Four-center Schiff base metal compound as well as preparation method and application thereof

Abstract

The invention relates to the technical field of catalysts, in particular to a four-center Schiff base metal compound and a preparation method and application thereof. The four-center Schiff base metal compound has a structure as shown in a formula I or a formula II. The four-center Schiff base metal compound provided by the invention has four active sites, and the catalytic activity of an original single-center catalyst is improved through an intramolecular multi-core synergistic effect. According to the technical scheme, the production process is greatly simplified, the multi-step reaction is continuously carried out and is completed by adopting a one-pot method, the use of an organic solvent and the multi-step separation and purification process in the technological process are reduced, the production process is simplified, the synthesis method is simple, the reaction condition is mild, the yield is high, and the production cost is reduced. The four-center Schiff base metal compound is high in catalytic activity, the polymerization reaction speed is increased, the polymerization completion time can be shortened to 2 h, and experimental results show that when the Schiff base metal compound is used for preparing polyglycolic acid, the reaction yield can reach 98.2%.

Description

Technical Field

[0001] The invention relates to the technical field of catalysts, and in particular to a four-center Schiff alkali metal compound and a preparation method and application thereof. Background Art

[0002] Polyglycolic acid is a synthetic polymer material with good biodegradability and biocompatibility, excellent processing performance, high mechanical strength and modulus, high solvent resistance and high gas barrier properties. It can be used in medical polymer materials (such as surgical sutures and artificial skin, etc.). Polyglycolic acid can be decomposed into environmentally friendly compounds under the action of water, microorganisms and enzymes, so it has important application prospects in the fields of packaging materials and degradable films as a biodegradable plastic.

[0003] At present, the synthesis of polyglycolic acid with high molecular weight by ring-opening polymerization of glycolide is a feasible process route. In the process of preparing aliphatic polyesters by ring-opening polymerization of cyclic esters, stannous octoate is generally used as a catalyst for ring-opening polymerization, and its catalytic activity is much higher than that of other metal catalysts. In the commercial production of aliphatic polyesters, faster polymerization rates will improve production efficiency and reduce production costs. Increasing the polymerization temperature may be a solution. However, if the polymerization temperature is only increased, this will destroy the reaction balance, increase the depolymerization rate of the product, and seriously affect the molecular chain growth of the polymer. In addition, this solution increases side reactions, resulting in an increase in the yellowness index of the product. Another solution to increase the polymerization rate is to increase the amount of metal catalyst. In the ring-opening polymerization process of cyclic esters, if an excessive amount of catalyst is added to the reaction system, the residual metal compounds in the product will reduce its thermal stability. Therefore, the use of highly active catalysts to synthesize polyglycolic acid is a feasible solution.

[0004] Schiff base catalysts are highly active catalysts. At present, there have been some reports on the synthesis of Schiff base catalysts. The preparation of conventional Schiff base metal compounds often requires a large amount of organic solvents, and the preparation process is cumbersome, requiring multiple steps of purification in the middle, and the yield is low. The yield of the final Schiff base catalyst is only about 80% at most. Moreover, the yield of the current Schiff base catalyst-catalyzed glycolide ring-opening polymerization reaction is only about 96% at most, and it is difficult to reach more than 97%. Summary of the invention

[0005] In view of this, the technical problem to be solved by the present invention is to provide a four-center Schiff base metal compound and a preparation method and application thereof, which have high catalytic activity.

[0006] To achieve the above object, the present invention provides a four-center Schiff alkali metal compound having a structure shown in Formula I or Formula II:

[0007]

[0008] Among them, R 1 The diglycidyl ether is a group remaining after removing the glycidyl ether from the diglycidyl ether, wherein the diglycidyl ether is selected from any one or more of ethylene glycol diglycidyl ether, glycerol diglycidyl ether, butanediol diglycidyl ether, neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, 1,2-cyclohexanediol diglycidyl ether, resorcinol diglycidyl ether, bisphenol A diglycidyl ether or bisphenol F diglycidyl ether;

[0009] The R 2 independently selected from C2-C10 alkylene, C5-C7 cycloalkylene, C6-C12 arylene;

[0010] The R 3 and R 4 Independently selected from hydrogen, halogen, substituted or unsubstituted C1-C6 alkyl, substituted or unsubstituted C1-C6 alkoxy or nitro;

[0011] The R 5 Selected from halogen, substituted or unsubstituted C1-C6 alkoxy or ester group;

[0012] The M 1 Any one selected from zinc, cobalt, nickel or tin;

[0013] The M 2 Any one selected from aluminum, indium, chromium, iron, manganese, cerium or yttrium.

[0014] In the present invention, removing the glycidyl ether refers to removing the following groups in the diglycidyl ether:

[0015]

[0016] For example, the remaining group after removal of the glycidyl ether of ethylene glycol diglycidyl ether is ethylene.

[0017] The group remaining after removal of the glycidyl ether of 1,4-butanediol diglycidyl ether is a butylene group.

[0018] The group remaining after removal of the glycidyl ether of 1,2-cyclohexanediol diglycidyl ether is a cyclohexylene group.

[0019] The remaining group after removal of the glycidyl ether of resorcinol diglycidyl ether is a phenylene group.

[0020] Preferably, the R 2 is selected from C2-C6 alkylene, five- to seven-membered monocyclic cycloalkylene or phenylene; more preferably, the R 2Selected from C2 alkylene, C3 alkylene, C4 alkylene, C5 alkylene, C6 alkylene, cyclopentyl, cyclohexyl or phenyl.

[0021] In some specific embodiments of the present invention, the R 2 The remaining groups after removing two amino groups from ethylenediamine, 1,3-propylenediamine, 1,2-propylenediamine, dimethylpropylenediamine, 1,2-butylenediamine, 1,4-butylenediamine, 1,2-cyclohexanediamine or o-phenylenediamine are independently selected.

[0022] Preferably, the R 3 and R 4 is selected from hydrogen, halogen, nitro, substituted or unsubstituted methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, n-hexyl, methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, isobutoxy, tert-butoxy, n-pentoxy, isopentyl or n-hexyl.

[0023] The R 3 and R 4 The substituent group is preferably one or more of halogen, nitro, amino and cyano.

[0024] In some specific embodiments of the present invention, the R 3 and R 4 Selected from -H, -CH 3 、-CH 2 Cl, -CH 2 CH 3 、-CH(CH 3 ) 2 、-OCH(CH 3 ) 2 、-C(CH 3 ) 3 、-OCH 3 、-OCH 2 CH 3 、-OCF 3 , -F, -Cl, -Br, I or -NO 2 .

[0025] Preferably, the R 5 Selected from halogen, substituted or unsubstituted methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, isobutoxy, tert-butoxy, n-pentoxy, isopentyloxy, n-hexyloxy or C1-C6 ester group.

[0026] The C1-C6 ester group is more preferably a C1-C3 ester group, including but not limited to a methyl ester group, an ethyl ester group or a propyl ester group.

[0027] The R 5The substituent group is preferably one or more of halogen, nitro, amino and cyano.

[0028] In some specific embodiments of the present invention, the R 5 Selected from -OCH 3 、-OCH 2 CH 3 、-OCH(CH 3 ) 2 , -Cl or -OOCCH 3 .

[0029] The present invention provides a method for preparing the above-mentioned four-center Schiff alkali metal compound, comprising the following steps:

[0030] a) reacting a tetrasalicylaldehyde compound with a diamine monomer to obtain amino-functionalized salicylaldehyde;

[0031] b) reacting the amino-functionalized salicylaldehyde with a salicylaldehyde monomer represented by formula A to obtain a four-center Schiff base compound;

[0032] c) reacting the four-center Schiff base compound with a metal compound to obtain a four-center Schiff base metal compound;

[0033]

[0034] The R 3 and R 4 Independently selected from hydrogen, halogen, substituted or unsubstituted C1-C6 alkyl, substituted or unsubstituted C1-C6 alkoxy or nitro.

[0035] The R 3 and R 4 The scope is the same as above and will not be repeated here.

[0036] The invention firstly reacts a tetrasalicylaldehyde compound with a diamine monomer to obtain amino-functionalized salicylaldehyde.

