A branched polymeric Schiff alkali metal compound, its preparation method and application

Abstract

This invention provides a branched polymerizable Schiff alkali metal compound having the structures shown in Formulas I to IV. The method for synthesizing the branched multicenter polymerizable Schiff alkali metal compound provided by this invention is simple, easy to separate and purify, and yields products with high purity. When used as a catalyst for the polymerization of glycolide and lactide, it exhibits high catalytic activity, improves the polymerization rate, and results in high product conversion. Experimental results show that the yield of polyglycolic acid and lactide prepared using the catalyst of this invention can reach 96.9%.

Description

Technical Field

[0001] This invention relates to the field of organic synthesis technology, and in particular to a branched polymeric Schiff alkali metal compound, its preparation method, and its applications. Background Technology

[0002] Poly(lactic acid)-glycolic acid (PLGA) is a biodegradable functional polymer with good biocompatibility, non-toxicity, and excellent film-forming properties. Composed of lactic acid and glycolic acid structural units, PLGA combines the advantages of both polyester materials and is widely used in biomedical fields, such as surgical sutures, orthopedic fixation, and tissue repair materials. Compared to polylactic acid (PLA), the degradation time of PLGA can be controlled by adjusting the glycolic acid content; different monomer ratios can produce different types of PLGA. Generally, the degradation rate of PLGA increases with increasing glycolic acid content.

[0003] Currently, PLGA is mostly prepared using ring-opening polymerization. A common ring-opening polymerization method involves converting glycolic acid and lactic acid into glycolide (GA) and lactide (LA) monomers, respectively, and then ring-opening polymerization of GA and LA to obtain a random copolymer of PLGA. Another ring-opening polymerization route involves converting glycolic acid and lactic acid monomers into lactide, and then ring-opening polymerization to obtain an alternating copolymer of PLGA. This polymer has a regular structure, fixed composition, and relatively stable degradation performance. In the above ring-opening polymerization processes, stannous octoate is mostly used as a catalyst. To further improve production efficiency, the amount of stannous octoate catalyst is generally increased. However, if an excess of catalyst is added to the reaction system during ring-opening polymerization, the residual metal compounds in the product will reduce its thermal stability. Therefore, there is a need to provide a catalyst with higher catalytic activity to improve the production efficiency of PLGA without excessive addition.

[0004] In recent years, Schiff base catalysts have been widely used due to their high catalytic activity, but their use as catalysts for the preparation of PLGA is rarely reported. Furthermore, current Schiff base compounds typically require purification and other post-treatment processes before reacting with metal compounds to obtain Schiff base catalysts. These post-treatment processes are quite cumbersome; purification usually requires large amounts of organic solvents, increasing economic costs and polluting the environment. Moreover, the yield of the final Schiff base catalyst is only around 80% at most. Summary of the Invention

[0005] In view of this, the technical problem to be solved by the present invention is to provide a branched polymerized Schiff alkali metal compound, its preparation method and application, wherein the branched polymerized Schiff alkali metal compound has high catalytic activity.

[0006] To achieve the above objectives, the present invention provides a branched polymeric Schiff alkali metal compound having any one of the structures of formulas I to IV:

[0007]

[0008]

[0009] Wherein, R1 is selected from substituted or unsubstituted alkyl or cycloalkyl groups;

[0010] R2 is selected from substituted or unsubstituted alkyl groups;

[0011] R3 is selected from hydrogen, halogen, nitro, substituted or unsubstituted alkyl or alkoxy groups;

[0012] R4 is selected from substituted or unsubstituted alkyl, cycloalkyl, aryl or heteroaryl groups;

[0013] R5 is selected from halogen, substituted or unsubstituted alkoxy or ester groups;

[0014] M1 is selected from zinc, cobalt, nickel, or tin;

[0015] M2 is selected from aluminum, indium, chromium, iron, manganese, cerium, or yttrium;

[0016] m, n, and p represent the degree of polymerization.

[0017] R1 is preferably a substituted or unsubstituted C2-C10 alkyl or C3-C12 cycloalkyl; more preferably a substituted or unsubstituted C2-C6 alkyl or C5-C6 cycloalkyl; and even more preferably a substituted or unsubstituted C2 alkyl, C3 alkyl, C4 alkyl, C5 alkyl, C6 alkyl, cyclopropyl, cyclobutyl, cyclopentyl, or cyclohexyl. R1 has two connecting positions.

[0018] The substituent of R1 is preferably one or more selected from halogen, nitro, hydroxyl, amino, cyano, C1-C6 alkyl, C1-C6 alkoxy, C1-C6 haloalkyl, and C1-C6 haloalkoxy. More preferably, it is one or more selected from fluorine, chlorine, bromine, nitro, hydroxyl, amino, cyano, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, n-hexyl, methoxy, ethoxy, propoxy, fluoromethyl, difluoromethyl, and trifluoromethyl.

[0019] In some specific embodiments of the present invention, R1 is selected from ethylene glycol, 1,3-propanediol, 1,2-propanediol, 1,4-butanediol, 1,3-butanediol, 1,2-butanediol, 2,3-butanediol, 1,5-pentanediol, 1,2-pentanediol, 1,6-hexanediol, 1,2-hexanediol, 1,4-cyclohexanediol, 1,2-cyclohexanediol, heptanediol, octanediol, nonanediol, and decanediol, after removing two hydroxyl groups.

[0020] The R2 is preferably a substituted or unsubstituted C3 to C10 alkyl group; more preferably a substituted or unsubstituted C3 alkyl, C4 alkyl, C5 alkyl, C6 alkyl, C7 alkyl, C8 alkyl, C9 alkyl or C10 alkyl group; the R2 has three connection positions.

[0021] The substituent of R2 is preferably one or more selected from halogen, nitro, hydroxyl, amino, cyano, C1-C6 alkyl, C1-C6 alkoxy, C1-C6 haloalkyl, and C1-C6 haloalkoxy. More preferably, it is one or more selected from fluorine, chlorine, bromine, nitro, hydroxyl, amino, cyano, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, n-hexyl, methoxy, ethoxy, propoxy, fluoromethyl, difluoromethyl, and trifluoromethyl.

[0022] In some specific embodiments of the present invention, R2 is selected from glycerol, 1,1,1-trimethylolpropane, 1,1,1-(trimethylol)-ethane, 1,2,4-butanetriol, 1,2,3-butanetriol, 1,2,5-pentanetriol, 1,2,6-hexanetriol, 1,2,3-hexanetriol, 1,3,5-cyclohexanetriol, 1,2,7-heptanetriol, 1,2,3-heptanetriol, 1,2,8-octanetriol, 1,2,9-nonanetriol, and 1,2,10-decanetriol, after removing three hydroxyl groups.

[0023] The R3 is preferably hydrogen, halogen, nitro, substituted or unsubstituted C1-C6 alkyl or C1-C6 alkoxy; more preferably hydrogen, halogen, nitro, substituted or unsubstituted C1 alkyl, C2 alkyl, C3 alkyl, C4 alkyl, C5 alkyl, C6 alkyl, C1 alkoxy, C2 alkoxy, C3 alkoxy, C4 alkoxy, C5 alkoxy, C6 alkoxy; even more preferably hydrogen, halogen, nitro, substituted or unsubstituted methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, methoxy, ethoxy, n-propoxy or isopropoxy.

[0024] The substituent of R3 is preferably one or more selected from halogen, nitro, hydroxyl, amino, cyano, C1-C6 alkyl, C1-C6 alkoxy, C1-C6 haloalkyl, and C1-C6 haloalkoxy. More preferably, it is one or more selected from fluorine, chlorine, bromine, nitro, hydroxyl, amino, cyano, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, n-hexyl, methoxy, ethoxy, propoxy, fluoromethyl, difluoromethyl, and trifluoromethyl.

[0025] In some specific embodiments of the present invention, R3 is selected from hydrogen, -CH3, -CH2CH3, -CH(CH3)2, -OCH(CH3)2, -C(CH3)3, -OCH3 or -OCH2CH3.

