CN108570142B - Method for catalyzing lactide polymerization by using aluminum compound containing chiral cyclohexanediamine - Google Patents
Method for catalyzing lactide polymerization by using aluminum compound containing chiral cyclohexanediamine Download PDFInfo
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- CN108570142B CN108570142B CN201711314932.3A CN201711314932A CN108570142B CN 108570142 B CN108570142 B CN 108570142B CN 201711314932 A CN201711314932 A CN 201711314932A CN 108570142 B CN108570142 B CN 108570142B
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- 229910052782 aluminium Inorganic materials 0.000 title claims abstract description 69
- -1 aluminum compound Chemical class 0.000 title claims abstract description 50
- 238000000034 method Methods 0.000 title claims abstract description 32
- JJTUDXZGHPGLLC-UHFFFAOYSA-N lactide Chemical compound CC1OC(=O)C(C)OC1=O JJTUDXZGHPGLLC-UHFFFAOYSA-N 0.000 title claims abstract description 30
- YMHQVDAATAEZLO-UHFFFAOYSA-N cyclohexane-1,1-diamine Chemical compound NC1(N)CCCCC1 YMHQVDAATAEZLO-UHFFFAOYSA-N 0.000 title claims abstract description 29
- 238000006116 polymerization reaction Methods 0.000 title claims abstract description 15
- 238000006243 chemical reaction Methods 0.000 claims abstract description 119
- 239000003054 catalyst Substances 0.000 claims abstract description 70
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims abstract description 25
- 229920000747 poly(lactic acid) Polymers 0.000 claims abstract description 20
- 238000007151 ring opening polymerisation reaction Methods 0.000 claims abstract description 19
- WVDDGKGOMKODPV-UHFFFAOYSA-N Benzyl alcohol Chemical compound OCC1=CC=CC=C1 WVDDGKGOMKODPV-UHFFFAOYSA-N 0.000 claims abstract description 18
- 239000011261 inert gas Substances 0.000 claims abstract description 14
- 239000003960 organic solvent Substances 0.000 claims abstract description 12
- 235000019445 benzyl alcohol Nutrition 0.000 claims abstract description 6
- 238000002156 mixing Methods 0.000 claims abstract description 5
- 239000000376 reactant Substances 0.000 claims abstract description 3
- YXFVVABEGXRONW-UHFFFAOYSA-N Toluene Chemical compound CC1=CC=CC=C1 YXFVVABEGXRONW-UHFFFAOYSA-N 0.000 claims description 80
- VLKZOEOYAKHREP-UHFFFAOYSA-N n-Hexane Chemical compound CCCCCC VLKZOEOYAKHREP-UHFFFAOYSA-N 0.000 claims description 65
- 229940126062 Compound A Drugs 0.000 claims description 28
- NLDMNSXOCDLTTB-UHFFFAOYSA-N Heterophylliin A Natural products O1C2COC(=O)C3=CC(O)=C(O)C(O)=C3C3=C(O)C(O)=C(O)C=C3C(=O)OC2C(OC(=O)C=2C=C(O)C(O)=C(O)C=2)C(O)C1OC(=O)C1=CC(O)=C(O)C(O)=C1 NLDMNSXOCDLTTB-UHFFFAOYSA-N 0.000 claims description 28
- 238000002360 preparation method Methods 0.000 claims description 28
- 238000005406 washing Methods 0.000 claims description 17
- 125000001495 ethyl group Chemical group [H]C([H])([H])C([H])([H])* 0.000 claims description 15
- 125000002496 methyl group Chemical group [H]C([H])([H])* 0.000 claims description 14
- 125000001280 n-hexyl group Chemical group C(CCCCC)* 0.000 claims description 14
- 239000002904 solvent Substances 0.000 claims description 14
- 238000001914 filtration Methods 0.000 claims description 13
- 125000000217 alkyl group Chemical group 0.000 claims description 11
- WYURNTSHIVDZCO-UHFFFAOYSA-N Tetrahydrofuran Chemical compound C1CCOC1 WYURNTSHIVDZCO-UHFFFAOYSA-N 0.000 claims description 8
- HTSGKJQDMSTCGS-UHFFFAOYSA-N 1,4-bis(4-chlorophenyl)-2-(4-methylphenyl)sulfonylbutane-1,4-dione Chemical compound C1=CC(C)=CC=C1S(=O)(=O)C(C(=O)C=1C=CC(Cl)=CC=1)CC(=O)C1=CC=C(Cl)C=C1 HTSGKJQDMSTCGS-UHFFFAOYSA-N 0.000 claims description 7
- XDTMQSROBMDMFD-UHFFFAOYSA-N Cyclohexane Chemical compound C1CCCCC1 XDTMQSROBMDMFD-UHFFFAOYSA-N 0.000 claims description 6
- JJTUDXZGHPGLLC-ZXZARUISSA-N (3r,6s)-3,6-dimethyl-1,4-dioxane-2,5-dione Chemical compound C[C@H]1OC(=O)[C@H](C)OC1=O JJTUDXZGHPGLLC-ZXZARUISSA-N 0.000 claims description 4
- 239000007789 gas Substances 0.000 claims description 4
- YLQBMQCUIZJEEH-UHFFFAOYSA-N tetrahydrofuran Natural products C=1C=COC=1 YLQBMQCUIZJEEH-UHFFFAOYSA-N 0.000 claims description 4
- 230000035484 reaction time Effects 0.000 claims description 3
- 238000005086 pumping Methods 0.000 claims 1
- 125000003944 tolyl group Chemical group 0.000 claims 1
- 239000003446 ligand Substances 0.000 abstract description 32
- 229910052757 nitrogen Inorganic materials 0.000 abstract description 16
- 229910052751 metal Inorganic materials 0.000 abstract description 10
- 230000003197 catalytic effect Effects 0.000 abstract description 8
- 229910052760 oxygen Inorganic materials 0.000 abstract description 6
- 229920000642 polymer Polymers 0.000 abstract description 4
- 238000009826 distribution Methods 0.000 abstract description 3
- 239000000047 product Substances 0.000 description 32
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 22
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 description 21
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 20
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 19
- 239000000203 mixture Substances 0.000 description 16
- 150000001875 compounds Chemical class 0.000 description 14
- HEDRZPFGACZZDS-MICDWDOJSA-N Trichloro(2H)methane Chemical compound [2H]C(Cl)(Cl)Cl HEDRZPFGACZZDS-MICDWDOJSA-N 0.000 description 12
- 238000001035 drying Methods 0.000 description 12
- 239000012299 nitrogen atmosphere Substances 0.000 description 12
- 239000003708 ampul Substances 0.000 description 11
- 239000007787 solid Substances 0.000 description 11
- 238000010438 heat treatment Methods 0.000 description 10
- WVDDGKGOMKODPV-ZQBYOMGUSA-N phenyl(114C)methanol Chemical compound O[14CH2]C1=CC=CC=C1 WVDDGKGOMKODPV-ZQBYOMGUSA-N 0.000 description 10
- 239000012043 crude product Substances 0.000 description 8
- 230000001376 precipitating effect Effects 0.000 description 8
- 235000019441 ethanol Nutrition 0.000 description 7
- 239000002184 metal Substances 0.000 description 7
- 125000004108 n-butyl group Chemical group [H]C([H])([H])C([H])([H])C([H])([H])C([H])([H])* 0.000 description 7
- 239000012074 organic phase Substances 0.000 description 7
- 229920000728 polyester Polymers 0.000 description 7
- 238000005160 1H NMR spectroscopy Methods 0.000 description 6
- QTBSBXVTEAMEQO-UHFFFAOYSA-N Acetic acid Chemical compound CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 description 6
- 238000007259 addition reaction Methods 0.000 description 6
- 229910052799 carbon Inorganic materials 0.000 description 6
- 230000000052 comparative effect Effects 0.000 description 6
- 239000007788 liquid Substances 0.000 description 6