[0037] The present invention has no particular limitation on the source of the tetrasalicylic aldehyde compound, which can be commercially available or prepared according to methods well known to those skilled in the art. Preferably, the tetrasalicylic aldehyde compound is prepared according to the following method:

[0038] S1) reacting diglycidyl ether under the action of Lewis acid and quaternary ammonium salt to obtain a tetrahydroxy compound;

[0039] S2) reacting the tetrahydroxy compound with an alkali metal to obtain a tetrahydroxy alkali metal compound;

[0040] S3) reacting a tetrahydroxy alkali metal compound with a salicylaldehyde compound to obtain a tetrasalicylicylaldehyde compound.

[0041] The diglycidyl ether may be a compound containing two glycidyl ether groups well known in the art, preferably including at least one of ethylene glycol diglycidyl ether, glycerol diglycidyl ether, butanediol diglycidyl ether, neopentyl glycol diglycidyl ether, 1,2-cyclohexanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, resorcinol diglycidyl ether, bisphenol A diglycidyl ether and bisphenol F diglycidyl ether.

[0042] The reaction temperature of step S1) is preferably 20-100° C., and the reaction time is preferably 2-20 h.

[0043] The Lewis acid preferably includes one or more of concentrated sulfuric acid, zinc perchlorate, aluminum trichloride, ferric chloride, boron trifluoride etherate, fluoroboric acid and tin tetrachloride.

[0044] The amount of the Lewis acid used is preferably 0.1% to 10% by weight of the diglycidyl ether.

[0045] The quaternary ammonium salt preferably includes tetramethylammonium chloride, (1-dodecyl)trimethylammonium chloride, tetraethylammonium chloride, benzyltributylammonium chloride, benzyltriethylammonium chloride, benzyltrimethylammonium chloride, benzyltri-n-propylammonium chloride, benzyldimethyloctadecylammonium chloride, tetradecyldimethylbenzylammonium chloride, trimethylphenylammonium chloride, benzyldodecyldimethylammonium chloride, benzyldimethylphenylammonium chloride, benzyldimethyloctylammonium chloride, tetra-n-butylammonium chloride, hexadecyltrimethylammonium chloride, methyltrioctylammonium chloride, methyltributylammonium chloride, tetradecyltrimethyl chloride ammonium chloride, tetra-n-propylammonium chloride, didecyldimethylammonium chloride, triethylmethylammonium chloride, dimethyldioctadecylammonium chloride, octadecyltrimethylammonium chloride, octyltrimethylammonium chloride, didodecyldimethylammonium chloride, tetrapentylammonium chloride, benzyldimethylhexylammonium chloride, benzylethyltrimethylammonium chloride, tetraheptylammonium chloride, tetraoctylammonium chloride, disoctyldimethylammonium chloride, phenyltriethylammonium chloride, tetrabutylammonium bromide, benzyltrimethylammonium bromide, dimethylethylhexadecylammonium bromide, hexyltrimethylammonium bromide and hexadecyltrimethylammonium bromide.

[0046] The amount of the quaternary ammonium salt used is preferably 0.1% to 10% by weight of the diglycidyl ether.

[0047] The reaction temperature in step S2) is preferably 25-100° C., and the reaction time is preferably 2-8 hours.

[0048] The molar ratio of the tetrahydroxy compound to the alkali metal is preferably 1:5 to 1:10.

[0049] The present invention has no particular limitation on the alkali metal, and may be an alkali metal well known in the art, including but not limited to metallic sodium, metallic potassium, and the like.

[0050] The reaction temperature in step S3) is preferably 20-100° C., and the reaction time is preferably 2-48 hours.

[0051] The molar ratio of the tetrahydroxy alkali metal compound to the salicylaldehyde compound is preferably 1:4 to 1:8.

[0052] The salicylaldehyde compound is preferably 3-chloromethyl-5-nitrosalicylicylaldehyde.

[0053] The molar ratio of the tetrasalicylaldehyde compound to the diamine monomer is preferably 1:8 to 1:30.

[0054] The reaction temperature in step a) is preferably 20 to 100° C., and the reaction time is preferably 2 to 48 hours.

[0055] The diamine monomer preferably includes ethylenediamine, 1,3-propylenediamine, 1,2-propylenediamine, dimethylpropylenediamine, 1,2-butylenediamine, 1,4-butylenediamine, 1,2-cyclohexanediamine or o-phenylenediamine.

[0056] After obtaining amino-functionalized salicylaldehyde, it is reacted with a salicylaldehyde monomer shown in formula A to obtain a four-center Schiff base compound.

[0057] The molar ratio of the amino-functionalized salicylaldehyde to the salicylaldehyde monomer represented by formula A is preferably 1:5 to 1:12.

[0058] The reaction temperature of the amino-functionalized salicylaldehyde and the salicylaldehyde monomer represented by formula A is preferably 20 to 100° C., and the reaction time is preferably 2 to 48 hours.

[0059] Finally, the four-center Schiff base compound is reacted with a metal compound to obtain a four-center Schiff base metal compound.

[0060] The molar ratio of the four-center Schiff base compound to the metal compound is preferably 1:4 to 1:8.

[0061] The temperature for the reaction of the four-center Schiff base compound with the metal compound is preferably 20 to 120° C., and the reaction time is preferably 2 to 48 hours.

[0062] The metal compound is preferably a metal compound containing zinc, cobalt, nickel, tin, aluminum, indium, chromium, iron, manganese, cerium or yttrium.

[0063] The anion of the metal compound is preferably a halogen, an acid ion or an alkoxy group.

[0064] The halogen is preferably Cl.

[0065] The acid ion is preferably acetate.

[0066] The alkoxy group is preferably a C2-C6 alkoxy group, and more preferably an ethoxy group, a n-propoxy group, an isopropoxy group, a n-butoxy group, an isobutoxy group or a tert-butoxy group.

[0067] In some specific embodiments of the present invention, the metal compound is preferably aluminum isopropoxide, cobalt acetate, nickel acetate, indium chloride, aluminum ethoxide, and the like.

[0068] The four-center Schiff alkali metal compound provided by the present invention can be used as a catalyst for preparing polyglycolide. In the reaction, an alcohol compound is generally added as an initiator.

[0069] The present invention ingeniously conducts a one-pot reaction on the excess salicylaldehyde monomer in step b) to prepare an alcohol compound, which is directly used as an initiator.

[0070] Based on this, the present invention provides a method for preparing a four-center Schiff alkali metal compound, comprising the following steps:

[0071] a) reacting a tetrasalicylaldehyde compound with a diamine monomer to obtain amino-functionalized salicylaldehyde;

[0072] b1) reacting amino-functionalized salicylaldehyde with an excess of a salicylaldehyde monomer represented by formula A to obtain a mixture of a four-center Schiff base compound and residual salicylaldehyde monomer;

[0073] b2) reacting the mixture obtained in step b1) with an amino alcohol monomer to obtain a mixture of a four-center Schiff base compound and an alcohol substance represented by formula B;

[0074] c1) reacting the mixture obtained in step b2) with a metal compound to obtain a mixture of a four-center Schiff alkali metal compound and an alcohol substance;

[0075]

[0076] The R 3 and R 4 Independently selected from hydrogen, halogen, substituted or unsubstituted C1-C6 alkyl, substituted or unsubstituted C1-C6 alkoxy or nitro;

[0077] The R 6 The alkylene group is selected from C2 to C10, and more preferably C2 to C8.

[0078] The molar ratio of the remaining salicylaldehyde monomer to the amino alcohol monomer is preferably 1:1 to 1:10.

[0079] The reaction temperature in step b2) is preferably 20-100° C., and the reaction time is preferably 2-48 hours.

[0080] The amino alcohol monomer is preferably a C2-C10 amino alcohol compound, and more preferably a C2-C8 amino alcohol compound.

[0081] The specific parameters of the remaining steps are the same as above and will not be repeated here.

[0082] In some specific embodiments of the present invention, the amino alcohol monomer is selected from 2-amino-1-ethanol, 3-amino-1-propanol, 4-amino-1-butanol, 3-amino-1-butanol, 5-amino-1-pentanol, 6-amino-1-hexanol or 8-amino-1-octanol.