[0026] The R4 is preferably a substituted or unsubstituted C2-C6 alkyl, C3-C12 cycloalkyl, C6-C12 aryl, or C4-C11 heteroaryl; more preferably a substituted or unsubstituted C2-C6 alkyl, C5-C6 cycloalkyl, C6 aryl, or C4-C5 heteroaryl. The aryl or heteroaryl group is preferably a monocyclic aryl or heteroaryl group. The heteroatom of the heteroaryl group includes, but is not limited to, one or more of N, O, and S. The R4 is further preferably a substituted or unsubstituted C2 alkyl, C3 alkyl, C4 alkyl, C5 alkyl, C6 alkyl, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, or phenyl group.

[0027] The substituent of R4 is preferably one or more selected from halogen, nitro, hydroxyl, amino, cyano, C1-C6 alkyl, C1-C6 alkoxy, C1-C6 haloalkyl, and C1-C6 haloalkoxy. More preferably, it is one or more selected from fluorine, chlorine, bromine, nitro, hydroxyl, amino, cyano, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, n-hexyl, methoxy, ethoxy, propoxy, fluoromethyl, difluoromethyl, and trifluoromethyl. R4 has two connecting positions.

[0028] In some specific embodiments of the present invention, R4 is selected from ethylenediamine, 1,3-propanediamine, 1,2-propanediamine, 2-methyl-1,3-propanediamine, 2,2'-dimethylpropanediamine, 1,4-butanediamine, 1,2-cyclohexanediamine, o-phenylenediamine, 3-nitro-o-phenylenediamine, 4-nitro-o-phenylenediamine, 3-bromo-o-phenylenediamine, 4-bromo-o-phenylenediamine, 4,5-dibromo-o-phenylenediamine, 4-bromo-5-fluoro-o-phenylenediamine, 4-bromo-5-methyl-o-phenylenediamine, 4-chloro-5-bromo-o-phenylenediamine, 3-methyl-5-bromo-o-phenylenediamine, 4 The groups remaining after removing two amino groups from 4-methoxy-o-phenylenediamine, 4-chloro-5-fluoro-o-phenylenediamine, 4,5-dichloro-o-phenylenediamine, 4-chloro-o-phenylenediamine, 4-trifluoromethyl-o-phenylenediamine, 3-chloro-o-phenylenediamine, 3-chloro-5-trifluoromethyl-o-phenylenediamine, 4,5-difluoro-o-phenylenediamine, 4-fluoro-o-phenylenediamine, 3-fluoro-o-phenylenediamine, 3,4-difluoro-o-phenylenediamine, 3,5-difluoro-o-phenylenediamine, 4,5-dimethyl-o-phenylenediamine, 4-methyl-o-phenylenediamine, 3,5-dimethyl-o-phenylenediamine, and 4-chloro-5-methyl-o-phenylenediamine.

[0029] The R5 is preferably a halogen, a substituted or unsubstituted C1-C6 alkoxy or ester group; more preferably a fluorine, chlorine, bromine, a substituted or unsubstituted methoxy, ethoxy, n-propoxy, isopropoxy, methyl ester or ethyl ester group.

[0030] The substituent of R4 is preferably one or more selected from halogen, nitro, hydroxyl, amino, cyano, C1-C6 alkyl, C1-C6 alkoxy, C1-C6 haloalkyl, and C1-C6 haloalkoxy. More preferably, it is one or more selected from fluorine, chlorine, bromine, nitro, hydroxyl, amino, cyano, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, n-hexyl, methoxy, ethoxy, propoxy, fluoromethyl, difluoromethyl, and trifluoromethyl.

[0031] In some specific embodiments of the present invention, R4 is selected from -OCH3, -OCH2CH3, -OCH(CH3)2, -Cl or -OOCCH3.

[0032] The degree of aggregation is m, which is preferably any integer from 5 to 100.

[0033] The degree of aggregation is n, which is preferably any integer from 1 to 20.

[0034] p represents the degree of aggregation, which is preferably any integer from 5 to 100.

[0035] This invention provides a method for preparing the above-mentioned branched polymeric Schiff alkali metal compound, comprising the following steps:

[0036] a) Reaction of chloromethyl salicylaldehyde compounds with diol metal compounds and triol metal compounds yields a mixture of disalicylaldehyde compounds and trisalicylaldehyde compounds;

[0037] b) React a mixture of disalicylaldehyde and trisalicylaldehyde compounds with a diamino compound to obtain a branched Schiff base polymer.

[0038] c) Reaction of branched Schiff base polymers with metal compounds yields multicenter branched polymeric Schiff base metal compounds.

[0039] The present invention does not specifically limit the source of the above-mentioned chloromethyl salicylic aldehyde, which can be commercially available or prepared according to methods known to those skilled in the art. Preferably, the synthesis of the chloromethyl salicylic aldehyde includes the following steps:

[0040] Salicylaldehyde compounds react with formaldehyde compounds in the presence of a catalyst to produce chloromethylsalicylaldehyde.

[0041] The salicylaldehyde compounds preferably include at least one of salicylaldehyde, 3-methylsalicylaldehyde, 3-methoxysalicylaldehyde, 3-ethoxysalicylaldehyde, 3-tert-butylsalicylaldehyde, 3-bromosalicylaldehyde, 3-chlorosalicylaldehyde, 5-chlorosalicylaldehyde, 5-methylsalicylaldehyde, and 5-nitrosalicylaldehyde.

[0042] The formaldehyde compounds preferably include at least one of formaldehyde, trioxymethylene, or paraoxymethylene.

[0043] The preferred molar ratio of the salicylaldehyde compound to the formaldehyde compound is 1:1 to 1:2.

[0044] The preferred temperature for the reaction is 0–100°C, and the preferred reaction time is 2–72 h.

[0045] The catalyst is preferably at least one of HCl, concentrated sulfuric acid, phosphoric acid, acetic acid, aluminum trichloride, zinc chloride, and tin chloride.

[0046] The present invention does not have any particular limitation on the source of the above-mentioned diol metal compounds and triol metal compounds, which can be commercially available or prepared according to methods known to those skilled in the art. Preferably, the synthesis of the diol metal compounds includes the following steps:

[0047] Diols are reacted with alkali metals to give diol-alkali metal compounds.

[0048] The preferred temperature for the reaction is 25–100°C, and the preferred reaction time is 1–10 h.

[0049] The preferred molar ratio of the diol to the alkali metal is 1:2.5 to 1:4.

[0050] The alkali metal preferably includes one or more of lithium, sodium, and potassium.

[0051] The diol preferably includes at least one of ethylene glycol, 1,3-propanediol, 1,2-propanediol, 1,4-butanediol, 1,3-butanediol, 1,2-butanediol, 2,3-butanediol, 1,5-pentanediol, 1,2-pentanediol, 1,6-hexanediol, 1,2-hexanediol, 1,4-cyclohexanediol, 1,2-cyclohexanediol, heptanediol, octanediol (preferably 1,2-octanediol), nonanediol, and decanediol (preferably 1,2-decanediol).

[0052] Preferably, the synthesis of the triol metal compound includes the following steps:

[0053] Triols are reacted with alkali metals to yield triol-alkali metal compounds.

[0054] The preferred temperature for the reaction is 25–100°C, and the preferred reaction time is 1–10 h.

[0055] The preferred molar ratio of the triol to the alkali metal is 1:3.5 to 1:6.

[0056] The alkali metal preferably includes one or more of lithium, sodium, and potassium.

[0057] The triol preferably includes at least one selected from glycerol, 1,1,1-trimethylolpropane, 1,1,1-(trimethylol)-ethane, 1,2,4-butanetriol, 1,2,3-butanetriol, 1,2,5-pentanetriol, 1,2,6-hexanetriol, 1,2,3-hexanetriol, 1,3,5-cyclohexanetriol, 1,2,7-heptanetriol, 1,2,3-heptanetriol, 1,2,8-octanetriol, 1,2,9-nonanetriol, and 1,2,10-decanetriol.

[0058] Preferably, in step a), the molar ratio of the chloromethyl salicylaldehyde compound to the total molar ratio of the diol metal compound and the triol metal compound is 2:1 to 4:1.

[0059] The molar ratio of the diol metal compound to the triol metal compound is preferably 100:0.5 to 20.

[0060] The preferred temperature for the reaction is 20–110°C, and the preferred reaction time is 2–48 h.

