (58 mg, 0.25 mmol) were added to a polymerization flask, and 0.5 mL of a toluene solution of benzyl alcohol was added. 0.5 mL of a toluene solution of catalyst Zn2 was measured and added to the polymerization flask. So that [Cat.]0 = 0.005 M, [rac-LA]:[NDOX-1]:[Cat.]:[BnOH] = 150:50:1:1. The reaction temperature was controlled at 45 °C, and the reaction was carried out for 6 h. Petroleum ether was added to terminate the reaction. Other treatments were the same as in Example 11. The conversion of lactide was 99%, and the conversion of NDOX-1 was 31%; the content of lactide linkages in the polymer was 95%, and the content of NDOX-1 linkages was 5%; M n = 8.54×10 3 g / mol, and the molecular weight distribution PDI = 3.27.

[0172] Example 19

[0173] Under argon protection, rac-lactide (130 mg, 0.9 mmol) and NDOX-1 (23 mg, 0.1 mmol) were added to a polymerization flask, and 0.5 mL of a toluene solution of benzyl alcohol was added. 0.5 mL of a toluene solution of catalyst Zn2 was measured and added to the polymerization flask. So that [Cat.]0 = 0.005 M, [rac-LA]:[NDOX-1]:[Cat.]:[BnOH] = 180:20:1:1. The reaction temperature was controlled at 45 °C, and the reaction was carried out for 6 h. Petroleum ether was added to terminate the reaction. Other treatments were the same as in Example 11. The conversion of lactide was 99%, and the conversion of NDOX-1 was 36%; the content of lactide linkages in the polymer was 98%, and the content of NDOX-1 linkages was 2%; M n = 5.35×10 3 g / mol, and the molecular weight distribution PDI = 4.20.

[0174] Example 20

[0175] Under argon protection, rac-lactide (72 mg, 0.5 mmol) and NDOX-3 (96 mg, 0.5 mmol) were added to a polymerization flask, and 0.5 mL of a toluene solution of benzyl alcohol was added. 0.5 mL of a toluene solution of Zn1 was measured and added to the polymerization flask. So that [Cat.]0 = 0.005 M, [rac-LA]:[NDOX-3]:[Cat.]:[BnOH] = 100:100:1:1. The reaction temperature was controlled at 25 °C, and the reaction was carried out for 6 h. Petroleum ether was added to terminate the reaction. Other treatments were the same as in Example 11. The conversion of lactide was 99%, and the conversion of NDOX-3 was 22%; the content of lactide linkages in the polymer was 90%, and the content of NDOX-3 linkages was 10%; M n = 1.36×10 4g / mol, the polydispersity index of the molecular weight distribution PDI = 1.78.

[0176] Example 21

[0177] Under argon protection, rac-lactide (72 mg, 0.5 mmol) and NDOX-3 (96 mg, 0.5 mmol) were added to the polymerization flask, and 0.5 mL of toluene solution was added. 0.5 mL of the toluene solution of Zn1 was measured and added to the polymerization flask. So that [Cat.]0 = 0.005 M, [rac-LA]:[NDOX-3]:[Cat.]:[BnOH] = 100:100:1:0. The reaction temperature was controlled at 25 °C, and the reaction was carried out for 6 h. Petroleum ether was added to terminate the reaction. Other treatments were the same as in Example 11. The conversion rate of lactide was 99%, and the conversion rate of NDOX-3 was 2%; the content of lactide linkages in the polymer was 99%, and the content of NDOX-3 linkages was 1%; M n = 3.33×10 4 g / mol, the polydispersity index of the molecular weight distribution PDI = 2.02.

[0178] Example 22

[0179] Under argon protection, rac-lactide (108 mg, 0.75 mmol) and NDOX-3 (48 mg, 0.25 mmol) were added to the polymerization flask, and 0.5 mL of toluene solution was added. 0.5 mL of the toluene solution of Zn1 was measured and added to the polymerization flask. So that [Cat.]0 = 0.005 M, [rac-LA]:[NDOX-3]:[Cat.]:[BnOH] = 150:50:1:1. The reaction temperature was controlled at 25 °C, and the reaction was carried out for 6 h. Petroleum ether was added to terminate the reaction. Other treatments were the same as in Example 11. The conversion rate of lactide was 99%, and the conversion rate of NDOX-3 was 35%; the content of lactide linkages in the polymer was 94%, and the content of NDOX-3 linkages was 6%; M n = 6.32×10 3 g / mol, the polydispersity index of the molecular weight distribution PDI = 4.22.

