CN104448283B - A kind of preparation method of Merlon - Google Patents

Abstract

The invention provides a method for preparing polycarbonate, comprising the following steps: under the action of a main catalyst and a co-catalyst, carbon dioxide and an epoxide are subjected to a copolymerization reaction to obtain polycarbonate; the main catalyst has a structure of formula I The co-catalyst includes one or more of quaternary ammonium salt, quaternary phosphonium salt and organic base; the ratio of the main catalyst to the co-catalyst is 1:0.2-4. Compared with the prior art, the preparation method uses the aluminum porphyrin complex as the main catalyst, and adjusts the electronic environment of the metal active center aluminum by changing the substituent, so that it exhibits higher performance in the copolymerization reaction of carbon dioxide and epoxides. activity. In addition, the main catalyst also has high product selectivity in the copolymerization reaction, and the prepared polycarbonate has a high molecular weight. The experimental results show that when the aluminum porphyrin complex catalyzes the copolymerization of carbon dioxide and epoxide, the conversion number of the catalytic system can reach up to 5563h ^‑1 .

Description

A kind of preparation method of polycarbonate

technical field

The invention belongs to the technical field of polymers, in particular to a preparation method of polycarbonate.

Background technique

Polycarbonate can be prepared by copolymerization of carbon dioxide and epoxide. Polycarbonate is a fully degradable polymer material with good transparency and excellent oxygen and water barrier properties. It is an ideal raw material for disposable packaging materials. , has wide application potential in food and medical packaging and other fields.

Since Inoue realized the copolymerization of carbon dioxide and propylene oxide for the first time in 1969, alkyl zinc/active hydrogen catalytic systems, zinc carboxylate systems, double metal cyanide catalysts, rare earth three-way catalysts, diimine zinc catalysts, and tetradentate catalysts have successively appeared. A series of catalytic systems such as Schiff base cobalt complex catalytic system, zinc phenate catalytic system and metal porphyrin catalyst. Among them, the four-dentate Schiff base cobalt complex (SelenCo) catalytic system that began to appear in 2003 has developed rapidly, and two-component catalytic systems composed of SalenCo complexes and quaternary ammonium salts or quaternary phosphonium salts have appeared successively. A one-component bifunctional SalenCo catalyst with steric hindrance organic base groups integrated, the activity of these two types of catalysts can reach 10 ⁶ g of polymer/mole of catalyst. However, this type of catalyst uses toxic metals such as cobalt and chromium as the active center, resulting in excessive toxic metal content in the polycarbonate produced by catalytic polymerization, which has become an important obstacle for the application of polycarbonate materials in the fields of food and medical packaging. Therefore, the development Catalysts with low-toxicity metal active sites are particularly important.

Due to the simple preparation method of porphyrin ligands, special space electronic arrangement and strong coordination ability with metals, metalloporphyrin catalysts have received attention in the field of carbon dioxide-epoxide catalysts. For example, the publication number is The Chinese patent of CN 102558199A discloses a metal porphyrin complex, which is used to catalyze the polymerization reaction of carbon dioxide and epoxy compounds to prepare polycarbonate. However, the metalloporphyrin complexes disclosed in the prior art have relatively low catalytic activity when catalyzing the copolymerization reaction of carbon dioxide and epoxy compounds.

Contents of the invention

In view of this, the object of the present invention is to provide a preparation method of polycarbonate, and the aluminum porphyrin complex in the preparation method provided by the present invention shows higher catalytic activity.

The invention provides a kind of preparation method of polycarbonate, comprises the following steps:

Under the action of the main catalyst and the co-catalyst, the carbon dioxide and the epoxide are copolymerized to obtain polycarbonate;

The main catalyst is an aluminum porphyrin complex, and the aluminum porphyrin complex has a structure shown in formula I:

Formula I;

In formula _I , the R is selected from halogen, aliphatic group, substituted aliphatic group, substituted heteroaliphatic group, aryl, substituted aryl or substituted heteroaryl;

_The R2 and _R3 are independently selected from hydrogen, halogen, aliphatic group, substituted aliphatic group, substituted heteroaliphatic group, aryl group, substituted aryl group or substituted heteroaryl group;