[0061] In some specific embodiments of the present invention, the reaction equations for chloromethyl salicylaldehyde compounds and diol metal compounds are as follows:

[0062]

[0063] M is selected from lithium, sodium, or potassium.

[0064] In some specific embodiments of the present invention, the reaction equations for chloromethyl salicylaldehyde compounds and triol metal compounds are as follows:

[0065]

[0066] M is selected from lithium, sodium, or potassium.

[0067] The present invention provides a one-pot process for obtaining disalicylaldehyde and trisalicylaldehyde compounds by reacting chloromethylsalicylaldehyde with diol metal compounds and triol metal compounds, which simplifies the process by eliminating the need for product separation.

[0068] In step b), the ratio of the total molar amount of the disalicylaldehyde compound and the trisalicylaldehyde compound to the molar amount of the diamino compound is preferably 1:0.6 to 1.5.

[0069] The molar ratio of the disalicylaldehyde compound and the trisalicylaldehyde compound is preferably 100:0.5 to 20.

[0070] The preferred temperature for the reaction is 20–100°C, and the preferred reaction time is 1–48 h.

[0071] The diamino compound preferably includes ethylenediamine, 1,3-propanediamine, 1,2-propanediamine, 2-methyl-1,3-propanediamine, 2,2'-dimethylpropanediamine, 1,4-butanediamine, 1,2-cyclohexanediamine, o-phenylenediamine, 3-nitro-o-phenylenediamine, 4-nitro-o-phenylenediamine, 3-bromo-o-phenylenediamine, 4-bromo-o-phenylenediamine, 4,5-dibromo-o-phenylenediamine, 4-bromo-5-fluoro-o-phenylenediamine, 4-bromo-5-methyl-o-phenylenediamine, 4-chloro-5-bromo-o-phenylenediamine, 3-methyl-5-bromo-o-phenylenediamine, 4 At least one of the following: methoxy-o-phenylenediamine, 4-chloro-5-fluoro-o-phenylenediamine, 4,5-dichloro-o-phenylenediamine, 4-chloro-o-phenylenediamine, 4-trifluoromethyl-o-phenylenediamine, 3-chloro-o-phenylenediamine, 3-chloro-5-trifluoromethyl-o-phenylenediamine, 4,5-difluoro-o-phenylenediamine, 4-fluoro-o-phenylenediamine, 3-fluoro-o-phenylenediamine, 3,4-difluoro-o-phenylenediamine, 3,5-difluoro-o-phenylenediamine, 4,5-dimethyl-o-phenylenediamine, 4-methyl-o-phenylenediamine, 3,5-dimethyl-o-phenylenediamine, and 4-chloro-5-methyl-o-phenylenediamine.

[0072] In some specific embodiments of the present invention, the reaction equation for step b) is as follows:

[0073]

[0074] In step c), the metal compound preferably includes at least one of zinc chloride, zinc acetate, ethyl zinc, stannous chloride, ferric chloride, indium chloride, cobalt acetate, aluminum isopropoxide, aluminum ethoxylate, nickel acetate, and triethylaluminum.

[0075] The preferred molar ratio of diamino compound residues to metal compounds in the branched Schiff base polymer is 1:1 to 1:1.2.

[0076] The preferred temperature for the reaction is 20–120°C, and the preferred reaction time is 2–100 h.

[0077] This invention provides the application of the above-mentioned branched polymeric Schiff alkali metal compound or the branched polymeric Schiff alkali metal compound prepared by the above preparation method as a catalyst in the preparation of poly(lactic acid) lactide.

[0078] Based on this, the present invention provides a method for preparing poly(lactic-co-liquid) lactide, comprising the following steps:

[0079] Poly(glycolic acid) and lactide, or glycolide, lactide and epoxide, react under an inert atmosphere with a catalyst and an initiator to obtain poly(glycolic acid) and lactide.

[0080] The catalyst is the branched polymerized Schiff alkali metal compound described above or the branched polymerized Schiff alkali metal compound prepared by the above preparation method.

[0081] The preferred ratio of the mass of the catalyst to the total mass of the glycolide and the lactide is 1:(20-2000).

[0082] The initiator is preferably an alcohol compound.

[0083] The alcohols preferably include at least one of isopropanol, butanol, pentanol, hexanol, benzyl alcohol, cyclohexanol, ethylene glycol, 1,3-propanediol, 1,2-propanediol, 1,4-butanediol, 1,3-butanediol, 1,2-butanediol, 2,3-butanediol, 1,5-pentanediol, 1,2-pentanediol, 1,6-hexanediol, 1,2-hexanediol, 1,4-cyclohexanediol, 1,2-cyclohexanediol, heptanediol, octanediol, 1,2-octanediol, nonanediol, decanediol, 1,2-decanediol, undecylol, and dodecaylol.

[0084] The ratio of the molar amount of the initiator to the total molar amount of the glycolide and the lactide is preferably 1:(100-2000).

[0085] The preferred ratio of the molar amount of the epoxy compound to the total molar amount of the glycolide and the lactide is (0-10):(90-100).

[0086] The epoxy compound is preferably any one or more of the following: propylene oxide, butane oxide, 1,2-epoxycyclopentane, 1,2-epoxycyclohexane, 1,2-epoxyoctane, 1,2-epoxydodecane, 1,2-epoxytetradecane, 1,2-epoxyhexadecane, allyl glycidyl ether, styrene oxide, isopropyl glycidyl ether, tert-butyl glycidyl ether, octyl glycidyl, phenyl glycidyl ether, 2-toluene glycidyl ether, or benzyl glycidyl ether.

[0087] In the above reaction, the epoxy compound may or may not be added. Whether it is added depends on the metal element in the catalyst. When the metal element is aluminum, tin or indium, the amount of epoxy compound added is 0; when the metal element is zinc, iron, cobalt, nickel, manganese, chromium, cerium or yttrium, the amount of epoxy compound added is not 0.

[0088] The preferred molar ratio of glycolide to lactide is (1-99):(99-1).

[0089] The preferred temperature for the reaction is 120–240°C, and the preferred time is 2–24 h.

[0090] The above preparation method has mild reaction conditions, high product yield, and reduces the production cost of the catalyst.

[0091] Compared with existing technologies, this invention provides a branched polymerizable Schiff alkali metal compound with structures shown in Formulas I to IV. The method for synthesizing the branched multicenter polymerizable Schiff alkali metal compound provided by this invention is simple, easy to separate and purify, and yields products with high purity. When used as a catalyst for the polymerization of glycolide and lactide, it exhibits high catalytic activity, improves the polymerization rate, and achieves high product conversion. Experimental results show that the yield of polyglycolic acid and lactide prepared using the catalyst of this invention can reach 96.9%. Detailed Implementation

[0092] To further illustrate the present invention, the branched polymeric Schiff alkali metal compounds, their preparation methods, and applications provided by the present invention are described in detail below with reference to embodiments. However, it should be understood that these descriptions are merely for further illustrating the features and advantages of the present invention and are not intended to limit the scope of the claims.

[0093] There are no particular restrictions on the source of any raw materials used in this invention; they can be purchased from the market or prepared using conventional methods known to those skilled in the art.

[0094] Example 1

[0095] 1 mol of ethylene glycol, 2.5 mol of metallic sodium, and 400 mL of anhydrous toluene were added to a 1 L round-bottom flask. The mixture was stirred and heated to 65 °C. After the sodium content stopped decreasing, the unreacted sodium was removed, and then the toluene was removed under vacuum to obtain 105.1 g of sodium ethylene glycol. In the embodiments of this invention, sodium butanediol, sodium hexanediol, and sodium cyclohexanediol were all prepared according to this method, with ethylene glycol replaced by butanediol, hexanediol, and cyclohexanediol, respectively.

[0096] Example 2

[0097] 0.1 mol glycerol, 0.4 mol sodium metal, and 100 mL anhydrous toluene were added to a 500 mL round-bottom flask, mixed and stirred, and heated to 70 °C. After the sodium metal stopped decreasing, the unreacted sodium metal was removed, and then the toluene was removed under vacuum to obtain 15.6 g of sodium glycerol. In the embodiments of this invention, sodium 1,2,4-butanetriol, sodium 1,2,6-hexanetriol, and sodium trimethylolpropane were all prepared according to this method, with glycerol replaced by 1,2,4-butanetriol, 1,2,6-hexanetriol, and 1,1,1-trimethylolpropane, respectively.