[0180] Example 23

[0181] Under argon protection, rac-lactide (72 mg, 0.5 mmol) and NDOX-4 (103 mg, 0.5 mmol) were added to a polymerization flask, and 0.5 mL of a benzyl alcohol toluene solution was added. 0.5 mL of the toluene solution of Zn1 was measured and added to the polymerization flask. So that [Cat.]0 = 0.005 M, [rac-LA]:[NDOX-4]:[Cat.]:[BnOH] = 100:100:1:1. The reaction temperature was controlled at 25 °C, and the reaction was carried out for 6 h. Petroleum ether was added to terminate the reaction. Other treatments were the same as in Example 11. The conversion rate of lactide was 99%, and the conversion rate of NDOX-4 was 30%; the content of lactide linkages in the polymer was 87%, and the content of NDOX-4 linkages was 13%; M n = 6.10×10 3 g / mol, and the molecular weight distribution PDI = 3.01.

[0182] Example 24

[0183] Under argon protection, L-lactide (72 mg, 0.5 mmol) and NDOX-4 (103 mg, 0.5 mmol) were added to a polymerization flask, and 0.5 mL of a benzyl alcohol toluene solution was added. 0.5 mL of the toluene solution of Zn1 was measured and added to the polymerization flask. So that [Cat.]0 = 0.005 M, [rac-LA]:[NDOX-4]:[Cat.]:[BnOH] = 100:100:1:1. The reaction temperature was controlled at 25 °C, and the reaction was carried out for 50 minutes. Petroleum ether was added to terminate the reaction. Other treatments were the same as in Example 11. The conversion rate of lactide was 99%, and the conversion rate of NDOX-4 was 10%; the content of lactide linkages in the polymer was 95%, and the content of NDOX-4 linkages was 5%; M n = 1.55×10 4 g / mol, and the molecular weight distribution PDI = 1.96.

[0184] Example 25

[0185] Under argon protection, rac-lactide (72 mg, 0.5 mmol) and NDOX-4 (103 mg, 0.5 mmol) were added to a polymerization flask, and 0.5 mL of a benzyl alcohol toluene solution was added. 0.5 mL of the toluene solution of Zn1 was measured and added to the polymerization flask. So that [Cat.]0 = 0.005 M, [rac-LA]:[NDOX-4]:[Cat.]:[BnOH] = 100:100:1:1. The reaction temperature was controlled at 45 °C, and the reaction was carried out for 6 h. Petroleum ether was added to terminate the reaction. Other treatments were the same as in Example 11. The conversion rate of lactide was 99%, and the conversion rate of NDOX-4 was 56%; the content of lactide linkages in the polymer was 75%, and the content of NDOX-4 linkages was 25%; M n = 5.70×10 3g / mol, the molecular weight distribution PDI = 2.98.

[0186] Example 26

[0187] Under argon protection, add NDOX-4 (206 mg, 1 mmol) into the polymerization flask, and add 0.5 mL of benzyl alcohol toluene solution. Measure 0.5 mL of the toluene solution of catalyst Zn1 and add it to the polymerization flask. Make [Cat.]0 = 0.01 M, [NDOX-4] = 1 M. [NDOX-4]:[Cat.]:[BnOH] = 100:1:1. Control the reaction temperature at 70 °C, react for 12 h, and add petroleum ether to terminate the reaction. Through calculation and detection, the conversion rate of NDOX-4 is 38%. The number average molecular weight M of the polymer n = 4.71×10 3 g / mol, the molecular weight distribution PDI = 1.52.

[0188] Example 27

[0189] Under argon protection, add NDOX-4 (206 mg, 1 mmol) into the polymerization flask, and add 0.1 mL of benzyl alcohol toluene solution. Measure 0.1 mL of the toluene solution of catalyst Zn1 and add it to the polymerization flask. Make [Cat.]0 = 0.01 M, [NDOX-4] = 5 M. [NDOX-4]:[Cat.]:[BnOH] = 100:1:1. Control the reaction temperature at 50 °C, react for 12 h, and add petroleum ether to terminate the reaction. Through calculation and detection, the conversion rate of NDOX-4 is 58%. The number average molecular weight M of the polymer n = 4.32×10 3 g / mol, the molecular weight distribution PDI = 1.86.

