CN116333003B - A Schiff base cobalt complex for catalyzing the synthesis of polycarbonate and a preparation method thereof - Google Patents
A Schiff base cobalt complex for catalyzing the synthesis of polycarbonate and a preparation method thereof Download PDFInfo
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- CN116333003B CN116333003B CN202310235348.8A CN202310235348A CN116333003B CN 116333003 B CN116333003 B CN 116333003B CN 202310235348 A CN202310235348 A CN 202310235348A CN 116333003 B CN116333003 B CN 116333003B
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- 239000002262 Schiff base Substances 0.000 title claims abstract description 56
- -1 Schiff base cobalt complex Chemical class 0.000 title claims abstract description 48
- 239000004417 polycarbonate Substances 0.000 title claims abstract description 20
- 229920000515 polycarbonate Polymers 0.000 title claims abstract description 19
- 230000015572 biosynthetic process Effects 0.000 title claims abstract description 18
- 238000003786 synthesis reaction Methods 0.000 title claims abstract description 18
- 238000002360 preparation method Methods 0.000 title claims abstract description 6
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical class O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 claims abstract description 34
- 239000003446 ligand Substances 0.000 claims abstract description 34
- 238000006243 chemical reaction Methods 0.000 claims abstract description 31
- GOOHAUXETOMSMM-UHFFFAOYSA-N Propylene oxide Chemical compound CC1CO1 GOOHAUXETOMSMM-UHFFFAOYSA-N 0.000 claims abstract description 20
- 239000001569 carbon dioxide Substances 0.000 claims abstract description 17
- 229910002092 carbon dioxide Inorganic materials 0.000 claims abstract description 17
- 238000006116 polymerization reaction Methods 0.000 claims abstract description 17
- CDAWCLOXVUBKRW-UHFFFAOYSA-N 2-aminophenol Chemical compound NC1=CC=CC=C1O CDAWCLOXVUBKRW-UHFFFAOYSA-N 0.000 claims abstract description 12
- LEQAOMBKQFMDFZ-UHFFFAOYSA-N glyoxal Chemical compound O=CC=O LEQAOMBKQFMDFZ-UHFFFAOYSA-N 0.000 claims abstract description 12
- 230000029936 alkylation Effects 0.000 claims abstract description 9
- 238000005804 alkylation reaction Methods 0.000 claims abstract description 9
- 239000010941 cobalt Substances 0.000 claims abstract description 8
- 229910017052 cobalt Inorganic materials 0.000 claims abstract description 8
- 229940015043 glyoxal Drugs 0.000 claims abstract description 6
- 150000001875 compounds Chemical class 0.000 claims abstract description 3
- 150000003512 tertiary amines Chemical class 0.000 claims abstract description 3
- WEVYAHXRMPXWCK-UHFFFAOYSA-N Acetonitrile Chemical compound CC#N WEVYAHXRMPXWCK-UHFFFAOYSA-N 0.000 claims description 36
- WYURNTSHIVDZCO-UHFFFAOYSA-N Tetrahydrofuran Chemical compound C1CCOC1 WYURNTSHIVDZCO-UHFFFAOYSA-N 0.000 claims description 34
- 150000004753 Schiff bases Chemical class 0.000 claims description 25
- 239000000243 solution Substances 0.000 claims description 22
- YLQBMQCUIZJEEH-UHFFFAOYSA-N tetrahydrofuran Natural products C=1C=COC=1 YLQBMQCUIZJEEH-UHFFFAOYSA-N 0.000 claims description 17
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 claims description 15
- 125000002496 methyl group Chemical group [H]C([H])([H])* 0.000 claims description 15
- 125000001424 substituent group Chemical group 0.000 claims description 15
- 239000012265 solid product Substances 0.000 claims description 11
- 239000000047 product Substances 0.000 claims description 10
- RTZKZFJDLAIYFH-UHFFFAOYSA-N Diethyl ether Chemical compound CCOCC RTZKZFJDLAIYFH-UHFFFAOYSA-N 0.000 claims description 9
- XEKOWRVHYACXOJ-UHFFFAOYSA-N Ethyl acetate Chemical compound CCOC(C)=O XEKOWRVHYACXOJ-UHFFFAOYSA-N 0.000 claims description 9
- ZMANZCXQSJIPKH-UHFFFAOYSA-N Triethylamine Chemical compound CCN(CC)CC ZMANZCXQSJIPKH-UHFFFAOYSA-N 0.000 claims description 9
- 125000001997 phenyl group Chemical group [H]C1=C([H])C([H])=C(*)C([H])=C1[H] 0.000 claims description 9
- 239000002904 solvent Substances 0.000 claims description 9
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 claims description 8
- 238000000967 suction filtration Methods 0.000 claims description 8
- 238000005406 washing Methods 0.000 claims description 8