- 238000000926 separation method Methods 0.000 description 6
- JLTRXTDYQLMHGR-UHFFFAOYSA-N trimethylaluminium Chemical compound C[Al](C)C JLTRXTDYQLMHGR-UHFFFAOYSA-N 0.000 description 6
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 5
- LGRFSURHDFAFJT-UHFFFAOYSA-N Phthalic anhydride Natural products C1=CC=C2C(=O)OC(=O)C2=C1 LGRFSURHDFAFJT-UHFFFAOYSA-N 0.000 description 5
- JHIWVOJDXOSYLW-UHFFFAOYSA-N butyl 2,2-difluorocyclopropane-1-carboxylate Chemical compound CCCCOC(=O)C1CC1(F)F JHIWVOJDXOSYLW-UHFFFAOYSA-N 0.000 description 5
- 239000013078 crystal Substances 0.000 description 5
- JJTUDXZGHPGLLC-IMJSIDKUSA-N 4511-42-6 Chemical compound C[C@@H]1OC(=O)[C@H](C)OC1=O JJTUDXZGHPGLLC-IMJSIDKUSA-N 0.000 description 4
- 238000012512 characterization method Methods 0.000 description 4
- 229910001873 dinitrogen Inorganic materials 0.000 description 4
- 239000000178 monomer Substances 0.000 description 4
- 239000002861 polymer material Substances 0.000 description 4
- VOITXYVAKOUIBA-UHFFFAOYSA-N triethylaluminium Chemical compound CC[Al](CC)CC VOITXYVAKOUIBA-UHFFFAOYSA-N 0.000 description 4
- ORYGRKHDLWYTKX-UHFFFAOYSA-N trihexylalumane Chemical compound CCCCCC[Al](CCCCCC)CCCCCC ORYGRKHDLWYTKX-UHFFFAOYSA-N 0.000 description 4
- 238000005303 weighing Methods 0.000 description 4
- YMWUJEATGCHHMB-UHFFFAOYSA-N Dichloromethane Chemical compound ClCCl YMWUJEATGCHHMB-UHFFFAOYSA-N 0.000 description 3
- 125000005234 alkyl aluminium group Chemical group 0.000 description 3
- 238000000921 elemental analysis Methods 0.000 description 3
- 125000000816 ethylene group Chemical group [H]C([H])([*:1])C([H])([H])[*:2] 0.000 description 3
- 229910052739 hydrogen Inorganic materials 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 239000002994 raw material Substances 0.000 description 3
- SQBBHCOIQXKPHL-UHFFFAOYSA-N tributylalumane Chemical compound CCCC[Al](CCCC)CCCC SQBBHCOIQXKPHL-UHFFFAOYSA-N 0.000 description 3
- 238000001291 vacuum drying Methods 0.000 description 3
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 2
- AZDRQVAHHNSJOQ-UHFFFAOYSA-N alumane Chemical class [AlH3] AZDRQVAHHNSJOQ-UHFFFAOYSA-N 0.000 description 2
- 150000004696 coordination complex Chemical group 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 239000002685 polymerization catalyst Substances 0.000 description 2
- 238000010992 reflux Methods 0.000 description 2
- 238000003756 stirring Methods 0.000 description 2
- 125000001424 substituent group Chemical group 0.000 description 2
- MCULRUJILOGHCJ-UHFFFAOYSA-N triisobutylaluminium Chemical compound CC(C)C[Al](CC(C)C)CC(C)C MCULRUJILOGHCJ-UHFFFAOYSA-N 0.000 description 2
- 238000012795 verification Methods 0.000 description 2
- 238000010792 warming Methods 0.000 description 2
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- 238000005481 NMR spectroscopy Methods 0.000 description 1
- PMZURENOXWZQFD-UHFFFAOYSA-L Sodium Sulfate Chemical compound [Na+].[Na+].[O-]S([O-])(=O)=O PMZURENOXWZQFD-UHFFFAOYSA-L 0.000 description 1
- MQRWBMAEBQOWAF-UHFFFAOYSA-N acetic acid;nickel Chemical compound [Ni].CC(O)=O.CC(O)=O MQRWBMAEBQOWAF-UHFFFAOYSA-N 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 150000001399 aluminium compounds Chemical class 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 125000004432 carbon atom Chemical group C* 0.000 description 1
- 239000001569 carbon dioxide Substances 0.000 description 1
- 229910002092 carbon dioxide Inorganic materials 0.000 description 1
- 239000012295 chemical reaction liquid Substances 0.000 description 1
- 239000007795 chemical reaction product Substances 0.000 description 1
- 238000013270 controlled release Methods 0.000 description 1
- 239000013256 coordination polymer Substances 0.000 description 1
- 239000003814 drug Substances 0.000 description 1
- 229940079593 drug Drugs 0.000 description 1
- 238000003912 environmental pollution Methods 0.000 description 1
- 239000000706 filtrate Substances 0.000 description 1
- 125000004051 hexyl group Chemical group [H]C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])* 0.000 description 1
- 239000002815 homogeneous catalyst Substances 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 239000013067 intermediate product Substances 0.000 description 1
- 125000000959 isobutyl group Chemical group [H]C([H])([H])C([H])(C([H])([H])[H])C([H])([H])* 0.000 description 1
- 150000002596 lactones Chemical class 0.000 description 1
- 238000001819 mass spectrum Methods 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 244000005700 microbiome Species 0.000 description 1
- DOTMOQHOJINYBL-UHFFFAOYSA-N molecular nitrogen;molecular oxygen Chemical compound N#N.O=O DOTMOQHOJINYBL-UHFFFAOYSA-N 0.000 description 1
- 125000000740 n-pentyl group Chemical group [H]C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])* 0.000 description 1
- 125000004123 n-propyl group Chemical group [H]C([H])([H])C([H])([H])C([H])([H])* 0.000 description 1
- 229940078494 nickel acetate Drugs 0.000 description 1
- 231100000344 non-irritating Toxicity 0.000 description 1
- 231100000252 nontoxic Toxicity 0.000 description 1
- 230000003000 nontoxic effect Effects 0.000 description 1
- 239000005022 packaging material Substances 0.000 description 1
- 238000004806 packaging method and process Methods 0.000 description 1
- 239000003208 petroleum Substances 0.000 description 1
- 238000006068 polycondensation reaction Methods 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 239000003586 protic polar solvent Substances 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 238000001953 recrystallisation Methods 0.000 description 1
- 239000002689 soil Substances 0.000 description 1
- 238000004611 spectroscopical analysis Methods 0.000 description 1
- 238000009987 spinning Methods 0.000 description 1
- 238000003786 synthesis reaction Methods 0.000 description 1
- FQMMZTDQJFUYSA-UHFFFAOYSA-N triheptylalumane Chemical compound CCCCCCC[Al](CCCCCCC)CCCCCCC FQMMZTDQJFUYSA-UHFFFAOYSA-N 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G63/00—Macromolecular compounds obtained by reactions forming a carboxylic ester link in the main chain of the macromolecule
- C08G63/02—Polyesters derived from hydroxycarboxylic acids or from polycarboxylic acids and polyhydroxy compounds
- C08G63/06—Polyesters derived from hydroxycarboxylic acids or from polycarboxylic acids and polyhydroxy compounds derived from hydroxycarboxylic acids
- C08G63/08—Lactones or lactides
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07F—ACYCLIC, CARBOCYCLIC OR HETEROCYCLIC COMPOUNDS CONTAINING ELEMENTS OTHER THAN CARBON, HYDROGEN, HALOGEN, OXYGEN, NITROGEN, SULFUR, SELENIUM OR TELLURIUM