[0083] The preparation method of the four-center Schiff base metal compound provided by the present invention has mild reaction conditions and a simple synthesis method. In the process of preparing the four-center Schiff base compound and the four-center Schiff base metal compound from the tetrasalicylaldehyde compound, a one-pot method can be adopted, and no purification is required after the synthesis of the four-center Schiff base compound is completed; by adding amino alcohol, the excess salicylaldehyde monomer is converted into a compound containing hydroxyl group, and the compound can be used as an initiator for glycolide polymerization, so that the excess salicylaldehyde participates in the synthesis of the polymer, and the catalyst yield is high, which can reach more than 90%.

[0084] The present invention provides a method for preparing polyglycolide, comprising the following steps:

[0085] In an inert atmosphere, glycolide, or glycolide and an epoxy compound are reacted in the presence of a catalyst and an initiator to obtain polyglycolide;

[0086] The catalyst is the four-center Schiff alkali metal compound or the four-center Schiff alkali metal compound prepared by the above preparation method.

[0087] The initiator is preferably an alcohol compound, more preferably an alcohol substance represented by formula B prepared simultaneously in the process of preparing the catalyst.

[0088] The ratio of the mass of the catalyst to the glycolide or to the total mass of the glycolide and the epoxy compound is preferably 1:(30-3000).

[0089] The molar ratio of the epoxy compound to the glycolide is (0-10):(90-100).

[0090] The reaction temperature is preferably 120-240° C., and the reaction time is preferably 2-24 hours.

[0091] The epoxy compound is preferably any one or more of propylene oxide, butylene 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 ether, phenyl glycidyl ether, 2-toluene glycidyl ether or benzyl glycidyl ether.

[0092] In the above reaction, the epoxy compound may be added or not, and 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.

[0093] Compared with the prior art, the present invention provides a four-center Schiff alkali metal compound having a structure shown in Formula I or Formula II. The four-center Schiff alkali metal compound provided by the present invention has four active sites, and the catalytic activity of the original single-center catalyst can be improved through the intramolecular multi-nuclear synergistic effect. The technical scheme greatly simplifies the production process, and the multi-step reaction is carried out continuously and completed by a one-pot method, which reduces the use of organic solvents and the multi-step separation and purification process in the process flow, simplifies the production process, has a simple synthesis method, mild reaction conditions, high yield, and reduced production costs. The four-metal center Schiff alkali metal compound of the present invention has high catalytic activity, improves the polymerization reaction speed, and the polymerization completion time can be shortened to 2h. Experimental results show that the reaction yield of polyglycolic acid prepared by the Schiff alkali metal compound of the present invention can reach 98.2%. DETAILED DESCRIPTION

[0094] In order to further illustrate the present invention, the following is a detailed description in conjunction with the embodiments. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, rather than limiting the claims of the invention.

[0095] All raw materials of the present invention have no particular limitation on their sources, and can be purchased from the market or prepared according to conventional methods known to those skilled in the art.

[0096] Preparation Example 1

[0097] 1.1 Add 202g 1,4-butanediol diglycidyl ether, 3g concentrated sulfuric acid (98%) and 300g water into a 2L round-bottom flask, mix and stir and heat to 50°C. After 6h, add 20% Na 2 CO 3The solution was adjusted to a near-neutral pH value, mixed with 200 mL of toluene and 5 g of benzyltrimethylammonium bromide, and the material was transferred to a separatory funnel and allowed to stand to separate into layers. The oil phase was washed with deionized water several times until the aqueous phase was neutral, and dried with 50 g of anhydrous sodium sulfate for 24 h. After filtering, the solvent was removed by distillation under reduced pressure to obtain 220.2 g of 1,4-butanediethertetraol.

[0098] 1.2 Add 119g of the above-mentioned 1,4-butanediether tetraol, 57.5g of metallic sodium and 200mL of anhydrous toluene into a 1L round-bottom flask, mix and stir, and heat to 60°C. After the metallic sodium no longer decreases, remove the unreacted metallic sodium, and then remove the toluene in vacuo to obtain 160.5g of 1,4-butanediether tetraol sodium.

[0099] 1.3 Dissolve 65.2g of the above-mentioned 1,4-butylene tetrasodium ether in 600mL of toluene, and then add it dropwise at a rate of 5mL / min to a toluene solution of 1200mL of 3-chloromethyl-5-nitrosalicylicaldehyde (172g). After the addition is complete, raise the temperature to 60°C, continue the reaction for 10h, stop heating, add 300mL of water, mix well and transfer the material to a separatory funnel, let it stand to separate the salt solution, wash the oil phase three times with deionized water, add 80g of anhydrous sodium sulfate and dry for 24h, filter and remove the solvent in vacuo to obtain 172.9g of tetrasalicylicaldehyde compound.

[0100] The obtained tetrasalicylic aldehyde compound was analyzed by mass spectrometer, and the results were as follows: m / z=950, corresponding to the molecular weight of the tetrasalicylic aldehyde compound.

[0101] Using hydrogen nuclear magnetic 1 H NMR (300.00 Hz, CDCl 3 ) The tetrasalicylaldehyde compound obtained in Preparation Example 1 was analyzed, and the hydrogen spectrum results were as follows: δ=12ppm corresponds to the characteristic chemical shift of the hydroxyl hydrogen on the benzene ring in salicylaldehyde, δ=10.11-10.22ppm corresponds to the characteristic chemical shift of the hydrogen in the aldehyde group on salicylaldehyde, δ=8.20-8.36ppm corresponds to the characteristic chemical shift of the hydrogen on the benzene ring in salicylaldehyde, δ=4.56-4.68ppm corresponds to the characteristic chemical shift of the hydrogen on the methylene connected to the benzene ring in salicylaldehyde, δ=3.22-3.70ppm corresponds to the characteristic chemical shift of the hydrogen on the methylene connected to oxygen in butanediol diglycidyl ether, and δ=1.45-1.55ppm corresponds to the characteristic chemical shift of the hydrogen on the methylene not connected to oxygen in butanediol diglycidyl ether.

[0102] This proves the successful synthesis of tetrasalicylic aldehyde compounds.

[0103] Preparation Example 2

[0104] 2.1 Add 228 g of 1,2-cyclohexanediol diglycidyl ether, 5 g of zinc perchlorate and 400 mL of water into a 2 L round bottom flask, mix and stir and heat to 60 °C. After 8 h, add 15% NaHCO 3 The solution was adjusted to a near-neutral pH value, mixed with 300 mL of toluene and 8 g of benzyltrimethylammonium bromide, and the material was transferred to a separatory funnel and allowed to stand to separate into layers. The oil phase was washed with deionized water several times until the aqueous phase was neutral, and dried with 80 g of anhydrous sodium sulfate for 24 h. After filtering, the solvent was removed by distillation under reduced pressure to obtain 241.8 g of 1,2-cyclohexanediethertetraol.

[0105] 2.2 Add 133g of the above-mentioned 1,2-cyclohexanediether tetraol, 69g of metallic sodium and 300mL of anhydrous toluene into a 1L round-bottom flask, mix and stir, and heat to 65°C. After the metallic sodium no longer decreases, remove the unreacted metallic sodium and remove the toluene in vacuo to obtain 174.2g of 1,2-cyclohexanediether tetrasodium.

[0106] 2.3 Dissolve 35.2 g of the above-mentioned 1,2-cyclohexanediether tetrasodium in 400 mL of toluene, and then add it dropwise at a rate of 5 mL / min to a toluene solution of 600 mL of 3-chloromethyl-5-nitrosalicylicaldehyde (86 g). After the addition is complete, raise the temperature to 75°C, continue the reaction for 6 h, stop heating, add 150 mL of water, mix well, and transfer the material to a separatory funnel. Let it stand to separate the deionized water solution. Wash the oil phase with deionized water several times until the water phase is neutral, add 60 g of anhydrous sodium sulfate, dry for 24 h, filter, and remove the solvent in vacuo to obtain 92.2 g of tetrasalicylicaldehyde compound.