[0190] Example 28

[0191] Except that the reaction temperature is changed to 70 °C and the reaction time is changed to 6 h, other operations are the same as those in Example 27.

[0192] Through calculation and detection, the conversion rate of NDOX-4 is 50%. The number average molecular weight M of the polymer n = 4.23×10 3 g / mol, the molecular weight distribution PDI = 1.86.

[0193] Example 29

[0194] Except that the reaction temperature is changed to 90 °C and the reaction time is changed to 6 h, other operations are the same as those in Example 27.

[0195] Through calculation and detection, the conversion rate of NDOX-4 is 47%. The number average molecular weight M of the polymer n = 3.88×103 g / mol, the molecular weight distribution PDI = 1.71.

[0196] Example 30

[0197] Except that the reaction temperature was changed to 110 °C and the reaction time was changed to 6 h, other operations were the same as in Example 27.

[0198] Through calculation and detection, the conversion rate of NDOX-4 was 46%. The number-average molecular weight of the polymer M n = 3.70×10 3 g / mol, the molecular weight distribution PDI = 1.68.

[0199] Example 31

[0200] Under argon protection, NDOX-4 (206 mg, 1 mmol) was added to the polymerization flask, and 0.1 mL of benzyl alcohol toluene solution was added. 0.1 mL of the toluene solution of catalyst Zn2 was measured and added to the polymerization flask. Make [Cat.]0 = 0.01 M, [NDOX-4] = 5 M. [NDOX-4]:[Cat.]:[BnOH] = 100:1:1. The reaction temperature was controlled at 50 °C, and the reaction was carried out for 12 h. Petroleum ether was added to terminate the reaction. Through calculation and detection, the conversion rate of NDOX-4 was 50%. The number-average molecular weight of the polymer M n = 4.72×10 3 g / mol, the molecular weight distribution PDI = 1.77.

[0201] Example 32

[0202] Except that the reaction temperature was changed to 70 °C and the reaction time was changed to 6 h, other operations were the same as in Example 31.

[0203] Through calculation and detection, the conversion rate of NDOX-4 was 77%. The number-average molecular weight of the polymer M n = 3.27×10 3 g / mol, the molecular weight distribution PDI = 1.75.

[0204] Example 33

[0205] Except that the reaction temperature was changed to 110 °C and the reaction time was changed to 6 h, other operations were the same as in Example 31.

[0206] Through calculation and detection, the conversion rate of NDOX-4 was 49%. The number-average molecular weight of the polymer M n = 3.63×10 3 g / mol, the molecular weight distribution PDI = 1.80.

[0207] Example 34

[0208] Under argon protection, NDOX-4 (206 mg, 1 mmol) was added to a polymerization flask, and 0.1 mL of benzyl alcohol toluene solution was added. 0.01 mmol of catalyst Zn2 was weighed and added to the polymerization flask. The ratio of [NDOX-4]:[Cat.]:[BnOH] was 100:1:1. The reaction temperature was controlled at 130 °C, and the reaction was carried out for 6 h. Petroleum ether was added to terminate the reaction. Through calculation and detection, the conversion rate of NDOX-4 was 94%. The number-average molecular weight M n = 3.90×10 3 g / mol, and the molecular weight distribution PDI = 1.88.

Claims

1. A six-toothed aminophenoxo rare earth complex (I) substituted by nitrogen-containing heterocycles, characterized in that, Has the following general formula: In formula (I): R 1 represents an alkyl group having a C4-C 20 branched-chain structure, a C7-C 30 alkyl group substituted with a single or multiple aryl groups; R 2 represents a C1-C 20 alkyl group having a straight-chain or branched-chain structure, a C7-C 30 alkyl group substituted with a single or multiple aryl groups; A is a group having a structure shown in formula (II), (III), (IV) or (V): A coordinates with the metal center Re through its nitrogen atom; Re represents Y, La; B is an alkylene bridge having a structure shown in formula (VI) or (VII); R 3 represents an alkyl group having a straight-chain or branched-chain structure with 4 to 10 carbon atoms, an alkyl group having a straight-chain or branched-chain structure with 7 to 12 carbon atoms, or a mono-aryl-substituted alkyl group.