- C07F5/00—Compounds containing elements of Groups 3 or 13 of the Periodic Table
- C07F5/06—Aluminium compounds
- C07F5/061—Aluminium compounds with C-aluminium linkage
- C07F5/066—Aluminium compounds with C-aluminium linkage compounds with Al linked to an element other than Al, C, H or halogen (this includes Al-cyanide linkage)
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G63/00—Macromolecular compounds obtained by reactions forming a carboxylic ester link in the main chain of the macromolecule
- C08G63/78—Preparation processes
- C08G63/82—Preparation processes characterised by the catalyst used
- C08G63/823—Preparation processes characterised by the catalyst used for the preparation of polylactones or polylactides
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Health & Medical Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Medicinal Chemistry (AREA)
- Polymers & Plastics (AREA)
- Toxicology (AREA)
- Polyesters Or Polycarbonates (AREA)
Abstract
The invention discloses a method for catalyzing lactide polymerization by using an aluminum compound containing chiral cyclohexanediamine, which comprises the following steps: mixing a catalyst, an organic solvent, a benzyl alcohol cocatalyst and lactide, carrying out ring-opening polymerization reaction under the protection of anhydrous and oxygen-free inert gases, and treating reactants after reaction to obtain polylactide, wherein the catalyst is an aluminum compound containing chiral cyclohexanediamine. The catalyst has various structural changes, the metal center aluminum and the ligand N, N, O and O are in tetradentate coordination, the catalytic activity is high, the stereoselectivity is high, the reaction rate is high, the catalyst is an ideal catalyst, the polymer obtained by the reaction is a benzyloxy-terminated polymer, the molecular mass distribution is narrow, the molecular weight is controllable, and the yield is high.
Description
Technical Field
The invention relates to a method for catalyzing lactide polymerization, in particular to a method for catalyzing lactide polymerization by adopting an aluminum compound catalyst with a special structure and containing chiral cyclohexanediamine.
Background
The traditional polymer materials face two problems of energy crisis and environmental pollution, renewable resources for replacing petroleum are searched, and the development of environment-friendly and biodegradable new materials becomes the development trend of future polymer materials. Polyester is receiving more and more attention as a green and environment-friendly polymer material which is biocompatible and biodegradable. In a natural living environment, the waste polyester material can be thoroughly decomposed into water and carbon dioxide by microorganisms in soil, is environment-friendly and is renewable. Because polyester is non-toxic, non-irritating, and has good biocompatibility, it is widely used in biomedical and packaging materials such as surgical sutures, packaging, drug controlled release and tissue engineering scaffolds, etc. The polyester has excellent biocompatibility, biodegradability and sustainable development and utilization performance, so that the polyester becomes a polymer material with the greatest development prospect in the 21 st century.
The polyester material can be obtained directly from the corresponding monomer acid by a polycondensation method or obtained by catalyzing the ring-opening polymerization of the corresponding monomer by a homogeneous catalyst. The most efficient and commonly used method is to catalyze the ring-opening polymerization of monomers with a metal catalyst to obtain the corresponding polyester. Due to the excellent catalytic effect of the metal catalyst, the molecular weight and molecular weight distribution of the polymerization can be effectively controlled, and various metal catalytic compounds are prepared to be used as ring-opening polymerization catalysts of cyclic lactone monomers, the most commonly used metal catalyst is a metal complex catalyst formed by a metal center and a ligand, wherein, due to the excellent performance of the metal aluminum complex catalyst, people have attracted extensive attention, and various aluminum metal complex catalysts are synthesized therewith to be used as the ring-opening polymerization catalysts of lactones. In the metal complex catalyst, the selection of the ligand and the selective catalyst of the metal is very critical to the speed of the ring-opening polymerization reaction and the performance of the obtained product, and under the condition of the same metal, the replacement and selection of the ligand often show unexpected catalytic effect, so that the research of a new catalyst with good performance is very necessary.
Disclosure of Invention
The invention provides a method for catalyzing lactide polymerization by using an aluminum compound containing chiral cyclohexanediamine, which is simple to operate, takes a self-developed aluminum compound containing chiral cyclohexanediamine as a catalyst, has good reaction controllability and high stereoselectivity of the catalyst, and the obtained polylactide has controllable molecular weight and high yield.
The invention is completed under the subsidization of the national Natural fund Commission youth project (No 21104026), and the technical scheme of the invention is as follows:
the invention provides an aluminum compound catalyst containing chiral cyclohexanediamine with a special structure, which has a structural formula shown as the following formula (I):
in the above formula I, the substituent R is selected from C1-C6 linear alkyl groups such as methyl, ethyl, n-propyl, n-butyl, n-pentyl and n-hexyl, in consideration of steric hindrance. When these groups are selected, the aluminum compound can be easily synthesized, and if other groups are selected, the aluminum compound is formed with difficulty or is not available. R is preferably methyl, ethyl or n-hexyl, most preferably n-hexyl.
The aluminum compound containing chiral cyclohexanediamine is prepared by the reaction of ligand and alkyl aluminum, and the preparation thereofThe method comprises the following steps: adding a compound A (namely a ligand) into an organic solvent at-10-0%oAdding trialkyl aluminum under C, naturally raising the reaction temperature to room temperature after the addition is finished, and then raising the temperature to 30-110 DEG CoC, reacting, and then, carrying out vacuum drying on the solvent, washing and filtering to obtain the chiral cyclohexanediamine-containing aluminum compound shown in the formula I.