[0107] The obtained tetrasalicylic aldehyde compound was analyzed by mass spectrometer, and the results were as follows: m / z=976, corresponding to the molecular weight of the tetrasalicylic aldehyde compound.

[0108] Preparation Example 3

[0109] 3.1 Add 222g of resorcinol diglycidyl ether, 7g of fluoroboric acid and 350mL of water into a 2L round-bottom flask, mix and stir and heat to 70℃. After 5h, add 20% Na 2 CO 3 The solution was adjusted to a near-neutral pH value, mixed with 200 mL of toluene and 10 g of benzyltrimethylammonium bromide, and the material was transferred to a separatory funnel and allowed to stand for stratification. The oil phase was washed with deionized water several times until the aqueous phase was neutral, and dried with 40 g of anhydrous sodium sulfate for 24 h. After filtering, the solvent was removed by distillation under reduced pressure to obtain 254 g of resorcinol diether tetraol with a yield of 98.4%.

[0110] 3.2 Add 129g of the above-mentioned resorcinol diether tetraol, 80.5g of metallic sodium and 400mL of anhydrous toluene into a 5L round-bottom flask, mix and stir, and heat to 70°C. After the metallic sodium no longer decreases, remove the unreacted metallic sodium, and then remove the toluene in vacuo to obtain 170.1g of sodium tetraol of resorcinol diether.

[0111] 3.3 Dissolve 17.3g of the above-mentioned sodium tetraol of resorcinol diether in 350mL of toluene, and then add it dropwise at a rate of 5mL / min to a toluene solution of 400mL of 3-chloromethyl-5-nitrosalicylicaldehyde (43g). After the addition is complete, raise the temperature to 65°C, continue the reaction for 8h, stop heating, add 100mL of water, mix well, and transfer the material to a separatory funnel. Let it stand to separate the deionized water solution, wash the oil phase with deionized water several times until the water phase is neutral, add 60g of anhydrous sodium sulfate, dry for 24h, filter and remove the solvent in vacuo to obtain 43.9g of tetrasalicylicaldehyde compound.

[0112] The obtained tetrasalicylic aldehyde compound was analyzed by mass spectrometer, and the results were as follows: m / z=970, corresponding to the molecular weight of the tetrasalicylic aldehyde compound.

[0113] Example 1

[0114] 1.1 500 ml toluene solution of 0.1 mol of the tetrasalicylaldehyde compound in Preparation Example 1 was added dropwise to 400 ml toluene solution of 2 mol of ethylenediamine at a rate of 5 ml / min, mixed and stirred, and heated to 45°C. After 20 hours, the temperature was raised to 60°C, and toluene and unreacted ethylenediamine were removed in vacuo to obtain amino-functionalized salicylaldehyde, which was then mixed with 350 ml toluene solution of 0.5 mol of salicylaldehyde, reacted at 50°C for 18 hours, and then 100 ml toluene solution of 0.2 mol of 4-amino-1-butanol was added. The reaction was continued at 60°C for 10 hours, and the temperature was raised to 110°C. Toluene and unreacted 4-amino-1-butanol were removed in vacuo. When no more liquid was distilled out, 179.1 g of a four-center Schiff base compound and an alcohol mixture was obtained.

[0115] The obtained product was analyzed by mass spectrometer, and the results were as follows: m / z=1678, m / z=211, corresponding to the molecular weights of the four-center Schiff base compound and the alcohol substance, respectively.

[0116] The four-center Schiff base compound obtained in Example 1 was analyzed by hydrogen nuclear magnetic resonance, and the hydrogen spectrum results were as follows: δ=10.95-11.05 ppm corresponds to the characteristic chemical shift of the hydroxyl hydrogen on the benzene ring in salicylaldehyde, δ=8.5-8.6 ppm corresponds to the characteristic chemical shift of the hydrogen in CHN of salicylaldehyde, δ=6.82-7.73 ppm and 7.95-8.45 ppm correspond to the characteristic chemical shifts of the hydrogen on the benzene ring in salicylaldehyde, δ=5.20-5.38 ppm corresponds to the characteristic chemical shift of the hydrogen on the methylene in ethylenediamine, δ=4.60-4.68 ppm corresponds to the characteristic chemical shift of the hydrogen on the methylene connected to the benzene ring in salicylaldehyde, δ=3.21-3.68 ppm corresponds to the characteristic chemical shift of the hydrogen on the methylene connected to oxygen in butanediol diglycidyl ether, and δ=1.48-1.62 ppm corresponds to the characteristic chemical shift of the hydrogen on the methylene not connected to oxygen in butanediol diglycidyl ether.

[0117] 1.2 Mix 300 mL toluene solution of 18.8 g of the above-mentioned four-center Schiff base compound and alcohol mixture and 100 mL toluene solution of 8.2 g of aluminum isopropoxide, heat to 80°C, and after 72 hours, vacuum remove toluene. When no liquid is distilled out, 21.2 g of a four-center Schiff base aluminum catalyst and an alcohol mixture is obtained. The theoretical mass of the four-center Schiff base aluminum catalyst is 20.2 g, which is calculated by feeding.

[0118] Take 1 g of the above-mentioned mixture of four-center Schiff base aluminum catalyst and alcohol substances, and purify it by column chromatography to obtain 0.91 g of the four-center Schiff base aluminum catalyst. The mass of the four-center Schiff base aluminum catalyst in the above-mentioned mixture is calculated to be 19.3 g. The yield is calculated by dividing the actual mass of the four-center Schiff base aluminum catalyst by the theoretical mass to be 95.5%.

[0119] 1.3 The reaction bottle was repeatedly evacuated and filled with nitrogen, and 116 g of glycolide, 2.22 g of the above-mentioned Schiff base aluminum catalyst and alcohol mixture were added into the reaction bottle in sequence, mixed and stirred, and the temperature was quickly raised to 180°C. After 4 hours, 113.9 g of polyglycolic acid was obtained with a yield of 98.2%.

[0120] The polyglycolic acid obtained by the present invention is subjected to gel permeation chromatography analysis, and the number average molecular weight of the polyglycolic acid is measured to be 99000 g / mol.

[0121] Example 2

[0122] 2.1 450 ml toluene solution of 0.09 mol of the tetrasalicylaldehyde compound in Preparation Example 1 was added dropwise to 350 ml toluene solution of 1.8 mol of 1,3-propylenediamine at a rate of 4 ml / min, mixed and stirred, and heated to 50°C. After 15 hours, the temperature was raised to 80°C, and toluene and unreacted 1,3-propylenediamine were removed in vacuo to obtain amino-functionalized salicylaldehyde, which was then mixed with 300 ml toluene solution of 0.45 mol of 3-methylsalicylaldehyde, reacted at 55°C for 12 hours, and then 150 ml toluene solution of 0.2 mol of 2-amino-1-ethanol was added. The reaction was continued at 60°C for 10 hours, and the temperature was raised to 90°C. Toluene and unreacted 2-amino-1-ethanol were removed in vacuo. When no more liquid was distilled out, 170.6 g of a four-center Schiff base compound and an alcohol mixture was obtained.

[0123] The obtained product was analyzed by mass spectrometer, and the results were as follows: m / z=1790, m / z=197, corresponding to the molecular weights of the four-center Schiff base compound and the alcohol substance, respectively.

[0124] 2.2 Mix 250 mL of isopropanol solution of 19.8 g of the above-mentioned four-center Schiff base compound and alcohol mixture and 100 mL of ethanol solution of 7.08 g of cobalt acetate, heat to 80°C, and after 24 hours, vacuum remove isopropanol and ethanol. When no liquid is distilled out, 21 g of a four-center Schiff base cobalt catalyst and an alcohol mixture is obtained. The theoretical mass of the four-center Schiff base cobalt catalyst is 20.3 g, which is calculated by feeding.

[0125] Take 1 g of the above-mentioned mixture of four-center Schiff base cobalt catalyst and alcohol substances, and purify it by column chromatography to obtain 0.92 g of the four-center Schiff base cobalt catalyst. The mass of the four-center Schiff base cobalt catalyst in the above-mentioned mixture is calculated to be 19.3 g. The yield is calculated by dividing the actual mass of the four-center Schiff base cobalt catalyst by the theoretical mass to be 95.1%.