- 125000001495 ethyl group Chemical group [H]C([H])([H])C([H])([H])* 0.000 claims description 7
- 238000010438 heat treatment Methods 0.000 claims description 7
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 claims description 6
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 6
- 239000007859 condensation product Substances 0.000 claims description 6
- BWHMMNNQKKPAPP-UHFFFAOYSA-L potassium carbonate Chemical compound [K+].[K+].[O-]C([O-])=O BWHMMNNQKKPAPP-UHFFFAOYSA-L 0.000 claims description 6
- GETQZCLCWQTVFV-UHFFFAOYSA-N trimethylamine Chemical compound CN(C)C GETQZCLCWQTVFV-UHFFFAOYSA-N 0.000 claims description 6
- 150000001450 anions Chemical class 0.000 claims description 5
- 238000001035 drying Methods 0.000 claims description 5
- 229910052736 halogen Inorganic materials 0.000 claims description 5
- 125000001449 isopropyl group Chemical group [H]C([H])([H])C([H])(*)C([H])([H])[H] 0.000 claims description 4
- 125000001436 propyl group Chemical group [H]C([*])([H])C([H])([H])C([H])([H])[H] 0.000 claims description 4
- 150000003242 quaternary ammonium salts Chemical class 0.000 claims description 4
- 238000010992 reflux Methods 0.000 claims description 4
- 230000002194 synthesizing effect Effects 0.000 claims description 4
- 125000000999 tert-butyl group Chemical group [H]C([H])([H])C(*)(C([H])([H])[H])C([H])([H])[H] 0.000 claims description 4
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical class [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 claims description 3
- 150000001347 alkyl bromides Chemical class 0.000 claims description 3
- 239000007864 aqueous solution Substances 0.000 claims description 3
- 238000001816 cooling Methods 0.000 claims description 3
- 238000001914 filtration Methods 0.000 claims description 3
- 238000000034 method Methods 0.000 claims description 3
- 239000000203 mixture Substances 0.000 claims description 3
- 229910000027 potassium carbonate Inorganic materials 0.000 claims description 3
- 229910001495 sodium tetrafluoroborate Inorganic materials 0.000 claims description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 3
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical group [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 2
- 125000004429 atom Chemical group 0.000 claims description 2
- 150000001868 cobalt Chemical class 0.000 claims description 2
- 229910021645 metal ion Inorganic materials 0.000 claims description 2
- 125000004433 nitrogen atom Chemical group N* 0.000 claims description 2
- 238000003756 stirring Methods 0.000 claims description 2
- 125000000484 butyl group Chemical group [H]C([*])([H])C([H])([H])C([H])([H])C([H])([H])[H] 0.000 claims 1
- 125000004432 carbon atom Chemical group C* 0.000 claims 1
- 238000007036 catalytic synthesis reaction Methods 0.000 claims 1
- 125000005359 phenoxyalkyl group Chemical group 0.000 claims 1
- 230000035484 reaction time Effects 0.000 claims 1
- 230000003197 catalytic effect Effects 0.000 abstract description 13
- 239000003054 catalyst Substances 0.000 abstract description 11
- 230000000694 effects Effects 0.000 abstract description 5
- 238000006555 catalytic reaction Methods 0.000 abstract description 3
- 230000007613 environmental effect Effects 0.000 abstract description 3
- 238000009833 condensation Methods 0.000 abstract description 2
- 230000005494 condensation Effects 0.000 abstract description 2
- 150000002148 esters Chemical class 0.000 abstract description 2
- 125000001453 quaternary ammonium group Chemical group 0.000 abstract description 2
- 239000004593 Epoxy Chemical class 0.000 abstract 1
- 239000007858 starting material Substances 0.000 abstract 1
- 238000001644 13C nuclear magnetic resonance spectroscopy Methods 0.000 description 6
- 238000005160 1H NMR spectroscopy Methods 0.000 description 6
- YMWUJEATGCHHMB-UHFFFAOYSA-N Dichloromethane Chemical compound ClCCl YMWUJEATGCHHMB-UHFFFAOYSA-N 0.000 description 6
- BZRRQSJJPUGBAA-UHFFFAOYSA-L cobalt(ii) bromide Chemical compound Br[Co]Br BZRRQSJJPUGBAA-UHFFFAOYSA-L 0.000 description 6
- 239000000843 powder Substances 0.000 description 6
- 239000007787 solid Substances 0.000 description 6
- FYGHSUNMUKGBRK-UHFFFAOYSA-N 1,2,3-trimethylbenzene Chemical compound CC1=CC=CC(C)=C1C FYGHSUNMUKGBRK-UHFFFAOYSA-N 0.000 description 2