In the preparation method, the reaction formula is as follows, wherein in the structural formula of the compound A, R is a linear alkyl group of C1-C6, preferably a methyl group, an ethyl group or an n-hexyl group:
in the preparation method, the compound A is obtained by reacting chiral cyclohexanediamine with phthalic anhydride, and the specific method comprises the following steps: dissolving phthalic anhydride into an acetic acid solution, adding chiral cyclohexanediamine with the molar weight of 0.5 time that of the phthalic anhydride, heating for reflux reaction, pouring the reaction solution into water after the reaction is finished, separating out crystals, and filtering and washing after the crystals are completely separated out to obtain the compound A.
In the above production method, the compound a and the alkylaluminum are subjected to addition reaction, and the alkyl group of the trialkylaluminum is added to the C = O double bond in the compound a, and the C = O double bond is changed to a C — O single bond. Is found in by nuclear magnetic characterizationA group of CH is arranged near the range of = 1.5-2.03Or CH2The characteristic peak of (A) is NC (O) (Ar) CH 3Or NC (O) (Ar) CH 2In R CH3Or CH2Characteristic peak of (2).
In the preparation method, the molecular formula of the trialkyl aluminum is AlR3Wherein the alkyl R is a C1-C6 linear alkyl group, preferably methyl, ethyl or n-hexyl, i.e. the trialkylaluminum is preferably trimethylaluminum, triethylaluminum or tri-n-hexylaluminum.
In the above production method, the molar ratio of the compound a to the trialkylaluminum is 1: 1 to 1.3, preferably 1: 1 to 1.05.
In the above preparation method, the organic solvent is one or two of dried hexane, toluene and cyclohexane, and preferably hexane or toluene.
In the preparation method, the dosage of the organic solvent is 5-40 times of the total mass of the reaction raw materials (the compound A and the trialkyl aluminum).
In the preparation method, the reaction is carried out under the protection of inert gas, and the gas is inert gas or nitrogen.
In the preparation method, the reaction is naturally raised to room temperature and then raised to 30-110 DEG CoC by reaction, e.g. 30oC、40oC、50oC、60oC、70oC、80oC、90oC、100oC、110oC, preferably 40 to 60oC. In the range of 30 to 110oC (preferably 40-60)oC) The reaction time is 1 to 12 hours, preferably 3 to 6 hours. After the reaction, the precipitate was washed with n-hexane.
The aluminum compound containing the chiral cyclohexanediamine is an intermediate product for preparing the compound shown in the formula II, the aluminum compound containing the chiral cyclohexanediamine is sensitive to water, water is added into a reaction liquid obtained after the compound A and alkyl aluminum react, the mixture is fully stirred to hydrolyze the aluminum compound, and the compound shown in the formula II is obtained after liquid separation, organic phase collection and solvent recovery of the organic phase. Therefore, the preparation of the aluminum compound is carried out in the absence of water and a protic solvent. In addition, the compound A is replaced by the compound shown in the formula II by using the compound shown in the formula II as a raw material, and the chiral cyclohexanediamine-containing aluminum compound shown in the formula I can be obtained according to the preparation method of the chiral cyclohexanediamine-containing aluminum compound.
When the compound shown in the formula II is used for preparing the aluminum compound containing the chiral cyclohexanediamine, the organic solvent is one or two of dry hexane, toluene and cyclohexane, and hexane or toluene is preferred. The dosage of the organic solvent is 5-40 times of the total mass of the reaction raw materials (the compound II and the trialkyl aluminum). After the reaction is finished, dried hexane is used for recrystallization, and the aluminum compound with high purity and containing chiral cyclohexanediamine in the formula I is obtained.
The aluminum compound containing chiral cyclohexanediamine is a complex, N, N, O, O of the ligand is coordinated with aluminum, the structure of the complex is very similar to that of a classical cyclic lactone catalyst (salenAl), the catalytic effect is good, and the stereoselectivity is high. The catalyst of the present invention can be used as a catalyst for ring-opening polymerization of cyclic lactones, such as levolactide, meso-lactide, racemic lactide, etc.
The invention specifically provides a method for catalyzing lactide polymerization by using an aluminum compound containing chiral cyclohexanediamine, which comprises the following steps: mixing an aluminum compound catalyst containing chiral cyclohexanediamine, an organic solvent, a benzyl alcohol cocatalyst and lactide, carrying out ring-opening polymerization reaction under the protection of anhydrous and oxygen-free inert gas, and treating reactants after reaction to obtain polylactide. The lactide can be levo-lactide, meso-lactide, racemic lactide.
When the aluminum compound containing the chiral cyclohexanediamine is used as a catalyst for ring-opening polymerization of the cyclic lactone, the stereoselectivity of the catalyst tends to be increased and the catalytic activity tends to be reduced along with the increase of the number of carbon atoms in a substituent R.
In the ring-opening polymerization reaction, cold methanol or ethanol is added to purify the polylactide after the reaction, so as to obtain the purified polylactide. The molecular weight of the obtained polylactide has high controllability and can be adjusted within the range of 1-17 ten thousand.
In the ring-opening polymerization reaction, the molar ratio of the lactide to the tetradentate nitrogen-oxygen coordination aluminum catalyst is 50-1500: 1, e.g., 50:1, 66:1, 100: 1. 200:1, 300:1, 400:1, 500:1, 600: 1. 1000:1, 1200:1, 1500: 1.
in the ring-opening polymerization reaction, the molar ratio of the benzyl alcohol cocatalyst to the catalyst is 1-3: 1.
in the ring-opening polymerization reaction, the organic solvent used in the reaction is toluene or tetrahydrofuran, and toluene is preferred.
In the ring-opening polymerization, the polymerization temperature is 20 to 110 ℃ such as 20 ℃, 30 ℃, 40 ℃, 50 ℃, 60 ℃, 70 ℃, 80 ℃, 90 ℃, 100 ℃ and 110 ℃. The stereoselectivity of the catalyst tends to be reduced and the catalytic activity tends to be improved along with the increase of the polymerization reaction temperature, and when the reaction temperature is 80 ℃, the stereoselectivity of the racemic lactide can be achievedP m= 0.67, stereoselectivity when catalyzing racemic lactide at 20 deg.CP m= 0.83。
In the ring-opening polymerization reaction, the polymerization reaction time is 1 to 1440 minutes, for example, 1 minute, 10 minutes, 30 minutes, 40 minutes, 60 minutes, 120 minutes, 240 minutes, 600 minutes, 900 minutes, 1200 minutes, 1440 minutes, and the like.
The aluminum compound catalyst containing the chiral cyclohexanediamine has the advantages of simple preparation method, low cost, high product yield, various catalyst structures, four-tooth coordination of metal center aluminum and ligands N, N, O and O, high catalytic activity, high stereoselectivity and high reaction rate, and is an ideal catalyst. When the chiral cyclohexanediamine-containing aluminum compound is used for catalyzing the ring-opening polymerization reaction of the lactide, the polymer obtained by the reaction is a benzyloxy-terminated polymer, has narrow molecular mass distribution, controllable molecular weight and high yield, can obtain isotactic polylactide with high melting point particularly when catalyzing the polymerization of racemic lactide, shows higher stereoselectivity, and has the highest stereoselectivityP m= 0.83。
Detailed Description
The invention is further illustrated by the following specific examples, which are not intended to be limiting and whose scope is indicated in the claims.