[0126] 2.3 The reaction bottle was repeatedly evacuated and filled with nitrogen, and 232 g of glycolide, 3.48 g of isopropyl glycidyl ether, 4.43 g of the above-mentioned four-center Schiff base cobalt catalyst and alcohol mixture were added to the reaction bottle in sequence. After mixing and stirring, the temperature was rapidly raised to 185°C. After 3 hours, 223.9 g of polyglycolic acid was obtained with a yield of 96.5%.

[0127] The polyglycolic acid obtained by the present invention is subjected to gel permeation chromatography analysis, and the number average molecular weight of the polyglycolic acid is measured to be 94000 g / mol.

[0128] Example 3

[0129] 3.1 400 ml toluene solution of 0.08 mol of the tetrasalicylaldehyde compound in Preparation Example 1 was added dropwise at a rate of 3 mL / min to 300 mL toluene solution of 1.2 mol of 1,2-propylenediamine, mixed and stirred, and heated to 55°C. After 12 hours, the temperature was raised to 90°C, and toluene and unreacted 1,2-propylenediamine were removed in vacuo to obtain amino-functionalized salicylaldehyde, which was then mixed with 400 mL toluene solution of 0.5 mol of 3-methoxysalicylaldehyde, reacted at 60°C for 10 hours, and then 200 mL ethanol solution of 0.3 mol of 3-amino-1-propanol was added. The reaction was continued at 65°C for 8 hours, and the temperature was raised to 100°C. Toluene and unreacted 3-amino-1-propanol were removed in vacuo. When no more liquid was distilled out, 181.5 g of a four-center Schiff base compound and an alcohol mixture was obtained.

[0130] The obtained product was analyzed by mass spectrometry, and the results were as follows: m / z=1854, m / z=227, corresponding to the molecular weights of the four-center Schiff base compound and the alcohol substance, respectively.

[0131] 3.2 Mix 300 mL of isopropanol solution of 23.4 g of the above-mentioned four-center Schiff base compound and alcohol mixture and 80 mL of ethanol solution of 8.84 g of indium chloride, heat to 80°C, and after 18 hours, vacuum remove isobutanol and ethanol. When no liquid is distilled out, 28.1 g of a four-center Schiff base indium catalyst and an alcohol mixture is obtained. The theoretical mass of the four-center Schiff base indium catalyst is 24.5 g as calculated by feeding.

[0132] Take 1 g of the above-mentioned mixture of four-center Schiff base indium catalyst and alcohol substances, and purify it by column chromatography to obtain 0.84 g of the four-center Schiff base indium catalyst. The mass of the four-center Schiff base indium catalyst in the above-mentioned mixture is calculated to be 23.6 g. The yield is calculated by dividing the actual mass of the four-center Schiff base indium catalyst by the theoretical mass to be 96.3%.

[0133] 3.3 The reaction bottle was repeatedly evacuated and filled with nitrogen, and 464 g of glycolide, 5.98 g of the above-mentioned four-center Schiff base indium catalyst and alcohol mixture were added to the reaction bottle in sequence, mixed and stirred, and quickly heated to 190°C. After 2 hours, 445.9 g of polyglycolic acid was obtained with a yield of 96.1%.

[0134] The polyglycolic acid obtained by the present invention is subjected to gel permeation chromatography analysis, and the number average molecular weight of the polyglycolic acid is measured to be 93000 g / mol.

[0135] Example 4

[0136] 4.1 350 ml toluene solution of 0.07 mol of the tetrasalicylaldehyde compound in Preparation Example 1 was added dropwise at a rate of 3 mL / min to 600 mL toluene solution of 1.4 mol 1,2-cyclohexanediamine, mixed and stirred, and heated to 60°C. After 10 hours, the temperature was raised to 120°C, and toluene and unreacted 1,2-cyclohexanediamine were removed in vacuo to obtain amino-functionalized salicylaldehyde, which was then mixed with 350 mL toluene solution of 0.45 mol 3-chlorosalicylaldehyde, reacted at 65°C for 8 hours, and then 150 mL ethanol solution of 0.3 mol 3-amino-1-propanol was added. The reaction was continued at 70°C for 6 hours, and the temperature was raised to 110°C. Toluene and unreacted 3-amino-1-propanol were removed in vacuo. When no more liquid was distilled out, 174.4 g of a four-center Schiff base compound and an alcohol mixture was obtained.

[0137] The obtained product was analyzed by mass spectrometry, and the results were as follows: m / z = 2030, m / z = 231, corresponding to the molecular weights of the four-center Schiff base compound and the alcohol substance, respectively.

[0138] 4.2 Mix 300 mL of isopropanol solution of 25.7 g of the above-mentioned four-center Schiff base compound and alcohol mixture and 100 mL of ethanol solution of 7.04 g of nickel acetate, heat to 80°C, and after 18 hours, vacuum remove isopropanol and ethanol. When no liquid is distilled out, 26.3 g of four-center Schiff base nickel catalyst and alcohol mixture is obtained. The theoretical mass of the four-center Schiff base nickel catalyst is 22.3 g as calculated by feeding.

[0139] Take 1 g of the above-mentioned mixture of four-center Schiff base nickel catalyst and alcohol substances, and purify it by column chromatography to obtain 0.81 g of the four-center Schiff base nickel catalyst. The mass of the four-center Schiff base nickel catalyst in the above-mentioned mixture is calculated to be 21.3 g. The yield is calculated by dividing the actual mass of the four-center Schiff base nickel catalyst by the theoretical mass to be 95.5%.

[0140] 4.3 The reaction bottle was repeatedly evacuated and filled with nitrogen, and 348 g of glycolide, 4.5 g of phenyl glycidyl ether, 2.8 g of the above-mentioned four-center Schiff base nickel catalyst and alcohol mixture were added to the reaction bottle in sequence. After mixing and stirring, the temperature was quickly raised to 185°C. After 2 hours, 334.8 g of polyglycolic acid was obtained with a yield of 96.2%.

[0141] The polyglycolic acid obtained by the present invention is subjected to gel permeation chromatography analysis, and the number average molecular weight of the polyglycolic acid is measured to be 93000 g / mol.

[0142] Example 5

[0143] 5.1 300 ml toluene solution of 0.06 mol of the tetrasalicylaldehyde compound in Preparation Example 2 was added dropwise to 400 ml toluene solution of 1.5 mol of dimethylpropylenediamine at a rate of 2 ml / min, mixed and stirred and heated to 65°C. After 12 hours, the temperature was raised to 120°C, and toluene and unreacted dimethylpropylenediamine were removed in vacuo to obtain amino-functionalized salicylaldehyde, which was then mixed with 300 ml toluene solution of 0.4 mol of 5-methylsalicylaldehyde, reacted at 70°C for 8 hours, and then 100 ml toluene solution of 0.25 mol of 3-amino-1-propanol was added. The reaction was continued at 75°C for 5 hours, and toluene and unreacted 3-amino-1-propanol were removed in vacuo. When no more liquid was distilled out, 143.7 g of a four-center Schiff base compound and an alcohol mixture was obtained.

[0144] The obtained product was analyzed by mass spectrometer, and the results were as follows: m / z=1928, m / z=211, corresponding to the molecular weights of the four-center Schiff base compound and the alcohol substance, respectively.

[0145] 5.2 Mix 24.7 g of the above-mentioned four-center Schiff base compound and alcohol mixture in 250 mL of toluene solution and 6.48 g of ethoxyaluminum in 110 mL of toluene solution, heat to 85°C, and after 20 hours, remove the toluene by vacuum. When no more liquid is distilled out, 26.4 g of the four-center Schiff base aluminum catalyst and alcohol mixture is obtained. The theoretical mass of the four-center Schiff base aluminum catalyst is 22.2 g as calculated by feeding.