[0098] Example 3

[0099] 3.1 122 g of salicylaldehyde, 85.1 g of formaldehyde solution (37 wt%), and 800 mL of concentrated hydrochloric acid (37 wt%) were added to a 2 L round-bottom flask. The mixture was stirred and HCl gas (dried from concentrated sulfuric acid) was continuously introduced. The reaction temperature was 15 °C, and HCl gas was introduced for 10 h. The round-bottom flask was then sealed and allowed to stand for 35 h. The temperature was then raised to 60 °C and the reaction was stirred. After 36 h, the crude product was filtered, dissolved in diethyl ether, and washed with saturated sodium bicarbonate solution until neutral. Then, it was washed three times with saturated NaCl solution. 40 g of anhydrous magnesium sulfate was added and dried for 24 h. After filtration, the solvent was removed under normal pressure. The obtained solid was recrystallized with petroleum ether and dried under vacuum at 30 °C for 24 h to obtain 153.6 g of 5-chloromethylsalicylaldehyde, with a yield of 90.1%.

[0100] 3.2 Dissolve 53g of sodium glycolate prepared in Example 1 in 200mL of toluene, and then add it dropwise at a rate of 2mL / min to 800mL of the above-mentioned 5-chloromethylsalicylaldehyde (173.1g) toluene solution. After the addition is complete, heat to 60℃ and react for 15h. Then add 0.79g of sodium glycerol prepared in Example 2 and react for 10h. Stop heating, add 100mL of water, mix well, and transfer the material to a separatory funnel. Let it stand to separate the aqueous layer. Wash the oil phase with deionized water several times until the aqueous phase is neutral. Add 30g of anhydrous sodium sulfate and dry for 24h. After filtration, remove the solvent under vacuum to obtain 159.8g of disalicylaldehyde compound and trisalicylaldehyde compound.

[0101] The obtained products were analyzed using MALDI-TOF-MS. The m / z values ​​(332, 497) on the spectrum corresponded to the molecular weights of the disalicylaldehyde and trisalicylaldehyde compounds, proving the successful synthesis of the disalicylaldehyde and trisalicylaldehyde compounds.

[0102] The obtained disalicylaldehyde and trisalicylaldehyde compounds were analyzed by nuclear magnetic resonance (NMR), and their proton NMR spectra were as follows: δ = 10.10-10.28 ppm corresponds to the characteristic chemical shifts of hydrogen atoms on the aldehyde group in disalicylaldehyde and trisalicylaldehyde compounds; δ = 6.82-7.65 ppm corresponds to the characteristic chemical shifts of hydrogen atoms on the benzene ring in disalicylaldehyde and trisalicylaldehyde compounds; δ = 4.73-4.87 ppm corresponds to the characteristic chemical shifts of hydrogen atoms on the methylene group attached to the benzene ring in salicylaldehyde; δ = 3.65-3.75 ppm corresponds to the characteristic chemical shifts of hydrogen atoms on the methine group in trisalicylaldehyde compounds; and δ = 3.42-3.56 ppm corresponds to the characteristic chemical shifts of hydrogen atoms on the methylene group attached to oxygen in ethylene glycol and glycerol in the compounds.

[0103] This further proves the successful synthesis of disalicylaldehyde and trisalicylaldehyde compounds.

[0104] Example 4

[0105] 4.1 136 g of 5-methylsalicylaldehyde, 121.6 g of formaldehyde solution (37 wt%), and 600 mL of concentrated hydrochloric acid (37 wt%) were added to a 2 L round-bottom flask. The mixture was stirred and HCl gas (dried from concentrated sulfuric acid) was continuously introduced. The reaction temperature was 10 °C, and HCl gas was introduced for 12 h. The round-bottom flask was then sealed, and the mixture was stirred at 25 °C for 30 h. The temperature was then raised to 50 °C and stirred for 24 h. After that, the crude product was filtered, dissolved in diethyl ether, and washed with saturated sodium bicarbonate solution until neutral. Then, it was washed three times with saturated NaCl solution. 60 g of anhydrous magnesium sulfate was added and dried for 24 h. After filtration, the solvent was removed under normal pressure. The resulting solid was then recrystallized with petroleum ether and dried under vacuum at 30 °C for 24 h to obtain 167 g of 3-chloromethyl-5-methylsalicylaldehyde, with a yield of 90.5%.

[0106] 4.2 Dissolve 67g of sodium butanediol prepared in Example 1 in 500mL of toluene, and then add it dropwise at a rate of 3mL / min to 900mL of the above-mentioned toluene solution of 3-chloromethyl-5-methylsalicylaldehyde (188.9g). After the addition is complete, heat to 55℃ and react for 20h. Then add 1.6g of sodium trimethylolpropane prepared in Example 2 and react for 12h. Add 150mL of water, mix well, and transfer the material to a separatory funnel. Let it stand to separate the aqueous layer. Wash the oil phase with deionized water several times until the aqueous phase is neutral. Add 50g of anhydrous sodium sulfate and dry for 24h. After filtration, remove the solvent under vacuum to obtain 175.3g of disalicylaldehyde compound and trisalicylaldehyde compound.

[0107] The obtained products were analyzed using MALDI-TOF-MS. The m / z values ​​(388, 581) on the spectrum corresponded to the molecular weights of the disalicylaldehyde and trisalicylaldehyde compounds, proving the successful synthesis of the disalicylaldehyde and trisalicylaldehyde compounds.

[0108] Example 5

[0109] 5.1 152 g of 3-methoxysalicylaldehyde, 89 g of formaldehyde solution (37 wt%), and 500 mL of concentrated hydrochloric acid (37 wt%) were added to a 2 L round-bottom flask. The mixture was stirred and HCl gas (dried from concentrated sulfuric acid) was continuously introduced. The reaction temperature was 20 °C, and HCl gas was introduced for 15 h. The round-bottom flask was then sealed, and the mixture was stirred at 30 °C for 24 h. The temperature was then raised to 55 °C, and the reaction was stirred for 20 h. The crude product was filtered, dissolved in diethyl ether, and washed with saturated sodium bicarbonate solution until neutral. Then, it was washed three times with saturated NaCl solution. 80 g of anhydrous magnesium sulfate was added and dried for 24 h. After filtration, the solvent was removed under normal pressure. The resulting solid was recrystallized with petroleum ether and dried under vacuum at 30 °C for 24 h to obtain 182.6 g of 5-chloromethyl-3-methoxysalicylaldehyde, with a yield of 91.1%.

[0110] 5.2 Dissolve 81g of sodium hexanediol prepared in Example 1 in 400mL of toluene, and then add it dropwise at a rate of 5mL / min to 1000mL of the above-mentioned toluene solution of 5-chloromethyl-3-methoxysalicylaldehyde (208.8g). After the addition is complete, heat to 65℃ and react for 12h. Then add 2.08g of sodium 1,2,4-butanetriol prepared in Example 2 and react for 8h. Add 200mL of water, mix well, and transfer the material to a separatory funnel. Let it stand to separate the aqueous layer. Wash the oil phase with deionized water several times until the aqueous phase is neutral. Add 60g of anhydrous sodium sulfate and dry for 24h. After filtration, remove the solvent under vacuum to obtain 220.2g of disalicylaldehyde compound and trisalicylaldehyde compound.

[0111] The obtained products were analyzed using MALDI-TOF-MS. The m / z values ​​(448, 601) on the spectrum correspond to the molecular weights of the disalicylaldehyde and trisalicylaldehyde compounds, proving the successful synthesis of the disalicylaldehyde and trisalicylaldehyde compounds.

[0112] Example 6

[0113] 6.1 178 g of 3-tert-butylsalicylaldehyde, 97.3 g of formaldehyde solution (37 wt%), and 400 mL of concentrated hydrochloric acid (37 wt%) were added to a 2 L round-bottom flask. The mixture was stirred and HCl gas (dried from concentrated sulfuric acid) was continuously introduced. The reaction temperature was 25 °C, and HCl gas was introduced for 8 h. The round-bottom flask was then sealed, and the mixture was stirred at 25 °C for 35 h. The temperature was then raised to 60 °C, and the reaction was stirred for 30 h. After that, the crude product was filtered, dissolved in diethyl ether, and washed with saturated sodium bicarbonate solution until neutral. Then, it was washed three times with saturated NaCl solution. 50 g of anhydrous magnesium sulfate was added, and the mixture was dried for 24 h. After filtration, the solvent was removed under normal pressure. The resulting solid was recrystallized with petroleum ether and dried under vacuum at 30 °C for 24 h to obtain 208.1 g of 5-chloromethyl-3-tert-butylsalicylaldehyde, with a yield of 91.5%.