The Y is halogen, -NO ₃ , CH ₃ COO-, CCl ₃ COO-, CF ₃ COO-, ClO ₄ -, BF ₄ -, BPh ₄ -, -CN, -N ₃ , p-toluic acid root, p-toluenesulfonate, o-nitrophenol oxyanion, p-nitrophenol oxyanion, m-nitrophenol oxyanion, 2,4-dinitrophenol oxyanion, 3,5-dinitrophenol oxyanion anion, 2,4,6-trinitrophenoloxyanion, 3,5-dichlorophenoloxyanion, 3,5-difluorophenoloxyanion, 3,5-di-trifluoromethylphenoloxyanion or penta Fluorophenol oxygen anion;

The promoter includes one or more of quaternary ammonium salts, quaternary phosphorus salts and organic bases;

The material ratio of the main catalyst and the co-catalyst is 1:0.2-4.

Preferably, the cocatalyst includes tetraethylammonium bromide, tetrabutylammonium bromide, tetrabutylammonium chloride, tetrabutylammonium bisulfate, bistriphenylphosphine ammonium chloride, bistriphenylphosphine One or more of ammonium bromide, bistriphenylphosphorylnitroamine, 4-dimethylaminopyridine and γ-chloropropylmethyldimethoxysilane.

Preferably, the molar ratio of the aluminum porphyrin complex to the epoxide is 1:2000-200000.

Preferably, the pressure of the carbon dioxide is 0.1MPa-8MPa.

Preferably, the temperature of the copolymerization reaction is 20°C to 120°C.

Preferably, the time for the copolymerization reaction is 1 h to 12 h.

Preferably, the epoxides include ethylene oxide, propylene oxide, 1,2-butylene oxide, cyclohexane oxide, cyclopentane oxide, epichlorohydrin glycidyl methacrylate, One or more of methyl glycidyl ether, phenyl glycidyl ether and styrene alkylene oxide.

Preferably, said R ₁ is selected from halogen or substituted aliphatic groups;

The R ₂ and R ₃ are independently selected from hydrogen, halogen or aliphatic groups.

Preferably, said R ₁ is selected from -Cl, -Br or -OCH ₃ ;

The R ₂ and R ₃ are independently selected from hydrogen, -Cl, -Br or -CH ₃ .

Preferably, the Y is -Cl, -Br or p-toluenesulfonate.

The invention provides a preparation method of polycarbonate, comprising the following steps: under the action of a main catalyst and a co-catalyst, carbon dioxide and an epoxide are subjected to a copolymerization reaction to obtain polycarbonate; the main catalyst is aluminum porphyrin Complex, the aluminum porphyrin complex has the structure shown in formula I; The co-catalyst includes one or more of quaternary ammonium salt, quaternary phosphonium salt and organic base; The material of the main catalyst and co-catalyst The amount ratio is 1:0.2~4. Compared with the prior art, the preparation method provided by the present invention adopts the aluminum porphyrin complex as the main catalyst, and adjusts the electronic environment of the metal active center aluminum by changing the substituent, so that it can perform in the copolymerization reaction of carbon dioxide and epoxide higher activity. In addition, the main catalyst used in the preparation method provided by the present invention also has high product selectivity in the copolymerization reaction, and the obtained polymerization product has a high molecular weight. The experimental results show that: when the aluminum porphyrin complex provided by the invention is used to catalyze carbon dioxide and epoxy compounds to carry out the polymerization reaction, the conversion number (TOF) of the catalytic system can reach up to 5563h ^-1 ; The product is less than 10.0%, and the carbonate unit content is higher than 96%. The number average molecular weight of the prepared polycarbonate is 34000g/mol-198000g/mol.

detailed description

The invention provides a kind of preparation method of polycarbonate, comprises the following steps:

Under the action of the main catalyst and the co-catalyst, the carbon dioxide and the epoxide are copolymerized to obtain polycarbonate;

The main catalyst is an aluminum porphyrin complex, and the aluminum porphyrin complex has a structure shown in formula I:

Formula I;

In formula _I , the R is selected from halogen, aliphatic group, substituted aliphatic group, substituted heteroaliphatic group, aryl, substituted aryl or substituted heteroaryl;

_The R2 and _R3 are independently selected from hydrogen, halogen, aliphatic group, substituted aliphatic group, substituted heteroaliphatic group, aryl group, substituted aryl group or substituted heteroaryl group;

The Y is halogen, -NO ₃ , CH ₃ COO-, CCl ₃ COO-, CF ₃ COO-, ClO ₄ -, BF ₄ -, BPh ₄ -, -CN, -N ₃ , p-toluic acid root, p-toluenesulfonate, o-nitrophenol oxyanion, p-nitrophenol oxyanion, m-nitrophenol oxyanion, 2,4-dinitrophenol oxyanion, 3,5-dinitrophenol oxyanion anion, 2,4,6-trinitrophenoloxyanion, 3,5-dichlorophenoloxyanion, 3,5-difluorophenoloxyanion, 3,5-di-trifluoromethylphenoloxyanion or penta Fluorophenol oxygen anion;

The promoter includes one or more of quaternary ammonium salts, quaternary phosphorus salts and organic bases;

The material ratio of the main catalyst and the co-catalyst is 1:0.2-4.

In the present invention, the aluminum porphyrin complex has a structure shown in formula I:

Formula I;

In formula _I , the R is selected from halogen, aliphatic group, substituted aliphatic group, substituted heteroaliphatic group, aryl, substituted aryl or substituted heteroaryl;

_The R2 and _R3 are independently selected from hydrogen, halogen, aliphatic group, substituted aliphatic group, substituted heteroaliphatic group, aryl group, substituted aryl group or substituted heteroaryl group;

Preferably, said R ₁ is selected from halogen or substituted aliphatic groups;

The R ₂ and R ₃ are independently selected from hydrogen, halogen or aliphatic groups;

More preferably, said R ₁ is selected from -Cl, -Br or -OCH ₃ ;

The R ₂ and R ₃ are independently selected from hydrogen, -Cl, -Br or -CH ₃ .

The Y is halogen, -NO ₃ , CH ₃ COO-, CCl ₃ COO-, CF ₃ COO-, ClO ₄ -, BF ₄ -, BPh ₄ -, -CN, -N ₃ , p-toluic acid root, p-toluenesulfonate, o-nitrophenol oxyanion, p-nitrophenol oxyanion, m-nitrophenol oxyanion, 2,4-dinitrophenol oxyanion, 3,5-dinitrophenol oxyanion anion, 2,4,6-trinitrophenoloxyanion, 3,5-dichlorophenoloxyanion, 3,5-difluorophenoloxyanion, 3,5-di-trifluoromethylphenoloxyanion or penta Fluorophenoxy anion, preferably, the Y is p-toluenesulfonate (-OTs), -Br or -Cl;

In the present invention, when said R ₁ is -Cl, R ₂ is -H, R ₃ is -H, and Y is -Cl, the aluminum porphyrin complex has a structure shown in formula II, which is denoted as complex 1:

Formula II

In the present invention, when said R ₁ is -Cl, R ₂ is -H, R ₃ is -H, and Y is -OTs, the aluminum porphyrin complex has a structure shown in formula III, which is denoted as complex 2:

Formula III;

In the present invention, when said R ₁ is -Br, R ₂ is -H, R ₃ is -H, and Y is -Cl, the aluminum porphyrin complex has a structure shown in formula IV, which is denoted as complex 3:

Formula IV;

When the R ₁ is -Br, R ₂ is -H, R ₃ is -H, and Y is -Br, the aluminum porphyrin complex has a structure shown in formula V, which is denoted as complex 4:

Formula V;

When R ₁ is -OCH ₃ , R ₂ is -H, R ₃ is -H, and Y is -Br, the aluminum porphyrin complex has the structure shown in formula VI, which is recorded as complex 5:

Formula VI;

When R ₁ is -Cl, R ₂ is -Cl, R ₃ is -H, and Y is -Cl, the aluminum porphyrin complex has the structure shown in formula VII, which is denoted as complex 6:

Formula VII;

When R ₁ is -Cl, R ₂ is -Cl, R ₃ is -Cl, and Y is -Cl, the aluminum porphyrin complex has the structure shown in formula VIII, which is denoted as complex 7:

Formula VIII;

In the present invention, the preparation method of the aluminum porphyrin complex preferably comprises the following steps:

a) reacting the benzaldehyde compound and pyrrole in the first solvent to obtain an intermediate having a structure shown in formula IX;

Formula IX;

b) reacting the intermediate having the structure shown in formula IX with the first metal salt compound in a second solvent to obtain the aluminum porphyrin complex having the structure shown in formula I.

In the present invention, the benzaldehyde compound and pyrrole are reacted in the first solvent to obtain the intermediate having the structure shown in formula IX. In the present invention, there is no special limitation on the mixing order of the benzaldehyde compound, pyrrole and the first solvent, preferably the first solvent and the benzaldehyde compound are mixed first, and then pyrrole is added. The present invention preferably carries out the reaction of benzaldehyde compound and pyrrole under the protection of nitrogen. In the present invention, the reaction between the benzaldehyde compound and pyrrole is preferably carried out under the condition of stirring; the present invention has no special limitation on the stirring method, and the stirring technical solution well known to those skilled in the art can be used. The present invention has no special limitation on the container for the reaction between the benzaldehyde compound and pyrrole, for example, a three-neck flask well known to those skilled in the art is used.

In the present invention, the benzaldehyde compounds preferably include 4-chlorobenzaldehyde, 4-bromobenzaldehyde, 4-methoxybenzaldehyde, 2,4-dichlorobenzaldehyde, 2,4,6-trichlorobenzaldehyde One or more of benzaldehyde and benzaldehyde.

The present invention has no special limitation on the pyrrole, and the pyrrole well-known to those skilled in the art can be used.

In the present invention, the first solvent preferably includes dichloromethane or propionic acid; the dichloromethane is preferably dry dichloromethane.

Specifically, when dichloromethane is used as the first solvent in the present invention, the benzaldehyde compound and pyrrole are preferably mixed with trifluoroacetic acid and 2,3-dichloro-5,6-dicyano-1,4-benzoquinone Carry out the reaction of benzaldehyde compound and pyrrole under the existence of (DDQ), obtain the intermediate with the structure shown in formula IX; The present invention is preferably after benzaldehyde compound and pyrrole dissolve completely in dichloromethane, to which adding three Fluoroacetic acid is reacted for the first time; DDQ is added thereto and reacted for the second time to obtain an intermediate having a structure shown in formula IX. The present invention preferably carries out the above reaction under the protection of _N2 .

In the present invention, the molar ratio of the benzaldehyde compound and pyrrole is preferably 1:0.8～1.5, more preferably 1:0.9～1.2, most preferably 1:1; the volume of the dichloromethane and The molar ratio of the benzaldehyde compound is preferably 100mL: (1-3) mol, more preferably 100mL: (1.5-2.5) mol; the molar ratio of the trifluoroacetic acid and the benzaldehyde compound is preferably 4.0 ～1:1, more preferably 3.0～2.0:1, most preferably 2.5:1; the mass ratio of the DDQ and benzaldehyde compounds is preferably 6.0～1.0:1, more preferably 5.0～2.0:1, most preferably Preferably it is 4.0-2.5:1.

In the present invention, the temperature at which the benzaldehyde compound and pyrrole react in dichloromethane is preferably 15°C to 35°C, more preferably 20°C to 30°C, most preferably 25°C; the first time Preferably it is 50 min to 80 min, more preferably 55 min to 70 min, most preferably 60 min; the second time is preferably 50 min to 80 min, more preferably 55 min to 70 min, most preferably 60 min;