[0146] Take 1 g of the above-mentioned mixture of four-center Schiff base aluminum catalyst and alcohol substances, and purify it by column chromatography to obtain 0.81 g of the four-center Schiff base aluminum catalyst. The mass of the four-center Schiff base aluminum catalyst in the above-mentioned mixture is calculated to be 21.4 g. The yield is calculated by dividing the actual mass of the four-center Schiff base aluminum catalyst by the theoretical mass to be 96.4%.

[0147] 5.3 The reaction bottle was repeatedly evacuated and filled with nitrogen, and 348 g of glycolide and 2.76 g of the four-center Schiff base aluminum catalyst and alcohol mixture in Example 5.2 were added into the reaction bottle in sequence. The mixture was mixed and stirred and the temperature was rapidly raised to 180°C. After 3 hours, 340.7 g of polyglycolic acid was obtained with a yield of 97.9%.

[0148] The polyglycolic acid obtained by the present invention is subjected to gel permeation chromatography analysis, and the number average molecular weight of the polyglycolic acid is measured to be 96000 g / mol.

[0149] Example 6

[0150] 6.1 350 ml toluene solution of 0.05 mol of the tetrasalicylaldehyde compound in Preparation Example 2 was added dropwise to 500 ml toluene solution of 1 mol of o-phenylenediamine at a rate of 3 ml / min, mixed and stirred, and heated to 70°C. After 10 hours, the temperature was raised to 150°C, and toluene and unreacted o-phenylenediamine were removed in vacuo to obtain amino-functionalized salicylaldehyde, which was then mixed with 200 ml toluene solution of 0.35 mol of 3-ethoxysalicylaldehyde, reacted at 75°C for 10 hours, and then 200 ml toluene solution of 0.3 mol of 4-amino-1-butanol was added. The reaction was continued at 75°C for 6 hours, and the temperature was raised to 110°C. Toluene and unreacted 4-amino-1-butanol were removed in vacuo. When no more liquid was distilled out, 135.8 g of a four-center Schiff base compound and an alcohol mixture was obtained.

[0151] The obtained product was analyzed by mass spectrometer, and the results were as follows: m / z=2072, m / z=255, corresponding to the molecular weights of the four-center Schiff base compound and the alcohol substance, respectively.

[0152] 6.2 Mix 350 mL of isopropanol solution of 28.2 g of the above-mentioned four-center Schiff base compound and alcohol mixture and 120 mL of ethanol solution of 7.08 g of cobalt acetate, heat to 80°C, and after 18 hours, vacuum remove isopropanol and ethanol. When no liquid is distilled out, 29.1 g of a four-center Schiff base cobalt catalyst and an alcohol mixture is obtained. The theoretical mass of the four-center Schiff base cobalt catalyst is 23.1 g, which is calculated by feeding.

[0153] Take 1 g of the above-mentioned mixture of four-center Schiff base cobalt catalyst and alcohol substances, and purify it by column chromatography to obtain 0.75 g of the four-center Schiff base cobalt catalyst. The mass of the four-center Schiff base cobalt catalyst in the above-mentioned mixture is calculated to be 21.8 g. The yield is calculated by dividing the actual mass of the four-center Schiff base cobalt catalyst by the theoretical mass to be 94.4%.

[0154] 6.3 The reaction flask was repeatedly evacuated and filled with nitrogen, and 348 g of glycolide, 3.9 g of tert-butyl glycidyl ether, 3.06 g of the above-mentioned four-center Schiff base cobalt catalyst and alcohol mixture were added to the reaction flask in sequence. After mixing and stirring, the temperature was rapidly raised to 175°C. After 3 hours, 336.2 g of polyglycolic acid was obtained with a yield of 96.6%.

[0155] The polyglycolic acid obtained by the present invention is subjected to gel permeation chromatography analysis, and the number average molecular weight of the polyglycolic acid is measured to be 88000 g / mol.

[0156] Example 7

[0157] 7.1 300 ml toluene solution of 0.04 mol of the tetrasalicylaldehyde compound in Preparation Example 2 was added dropwise to 200 ml toluene solution of 1 mol of ethylenediamine at a rate of 4 ml / min, the mixture was stirred and heated to 70°C. After 8 h, the mixture was filtered and toluene and unreacted ethylenediamine were removed in vacuo to obtain amino-functionalized salicylaldehyde, which was then mixed with 300 ml toluene solution of 0.3 mol of 3-tert-butyl salicylaldehyde and reacted at 65°C for 15 h. Then, 150 ml toluene solution of 0.3 mol of 4-amino-1-butanol was added and the reaction was continued at 70°C for 10 h. The mixture was heated to 120°C and toluene and unreacted 4-amino-1-butanol were removed in vacuo. When no more liquid was distilled out, 109 g of a four-center Schiff base compound and an alcohol mixture was obtained.

[0158] The obtained product was analyzed by mass spectrometer, and the results were as follows: m / z=1928, m / z=267, corresponding to the molecular weights of the four-center Schiff base compound and the alcohol substance, respectively.

[0159] 7.2 Mix 400 mL toluene solution of 28.5 g of the above-mentioned four-center Schiff base compound and alcohol mixture and 130 mL toluene solution of 8.2 g of aluminum isopropoxide, and heat to 85°C. After 15 hours, vacuum remove the toluene. When no liquid is distilled out, 30.4 g of the four-center Schiff base aluminum catalyst and alcohol mixture is obtained. The theoretical mass of the four-center Schiff base aluminum catalyst is 22.7 g, which is calculated by feeding.

[0160] Take 1 g of the above-mentioned mixture of four-center Schiff base aluminum catalyst and alcohol substances, and purify it by column chromatography to obtain 0.71 g of the four-center Schiff base aluminum catalyst. The mass of the four-center Schiff base aluminum catalyst in the above-mentioned mixture is calculated to be 21.6 g. The yield is calculated by dividing the actual mass of the four-center Schiff base aluminum catalyst by the theoretical mass to be 95.2%.

[0161] 7.3 The reaction bottle was repeatedly evacuated and filled with nitrogen, and 348 g of glycolide, 3.19 g of the above-mentioned four-center Schiff base aluminum catalyst and alcohol mixture were added into the reaction bottle in sequence. After mixing and stirring, the temperature was rapidly raised to 170°C. After 4 hours, 340.7 g of polyglycolic acid was obtained with a yield of 97.9%.

[0162] The polyglycolic acid obtained by the present invention is subjected to gel permeation chromatography analysis, and the number average molecular weight of the polyglycolic acid is measured to be 83000 g / mol.

[0163] Example 8

[0164] 8.1 250 ml toluene solution of 0.03 mol of the tetrasalicylaldehyde compound in Preparation Example 3 was added dropwise at a rate of 3 mL / min to 200 mL toluene solution of 0.8 mol of 1,3-propylenediamine, mixed and stirred, and heated to 65°C. After 15 hours, the mixture was heated to 100°C, and toluene and unreacted 1,3-propylenediamine were removed in vacuo to obtain amino-functionalized salicylaldehyde, which was then mixed with 250 mL toluene solution of 0.25 mol of 3,5-dichlorosalicylaldehyde, reacted at 60°C for 10 hours, and then 200 mL toluene solution of 0.25 mol of 8-amino-1-octanol was added. The reaction was continued at 65°C for 10 hours, and the mixture was heated to 140°C. Toluene and unreacted 8-amino-1-octanol were removed in vacuo. When no more liquid was distilled out, 100.1 g of a four-center Schiff base compound and an alcohol mixture was obtained.

[0165] The obtained product was analyzed by mass spectrometer, and the results were as follows: m / z=2030, m / z=336, corresponding to the molecular weights of the four-center Schiff base compound and the alcohol substance, respectively.

[0166] 8.2 Mix 34.5 g of the above-mentioned four-center Schiff base compound and alcohol mixture in 300 mL of toluene solution and 6.5 g of ethoxyaluminum in 140 mL of toluene solution, heat to 85°C, and after 26 hours, remove the toluene by vacuum. When no more liquid is distilled out, 35.8 g of the four-center Schiff base aluminum catalyst and alcohol mixture is obtained. The theoretical mass of the four-center Schiff base aluminum catalyst is 23.2 g as calculated by the feed.