In the examples described below, the stereoselectivity of isotactic polylactide was tested using NMR homonuclear decoupled hydrogen spectroscopy.
Preparation of an aluminum Compound (I) containing a chiral cyclohexanediamino group
The aluminum compound containing chiral cyclohexanediamine is generated by the reaction of a compound A and trialkylaluminum through alkyl addition reaction, or generated by the reaction of a compound II and trialkylaluminum, and the reaction formula is as follows.
The preparation method of the compound A comprises the following steps: dissolving phthalic anhydride into an acetic acid solution (with the concentration of 36-38 wt%), adding chiral cyclohexanediamine with the molar weight of 0.5 time that of the phthalic anhydride, heating and refluxing for 8 hours, pouring a reaction solution into water after the reaction is finished, separating out crystals, filtering and washing after the crystals are completely separated out to obtain white crystals, namely the compound A, wherein the yield is 94.2%.
Preparation of aluminum compounds of formula I from Compound A
Example 1
Dissolving 0.32 g of compound A in 10 mL of dry toluene under a nitrogen atmosphere, adding 1.0 time of trimethylaluminum in the molar amount of the compound A at-10 ℃, naturally raising the temperature to room temperature, heating to 80 ℃ for reaction for 4 hours, vacuumizing the solvent after the reaction is finished, adding dry n-hexane, filtering, washing with the dry n-hexane, filtering, collecting, drying and weighing to obtain 0.34 g of solid with the yield of 89.5%.
The nuclear magnetic information of the obtained product is shown as follows, and the aluminum compound with the formula I, wherein R is methyl, is successfully synthesized.
1H NMR (400 MHz, CDCl3)7.75 (d,J= 7.2 Hz, 2H, Ar–H), 7.40 (m, 6H,Ar–H), 3.70 (m, 2H, NCH), 2.10 (m, 6H, CH2CH 2), 1.69 (s, 6H, CCH 3), 1.57 (m,2H, CH2CH 2), –0.47(s, 3H, AlCH3). Anal. Calcd for C25H27AlN2O4: C 67.25, H 6.10,N 6.27. Found: C 67.21, H 6.13, N 6.31.
Example 2
0.40g of compound A was dissolved in 15 mL of dry cyclohexane under nitrogen, 1.05 times the molar amount of triethylaluminum was added at 0 deg.C, slowly warmed to room temperature, heated to 60 deg.C to react for 12 hours, after the reaction was completed, the solvent was vacuum-dried, dried by adding dry n-hexane, filtered and washed with dry n-hexane, filtered, collected, dried and weighed to give 0.42g of a solid in 80.8% yield.
The nuclear magnetic information of the obtained product is as follows, and the aluminum compound with the formula I, wherein R is ethyl, can be successfully synthesized.
1H NMR (400 MHz, CDCl3)7.70(d, 1H,J= 7.1 Hz, Ar–H), 7.39 (m, 6H,Ar–H), 3.67 (m,2H, NCH), 2.12 (m, 6H, CH2CH 2), 2.02 (q,J= 6.9 Hz, 4H,CH 2CH3), 1.52 (m, 2H, CH2CH 2), 1.25 (q, 2H, J = 6.1 Hz, AlCH 2CH3), 1.02 (t, 6H,J= 6.9 Hz, CH2CH 3), 0.62 (t, 3H, J = 6.1 Hz, AlCH2CH 3). Anal. Calcd forC28H33AlN2O4: C 68.84, H 6.81, N 5.73. Found: C 68.801, H 6.82, N 5.76.
Example 3
0.30 g of compound A is dissolved in 9 mL of dry hexane under nitrogen atmosphere, 1.1 times molar amount of tri-n-hexylaluminum is added at-5 ℃, after warming to room temperature, heating to 40 ℃ for reaction for 2 hours, after the reaction is finished, filtering and washing with dry n-hexane, filtering, collecting, drying and weighing to obtain 0.37 g of solid with 69.8% yield.
The nuclear magnetic information of the product obtained is shown below, from which it can be seen that the synthesis of the aluminium compound of formula I, in which R is n-hexyl, is successful.
1H NMR (400 MHz, CDCl3)7.80 (d, J = 7.2 Hz, 2H, Ar–H), 7.42 (m, 6H,Ar–H), 3.80 (m, 2H, NCH), 1.97 (m, 6H, CH2CH 2), 1.72 (m, 4H, CH2CH 2), 1.47 (m,4H, CH2CH 2), 1.32(m, 8H, CH2CH 2), 1.22 (m, 16H, CH2CH 2), 0.97 (m, 9H, CH2CH 3).Anal. Calcd for C40H57AlN2O4: C 73.14, H 8.75, N 4.26. Found: C 73.16, H 8.77,N 4.28.
Example 4
0.35g of compound A is dissolved in 10 mL of dry toluene under nitrogen, 1.1 times the molar amount of tri-n-butylaluminum is added at 0 ℃, after warming to room temperature, the mixture is heated to 110 ℃ for reaction for 1 hour, and after the reaction is finished, the mixture is filtered, washed with dry n-hexane, filtered, collected, dried and weighed to obtain 0.44 g of solid with the yield of 81.5%. Through nuclear magnetic verification, the structural formula of the product is shown as a formula I, and R is n-butyl.
Preparation of aluminum compounds of formula I from ligands of formula (II)
Example 5
Dissolving 0.42g of compound A in 10 mL of dry toluene in a nitrogen atmosphere, adding 1.0 time of trimethylaluminum in the molar weight of the compound A at-10 ℃, naturally heating to room temperature, heating to 80 ℃ for reaction for 4 hours, adding 61 microliter of water after the reaction is finished, fully stirring and mixing, standing for liquid separation, collecting an organic phase to obtain a crude product, and recrystallizing the crude product with methanol to obtain 0.44 g of a pure product with the yield of 95.7%.
The obtained product was characterized with the following results:
elemental analysis results: 70.93 percent of C, 6.48 percent of H and 6.92 percent of N.
1H NMR (400 MHz, CDCl3)7.72 (d,J= 7.0 Hz, 2H, Ar–H), 7.42 (m, 6H,Ar–H), 3.65 (m, 2H, NCH), 2.12 (m, 6H, CH2CH 2), 1.61 (s, 6H, CCH 3), 1.53 (m,2H, CH2CH 2).
HRESI-MS: m/z cacld. C24H26N2O4[M-H]-; 405.1817, found: 405.1819.
From the above characterization results, the obtained product is the ligand of formula (II) above in which R is methyl.