After the reaction between benzaldehyde compounds and pyrrole is completed, the present invention preferably removes the solvent from the reaction solution obtained by the reaction to obtain a crude product having a structure shown in formula IX, and then purifies the crude product to obtain a compound having a structure shown in formula IX intermediate. In the present invention, there is no special limitation on the method for removing the solvent from the reaction solution obtained by the reaction of benzaldehyde compounds and pyrrole, and it is preferably removed by vacuum distillation. The present invention preferably adopts chromatographic column separation to purify the crude product with the structure shown in formula IX; The stationary phase in the described chromatographic column separation preferably adopts Al2O3; The mobile phase in the described chromatographic column separation preferably adopts sherwood oil and Dichloromethane, more preferably petroleum ether and dichloromethane with a volume ratio of 1:(1.0-2.5), most preferably petroleum ether and dichloromethane with a volume ratio of 1:2.

Specifically, when R ₁ is -Cl, R ₂ is -H, and R ₃ is -H, the intermediate has the structure shown in formula X:

Formula X;

When R ₁ is -Br, R ₂ is -H, and R ₃ is -H, the intermediate has the structure shown in formula XI:

Formula XI;

When R ₁ is -OCH ₃ , R ₂ is -H, and R ₃ is -H, the intermediate has the structure shown in formula XII:

Formula XII;

When R ₁ is -Cl, R ₂ is -Cl, R ₃ is -H, the intermediate has the structure shown in formula XIII:

Formula XIII;

When R ₁ is -Cl, R ₂ is -Cl, R ₃ is -Cl, the intermediate has the structure shown in formula XIV:

Formula XIV;

After obtaining the intermediate with the structure shown in formula IX, the present invention reacts the intermediate with the structure shown in IX with the first metal salt compound in the second solvent to obtain the aluminum porphyrin with the structure shown in formula I Phenyl complexes.

The present invention preferably carries out the reaction of the intermediate having the structure shown in IX and the first metal salt compound under the protection of _N2 . In the present invention, the second solvent preferably includes dichloromethane or acetone.

In some embodiments of the present invention, the second solvent is dichloromethane. The present invention has no special restriction on the mixing order of the intermediate with the structure shown in IX, the first metal salt compound and methylene chloride, preferably the intermediate with the structure shown in formula IX and methylene chloride are first added to Mix in the reaction vessel, and then add the first metal salt compound for mixing; more preferably, the intermediate having the structure shown in formula IX and dichloromethane are first added to the reaction vessel, mixed and stirred until the solid is completely dissolved, and then the second metal salt compound is added thereto. A metal salt compound.

In the present invention, the first metal salt compound preferably includes diethylaluminum chloride, silver p-toluenesulfonate, magnesium bromide or sodium bromide; the first metal salt compound is preferably The form of compound solution reacts with the intermediate having the structure shown in formula IX.

In the present invention, the volume ratio of the dichloromethane to the substance of the intermediate having the structure shown in formula IX is preferably (15-25) mL: 1 mmol, more preferably (18-23) mL: 1 mmol, Most preferably 20mL:1mmol.

In some embodiments of the present invention, the third solvent in the first metal salt compound solution is preferably n-hexane; specifically, in some embodiments of the present invention, in the diethylaluminum chloride solution The solvent used is n-hexane, and the molar concentration of the diethylaluminum chloride solution is preferably 0.8 mol/L to 1.2 mol/L. In the present invention, the molar ratio of the first metal salt compound to the intermediate having the structure shown in formula IX is preferably 1-6:1, more preferably 1.2-5.5:1, most preferably 1.5- 5:1.

After completing the reaction of the intermediate having the structure shown in IX and the first metal salt compound, the present invention preferably removes dichloromethane and the third solvent from the reaction solution obtained by the reaction to obtain a crude product having the structure shown in Formula I , and then purify the crude product to obtain the aluminum porphyrin complex with the structure shown in formula I.

The method for removing the third solvent and methylene chloride is not particularly limited in the present invention. In some embodiments of the present invention, it is preferred to remove the third solvent and methylene chloride by vacuum distillation. The present invention preferably adopts chromatographic column separation to purify the crude product having the structure shown in formula I; The stationary phase in the described chromatographic column separation preferably adopts Al2O3; The mobile phase in the described chromatographic column separation preferably adopts dichloromethane The elution phase in the chromatographic column separation is preferably dichloromethane and methanol, more preferably dichloromethane and methanol in a volume ratio of 8 to 12:1, most preferably dichloromethane and methanol in a volume ratio of 10:1 Methanol.