[0167] Take 1 g of the above-mentioned mixture of four-center Schiff base aluminum catalyst and alcohol substances, and purify it by column chromatography to obtain 0.62 g of the four-center Schiff base aluminum catalyst. The mass of the four-center Schiff base aluminum catalyst in the above-mentioned mixture is calculated to be 22.2 g. The yield is calculated by dividing the actual mass of the four-center Schiff base aluminum catalyst by the theoretical mass to be 95.7%.

[0168] 8.3 The reaction bottle was repeatedly evacuated and filled with nitrogen, 464 g of glycolide, 1.41 g of the above-mentioned Schiff base aluminum catalyst and the alcohol mixture were added into the reaction bottle in sequence, mixed and stirred, and the temperature was rapidly raised to 165°C. After 4 hours, 452.4 g of polyglycolic acid was obtained with a yield of 97.5%.

[0169] The polyglycolic acid obtained by the present invention is subjected to gel permeation chromatography analysis, and the number average molecular weight of the polyglycolic acid is measured to be 91000 g / mol.

[0170] Example 9

[0171] 9.1 200 ml toluene solution of 0.02 mol of the tetrasalicylaldehyde compound in Preparation Example 3 was added dropwise at a rate of 1 mL / min to 250 mL toluene solution of 0.6 mol of dimethylpropylenediamine, mixed and stirred, and heated to 60°C. After 18 hours, the mixture was filtered, heated to 110°C, and toluene and unreacted dimethylpropylenediamine were removed in vacuo to obtain amino-functionalized salicylaldehyde, which was then mixed with 300 mL toluene solution of 0.2 mol of 3-bromosalicylaldehyde, reacted at 55°C for 15 hours, and then 100 mL toluene solution of 0.2 mol of 5-amino-1-pentanol was added. The reaction was continued at 65°C for 12 hours, heated to 120°C, and toluene and unreacted 5-amino-1-pentanol were removed in vacuo. When no more liquid was distilled out, 76.4 g of a four-center Schiff base compound and an alcohol mixture was obtained.

[0172] The obtained product was analyzed by mass spectrometer, and the results were as follows: m / z=2182, m / z=304, corresponding to the molecular weights of the four-center Schiff base compound and the alcohol substance, respectively.

[0173] 9.2 Mix 39.9 g of the above-mentioned four-center Schiff base compound and alcohol mixture in 350 mL of isobutanol solution and 7.04 g of nickel acetate in 100 mL of isopropanol solution, heat to 90°C, and after 24 hours, vacuum remove isobutanol and isopropanol. When no liquid is distilled out, 40 g of the four-center Schiff base nickel catalyst and alcohol mixture is obtained. The theoretical mass of the four-center Schiff base nickel catalyst is 24.2 g as calculated by feeding.

[0174] Take 1 g of the above-mentioned mixture of four-center Schiff base nickel catalyst and alcohol substances, and purify it by column chromatography to obtain 0.58 g of the four-center Schiff base nickel catalyst. The mass of the four-center Schiff base nickel catalyst in the above-mentioned mixture is calculated to be 23.2 g. The yield is calculated by dividing the actual mass of the four-center Schiff base nickel catalyst by the theoretical mass to be 95.9%.

[0175] 9.3 The reaction flask was repeatedly evacuated and filled with nitrogen. 348 g of glycolide, 4.64 g of isopropyl glycidyl ether and 2.11 g of the above-mentioned four-center Schiff base nickel catalyst and alcohol mixture were added into the reaction flask in sequence. The mixture was mixed and stirred and the temperature was rapidly raised to 160°C. After 5 hours, 336.5 g of polyglycolic acid was obtained with a yield of 96.7%.

[0176] The polyglycolic acid obtained by the present invention is subjected to gel permeation chromatography analysis, and the number average molecular weight of the polyglycolic acid is measured to be 81000 g / mol.

[0177] Example 10

[0178] 10.1 100 ml toluene solution of 0.01 mol of the tetrasalicylaldehyde compound in Preparation Example 3 was added dropwise at a rate of 1 mL / min to 150 mL toluene solution of 0.4 mol of 1,2-propylenediamine, mixed and stirred, and heated to 55°C. After 20 hours, the mixture was filtered, heated to 100°C, and toluene and unreacted 1,2-propylenediamine were removed in vacuo to obtain amino-functionalized salicylaldehyde, which was then mixed with 200 mL toluene solution of 0.1 mol of 3,5-di-tert-butyl salicylaldehyde, reacted at 50°C for 15 hours, and then 100 mL toluene solution of 0.15 mol of 6-amino-1-hexanol was added. The reaction was continued at 60°C for 15 hours, and the mixture was heated to 130°C. Toluene and unreacted 6-amino-1-hexanol were removed in vacuo. When no more liquid was distilled out, 40.7 g of a four-center Schiff base compound and an alcohol mixture was obtained.

[0179] The obtained product was analyzed by mass spectrometry, and the results were as follows: m / z = 2202, m / z = 351, corresponding to the molecular weights of the four-center Schiff base compound and the alcohol substance, respectively.

[0180] 10.2 Mix 42.9 g of the above-mentioned four-center Schiff base compound and alcohol mixture in 400 mL of isopropanol solution and 8.84 g of indium chloride in 150 mL of ethanol solution, heat to 85°C, and after 15 hours, vacuum remove isopropanol and ethanol. When no liquid is distilled out, 46.5 g of the four-center Schiff base indium catalyst and alcohol mixture is obtained. The theoretical mass of the four-center Schiff base indium catalyst is 28 g as calculated by feeding.

[0181] Take 1 g of the above-mentioned mixture of four-center Schiff base indium catalyst and alcohol substances, and purify it by column chromatography to obtain 0.57 g of the four-center Schiff base indium catalyst. The mass of the four-center Schiff base indium catalyst in the above-mentioned mixture is calculated to be 26.5 g. The yield is calculated by dividing the actual mass of the four-center Schiff base indium catalyst by the theoretical mass to be 94.6%.

[0182] 10.3 The reaction bottle was repeatedly evacuated and filled with nitrogen, 348 g of glycolide, 2.45 g of the above four-center Schiff base indium catalyst and the alcohol mixture were added to the reaction bottle in sequence, mixed and stirred, and the temperature was rapidly raised to 155°C. After 5 hours, 338.6 g of polyglycolic acid was obtained with a yield of 97.3%.

[0183] The polyglycolic acid obtained by the present invention is subjected to gel permeation chromatography analysis, and the number average molecular weight of the polyglycolic acid is measured to be 99000 g / mol.

[0184] Comparative Example 1

[0185] The reaction bottle was repeatedly evacuated and filled with nitrogen, and 348 g of glycolide and the same molar number of catalyst and initiator (0.2 g of stannous octoate and 0.003 mol benzyl alcohol) as in Example 10 were added into the reaction bottle in sequence. The mixture was mixed and stirred and the temperature was rapidly raised to 155° C. After 5 hours, 324.7 g of polyglycolic acid was obtained with a yield of 93.3%.

[0186] The polyglycolic acid was analyzed by gel permeation chromatography, and the number average molecular weight of the polyglycolic acid was measured to be 78000 g / mol. The yield and molecular weight of the polyglycolic acid were lower than those obtained by using a Schiff base catalyst.

[0187] The above embodiments are only used to help understand the method and core idea of ​​the present invention. It should be noted that, for those skilled in the art, several improvements and modifications can be made to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. A four-center Schiff alkali metal compound, characterized in that It has the structure shown in Formula I or Formula II: Wherein, R1 is the group remaining after the glycidyl ether is removed from the diglycidyl ether, and the diglycidyl ether is selected from any one or more of ethylene glycol diglycidyl ether, glycerol diglycidyl ether, butanediol diglycidyl ether, neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, 1,2-cyclohexanediol diglycidyl ether, resorcinol diglycidyl ether, bisphenol A diglycidyl ether or bisphenol F diglycidyl ether; The R2 is independently selected from C2-C10 alkylene, C5-C7 cycloalkylene, C6-C12 arylene; Said R3 and R4 are independently selected from hydrogen, halogen, substituted or unsubstituted C1-C6 alkyl, substituted or unsubstituted C1-C6 alkoxy or nitro; The R5 is selected from halogen, substituted or unsubstituted C1-C6 alkoxy or ester; The M1 is selected from any one of zinc, cobalt, nickel or tin; The M2 is selected from any one of aluminum, indium, chromium, iron, manganese, cerium or yttrium.