The structural formula of the ligand is shown as the formula (II), R is methyl, and the reaction process is as follows: 0.35g of ligand was dissolved in 8 mL of dry hexane under nitrogen atmosphere, 1.0 times the molar amount of trimethylaluminum was added at-10 ℃ and slowly warmed to room temperature, heated to 50 ℃ for reaction for 6 hours, after the reaction was completed, the solvent was concentrated in vacuo, filtered and washed with dry n-hexane, filtered, collected and dried weighing 0.35g of solid, yield 92.1%. The structural formula of the product is shown as formula I, and R is methyl.
Example 6
Under nitrogen atmosphere, 0.50 g of compound A is dissolved in 20 mL of dry cyclohexane, triethylaluminum with the molar weight of 1.05 times of the compound A is added at 0 ℃, the mixture is naturally heated to room temperature and then heated to 70 ℃ for reaction for 12 hours, after the reaction is finished, 72 microliters of water is added, the mixture is fully stirred and mixed and then stands for liquid separation, an organic phase is collected to obtain a crude product, and the crude product is recrystallized by methanol to obtain 0.47 g of a pure product with the yield of 81.0%.
The obtained product was characterized with the following results:
elemental analysis results: c, 71.87, H, 6.96 and N, 6.45 percent.
1H NMR (400 MHz, CDCl3)7.69(d, 1H,J= 7.1 Hz, Ar–H), 7.36 (m, 6H,Ar–H), 3.65 (m,2H, NCH), 2.14 (m, 6H, CH2CH 2), 2.05 (q,J= 6.4 Hz, 4H,CH 2CH3), 1.50 (m, 2H, CH2CH 2), 1.04 (t, 6H,J= 6.4 Hz, CH2CH 3)。
HRESI-MS: m/z cacld. C26H30N2O4[M-H]-; 433.2124, found: 433.2126.
From the above characterization results, the obtained product is the ligand of formula (II) above in which R is ethyl.
The structural formula of the ligand is shown as the formula (II), R is ethyl, and the reaction process is as follows: 0.40g of ligand was dissolved in 12 mL of dry cyclohexane under nitrogen, triethylaluminum in an amount of 1.05 times the molar amount of the ligand was added at 0 deg.C, slowly warmed to room temperature, heated to 60 deg.C for reaction for 4 hours, after the reaction was completed, the solvent was vacuum-dried, filtered by adding dry n-hexane and washed with dry n-hexane, filtered, collected and dried and weighed to obtain 0.40g of a solid in 88.9% yield. The structural formula of the product is shown as formula I, and R is ethyl.
Example 7
Under nitrogen atmosphere, 0.30 g of compound A is dissolved in 15 mL of dry toluene, 1.1 times of molar weight of tri-n-hexylaluminum is added at-5 ℃, naturally heated to room temperature and heated to 50 ℃ for reaction for 7 hours, 43 microliters of water is added after the reaction is finished, the mixture is fully stirred and mixed and then stands for liquid separation, an organic phase is collected to obtain a crude product, and the crude product is recrystallized by ethanol to obtain 0.36 g of a pure product, wherein the yield is 81.8%.
The obtained product was characterized with the following results:
elemental analysis results: 74.69 percent of C, 8.48 percent of H and 5.12 percent of N.
1H NMR (300 MHz, CDCl3)7.82 (d, J = 7.2 Hz, 2H, Ar–H), 7.38 (m, 6H,Ar–H), 3.68 (m, 2H, NCH), 2.04 (m, 4H, CH2CH2), 1.86 (m, 4H, CH2CH2), 1.45 (m,4H, CH2CH), 1.31 (m, 16H, CH2CH2), 0.95 (m, 6H, CH2CH3).
HRESI-MS: m/z cacld. C34H45N2O4[M-H]-; 545.3376, found: 545.3372.
From the above characterization results, the obtained product is the ligand of formula (II) above in which R is n-hexyl.
The structural formula of the ligand is shown as the formula (II), R is hexyl, and the reaction process is as follows: under nitrogen atmosphere, 0.30 g of ligand is dissolved in 10 mL of dry toluene, 1.1 times of ligand molar amount of tri-n-hexylaluminum is added at-5 ℃, the temperature is raised to room temperature, the mixture is heated to 80 ℃ for reaction for 2 hours, after the reaction is finished, the solvent is pumped out in vacuum, dried n-hexane is added for filtration, the mixture is washed by the dried n-hexane, the filtration is carried out, and the collection, drying and weighing are carried out to obtain 0.27 g of the ligand with the yield of 75.0%. The structural formula of the product is shown as a formula I, and R is n-hexyl.
Example 8
Dissolving 0.40g of compound A in 10 mL of dry toluene in nitrogen atmosphere, adding 1.0 time of tri-n-butyl aluminum in the molar weight of the compound A at-10 ℃, naturally heating to room temperature, heating to 110 ℃ for reaction for 2 hours, adding 58 microliters of water after the reaction is finished, fully stirring and mixing, standing for liquid separation, collecting an organic phase to obtain a crude product, recrystallizing by methanol to obtain 0.48g of a pure product, wherein the yield is 92.3%. The obtained product is the ligand of which R is n-butyl in the formula (II) through nuclear magnetic verification.
The structural formula of the ligand is shown as the formula (II), R is n-butyl, and the reaction process is as follows: under nitrogen atmosphere, 0.40g of ligand is dissolved in 10 mL of dry toluene, 1.1 times of the molar amount of tri-n-butylaluminum is added at-10 ℃, the temperature is raised to room temperature, the mixture is heated to 110 ℃ for reaction for 1 hour, after the reaction is finished, the solvent is pumped out in vacuum, dried n-hexane is added, the mixture is filtered and washed by the dried n-hexane, the filtrate is collected, dried and weighed to obtain 0.39 g of ligand with the yield of 83.0 percent. The structural formula of the product is shown as a formula I, and R is n-butyl.
Preparation of polylactide
Example 9
Carrying out reaction under the protection of anhydrous oxygen-free and inert gas, firstly sequentially adding 100 mu mol of catalyst (an aluminum compound shown in formula I, R is methyl), 100 mu mol of benzyl alcohol, 20 mL of toluene and 10mmol of racemic lactide into an ampoule after being washed and baked by high-purity nitrogen gas, and then 20 mu mol of catalyst, benzyl alcohol and 10mmol of racemic lactideoC, reacting for 21 hours, adding a small amount of water to terminate the reaction, precipitating with ethanol, washing for several times, and drying in vacuum at room temperature to obtain 1.38 g with the yield of 95.8%. The product obtained was isotactic polylactide having a molecular weight of 2.4 ten thousand and isotactic stereoselectivityP m= 0.80。
Example 10
Polylactide was prepared according to the method of example 9, except that: the catalyst used is an aluminum compound shown as a formula I, and R is ethyl. The product obtained after 22 hours of reaction had a mass of 1.37 g, a yield of 95.1%, a molecular weight of 2.1 ten thousand, and an isotactic stereoselectivityP m= 0.81。
Example 11
Polylactide was prepared according to the method of example 9, except that: the catalyst is an aluminum compound shown as a formula I, and R is n-butyl. The product obtained after 23 hours of reaction had a mass of 1.40 g, a yield of 97.2%, a molecular weight of 2.0 ten thousand, and an isotactic stereoselectivityP m= 0.82。
Example 12
Polylactide was prepared according to the method of example 9, except that: the catalyst is an aluminum compound shown as a formula I, and R is n-hexyl. The product obtained after 24 hours had a mass of 1.41 g, a yield of 97.9%, a molecular weight of 2.2 ten thousand, and an isotactic stereoselectivityP m= 0.83。
Example 13
Carrying out reaction under the protection of anhydrous oxygen-free and inert gas, firstly sequentially adding 100 mu mol of catalyst (aluminum compound shown in formula I, R is n-hexyl), 100 mu mol of benzyl alcohol, 10 mL of toluene and 10mmol of racemic lactide into an ampoule after being washed and baked by high-purity nitrogen gas, and then respectively adding the mixture into a reactor at 40 DEG CoC、60oC and 80oC, reaction, adding a small amount of water after the reaction is finished, precipitating with methanol, washing for several times, and vacuum drying at room temperature.