2. The hexa-dentate aminophenoxo rare earth complex (I) substituted by nitrogen heterocycles according to claim 1, characterized in that, R 1 is an alkyl group with a C4-C8 branched-chain structure, C7-C 20 alkyl group substituted with a single or multiple aryl groups; R 2 is an alkyl group with a C1-C8 straight-chain or branched-chain structure, C7-C 20 alkyl group substituted with a single or multiple aryl groups; R 3 is an alkyl group with a C4-C6 straight-chain or branched-chain structure, C7-C 10 alkyl group substituted with a single aryl group.

3. The nitrogen-containing heterocyclic substituted hexa-dentate aminophenoxo rare earth complex (I) according to claim 1, characterized in that, R 1 is tert-butyl, cumyl; R 2 is methyl, isopropyl, tert-butyl, cumyl, trityl; R 3 is tert-butyl, benzyl.

4. A method for preparing the nitrogen heterocyclic substituted hexa-dentate aminophenoxy rare earth complex (I) according to any one of claims 1 to 3, comprising the following steps: Performing a reductive amination reaction on a diamine and an aldehyde group-substituted nitrogen heterocyclic compound shown in formula (X) to generate a corresponding di-secondary amine, adding 2-bromomethyl-4,6-disubstituted phenol (IX), with the reaction temperature being 0 to 90 °C and the reaction time being 2 to 72 hours, and then collecting the nitrogen heterocyclic substituted hexa-dentate aminophenol ligand compound (VIII) from the reaction product; Optionally, the nitrogen heterocyclic substituted hexadentate aminophenol ligand compound represented by formula (VIII) is reacted with a rare earth metal raw material compound Re[N(SiMe3)2]3 in an organic medium, and then an alcohol R 3 OH is added to continue the reaction. The reaction temperature is 0 to 100 °C, and the reaction time is 2 to 24 hours. Then, the nitrogen heterocyclic substituted hexadentate aminophenoxo rare earth compound (I) is collected from the reaction product; Substituent R in the above preparation method 1 ~R 3 、A, and B are the same as the corresponding groups of the hexa-dentate aminophenoxy rare earth complex (I) substituted with a nitrogen-containing heterocycle as described in any one of claims 1 to 3.

5. The method according to claim 4, characterized in that The hexa-dentate aminophenol ligand compound (VIII) substituted by nitrogen heterocycles, the rare earth metal raw material compound Re[N(SiMe3)2]3, and the alcohol R 3 The molar ratio of OH is 1:1.0 to 1.5:0.8 to 1.5; the organic medium is selected from one or two of tetrahydrofuran, diethyl ether, toluene, benzene, petroleum ether and n-hexane.

6. Use of the nitrogen heterocyclic substituted hexa-dentate aminophenoxy rare earth complex according to any one of claims 1 to 3, characterized in that, For ring-opening polymerization of lactones.

7. The application according to claim 6, characterized in that, The lactones are selected from L-lactide, D-lactide, rac-lactide, meso-lactide, ε-caprolactone, β-butyrolactone, α-methyltrimethylene carbonate.

8. The application according to claim 6, wherein Using the nitrogen heterocyclic substituted hexa-dentate aminophenoxy rare earth complex according to any one of claims 1 to 3 as a catalyst to polymerize lactide, and the molar ratio of the catalyst to the monomer during polymerization is 1:1 to 50000.

9. The application according to claim 6, characterized in that, Using the nitrogen heterocyclic substituted hexa-dentate aminophenoxy rare earth complex according to any one of claims 1 to 3 as a catalyst to polymerize ε-caprolactone, and the molar ratio of the catalyst to the monomer during polymerization is 1:1 to 50000.

10. The application according to claim 6, wherein Using the nitrogen heterocyclic substituted hexa-dentate aminophenoxy rare earth complex according to any one of claims 1 to 3 as a catalyst to copolymerize ε-caprolactone and lactide, and in the copolymerization reaction, the molar ratio of the rare earth complex catalyst to lactide is 1:50 to 5000, and the molar ratio of the rare earth catalyst to ε-caprolactone is 1:1 to 5000.

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