2. The four-center Schiff alkali metal compound according to claim 1, characterized in that The R2 is independently selected from the group remaining after removing two amino groups from ethylenediamine, 1,3-propylenediamine, 1,2-propylenediamine, dimethylpropylenediamine, 1,2-butylenediamine, 1,4-butylenediamine, 1,2-cyclohexanediamine or o-phenylenediamine; Said R3 and R4 are independently selected from -H, -CH3, -CH2Cl, -CH2CH3, -CH(CH3)2, -OCH(CH3)2, -C(CH3)3, -OCH3, -OCH2CH3, -OCF3, -F, -Cl, -Br, I or -NO2; The R5 is selected from -OCH3, -OCH2CH3, -OCH(CH3)2, -Cl or -OOCCH3.

3. The method for preparing a four-center Schiff alkali metal compound according to any one of claims 1 to 2, characterized in that: The following steps are involved: a) reacting a tetrasalicylaldehyde compound with a diamine monomer to obtain amino-functionalized salicylaldehyde; b) reacting the amino-functionalized salicylaldehyde with a salicylaldehyde monomer represented by formula A to obtain a four-center Schiff base compound; c) reacting the four-center Schiff base compound with a metal compound to obtain a four-center Schiff base metal compound; The R3 and R4 are independently selected from hydrogen, halogen, substituted or unsubstituted C1-C6 alkyl, substituted or unsubstituted C1-C6 alkoxy or nitro.

4. The preparation method according to claim 3, characterized in that: The following steps are involved: a) reacting a tetrasalicylaldehyde compound with a diamine monomer to obtain amino-functionalized salicylaldehyde; b1) reacting amino-functionalized salicylaldehyde with an excess of a salicylaldehyde monomer represented by formula A to obtain a mixture of a four-center Schiff base compound and residual salicylaldehyde monomer; b2) reacting the mixture obtained in step b1) with an amino alcohol monomer to obtain a mixture of a four-center Schiff base compound and an alcohol substance represented by formula B; c1) reacting the mixture obtained in step b2) with a metal compound to obtain a mixture of a four-center Schiff alkali metal compound and an alcohol substance; Said R3 and R4 are independently selected from hydrogen, halogen, substituted or unsubstituted C1-C6 alkyl, substituted or unsubstituted C1-C6 alkoxy or nitro; The R6 is selected from C2 to C10 alkylene groups.

5. The preparation method according to claim 3 or 4, characterized in that: The tetrasalicylaldehyde compound is prepared according to the following method: S1) reacting diglycidyl ether under the action of Lewis acid and quaternary ammonium salt to obtain a tetrahydroxy compound; S2) reacting the tetrahydroxy compound with an alkali metal to obtain a tetrahydroxy alkali metal compound; S3) reacting a tetrahydroxy alkali metal compound with a salicylaldehyde compound to obtain a tetrasalicylicylaldehyde compound.

6. The preparation method according to claim 5, characterized in that: The diglycidyl ether includes at least one of ethylene glycol diglycidyl ether, glycerol diglycidyl ether, butanediol diglycidyl ether, neopentyl glycol diglycidyl ether, 1,2-cyclohexanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, resorcinol diglycidyl ether, bisphenol A diglycidyl ether and bisphenol F diglycidyl ether; The reaction temperature of step S1) is 20-100°C and the reaction time is 2-20h; The Lewis acid includes one or more of concentrated sulfuric acid, zinc perchlorate, aluminum trichloride, ferric chloride, boron trifluoride etherate, fluoroboric acid and tin tetrachloride; The Lewis acid is used in an amount of 0.1% to 10% by weight of the diglycidyl ether; The quaternary ammonium salts include tetramethylammonium chloride, (1-dodecyl)trimethylammonium chloride, tetraethylammonium chloride, benzyltributylammonium chloride, benzyltriethylammonium chloride, benzyltrimethylammonium chloride, benzyltri-n-propylammonium chloride, benzyldimethyloctadecylammonium chloride, tetradecyldimethylbenzylammonium chloride, trimethylphenylammonium chloride, benzyldodecyldimethylammonium chloride, benzyldimethylphenylammonium chloride, benzyldimethyloctylammonium chloride, tetra-n-butylammonium chloride, hexadecyltrimethylammonium chloride, methyltrioctylammonium chloride, methyltributylammonium chloride, tetradecyltrimethyl chloride ammonium, tetra-n-propylammonium chloride, didecyldimethylammonium chloride, triethylmethylammonium chloride, dimethyldioctadecylammonium chloride, octadecyltrimethylammonium chloride, octyltrimethylammonium chloride, didodecyldimethylammonium chloride, tetrapentylammonium chloride, benzyldimethylhexylammonium chloride, benzylethyltrimethylammonium chloride, tetraheptylammonium chloride, tetraoctylammonium chloride, dioctyldimethylammonium chloride, phenyltriethylammonium chloride, tetrabutylammonium bromide, benzyltrimethylammonium bromide, dimethylethylhexadecylammonium bromide, hexyltrimethylammonium bromide and hexadecyltrimethylammonium bromide; The dosage of the quaternary ammonium salt is 0.1% to 10% of the weight of the diglycidyl ether; The reaction temperature in step S2) is 25-100°C and the reaction time is 2-8h; The molar ratio of the tetrahydroxy compound to the alkali metal is 1:5 to 1:10; The reaction temperature in step S3) is 20-100°C and the reaction time is 2-48h; The molar ratio of the tetrahydroxy alkali metal compound to the salicylaldehyde compound is 1:4 to 1:

8.

7. The preparation method according to claim 3 or 4, characterized in that: The molar ratio of the tetrasalicylaldehyde compound to the diamine monomer is 1:8 to 1:30; The reaction temperature in step a) is 20-100° C. and the reaction time is 2-48 hours; The diamine monomers include ethylenediamine, 1,3-propylenediamine, 1,2-propylenediamine, dimethylpropylenediamine, 1,2-butylenediamine, 1,4-butylenediamine, 1,2-cyclohexanediamine or o-phenylenediamine; The molar ratio of the amino-functionalized salicylaldehyde to the salicylaldehyde monomer of formula A is 1:5 to 1:12; The temperature of the reaction of the amino-functionalized salicylaldehyde and the salicylaldehyde monomer represented by formula A is 20 to 100° C., and the reaction time is 2 to 48 hours; The molar ratio of the four-center Schiff base compound to the metal compound is 1:4 to 1:8; The temperature of the reaction between the four-center Schiff base compound and the metal compound is 20 to 120° C., and the reaction time is 2 to 48 hours; The metal compound is selected from metal compounds containing zinc, cobalt, nickel, tin, aluminum, indium, chromium, iron, manganese, cerium or yttrium; The anion of the metal compound is a halogen, an acid radical ion or an alkoxy group.

8. The preparation method according to claim 4, characterized in that: The molar ratio of the remaining salicylaldehyde monomer to the amino alcohol monomer is 1:1 to 1:10; The reaction temperature in step b2) is 20-100°C and the reaction time is 2-48h; The amino alcohol monomer is a C2-C10 amino alcohol compound.

9. A method for preparing polyglycolide, characterized in that: The following steps are involved: In an inert atmosphere, glycolide, or glycolide and an epoxy compound are reacted in the presence of a catalyst and an initiator to obtain polyglycolide; The catalyst is the four-center Schiff alkali metal compound described in any one of claims 1 to 2 or the four-center Schiff alkali metal compound prepared by the preparation method described in any one of claims 3 to 8.

10. The preparation method according to claim 9, characterized in that: The initiator is an alcohol substance shown in formula B prepared in claim 4; The ratio of the mass of the catalyst to the glycolide or to the total mass of the glycolide and the epoxy compound is 1:(30-3000); The molar ratio of the epoxy compound to the glycolide is (0-10):(90-100); The reaction temperature is 120-240° C., and the reaction time is 2-24 hours.

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