[0114] 6.2 Dissolve 80g of sodium cyclohexanediol prepared in Example 1 in 600mL of toluene, and then add it dropwise at a rate of 5mL / min to 1200mL of the above-mentioned toluene solution of 5-chloromethyl-3-tert-butylsalicylaldehyde (239.1g). After the addition is complete, heat to 70℃ and react for 10h. Then add 3.4g of sodium 1,2,6-hexanetriol prepared in Example 2 and react for 6h. Add 250mL of water, mix well, and transfer the material to a separatory funnel. Let it stand to separate the aqueous layer. Wash the oil phase with deionized water several times until the aqueous phase is neutral. Add 100g of anhydrous sodium sulfate and dry for 24h. After filtration, remove the solvent under vacuum to obtain 241.5g of disalicylaldehyde compound and trisalicylaldehyde compound.

[0115] The obtained products were analyzed using MALDI-TOF-MS. The m / z values ​​(498, 707) on the spectrum corresponded to the molecular weights of the disalicylaldehyde and trisalicylaldehyde compounds, proving the successful synthesis of the disalicylaldehyde and trisalicylaldehyde compounds.

[0116] Example 7

[0117] 7.1 Dissolve 37.1g of the mixture of disalicylaldehyde and trisalicylaldehyde prepared in Example 3 in 200mL of toluene, mix with 6g of ethylenediamine, stir and heat to 60°C. After 15h, remove toluene under vacuum of 300Pa. When no more liquid distills out, add 100mL of ethanol to wash, filter and dry to obtain 40.1g of branched polymerized Schiff base, yield 93%.

[0118] The obtained branched polymerized Schiff base was analyzed by gel permeation chromatography, and the number average molecular weight of the branched polymerized Schiff base was determined to be 7000 g / mol.

[0119] 7.2 Dissolve 8.6 g of the above branched polymerized Schiff base in 50 mL of toluene, mix with 4.08 g of aluminum isopropoxide in 50 mL of toluene solution, heat to 80 °C, and after 72 h, remove toluene under vacuum at a vacuum degree of 300 Pa. When no more liquid distills out, add 50 mL of ethanol to wash, filter, and dry to obtain 9.7 g of multi-center branched polymerized Schiff base aluminum catalyst, with a yield of 94.0%.

[0120] 7.3 The reaction flask was repeatedly evacuated and purged with nitrogen. 348g of glycolide, 21.6g of lactide, 0.558g of dodecanol and 0.5g of the above-mentioned multicenter branched polymerization Schiff base aluminum catalyst were added to the reaction flask in sequence. The mixture was stirred and the temperature was rapidly raised to 180℃. After 7 hours, 358.1g of polyethylene glycolide was obtained, with a yield of 96.9%.

[0121] The obtained poly(ethylene glycol) lactide was analyzed by gel permeation chromatography, and the number average molecular weight of the poly(ethylene glycol) lactide was determined to be 105,000 g / mol.

[0122] Example 8

[0123] 8.1 37.7 g of the mixture of disalicylaldehyde and trisalicylaldehyde prepared in Example 3 was dissolved in 200 mL of toluene, mixed with 11.4 g of 1,2-cyclohexanediamine, stirred and heated to 65 °C. After 12 h, toluene was removed by vacuum at a vacuum degree of 300 Pa. When no more liquid distilled out, 150 mL of ethanol was added for washing, filtration and drying to obtain 45.9 g of branched polymerized Schiff base, with a yield of 93.5%.

[0124] The obtained branched polymerized Schiff base was analyzed by gel permeation chromatography, and the number average molecular weight of the branched polymerized Schiff base was determined to be 6600 g / mol.

[0125] 8.2 Dissolve 9.82g of the above branched polymerized Schiff base in 100mL of tetrahydrofuran, mix with 50mL of tetrahydrofuran solution containing 3.54g of cobalt acetate, heat to 65℃, and after 24h, remove tetrahydrofuran by vacuum at a vacuum degree of 300Pa. When no more liquid distills out, add 50mL of ethanol to wash, filter, and dry to obtain 10.2g of multi-center branched polymerized Schiff base cobalt catalyst.

[0126] 8.3 The reaction flask was repeatedly evacuated and purged with nitrogen. 348g of glycolide, 43.2g of lactide, 1.16g of isopropyl glycidyl ether, 0.651g of dodecanol and 2.4g of the above-mentioned multicenter branched polymerization Schiff base cobalt catalyst were added to the reaction flask in sequence. The mixture was stirred and the temperature was rapidly raised to 185℃. After 6 hours, 372.8g of polyethylene glycolide was obtained, with a yield of 95.3%.

[0127] The obtained poly(ethylene glycol) lactide was analyzed by gel permeation chromatography, and the number-average molecular weight of the poly(ethylene glycol) lactide was determined to be 83,000 g / mol.

[0128] Example 9

[0129] 9.1 Dissolve 38.7g of the mixture of disalicylaldehyde and trisalicylaldehyde prepared in Example 3 in 200mL of toluene, mix with 15.3g of 4-nitro-o-phenylenediamine, stir and heat to 70°C. After 8h, remove toluene under vacuum of 300Pa. When no more liquid distills out, add 200mL of ethanol to wash, filter and dry to obtain 50.76g of branched polymerized Schiff base, yield 94%.

[0130] The obtained branched polymerized Schiff base was analyzed by gel permeation chromatography, and the number average molecular weight of the branched polymerized Schiff base was determined to be 5800 g / mol.

[0131] 9.2 Dissolve 10.8g of the above branched polymerized Schiff base in 100mL of toluene, mix with 20mL of a toluene solution containing 2.28g of triethylaluminum, heat to 75℃, and after 15h, add 20mL of ethanol. After 4h, remove toluene and ethanol under vacuum at a vacuum degree of 300Pa. When no more liquid distills out, add 100mL of ethanol to wash, filter, and dry to obtain 11.6g of the multi-center branched polymerized Schiff base aluminum catalyst.

[0132] 9.3 The reaction flask was repeatedly evacuated and purged with nitrogen. 348g of glycolide, 64.8g of lactide, 0.744g of dodecanol and 2.1g of the above-mentioned multicenter branched polymerization Schiff base aluminum catalyst were added to the reaction flask in sequence. The mixture was stirred and the temperature was rapidly raised to 190℃. After 5 hours, 398.4g of polyethylene glycolide was obtained, with a yield of 96.5%.

[0133] The obtained poly(ethylene glycol) lactide was analyzed by gel permeation chromatography, and the number-average molecular weight of the poly(ethylene glycol) lactide was determined to be 92,000 g / mol.

[0134] Example 10

[0135] 10.1 47.6 g of the mixture of disalicylaldehyde and trisalicylaldehyde prepared in Example 4 was dissolved in 250 ml of toluene, mixed with 7.4 g of 1,3-propanediamine, stirred, and heated to 75 °C. After 6 h, toluene was removed by vacuum at a vacuum degree of 300 Pa. When no more liquid distilled out, 200 mL of ethanol was added for washing, filtration, and drying to obtain 51.6 g of branched polymerized Schiff base, with a yield of 93.8%.

[0136] The obtained branched polymerized Schiff base was analyzed by gel permeation chromatography, and the number average molecular weight of the branched polymerized Schiff base was determined to be 4600 g / mol.

[0137] 10.2 Dissolve 11g of the above branched polymerized Schiff base in 150mL of tetrahydrofuran, mix with 3.66g of zinc acetate in 50mL of ethanol solution, heat to 60℃, and after 30h, remove toluene and ethanol under vacuum of 300Pa. When no more liquid distills out, add 50mL of ethanol to wash, filter, and dry to obtain 11.3g of multi-center branched polymerized Schiff base zinc catalyst.