In the present invention, the product obtained by reacting the intermediate having the structure shown in formula IX with the first metal salt compound is named as the aluminum porphyrin complex precursor. In the present invention, the temperature of the substitution reaction is preferably 10°C to 35°C, more preferably 15°C to 30°C, most preferably 25°C.

After completing the reaction of the intermediate having the structure shown in formula IX and the first metal salt compound, the present invention preferably carries out the substitution reaction between the product obtained by the reaction and the second metal salt compound to obtain the aluminum porphyrin with the structure shown in formula I Phenyl complexes. In the present invention, the type range of the second metal salt compound is consistent with the type range of the first metal salt compound, but the specific type selected when the second metal salt compound reacts with the first metal salt compound is different.

When Y is OTs, the second metal salt compound is preferably silver p-toluenesulfonate; the silver p-toluenesulfonate is preferably reacted in the form of silver p-toluenesulfonate solution; in the silver p-toluenesulfonate The solvent is preferably acetonitrile; the mass concentration of silver p-toluenesulfonate in the silver p-toluenesulfonate solution is preferably 0.01g/mL～0.5g/mL; more preferably 0.01g/mL～0.02g/mL; substitution reaction When the reaction solvent is preferably acetone; the molar ratio of the metal porphyrin complex precursor and silver p-toluenesulfonate is preferably 1 to 5:1, more preferably 1 to 1.2:1; the volume of the acetone and the metal The molar ratio of the porphyrin complex precursor is preferably 10 mL to 50 mL: 1 mmol, more preferably 10 mL to 20 mL: 1 mmol. After completing the substitution reaction with silver p-toluenesulfonate, the present invention preferably removes the solvent from the substitution reaction product solution; the present invention preferably uses vacuum distillation to remove the solvent from the substitution reaction product solution; after the substitution reaction product solution removes the solvent, the present invention The invention preferably adds methanol therein for dissolution, filters under reduced pressure, and then distills off the methanol under reduced pressure to obtain the aluminum porphyrin complex with the structure shown in formula I. When Y is Br, the second metal salt compound is preferably NaBr; the mass ratio of NaBr to the metal porphyrin complex precursor is preferably 1 to 10:1, more preferably 1 to 1.5 : 1, most preferably 1:1; the solvent of NaBr and metalloporphyrin complex substitution reaction is preferably dichloromethane; the reaction product solution that NaBr and metalloporphyrin complex precursor substitution reaction produces preferably underpressure distillation removes reaction product Solvent in the solution to obtain metal porphyrin complexes. In the present invention, the time for the substitution reaction between NaBr and the aluminum porphyrin complex precursor is preferably 20h-30h, more preferably 23h-27h, and most preferably 24h.

Specifically, when propionic acid is used as the first solvent in the present invention, the reaction between the benzaldehyde compound and pyrrole is preferably carried out in the form of reflux. In the present invention, the temperature of the reflux is preferably above 140°C, more preferably 140°C-160°C; the time of the reflux is preferably 25min-35min, more preferably 28min-32min. In order to improve the purity of the benzaldehyde compound and pyrrole, the present invention preferably reacts the benzaldehyde compound and pyrrole through redistillation; Just steam the technical solution. In the present invention, the purity of the benzaldehyde compound is preferably 95% to 99%, more preferably 97% to 99%; the purity of the pyrrole is preferably 92% to 99%, more preferably 95% to 98% %. In the present invention, the ice water cooling time is preferably 3.5h to 4.5h, more preferably 4h;

After the reaction between the benzaldehyde compound and pyrrole is completed, the present invention preferably cools the obtained reaction product to room temperature, continues cooling with ice water, and suction-filters to obtain the precipitated substance. In the present invention, the precipitated substance is preferably washed with methanol, and then washed with distilled water until the filtrate is neutral to obtain a crude product having a structure shown in formula IX. In the present invention, the crude product is preferably recrystallized to obtain an intermediate having the structure shown in formula IX.