- BDAGIHXWWSANSR-UHFFFAOYSA-N methanoic acid Natural products OC=O BDAGIHXWWSANSR-UHFFFAOYSA-N 0.000 description 2
- 239000004033 plastic Substances 0.000 description 2
- 229920003023 plastic Polymers 0.000 description 2
- 229920000642 polymer Polymers 0.000 description 2
- PAAZPARNPHGIKF-UHFFFAOYSA-N 1,2-dibromoethane Chemical group BrCCBr PAAZPARNPHGIKF-UHFFFAOYSA-N 0.000 description 1
- VEFLKXRACNJHOV-UHFFFAOYSA-N 1,3-dibromopropane Chemical compound BrCCCBr VEFLKXRACNJHOV-UHFFFAOYSA-N 0.000 description 1
- ULTHEAFYOOPTTB-UHFFFAOYSA-N 1,4-dibromobutane Chemical compound BrCCCCBr ULTHEAFYOOPTTB-UHFFFAOYSA-N 0.000 description 1
- OSWFIVFLDKOXQC-UHFFFAOYSA-N 4-(3-methoxyphenyl)aniline Chemical compound COC1=CC=CC(C=2C=CC(N)=CC=2)=C1 OSWFIVFLDKOXQC-UHFFFAOYSA-N 0.000 description 1
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- 238000005481 NMR spectroscopy Methods 0.000 description 1
- 150000001447 alkali salts Chemical class 0.000 description 1
- 239000010953 base metal Substances 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 150000004649 carbonic acid derivatives Chemical class 0.000 description 1
- 239000007795 chemical reaction product Substances 0.000 description 1
- 238000007334 copolymerization reaction Methods 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 235000019253 formic acid Nutrition 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- AUHZEENZYGFFBQ-UHFFFAOYSA-N mesitylene Substances CC1=CC(C)=CC(C)=C1 AUHZEENZYGFFBQ-UHFFFAOYSA-N 0.000 description 1
- 125000001827 mesitylenyl group Chemical group [H]C1=C(C(*)=C(C([H])=C1C([H])([H])[H])C([H])([H])[H])C([H])([H])[H] 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 238000000655 nuclear magnetic resonance spectrum Methods 0.000 description 1
- 230000037048 polymerization activity Effects 0.000 description 1
- 229920001451 polypropylene glycol Polymers 0.000 description 1
- 239000011541 reaction mixture Substances 0.000 description 1
- 230000009257 reactivity Effects 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 239000000126 substance 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
- C08G64/00—Macromolecular compounds obtained by reactions forming a carbonic ester link in the main chain of the macromolecule
- C08G64/20—General preparatory processes
-
- 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
- C07F15/00—Compounds containing elements of Groups 8, 9, 10 or 18 of the Periodic Table
- C07F15/06—Cobalt compounds
- C07F15/065—Cobalt compounds without a metal-carbon 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
- C08G64/00—Macromolecular compounds obtained by reactions forming a carbonic ester link in the main chain of the macromolecule
- C08G64/20—General preparatory processes
- C08G64/32—General preparatory processes using carbon dioxide
- C08G64/34—General preparatory processes using carbon dioxide and cyclic ethers
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P20/00—Technologies relating to chemical industry
- Y02P20/50—Improvements relating to the production of bulk chemicals
- Y02P20/584—Recycling of catalysts
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Health & Medical Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Medicinal Chemistry (AREA)
- Polymers & Plastics (AREA)
Abstract
The invention belongs to the field of catalytic polymerization, and discloses a Schiff base cobalt complex for catalyzing polycarbonate synthesis and a preparation method thereof. The ligand of the Schiff base cobalt complex takes 2-aminophenol as a starting compound and is synthesized by condensation with glyoxal, phenolic hydroxyl alkylation and tertiary amine salification. The ligand obtained is reacted with cobalt halide to obtain bivalent ionic Schiff base cobalt complex. The complex has changeable structure, convenient synthesis and environmental protection. In the catalytic reaction, the quaternary ammonium ionic structure can stabilize the Schiff base cobalt complex, and meanwhile, the activity of the reaction can be improved, so that the catalyst has a wide application prospect. In the reaction of catalyzing the polymerization of carbon dioxide and epoxy compounds to form carbonic ester, the conversion rate of propylene oxide can reach 91.8%, and the selectivity of polycarbonate can reach 89.9%.