[0138] 10.3 The reaction flask was repeatedly evacuated and purged with nitrogen. 348g of glycolide, 86.4g of lactide, 2.6g of tert-butyl glycidyl ether, 1.8g of the above-mentioned multicenter branched polymerization Schiff base zinc catalyst, and 0.48g of benzyl alcohol were added to the reaction flask in sequence. The mixture was stirred and the temperature was rapidly raised to 195℃. After 4 hours, 417.9g of polyethylene glycolide was obtained, with a yield of 96.2%.

[0139] The obtained poly(ethylene glycol) lactide was analyzed by gel permeation chromatography, and the number average molecular weight of the poly(ethylene glycol) lactide was determined to be 86,000 g / mol.

[0140] Example 11

[0141] 11.1 45.6 g of the mixture of disalicylaldehyde and trisalicylaldehyde prepared in Example 4 was dissolved in 250 ml of toluene, mixed with 18.7 g of 4-bromo-o-phenylenediamine, stirred and heated to 70 °C. After 12 h, toluene was removed by vacuum at a vacuum degree of 300 Pa. When no more liquid distilled out, 250 mL of ethanol was added for washing, filtration, and drying to obtain 60.6 g of branched polymerized Schiff base, with a yield of 94.3%.

[0142] The obtained branched polymerized Schiff base was analyzed by gel permeation chromatography, and the number average molecular weight of the branched polymerized Schiff base was determined to be 6900 g / mol.

[0143] 11.2 Dissolve 12.86g of the above branched polymerized Schiff base in 150mL of toluene, mix with 3.24g of aluminum ethoxy in 30mL of toluene solution, heat to 85℃, and after 36h, remove toluene by vacuum at a vacuum degree of 300Pa. When no more liquid distills out, add 100mL of ethanol to wash, filter, and dry to obtain 13.5g of multi-center branched polymerized Schiff base aluminum catalyst.

[0144] 11.3 The reaction flask was repeatedly evacuated and purged with nitrogen. 348g of glycolide, 108g of lactide, 0.558g of dodecanol and 2.7g of the above-mentioned multicenter branched polymerization Schiff base aluminum catalyst were added to the reaction flask in sequence. The mixture was stirred and the temperature was rapidly raised to 175℃. After 10h, 440.9g of polyethylene glycolide was obtained, with a yield of 96.7%.

[0145] The obtained poly(ethylene glycol) lactide was analyzed by gel permeation chromatography, and the number-average molecular weight of the poly(ethylene glycol) lactide was determined to be 95,000 g / mol.

[0146] Example 12

[0147] 12.1 44.1 g of the mixture of disalicylaldehyde and trisalicylaldehyde prepared in Example 4 was dissolved in 300 ml of toluene, mixed with 8.8 g of 2-methyl-1,3-propanediamine, stirred and heated to 65 °C. After 15 h, toluene was removed by vacuum at a vacuum degree of 300 Pa. When no more liquid distilled out, 200 mL of ethanol was added for washing, filtration, and drying to obtain 49.62 g of branched polymerized Schiff base, with a yield of 93.8%.

[0148] The obtained branched polymerized Schiff base was analyzed by gel permeation chromatography, and the number average molecular weight of the branched polymerized Schiff base was determined to be 7100 g / mol.

[0149] 12.2 Dissolve 10.58g of the above branched polymerized Schiff base in 200mL of tetrahydrofuran, mix with 4.42g of indium chloride in 60mL of ethanol solution, heat to 55℃, and after 24h, remove toluene and ethanol under vacuum of 300Pa. When no more liquid distills out, add 100mL of ethanol to wash, filter, and dry to obtain 12.4g of multi-center branched polymerized Schiff base indium catalyst.

[0150] 12.3 The reaction flask was repeatedly evacuated and purged with nitrogen. 348g of glycolide, 129.6g of lactide, 0.93g of dodecanol and 3g of the above-mentioned multicenter branched polymerization Schiff base indium catalyst were added to the reaction flask in sequence. The mixture was stirred and the temperature was rapidly raised to 170℃. After 12 hours, 454.2g of polyethylene glycolide was obtained, with a yield of 95.1%.

[0151] The obtained poly(ethylene glycol) lactide was analyzed by gel permeation chromatography, and the number-average molecular weight of the poly(ethylene glycol) lactide was determined to be 72,000 g / mol.

[0152] Example 13

[0153] 13.1 49.8 g of the mixture of disalicylaldehyde and trisalicylaldehyde prepared in Example 5 was dissolved in 300 ml of toluene, mixed with 10.8 g of o-phenylenediamine, stirred, and heated to 60 °C. After 20 h, toluene was removed by vacuum at a vacuum degree of 300 Pa. When no more liquid distilled out, 250 mL of ethanol was added for washing, filtration, and drying to obtain 56.53 g of branched polymerized Schiff base, with a yield of 93.3%.

[0154] The obtained branched polymerized Schiff base was analyzed by gel permeation chromatography, and the number average molecular weight of the branched polymerized Schiff base was determined to be 10500 g / mol.

[0155] 13.2 Dissolve 12.12 g of the above branched polymerized Schiff base in 150 mL of tetrahydrofuran, mix with 3.46 g of manganese acetate in 60 mL of ethanol solution, heat to 60 °C, and after 24 h, remove tetrahydrofuran and ethanol by vacuum at a vacuum degree of 500 Pa. When no more liquid distills out, add 50 mL of ethanol to wash, filter, and dry to obtain 12.1 g of multi-center branched polymerized Schiff base manganese catalyst.

[0156] 13.3 The reaction flask was repeatedly evacuated and purged with nitrogen. 348g of glycolide, 151.2g of lactide, 3g of phenyl glycidyl ether, 3.3g of the above-mentioned multicenter branched polymerization Schiff base manganese catalyst, and 0.54g of benzyl alcohol were added to the reaction flask in sequence. The mixture was stirred and the temperature was rapidly raised to 165℃. After 15h, 476.7g of polyethylene lactide was obtained, with a yield of 95.5%.

[0157] The obtained poly(ethylene glycol) lactide was analyzed by gel permeation chromatography, and the number average molecular weight of the poly(ethylene glycol) lactide was determined to be 80,000 g / mol.

[0158] Example 14

[0159] 14.1 49.3 g of the mixture of disalicylaldehyde and trisalicylaldehyde prepared in Example 5 was dissolved in 300 ml of tetrahydrofuran, mixed with 7.4 g of 1,2-propanediamine, stirred and heated to 55 °C. After 18 h, the tetrahydrofuran was removed by vacuum at a vacuum degree of 300 Pa. When no more liquid distilled out, 300 mL of ethanol was added for washing, filtration and drying to obtain 52.44 g of branched polymerized Schiff base, with a yield of 92.5%.

[0160] The obtained branched polymerized Schiff base was analyzed by gel permeation chromatography, and the number average molecular weight of the branched polymerized Schiff base was determined to be 10900 g / mol.

[0161] 14.2 Dissolve 11.34 g of the above branched polymerized Schiff base in 200 mL of toluene, mix with 50 mL of a toluene solution containing 4.08 g of aluminum isopropoxide, heat to 80 °C, and after 48 h, remove toluene by vacuum at a vacuum degree of 500 Pa. When no more liquid distills out, add 50 mL of ethanol to wash, filter, and dry to obtain 12.2 g of the multi-center branched polymerized Schiff base aluminum catalyst.

[0162] 14.3 The reaction flask was repeatedly evacuated and purged with nitrogen. 348g of glycolide, 172.8g of lactide, 0.93g of dodecanol and 3.6g of the above-mentioned multicenter branched polymerization Schiff base aluminum catalyst were added to the reaction flask in sequence. The mixture was stirred and the temperature was rapidly raised to 160℃. After 18h, 500.0g of polyethylene glycolide was obtained, with a yield of 96%.

[0163] The obtained poly(ethylene glycol) lactide was analyzed by gel permeation chromatography, and the number-average molecular weight of the poly(ethylene glycol) lactide was determined to be 90,000 g / mol.