Wherein, the reaction is carried out for 18 hours at 40 ℃ to obtain 1.38 g of product, the yield is 95.8 percent, the molecular weight is 2.1 ten thousand,P m= 0.80。
reacting at 60 ℃ for 12 hours to obtain 1.40 g of product, wherein the yield is 97.2 percent, the molecular weight is 2.5 ten thousand,P m= 0.73。
reacting at 80 ℃ for 10 hours to obtain 1.39 g of product, wherein the yield is 96.5 percent, the molecular weight is 2.0 ten thousand,P m= 0.67。
example 14
Reacting under the protection of anhydrous oxygen-free and inert gas, firstly sequentially adding 50 mu mol of catalyst (aluminum compound shown in formula I, R is ethyl), 100 mu mol of benzyl alcohol, 20 mL of tetrahydrofuran and 10mmol of L-lactide into an ampoule after being washed and baked by high-purity nitrogen, and then placing the ampoule in a 30-degree reactoroAnd C, in an oil bath, after reacting for 21 hours, adding a small amount of water to terminate the reaction, precipitating and washing the reaction by using ethanol for a plurality of times, and drying the reaction in vacuum at room temperature to obtain 1.40 g, wherein the yield is 97.2 percent, and the molecular weight is 5.6 ten thousand.
Example 15
The reaction is carried out under the protection of anhydrous oxygen-free and inert gas, and 100 mu mol of catalyst (shown in formula I) is firstly added in sequence into an ampoule after being washed and baked by high-purity nitrogen gasAn aluminum compound, R is n-butyl), 10 [ mu ] mol benzyl alcohol, 10 mL tetrahydrofuran and 5mmol meso-lactide, and then the mixture is placed in a 50-degree reactoroAnd C, in an oil bath, after reacting for 16 hours, adding a small amount of water to terminate the reaction, precipitating and washing the reaction for a plurality of times by using ethanol, and drying the reaction product in vacuum at room temperature to obtain 0. 70 g, yield 97.2% and molecular weight 1.0 ten thousand.
Example 16
Carrying out reaction under the protection of anhydrous oxygen-free and inert gas, firstly sequentially adding 10 mu mol of catalyst (an aluminum compound shown in formula I, R is n-hexyl), 30 mu mol of benzyl alcohol, 20 mL of toluene and 10mmol of L-lactide into an ampoule after being washed and baked by high-purity nitrogen gas, and then sequentially adding 90 mu mol of catalyst, 30 mu mol of benzyl alcohol, 20 mL of toluene and 10mmol of L-lactideoC, after 24 hours of reaction, adding a small amount of water to terminate the reaction, precipitating with ethanol, washing for several times, and drying in vacuum at room temperature to obtain 1.38 g, wherein the yield is 95.8 percent, and the molecular weight is 7.4 ten thousand.
Example 17
Carrying out reaction under the protection of anhydrous oxygen-free and inert gas, firstly sequentially adding 10 mu mol of catalyst (an aluminum compound shown in formula I, R is ethyl), 20 mu mol of benzyl alcohol, 20 mL of toluene and 15mmol of levorotatory lactide into an ampoule after being washed and baked by high-purity nitrogen, and then placing the ampoule in a 110-degree reactoroAnd C, in an oil bath, after reacting for 2 hours, adding a small amount of water to terminate the reaction, precipitating and washing the reaction by using ethanol for a plurality of times, and drying the reaction in vacuum at room temperature to obtain 1.40 g, wherein the yield is 97.2 percent, and the molecular weight is 16.4 ten thousand.
Comparative example 1
Preparation of nickel catalyst: the structural formula of the ligand is shown as the formula (II), R is methyl, and the reaction process is as follows: dissolving 0.40g of ligand in 15 mL of absolute ethyl alcohol, adding nickel acetate with the molar weight being 1.0 time of that of the ligand at room temperature, heating to 50 ℃ for reaction for 12 hours, concentrating the solvent in vacuum after the reaction is finished, adding dichloromethane to precipitate a solid, filtering, washing with hexane, and drying to obtain the nickel catalyst, wherein the structural formula of the nickel catalyst is shown in the specification, and R is methyl.
The reaction is carried out under the protection of anhydrous oxygen-free inert gas, and high-purity nitrogen is firstly usedSequentially adding 10 mu mol of the nickel catalyst, 20 mu mol of benzyl alcohol, 20 mL of toluene and 15mmol of L-lactide into an ampoule after gas washing and gas baking, and then placing the ampoule in a container of 110oAnd C, in an oil bath, after reacting for 72 hours, adding a small amount of water to terminate the reaction, precipitating and washing the reaction for a plurality of times by using methanol, and drying the reaction in vacuum at room temperature to obtain 0.78 g, wherein the yield is 36.1 percent, and the molecular weight is 6.3 ten thousand. The nickel catalyst has too low activity for lactide polymerization and is of no value.
Comparative example 2
Preparation of aluminum catalyst: the ligand has a structural formula shown as the following formula (LH)2) The reaction process is as follows: under the protection of anhydrous oxygen-free and inert gas, 0.20 g of ligand is dissolved in 10 mL of toluene, trimethylaluminum with the molar weight being 1.0 time of that of the ligand is added at the temperature of-5 ℃, the temperature is slowly raised to room temperature, the mixture is heated to 80 ℃ for reaction for 12 hours, after the reaction is finished, the solvent is concentrated in vacuum, dried hexane is added to separate out solid, the solid is filtered and washed by hexane, and the aluminum catalyst is dried to obtain the LAlMe with the structural formula shown in the specification.