Description
Technical Field
The invention belongs to the field of catalytic polymerization, and relates to an ionic Schiff base cobalt complex, in particular to a Schiff base cobalt complex for catalyzing the synthesis of polycarbonate and a preparation method thereof.
Background
In recent years, with the increase in energy consumption, carbon dioxide in the atmosphere accumulates in large amounts, and causes frequent occurrence of greenhouse effect and extreme weather. But at the same time, carbon dioxide is also a widely distributed and abundant carbon resource on earth. Therefore, from the standpoint of environmental protection and resource utilization, the conversion of carbon dioxide into valuable products is of great significance. At present, various chemical products such as: methanol, formic acid, carbonates, polycarbonates, and the like. Among them, polycarbonate is a kind of plastic products with good transparency, processability, high heat resistance and high flame retardance, and has wide application value. And the polycarbonate is a biodegradable environment-friendly material, can effectively solve the problem of white pollution caused by traditional plastics, and promotes the healthy development of a social ecosystem. However, the carbon dioxide has symmetrical molecular structure, is in a stable structure in thermodynamics, and has lower reactivity. Therefore, the key to preparing polycarbonate by using carbon dioxide is to develop a high-efficiency catalyst to activate carbon dioxide molecules so as to effectively participate in polymerization reaction. Wherein, the Schiff base-metal complex has higher catalytic activity and selectivity in the reaction, and has wide application prospect.
Disclosure of Invention
The invention aims to provide a Schiff base cobalt complex for catalyzing polycarbonate synthesis, which has a structural formula shown as follows:
wherein the ligand is ionized Schiff base, and the central atom is bivalent cobalt metal ion;
The central cobalt atom is respectively coordinated with two nitrogen atoms and two halogen ions of the Schiff base ligand;
R 1、R2 is a substituent;
n is alkyl carbon chain length.
Preferably, the structural formula of the ionized schiff base is as follows:
Wherein R 1 is substituent on benzene ring, which is one of methyl, ethyl, propyl, isopropyl and tert-butyl;
r 2 is substituent on quaternary ammonium salt and is one of methyl and ethyl;
n is alkyl carbon chain length, n=1-3;
X is a halogen ion;
The external anion Y - of the ligand is one of hexafluorophosphate ion, tetrafluoroborate ion or halogen ion.
The invention also provides a preparation method of the ionic Schiff base cobalt complex, which comprises the following steps:
S1, synthesizing an ionic bidentate Schiff base ligand: 2-aminophenol or a derivative thereof is taken as an initial compound, and ionic bidentate Schiff base ligand is obtained through condensation with glyoxal, phenolic hydroxyl alkylation and tertiary amine salification;
S2, synthesizing a Schiff base cobalt complex: tetrahydrofuran is used as a solvent, ionic bidentate Schiff base ligand and halogenated cobalt with the molar ratio of 1.1:1 are added, and the mixture reacts for 5 hours at room temperature to separate out a solid product; and (5) carrying out suction filtration, washing with tetrahydrofuran solution, and drying to obtain the Schiff base cobalt complex.
On the basis of the above method, preferably, the specific operation of step S1 is as follows:
s1, dissolving 2-aminophenol or a derivative thereof and glyoxal in a molar ratio of 1:2 in a round bottom bottle filled with 100 ml absolute ethyl alcohol, heating, stirring and refluxing 12: 12 h; cooling to room temperature to obtain a first-step condensation product; suction filtering, repeatedly washing the solid product with absolute ethanol solution, drying, and collecting;
S2, adding 3 equivalents of dibromoalkane and potassium carbonate into the condensation product of the first step, and heating at 80 ℃ in acetonitrile solution to react for 6-12 h; after the reaction is finished, removing acetonitrile solvent under reduced pressure, extracting with ethyl acetate, washing with saturated sodium chloride aqueous solution, concentrating, and separating by a chromatographic column to obtain a second-step alkylation product;
S3, dissolving the alkylation product obtained in the second step in acetonitrile solution, adding 5 equivalents of triethylamine or trimethylamine, and heating and refluxing overnight to enable the alkyl bromide to be fully salified; after the reaction is finished, concentrating an acetonitrile solvent under reduced pressure, then adding diethyl ether, and separating out ionic Schiff base ligand, wherein the yield is 40-65%; after dissolving the ionic schiff base ligand in methanol/water solution, sodium hexafluorophosphate or sodium tetrafluoroborate is added, and the ligand external anions can be exchanged into PF 6 - or BF 4 -.