In the present invention, the obtained intermediate with the structure shown in formula IX is reacted with the first metal salt compound in a fourth solvent to obtain the aluminum porphyrin complex with the structure shown in formula I. In the present invention, the fourth solvent is preferably dichloromethane; the volume of the dichloromethane and the mass ratio of the intermediate having the structure shown in formula IX are preferably (15-25) mL:1mol, more preferably It is preferably (18-22) mL:1 mol, most preferably 20 mL:1 mol. In the present invention, the type of the first metal salt compound is the same as that of the first metal salt compound described in the above technical solution, and will not be repeated here.

After completing the reaction between the intermediate having the structure shown in formula IX and the first metal salt compound, the present invention preferably removes the fourth solvent from the obtained reaction product, and then purifies the crude product obtained after removing the fourth solvent. In some embodiments of the present invention, the present invention preferably removes the fourth solvent by vacuum distillation; the present invention preferably uses chromatographic column separation to purify the crude product; the stationary phase in the chromatographic column separation preferably adopts Al2O3; the mobile phase in the separation of the chromatographic column preferably adopts dichloromethane; the eluent phase in the separation of the chromatographic column preferably adopts dichloromethane and methanol, more preferably dichloromethane and methanol in a volume ratio of 8 to 12:1. Chloromethane and methanol, most preferably dichloromethane and methanol in a volume ratio of 10:1.

The present invention adopts the method of mass spectrometry to characterize the obtained aluminum porphyrin complex, and the experimental results show that the aluminum porphyrin complex provided by the present invention has the structure shown in formula I.

The present invention preferably adds carbon dioxide, epoxide, procatalyst and cocatalyst in the autoclave, carries out copolymerization reaction, obtains polycarbonate; Add it to the reactor that has been treated with water and oxygen removal beforehand, then remove the reactor from the glove box, and then fill the reactor with CO ₂ to carry out the copolymerization reaction.

In the present invention, the cocatalyst is one or more of quaternary ammonium salt, quaternary phosphonium salt and organic base, preferably tetraethylammonium bromide, tetrabutylammonium bromide, tetrabutylammonium chloride , tetrabutylammonium bisulfate, bistriphenylphosphine ammonium chloride, bistriphenylphosphine ammonium bromide, bistriphenylphosphonium nitroamine, 4-dimethylaminopyridine and γ-chloropropylmethyl di One or more of methoxysilanes, more preferably one of tetrabutylammonium bromide, bistriphenylphosphine ammonium chloride, bistriphenylphosphine ammonium bromide and 4-dimethylaminopyridine or more.

In the present invention, the carbon dioxide is preferably gaseous carbon dioxide with a purity of 99.99%; the pressure of the carbon dioxide is preferably 0.1MPa-8MPa, more preferably 1.0MPa-7MPa, most preferably 2MPa-6MPa.

In the present invention, there is no special limitation on the source and type of the epoxide, and the epoxide well known to those skilled in the art can be used, for example, it can be purchased from the market. In the present invention, the epoxide is preferably ethylene oxide, propylene oxide, 1,2-epoxybutylene, epoxycyclohexane, epoxycyclopentane, epichlorohydrin, methacrylic acid One of glycidyl ether, methyl glycidyl ether, phenyl glycidyl ether, styrene alkylene oxide, ethylene glycol diglycidyl ether, butanediol diglycidyl ether and neopentyl glycol diglycidyl ether or several, more preferably including one or more of ethylene oxide, ethylene glycol diglycidyl ether, butanediol diglycidyl ether, propylene oxide and epichlorohydrin.

In the present invention, the main catalyst can prepare polycarbonate with high activity at a lower catalyst concentration; the molar ratio of the main catalyst and epoxy is preferably 1:(2000～200000), more preferably 1: (3000-190000); the molar ratio of the main catalyst and the co-catalyst is 1:0.2-4, preferably 1:0.3-3.8, more preferably 1:0.5-3.5.