Polylactide was prepared according to the method of example 13, except that: the catalyst used was the aluminum catalyst. Carrying out reaction under the protection of anhydrous oxygen-free and inert gas, firstly sequentially adding 100 mu mol of the aluminum catalyst, 100 mu mol of benzyl alcohol, 10 mL of toluene and 10mmol of racemic lactide into an ampoule after being washed and baked by high-purity nitrogen gas, and then respectively adding the mixture into a flask with the volume of 20 mu mol of the aluminum catalyst, 100 mu mol of benzyl alcohol, 10 mL of toluene and 10mmol of racemic lactideoC and 80oC, reaction, adding a small amount of water after the reaction is finished, precipitating with methanol, washing for several times, and vacuum drying at room temperature.
Wherein, no product is generated after the reaction is carried out for 36 hours at 20 ℃, which indicates that the catalyst can not catalyze the polymerization of the lactide at lower temperature.
Reacting at 80 deg.C for 24 hr to obtain 1.15 g product with 79.9% yield, 1.4 ten thousand molecular weight and isotactic stereoselectivityP m= 0.53. Both stereoselectivity and activity were low compared to the aluminum catalyst of example 13.
Comparative example 3
Polylactide was prepared according to the method of example 9, except that: the catalyst used was the catalyst used in example 10 of patent 201410609375.8. The polylactide obtained after the reaction is non-uniform stereoregular polylactide with the mass of 1.33 g, the yield of 92.4 percent, the molecular weight of 1.7 ten thousand and the non-uniform stereoregular stereoselectivityP rIs 0.71.
Comparative example 4
Under a nitrogen atmosphere, 0.40g of compound a was dissolved in 10 mL of dry toluene, 1.0 time the molar amount of compound a was added triisobutylaluminum at-5 ℃, after the reaction temperature naturally rose to room temperature, the mixture was heated to 110 ℃ for reaction for 24 hours, 60 μ l of water was added after the reaction to stop the reaction, the organic phase was collected by liquid separation, dried over anhydrous sodium sulfate, and the solvent was dried by spinning to obtain a crude product, and it was found that the obtained compound was not changed (isobutyl group did not undergo C = O addition reaction). Triisobutylaluminum cannot undergo addition reaction. C = O double bond addition reaction did not proceed and the expected aluminum compound was not obtained.
Comparative example 5
Preparation of aluminum catalyst: under nitrogen atmosphere, 0.40g of compound A is dissolved in 10 mL of dry toluene, 1.0 time of the molar weight of the compound A is added with tri-n-heptyl aluminum at the temperature of minus 5 ℃, after the reaction temperature naturally rises to room temperature, the mixture is heated to 100 ℃ for reaction for 12 hours, after the reaction is finished, the solvent is pumped out in vacuum, and dried n-hexane is added for washing, filtering and drying to obtain 0.17 g of solid with the yield of 22.7 percent (the yield of the aluminum compound is lower).
Polylactide was prepared according to the method of example 9, except that: the catalyst used was the aluminum catalyst. The product obtained after the reaction had a mass of 0.67 g, a yield of 46.5%, a molecular weight of 1.3 ten thousand, and an isotactic stereoselectivityP m=0.72。
Comparative example 6
Preparation of aluminum catalyst: dissolving 0.20 g of compound LD in the following formula in 10 mL of dry toluene under nitrogen atmosphere, adding 1.1 times of trimethylaluminum in the molar amount of the compound LD at-5 ℃, heating to 90 ℃ after the reaction temperature naturally rises to room temperature for reaction for 3 hours, vacuumizing the solvent after the reaction is finished, adding dry n-hexane for washingWashing, filtering and drying to obtain 0.21 g of solid with the structural formula of LDAlMe2The yield is 85.7 percent, and the aluminum compound is hydrolyzed and then subjected to mass spectrum characterization to find that the ligand can only perform unilateral addition reaction (HRESI-MS: m/z calcd. C)20H1876N2O4[M-H]-; 349.1188,found: 349.1190）。
Polylactide was prepared according to the method of example 9, except that: the catalyst used was the aluminum catalyst. The mass of the product obtained after the reaction is 0.52 g, the yield is 36.1%, the molecular weight is 1.8 ten thousand, and stereoselectivity is avoided.
Claims (14)
1. The method for catalyzing lactide polymerization by using the aluminum compound containing the chiral cyclohexanediamine is characterized by comprising the following steps: mixing a catalyst, an organic solvent, a benzyl alcohol cocatalyst and lactide, carrying out ring-opening polymerization reaction under the protection of anhydrous and oxygen-free inert gases, and treating reactants after reaction to obtain polylactide; the catalyst is an aluminum compound containing chiral cyclohexanediamine, and the structural formula of the catalyst is shown as the following formula I, wherein R is a linear alkyl group of C1-C6;
2. the method of claim 1, wherein: in the formula, R is methyl, ethyl or n-hexyl.
3. The method of claim 1, wherein: the preparation method of the catalyst comprises the following steps: adding the compound A or the compound II into an organic solvent at-10 to 0%oAdding trialkyl aluminum under C, naturally raising the reaction temperature to room temperature after the addition is finished, and then raising the temperature to 30-110 DEG CoC, reacting, then vacuum-pumping the solvent, washing and filtering to obtainAn aluminum compound containing chiral cyclohexanediamine as shown in a formula I; in the compound II, R is a linear alkyl group of C1-C6; the alkyl of the trialkyl aluminum is a linear alkyl of C1-C6;
4. the method of claim 3, wherein: in the preparation process of the catalyst, in the compound II, R is methyl, ethyl or n-hexyl.
5. The method of claim 3, wherein: in the preparation process of the catalyst, the alkyl of the trialkyl aluminum is methyl, ethyl or n-hexyl.
6. The method of claim 3, wherein: in the preparation process of the catalyst, the molar ratio of the compound A or the compound II to the trialkyl aluminum is 1: 1 to 1.3.
7. The method of claim 6, wherein: in the preparation process of the catalyst, the molar ratio of the compound A or the compound II to the trialkyl aluminum is 1: 1 to 1.05.
8. The method of claim 1, further comprising: in the preparation process of the catalyst, the organic solvent is one or two of dry hexane, toluene and cyclohexane; the reaction is carried out under the protection of gas.
9. The method of claim 1, wherein: in the preparation process of the catalyst, after the temperature is raised to the room temperature, the temperature is raised to 30-110 DEGoC, reacting for 1-12 hours.
10. The method of claim 9, wherein: in the preparation process of the catalyst, after the temperature is raised to the room temperature, the temperature is raised to 40-60 DEGoC, reacting for 3-6 hours.
11. The method according to any one of claims 1 to 10, wherein: the molar ratio of the lactide to the catalyst is 50-1500: 1; the molar ratio of the benzyl alcohol cocatalyst to the catalyst is 1-3: 1.
12. the method according to any one of claims 1 to 10, wherein: and during the ring-opening polymerization reaction, the organic solvent is toluene or tetrahydrofuran.
13. The method according to any one of claims 1 to 10, wherein: during the ring-opening polymerization reaction, the reaction temperature is 20-110 ℃, and the reaction time is 1-1440 minutes.
14. The method according to any of claims 1-10, characterized by: the lactide is racemic lactide, levo-lactide or meso-lactide.
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