The invention also aims to prepare a catalyst for catalyzing the polymerization of carbon dioxide and propylene oxide to form carbonic ester by using the ionic Schiff base cobalt complex, wherein the dosage of the catalyst in the polymerization reaction is 0.05 percent of the molar quantity of propylene oxide, the conversion rate of propylene oxide can reach 91.8 percent after the polymerization reaction is catalyzed for 6 hours, and the selectivity of polycarbonate reaches 89.9 percent.
The beneficial technical effects of the invention are as follows: the novel ionic Schiff base cobalt complex synthesized by the invention has the advantages of easy change of substituent groups on benzene rings and substituent groups on quaternary ammonium salts, easy synthesis, stable performance and environmental friendliness. The quaternary ammonium ionic structure can stabilize the Schiff base cobalt complex, and can improve the activity of catalytic reaction, and the cobalt metal complex can effectively catalyze the polymerization of carbon dioxide and propylene oxide to form carbonate.
Detailed Description
The technical solutions of the present invention will be clearly and completely described in conjunction with the embodiments of the present invention, and it is apparent that the described embodiments are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
Example 1
Synthesis of ionic Schiff base ligand L1-L6
The ionic Schiff base ligand (L1-L6) is synthesized in three steps:
(1) First, 0.05 mol of 2-aminophenol or a derivative thereof and 0.1mol of glyoxal are dissolved in a round bottom flask containing 100ml of absolute ethanol, heated and refluxed with 12 h. Cooling to room temperature to obtain the condensation product of the first step, filtering, repeatedly washing the solid product with absolute ethanol solution, drying, and collecting.
(2) Adding 3 equivalents of dibromoalkane and potassium carbonate into the condensation product of the first step, heating and reacting at 80 ℃ in acetonitrile solution for 6-12 h, wherein the dibromoalkane is 1, 2-dibromoethane, 1, 3-dibromopropane or 1, 4-dibromobutane, decompressing and removing acetonitrile solvent after the reaction is finished, extracting by using ethyl acetate, washing by using saturated sodium chloride aqueous solution, concentrating and separating by using chromatographic columns to obtain the alkylation product of the second step.
(3) The alkylation product obtained in the second step is dissolved in acetonitrile solution, 5 equivalents of triethylamine or trimethylamine are added, and the mixture is heated and refluxed overnight to enable the alkyl bromide to be fully salified. After the reaction is finished, the acetonitrile solvent is decompressed and concentrated, then diethyl ether is added, and ionic Schiff base ligand L1-L6 is separated out, and the yield is 40-65%. After the ionic Schiff base ligand L1-L6 is dissolved in methanol/water solution, sodium hexafluorophosphate or sodium tetrafluoroborate is added, and the ligand external anions can be exchanged into PF 6 - or BF 4 -.
Example 2
Example 2 (Synthesis of Ionic Schiff base cobalt Complex Co 1),
The ligand L1 (1.25 g,2.2 mmol) prepared in example 1, anhydrous cobalt bromide (0.44 g, 2.0 mmol) was stirred in 15 mL tetrahydrofuran at room temperature to precipitate a solid powder, which was then subjected to suction filtration after 5 hours of further reaction, and the solid product was washed with tetrahydrofuran solution and dried to give complex Co1 in yield 73%.1H NMR (dmso-d6): 7.96 (s, CH, 2H), 7.42 (d,J= 8.0 Hz, Ph CH, 2H), 7.23-7.17 (m, Ph CH, 4H), 6.94 (d,J= 4.0 Hz, Ph CH, 2H), 4.55 (t,J= 4.0 Hz, CH2, 4H), 3.80 (t,J= 4.0 Hz, CH2, 4H), 3.22 (s, CH3, 18H).13C NMR (dmso-d6): 151.1, 150.1, 138.9, 127.7, 127.4, 123.3, 113.0, 64.8, 64.7, 54.6 ppm.