[0164] Example 15

[0165] 15.1 48.8 g of the mixture of disalicylaldehyde and trisalicylaldehyde prepared in Example 5 was dissolved in 300 ml of tetrahydrofuran, mixed with 14.2 g of 3-chloro-o-phenylenediamine, stirred and heated to 50 °C. After 24 h, the tetrahydrofuran was removed by vacuum at a vacuum degree of 300 Pa. When no more liquid distilled out, 250 mL of ethanol was added for washing, filtration, and drying to obtain 58.09 g of branched polymerized Schiff base, with a yield of 92.2%.

[0166] The obtained branched polymerized Schiff base was analyzed by gel permeation chromatography, and the number average molecular weight of the branched polymerized Schiff base was determined to be 14100 g / mol.

[0167] 15.2 Dissolve 12.6g of the above branched polymerized Schiff base in 200mL of tetrahydrofuran, mix with 3.52g of nickel acetate in 60mL of ethanol solution, heat to 65℃, and after 20h, remove tetrahydrofuran and ethanol by vacuuming to a vacuum degree of 300Pa. Add 50mL of ethanol to wash, filter, and dry. When no more liquid distills out, 12.63g of multi-center branched polymerized Schiff base nickel catalyst is obtained.

[0168] 15.3 The reaction flask was repeatedly evacuated and purged with nitrogen. 348g of glycolide, 194.4g of lactide, 1.16g of isopropyl glycidyl ether, 1.12g of dodecanol and 3.9g of the above-mentioned multicenter branched polymerization Schiff base nickel catalyst were added to the reaction flask in sequence. The mixture was stirred and the temperature was rapidly raised to 165℃. After 10h, 518.5g of polyethylene glycolide was obtained, with a yield of 95.6%.

[0169] The poly(ethylene glycol) obtained in this invention was analyzed by gel permeation chromatography, and the number-average molecular weight of the poly(ethylene glycol) was determined to be 78,000 g / mol.

[0170] Example 16

[0171] 16.1 53.9 g of the mixture of disalicylaldehyde and trisalicylaldehyde prepared in Example 6 was dissolved in 300 ml of tetrahydrofuran, mixed with 12.2 g of 4-methyl-o-phenylenediamine, stirred and heated to 45 °C. After 30 h, the tetrahydrofuran was removed by vacuum at a vacuum degree of 300 Pa. When no more liquid distilled out, 300 mL of ethanol was added for washing, filtration, and drying to obtain 60.81 g of branched polymerized Schiff base, with a yield of 92%.

[0172] The obtained branched polymerized Schiff base was analyzed by gel permeation chromatography, and the number average molecular weight of the branched polymerized Schiff base was determined to be 16100 g / mol.

[0173] 16.2 Dissolve 13.22g of the above branched polymerized Schiff base in 250mL of toluene, mix with 50mL of a toluene solution containing 3.24g of aluminum ethoxy, heat to 90℃, and after 16h, remove toluene under vacuum of 500Pa. When no more liquid distills out, add 80mL of ethanol to wash, filter, and dry to obtain 13.63g of the multi-center branched polymerized Schiff base aluminum catalyst.

[0174] 16.3 The reaction flask was repeatedly evacuated and purged with nitrogen. 348g of glycolide, 216g of lactide, 1.12g of dodecanol and 4.2g of the above-mentioned multicenter branched polymerization Schiff base aluminum catalyst were added to the reaction flask in sequence. The mixture was stirred and the temperature was rapidly raised to 170℃. After 8 hours, 543.1g of polyethylene glycolide was obtained, with a yield of 96.3%.

[0175] The obtained poly(ethylene glycol) lactide was analyzed by gel permeation chromatography, and the number average molecular weight of poly(ethylene glycol) lactide was determined to be 87,000 g / mol.

[0176] Example 17

[0177] 17.1 53.4 g of the mixture of disalicylaldehyde and trisalicylaldehyde prepared in Example 6 was dissolved in 300 ml of tetrahydrofuran, mixed with 7.4 g of 1,3-propanediamine, stirred and heated to 50 °C. After 36 h, the tetrahydrofuran was removed by vacuum at a vacuum degree of 300 Pa. When no more liquid distilled out, 350 mL of ethanol was added for washing, filtration, and drying to obtain 56.18 g of branched polymerized Schiff base, with a yield of 92.4%.

[0178] The obtained branched polymerized Schiff base was analyzed by gel permeation chromatography, and the number average molecular weight of the branched polymerized Schiff base was determined to be 17100 g / mol.

[0179] 17.2 Dissolve 12.16 g of the above branched polymerized Schiff base in 250 mL of tetrahydrofuran, mix with 3.24 g of ferric chloride in 60 mL of ethanol solution, heat to 60 °C, and after 20 h, remove tetrahydrofuran and ethanol by vacuum at a vacuum degree of 300 Pa. When no more liquid distills out, add 100 mL of ethanol to wash, filter, and dry to obtain 12.9 g of multi-center branched polymerized Schiff base iron catalyst.

[0180] 17.3 The reaction flask was repeatedly evacuated and purged with nitrogen. 348g of glycolide, 244.8g of lactide, 1.3g of tert-butyl glycidyl ether, 1.12g of dodecanol and 4.2g of the above-mentioned multicenter branched polymerization Schiff base iron catalyst were added to the reaction flask in sequence. The mixture was stirred and the temperature was rapidly raised to 155℃. After 12 hours, 565.5g of polyethylene glycolide was obtained, with a yield of 95.4%.

[0181] The obtained poly(ethylene glycol) lactide was analyzed by gel permeation chromatography, and the number average molecular weight of the poly(ethylene glycol) lactide was determined to be 80,000 g / mol.

[0182] Example 18

[0183] 18.1 52.9 g of the mixture of disalicylaldehyde and trisalicylaldehyde prepared in Example 6 was dissolved in 300 ml of toluene, mixed with 17.7 g of 4,5-dichloro-o-phenylenediamine, stirred, and heated to 55 °C. After 30 h, toluene was removed by vacuum at a vacuum degree of 300 Pa. When no more liquid distilled out, 300 mL of ethanol was added for washing, filtration, and drying to obtain 65.59 g of branched polymerized Schiff base, with a yield of 92.9%.

[0184] The obtained branched polymerized Schiff base was analyzed by gel permeation chromatography, and the number average molecular weight of the branched polymerized Schiff base was determined to be 23600 g / mol.

[0185] 18.2 Dissolve 14.12 g of the above branched polymerized Schiff base in 200 mL of tetrahydrofuran, mix with 40 mL of ethanol solution containing 2.72 g of zinc chloride, heat to 65 °C, and after 15 h, remove tetrahydrofuran and ethanol by vacuuming at a vacuum degree of 300 Pa. When no more liquid distills out, add 50 mL of ethanol to wash, filter, and dry to obtain 14.19 g of multi-center branched polymerized Schiff base zinc catalyst.

[0186] 18.3 The reaction flask was repeatedly evacuated and purged with nitrogen. 348g of glycolide, 288g of lactide, 3g of phenyl glycidyl ether, 1.12g of dodecanol and 4.2g of the above-mentioned multicenter branched polymerization type Schiff base zinc catalyst were added to the reaction flask in sequence. The mixture was stirred and the temperature was rapidly raised to 150°C. After 15 hours, 609.3g of polyethylene glycolide was obtained, with a yield of 95.8%.

[0187] The obtained poly(ethylene glycol) lactide was analyzed by gel permeation chromatography, and the number-average molecular weight of the poly(ethylene glycol) lactide was determined to be 82000 g / mol.

[0188] The above description of the embodiments is only for the purpose of helping to understand the method and core ideas of the present invention. It should be noted that those skilled in the art can make several improvements and modifications to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims

1. A branched polymeric Schiff alkali metal compound having the structures shown in Formulas I to IV: Formula I; Formula II; Formula III; Formula IV; in, R1 is selected from substituted or unsubstituted C2-C10 alkyl groups or C3-C12 cycloalkyl groups; The R2 is selected from substituted or unsubstituted C3-C10 alkyl groups; The R3 is selected from hydrogen, halogen, nitro, substituted or unsubstituted C1-C6 alkyl or C1-C6 alkoxy; The R4 is selected from substituted or unsubstituted C2-C6 alkyl, C3-C12 cycloalkyl, C6-C12 aryl or C4-C11 heteroaryl; The R5 is selected from halogenated, substituted or unsubstituted C1-C6 alkoxy groups; M1 is selected from zinc, cobalt, nickel, or tin; M2 is selected from aluminum, indium, chromium, iron, manganese, cerium, or yttrium; The m is any integer from 5 to 100; The n is any integer from 1 to 20; p can be any integer from 5 to 100.