Example 3
Synthesis of ionic Schiff base cobalt complex Co2
Ligand L2 (1.32 g,2.2 mmol), anhydrous cobalt bromide (0.44 g, 2.0 mmol) and 15 mL tetrahydrofuran are stirred at room temperature to separate out solid powder, after the reaction is continued for 5 hours, suction filtration is carried out, and the solid product is washed by tetrahydrofuran solution and dried to obtain complex Co2, the yield is high 65%.1H NMR (dmso-d6): 7.99 (s, CH, 2H), 7.44-7.41 (m, Ph CH, 2H), 7.22-7.17 (m, Ph CH, 4H), 6.98-6.95 (m, Ph CH, 2H), 4.20 (t,J= 4.0 Hz, CH2, 4H), 3.41 (t,J= 8.0 Hz, CH2, 4H), 3.23 (s, CH3, 18H), 2.27-2.21 (m, CH2, 4H).13C NMR (dmso-d6): 151.8, 149.8, 139.2, 127.6, 127.3, 123.2, 112.9, 66.1, 64.6, 53.0, 26.2 ppm.
Example 4
Synthesis of ionic Schiff base cobalt complex Co3
Ligand L3 (1.38 g,2.2 mmol), anhydrous cobalt bromide (0.44 g, 2.0 mmol) and 15 mL tetrahydrofuran are stirred at room temperature to separate out solid powder, after the reaction is continued for 5 hours, suction filtration is carried out, and the solid product is washed by tetrahydrofuran solution and dried to obtain complex Co3, the yield 53%.1H NMR (dmso-d6): 7.97 (s, CH, 2H), 7.43-7.41 (m, Ph CH, 2H), 7.21-7.17 (m, Ph CH, 4H), 6.98-6.95 (m, Ph CH, 2H), 4.09 (t,J= 4.0 Hz, CH2, 4H), 3.40 (t,J= 8.0 Hz, CH2, 4H), 3.22 (s, CH3, 18H), 1.90-1.80 (m, CH2, 8H).13C NMR (dmso-d6): 151.9, 149.8, 139.2, 127.7, 127.3, 123.2, 112.9, 68.8, 67.2, 53.0, 25.9, 23.4 ppm.
Example 5
Synthesis of ionic Schiff base cobalt complex Co4
Ligand L4 (1.44 g,2.2 mmol), anhydrous cobalt bromide (0.44 g, 2.0 mmol) and 15 mL tetrahydrofuran are stirred at room temperature to separate out solid powder, after the reaction is continued for 5 hours, suction filtration is carried out, and the solid product is washed by tetrahydrofuran solution and dried to obtain complex Co4, the yield 58%.1H NMR (dmso-d6): 7.96 (s, CH, 2H), 7.42 (d,J= 8 Hz, Ph CH, 2H), 7.23-7.17 (m, Ph CH, 4H), 6.94 (d,J= 4 Hz, Ph CH, 2H), 4.40 (t,J= 4.0 Hz, CH2, 4H), 3.89 (t,J= 8.0 Hz, CH2, 4H), 3.40 (q,J= 4.0 Hz, CH2, 12H), 1.30 (t, CH2,J= 4.0 Hz, CH2, 18H).13C NMR (dmso-d6): 151.0, 149.8, 138.8, 127.6, 127.3, 123.2, 113.0, 62.8, 56.7, 53.8, 8.7 ppm.
Example 6
Synthesis of ionic Schiff base cobalt complex Co5
Ligand L5 (1.32 g,2.2 mmol), anhydrous cobalt bromide (0.44 g, 2.0 mmol) and 15 mL tetrahydrofuran are stirred at room temperature to separate out solid powder, after the reaction is continued for 5 hours, suction filtration is carried out, and the solid product is washed by tetrahydrofuran solution and dried to obtain complex Co5, the yield is high 71%.1H NMR (dmso-d6): 7.97 (s, CH, 2H), 7.17 (d,J= 8 Hz, Ph CH, 2H), 7.00 (d,J= 8 Hz, Ph CH, 2H), 677 (d,J= 4 Hz, Ph CH, 2H), 4.53 (t,J= 4.0 Hz, CH2, 4H), 3.79 (t,J= 8.0 Hz, CH2, 4H), 3.22 (s, CH3, 18H), 2.33 (s, CH3, 6H).13C NMR (dmso-d6): 151.2, 149.6, 138.3, 136.0, 126.4, 123.8, 113.6, 64.7, 64.6, 54.2, 21.5 ppm.
Example 7
Synthesis of ionic Schiff base cobalt complex Co6
Ligand L6 (1.50 g,2.2 mmol), anhydrous cobalt bromide (0.44 g, 2.0 mmol) and 15 mL tetrahydrofuran are stirred at room temperature to separate out solid powder, after the reaction is continued for 5 hours, suction filtration is carried out, and the solid product is washed by tetrahydrofuran solution and dried to obtain complex Co6, the yield 65%.1H NMR (dmso-d6): 7.96 (s, CH, 2H), 7.17-7.12 (m, Ph CH, 4H), 6.77 (d,J= 4 Hz, Ph CH, 2H), 4.53 (t,J= 4.0 Hz, CH2, 4H), 3.79 (t,J= 8.0 Hz, CH2, 4H), 3.29 (s, CH3, 18H), 1.33 (s, CH3, 18H).13C NMR (dmso-d6): 151.3, 150.4, 149.7, 135.6, 126.5, 121.0, 111.5, 64.7, 64.6, 54.2, 35.0, 31.6 ppm.
Example 8
Catalytic polycarbonate synthesis
Anhydrous propylene oxide (6.5 mL,100 mmol) is added into a 100mL high-pressure reaction kettle, the ionic Schiff base cobalt catalyst prepared in the examples 2-7 is added, trimethylbenzene (30 [ mu ] L) as an internal standard is added, carbon dioxide gas is introduced, the pressure is regulated to 3 Mpa, the temperature is increased to 30-50 ℃, and the reaction is carried out for 6-12 h. After the reaction was completed, the reaction mixture was cooled to room temperature, the carbon dioxide remaining in the reaction vessel was released under reduced pressure, the reaction product was dissolved with methylene chloride, transferred to a round-bottomed flask, and the solvent methylene chloride and unreacted propylene oxide were distilled off under reduced pressure. A small sample was taken for hydrogen nuclear magnetic resonance detection and the remaining product was dissolved with a small amount of tetrahydrofuran, precipitated by dropwise addition to methanol, the solution was decanted and the polymer was dried in vacuo. The conversion of Propylene Oxide (PO) in the catalytic reaction and the selectivity of polycarbonate (PPC) and carbonate (PC) were calculated from the integral ratio of the nuclear magnetic resonance spectrum ascribed to polycarbonate (4.92 ppm, 1H), carbonate (4.77 ppm, 1H), polypropylene oxide (3.46-3.64 ppm, 3H) to the internal standard mesitylene (6.70 ppm, 3H).
The steric hindrance and the electronic effect of the ionic Schiff base cobalt catalyst are adjusted by changing the substituent on the benzene ring of the Schiff base ligand, the length of the alkyl carbon chain and the substituent on the quaternary ammonium salt, so that the catalytic activity of the catalyst is influenced. As can be seen from Table 1, co6 having a tertiary butyl substituent on the benzene ring has a catalytic activity greater than Co5 containing methyl on the benzene ring and greater than Co1 having no substituent on the benzene ring (Co 6> Co5> Co 1). This demonstrates that the electron-donating property and steric hindrance of the substituents on the benzene ring have a large influence on the catalytic polymerization activity. Compared with the catalytic activity of Co1, co2 and Co3, the alkyl carbon chain length has little influence on the catalytic activity of the ionic Schiff base cobalt catalyst. The R 2 substituent on the alkali salt is changed from methyl (Co 1) to ethyl (Co 4), and the catalytic activity of the ionic Schiff base cobalt catalyst is not changed significantly.
TABLE 1 catalysts Co1-Co6 catalyze the copolymerization of Propylene Oxide (PO) with carbon dioxide
Example 9
Influence of the reaction conditions on the polymerization, the catalyst here being Co6 prepared in example 7
TABLE 2 influence of temperature and time on catalytic polymerization
When carbon dioxide and propylene oxide are polymerized, the selectivity of the polymer has a great relationship with the temperature, and as shown in tables 2 (1-3), after catalytic polymerization of 3 h, the selectivity of polycarbonate (PPC) tends to be increased and then decreased with the increase of the reaction temperature. When the reaction temperature was 20 ℃, the selectivity of PPC was 81.6%, and when the reaction temperature was increased to 40 ℃, the selectivity of PPC was increased to 87.5%, but the temperature was further increased to 50 ℃, the selectivity of PPC was reduced to 83.4%, so that the selectivity of polymerization reaction was the best at 40 ℃. Subsequently we extended the catalytic polymerization time to 6 h (tables 2-4) at which point the PPC selectivity reached 89.9 and the Propylene Oxide (PO) conversion reached 91.8%. After extension to 12h, the PPC selectivity and PO conversion did not change significantly (tables 2-5).