2. The branched polymeric Schiff alkali metal compound according to claim 1, characterized in that, R1 is selected from substituted or unsubstituted C2 alkyl, C3 alkyl, C4 alkyl, C5 alkyl, C6 alkyl, cyclopropyl, cyclobutyl, cyclopentyl, and cyclohexyl; The R2 is selected from substituted or unsubstituted C3 alkyl, C4 alkyl, C5 alkyl, C6 alkyl, C7 alkyl, C8 alkyl, C9 alkyl or C10 alkyl; The R3 is selected from hydrogen, halogen, nitro, substituted or unsubstituted methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, methoxy, ethoxy, n-propoxy, and isopropoxy. The R4 is selected from substituted or unsubstituted C2 alkyl, C3 alkyl, C4 alkyl, C5 alkyl, C6 alkyl, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl or phenyl; The R5 is selected from halogens, substituted or unsubstituted methoxy, ethoxy, n-propoxy or isopropoxy.

3. The branched polymeric Schiff alkali metal compound according to claim 2, characterized in that, R1 is selected from ethylene glycol, 1,3-propanediol, 1,2-propanediol, 1,4-butanediol, 1,3-butanediol, 1,2-butanediol, 2,3-butanediol, 1,5-pentanediol, 1,2-pentanediol, 1,6-hexanediol, 1,2-hexanediol, 1,4-cyclohexanediol, 1,2-cyclohexanediol, heptanediol, octanediol, nonanediol, and decanediol, after removing two hydroxyl groups. The R2 is selected from the following groups after removing three hydroxyl groups: glycerol, 1,1,1-trimethylolpropane, 1,1,1-(trimethylol)-ethane, 1,2,4-butanetriol, 1,2,3-butanetriol, 1,2,5-pentanetriol, 1,2,6-hexanetriol, 1,2,3-hexanetriol, 1,3,5-cyclohexanetriol, 1,2,7-heptanetriol, 1,2,3-heptanetriol, 1,2,8-octanetriol, 1,2,9-nonanetriol, and 1,2,10-decanetriol. The R3 is selected from hydrogen, -CH3, -CH2CH3, -CH(CH3)2, -OCH(CH3)2, -C(CH3)3, -OCH3 or -OCH2CH3; R4 is selected from ethylenediamine, 1,3-propanediamine, 1,2-propanediamine, 2-methyl-1,3-propanediamine, 2,2'-dimethylpropanediamine, 1,4-butanediamine, 1,2-cyclohexanediamine, o-phenylenediamine, 3-nitro-o-phenylenediamine, 4-nitro-o-phenylenediamine, 3-bromo-o-phenylenediamine, 4-bromo-o-phenylenediamine, 4,5-dibromo-o-phenylenediamine, 4-bromo-5-fluoro-o-phenylenediamine, 4-bromo-5-methyl-o-phenylenediamine, 4-chloro-5-bromo-o-phenylenediamine, 3-methyl-5-bromo-o-phenylenediamine, 4-methoxy-o-phenylenediamine. The groups remaining after removing two amino groups from amines, 4-chloro-5-fluoro-o-phenylenediamine, 4,5-dichloro-o-phenylenediamine, 4-chloro-o-phenylenediamine, 4-trifluoromethyl-o-phenylenediamine, 3-chloro-o-phenylenediamine, 3-chloro-5-trifluoromethyl-o-phenylenediamine, 4,5-difluoro-o-phenylenediamine, 4-fluoro-o-phenylenediamine, 3-fluoro-o-phenylenediamine, 3,4-difluoro-o-phenylenediamine, 3,5-difluoro-o-phenylenediamine, 4,5-dimethyl-o-phenylenediamine, 4-methyl-o-phenylenediamine, 3,5-dimethyl-o-phenylenediamine, and 4-chloro-5-methyl-o-phenylenediamine; The R5 is selected from -OCH3, -OCH2CH3, -OCH(CH3)2 or -Cl.

4. A method for preparing the branched polymeric Schiff alkali metal compound according to any one of claims 1 to 3, comprising the following steps: a) Reaction of chloromethyl salicylaldehyde compounds with diol metal compounds and triol metal compounds yields a mixture of disalicylaldehyde compounds and trisalicylaldehyde compounds; b) Reaction of a mixture of disalicylaldehyde and trisalicylaldehyde compounds with a diamino compound yields a branched Schiff base polymer. c) Reaction of branched Schiff base polymers with metal compounds yields multicenter branched polymeric Schiff base metal compounds.

5. The preparation method according to claim 4, characterized in that, The synthesis of the chloromethyl salicylic aldehyde includes the following steps: Salicylaldehyde compounds react with formaldehyde compounds in the presence of a catalyst to produce chloromethylsalicylaldehyde; The salicylaldehyde compounds include at least one of salicylaldehyde, 3-methylsalicylaldehyde, 3-methoxysalicylaldehyde, 3-ethoxysalicylaldehyde, 3-tert-butylsalicylaldehyde, 3-bromosalicylaldehyde, 3-chlorosalicylaldehyde, 5-chlorosalicylaldehyde, 5-methylsalicylaldehyde, and 5-nitrosalicylicylaldehyde. The formaldehyde compounds include at least one of formaldehyde, trioxymethylene, or paraoxymethylene; The molar ratio of the salicylaldehyde compound to the formaldehyde compound is 1:1 to 1:2; The reaction temperature is 0 ~ 100℃, and the reaction time is 2 ~ 72h; The catalyst is at least one of HCl, concentrated sulfuric acid, phosphoric acid, acetic acid, aluminum trichloride, zinc chloride, and tin chloride.

6. The preparation method according to claim 4, characterized in that, The synthesis of the diol metal compound includes the following steps: Diols are reacted with alkali metals to give diol-alkali metal compounds; The reaction temperature is 25~100℃, and the reaction time is 1~10h; the molar ratio of the diol to the alkali metal is 1:2.5~1:4; the alkali metal includes one or more of lithium, sodium, and potassium; The synthesis of the triol metal compound includes the following steps: Triols are reacted with alkali metals to yield triol-alkali metal compounds. The reaction temperature is 25~100℃, and the reaction time is 1~10h; the molar ratio of the triol to the alkali metal is 1:3.5~1:6; the alkali metal includes one or more of lithium, sodium, and potassium.

7. The preparation method according to claim 4, characterized in that, In step a), the molar ratio of the chloromethyl salicylaldehyde compound to the total molar ratio of the diol metal compound and the triol metal compound is 2:1 to 4:1; the molar ratio of the diol metal compound to the triol metal compound is 100:0.5 to 20; the reaction temperature is 20 to 110°C; and the reaction time is 2 to 48 hours. In step b), the ratio of the total molar amount of the disalicylaldehyde compound and the trisalicylaldehyde compound to the molar amount of the diamino compound is 1:0.6~1.5; the reaction temperature is 20~100℃, and the reaction time is 1~48h; In step c), the metal compound includes at least one of zinc chloride, zinc acetate, ethyl zinc, stannous chloride, ferric chloride, indium chloride, cobalt acetate, aluminum isopropoxide, aluminum ethoxylate, and nickel acetate; the molar ratio of the diamino compound residues in the branched Schiff base polymer to the metal compound is 1:1 to 1:1.2; the reaction temperature is 20 to 120°C, and the reaction time is 2 to 100 h.

8. The use of the branched polymeric Schiff alkali metal compound according to any one of claims 1 to 3 or the branched polymeric Schiff alkali metal compound prepared by the preparation method according to any one of claims 4 to 7 as a catalyst in the preparation of poly(lactic acid) lactide.

9. A method for preparing poly(ethylene lactide), characterized in that, Includes the following steps: Poly(glycolic acid) and lactide, or glycolide, lactide and epoxide, react under an inert atmosphere with a catalyst and an initiator to obtain poly(glycolic acid) and lactide. The catalyst is a branched polymerized Schiff alkali metal compound according to any one of claims 1 to 3 or a branched polymerized Schiff alkali metal compound prepared by the preparation method according to any one of claims 4 to 7.

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