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (7)
1. A Schiff base cobalt complex for catalyzing the synthesis of polycarbonate is characterized in that:
The molecular structural formula of the complex is as follows:
wherein the ligand is ionized bidentate Schiff base, and the central atom is bivalent cobalt metal ion;
The central cobalt atom is respectively coordinated with two nitrogen atoms and two halogen ions of the Schiff base ligand;
The molecular formula structure of the ligand is as follows:
Wherein the substituent R 1 on the benzene ring is one of methyl, ethyl, propyl, isopropyl and tert-butyl;
The substituent R 2 on the quaternary ammonium salt is one of methyl and ethyl;
The upper carbon chain length of the phenoxyalkyl is 2-4 carbon atoms;
The external anion Y - of the ligand is one of hexafluorophosphate ion, tetrafluoroborate ion or halogen ion.
2. The Schiff base cobalt complex for catalyzing the synthesis of polycarbonate according to claim 1, wherein: the substituent R 1 on the benzene ring of the ionized bidentate Schiff base ligand is tertiary butyl.
3. A process for the preparation of a schiff base cobalt complex for the catalytic synthesis of polycarbonate according to any one of claims 1 to 2, characterized in that:
S1, synthesizing an ionized bidentate Schiff base ligand: taking 2-aminophenol with substituent R 1 as an initial compound, condensing with glyoxal, carrying out phenol hydroxyl alkylation and tertiary amine salifying reaction to obtain an ionized bidentate Schiff base ligand; wherein R 1 is one of methyl, ethyl, propyl, isopropyl and tert-butyl;
S2, synthesizing a Schiff base cobalt complex: tetrahydrofuran is used as a solvent, ionized bidentate Schiff base ligand and halogenated cobalt with the molar ratio of 1.1:1 are added, and the mixture reacts for 5 hours at room temperature to separate out a solid product; and (5) carrying out suction filtration, washing with tetrahydrofuran solution, and drying to obtain the Schiff base cobalt complex.
4. The method for preparing a schiff base cobalt complex for catalyzing the synthesis of polycarbonate according to claim 3, which is characterized in that: the specific operation of the step S1 is as follows:
S1, dissolving 2-aminophenol and glyoxal with substituent R 1 in a molar ratio of 1:2 into a round bottom bottle filled with 100 ml absolute ethyl alcohol, heating, stirring and refluxing 12 h; cooling to room temperature to obtain a first-step condensation product; suction filtering, repeatedly washing the solid product with absolute ethanol solution, drying, and collecting; wherein R 1 is one of methyl, ethyl, propyl, isopropyl and tert-butyl;
S2, adding 3 equivalents of dibromoalkane and potassium carbonate into the condensation product of the first step, and heating at 80 ℃ in acetonitrile solution to react for 6-12 h; after the reaction is finished, removing acetonitrile solvent under reduced pressure, extracting with ethyl acetate, washing with saturated sodium chloride aqueous solution, concentrating, and separating by a chromatographic column to obtain a second-step alkylation product;
S3, dissolving the alkylation product obtained in the second step in acetonitrile solution, adding 5 equivalents of triethylamine or trimethylamine, and heating and refluxing overnight to enable the alkyl bromide to be fully salified; after the reaction is finished, concentrating an acetonitrile solvent under reduced pressure, then adding diethyl ether, and separating out ionized bidentate Schiff base ligand, wherein the yield is 40-65%; after dissolving the ionized bidentate Schiff base ligand in methanol/water solution, adding sodium hexafluorophosphate or sodium tetrafluoroborate, and exchanging external anions of the ligand into PF 6 - or BF 4 -.
5. Use of a schiff base cobalt complex according to any one of claims 1-2 for catalyzing the polymerization of carbon dioxide and propylene oxide to form a carbonate.
6. The use of the schiff base cobalt complex according to claim 5 for catalyzing the polymerization of carbon dioxide and propylene oxide to form a carbonate, characterized in that: the addition amount of the Schiff base cobalt complex is 0.05% of the molar amount of propylene oxide.
7. The use of the schiff base cobalt complex according to claim 5 for catalyzing the polymerization of carbon dioxide and propylene oxide to form a carbonate, characterized in that: the reaction temperature of the polymerization reaction of the carbon dioxide and the propylene oxide is 40 ℃, and the reaction time is 6 hours.
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