In the present invention, the temperature of the copolymerization reaction is preferably 20°C to 120°C, more preferably 30°C to 110°C, most preferably 60°C to 100°C; the time of the copolymerization reaction is preferably 1h to 12h, more preferably It is preferably 2h to 11h, most preferably 3h to 10h.

After the copolymerization reaction is finished, the present invention preferably cools the reactor to room temperature, and releases the carbon dioxide therein; at the same time, it is preferred to place the reactor in a cold trap at -20°C to collect unreacted epoxide.

In the present invention, it is preferred to add dichloromethane to the reaction product to dissolve the reaction product, and then add methanol to obtain the crude product of polycarbonate. In the present invention, the crude product of polycarbonate is preferably washed and dried to obtain polycarbonate. In the present invention, the solvent used for washing the crude polycarbonate is preferably methanol. The present invention preferably adopts vacuum drying; the drying temperature is preferably 40° C. to 60° C.; preferably drying to constant weight.

The invention carries out gel permeation chromatographic analysis on the obtained polycarbonate, and the number average molecular weight of the obtained polycarbonate is 34000g/mol-198000g/mol.

The present invention carries out nuclear magnetic resonance spectrum identification to the obtained product, and the identification result shows that: the obtained product is polycarbonate; the carbonate unit content in the polymer is higher than 96%; the cyclic carbonate by-product in the polycarbonate is less than 10.0% %.

The invention provides a preparation method of polycarbonate, comprising the following steps: under the action of a main catalyst and a co-catalyst, carbon dioxide and an epoxide are subjected to a copolymerization reaction to obtain polycarbonate; the main catalyst is aluminum porphyrin Complex, the aluminum porphyrin complex has the structure shown in formula I; The co-catalyst includes one or more of quaternary ammonium salt, quaternary phosphonium salt and organic base; The material of the main catalyst and co-catalyst The amount ratio is 1:0.2~4. Compared with the prior art, the preparation method provided by the present invention adopts the aluminum porphyrin complex as the main catalyst, and the electronic environment of the metal active center aluminum can be adjusted by changing the substituent, so that it can react with carbon dioxide and epoxides in the copolymerization reaction. showed higher activity. In addition, the main catalyst used in the preparation method provided by the present invention also has high product selectivity in the copolymerization reaction, and the obtained polymerization product has a high molecular weight. The experimental results show that: when the aluminum porphyrin complex provided by the invention is used to catalyze carbon dioxide and epoxy compounds to carry out the polymerization reaction, the conversion number (TOF) of the catalytic system can reach up to 5563h ^-1 ; The product is less than 10.0%, and the carbonate unit content is higher than 96%. The number average molecular weight of the prepared polycarbonate is 34000g/mol-198000g/mol.

In order to further illustrate the present invention, the preparation method of a polycarbonate provided by the present invention is described in detail below in conjunction with the examples, but they cannot be interpreted as limiting the protection scope of the present invention.

Example 1

At 25°C, add 800mL of dry dichloromethane, 2.8g of 4-chlorobenzaldehyde (20mmol), and 1.4mL of pyrrole (20mmol) into a 1000mL round-bottomed three-neck flask under the protection of _N2 , stir until the solid is completely dissolved, then add 3.7 mL of trifluoroacetic acid (50 mmol, 2.5 eq) was stirred for 1 h, then 9.08 g of DDQ (2.3-dichloro-5,6-dicyano-1,4-benzoquinone) was added and stirred for 1 h. The above liquid was filtered under reduced pressure, the solvent was distilled off under reduced pressure, and the obtained crude product was separated by chromatographic column [stationary phase: aluminum oxide; mobile phase: dichloromethane/petroleum ether (volume ratio)=2:1] to obtain four (4-chlorophenyl) porphyrin, the product conversion rate is 20.8%; the present invention carries out proton nuclear magnetic resonance spectrum test to the tetrakis (4-chlorophenyl) porphyrin obtained, and test result shows: ¹ H NMR (300MHz, CDCl3) , δ: 8.83(s, 8H), 8.12(d, J=9.0Hz, 8H), 7.78(d, J=9.0Hz, 8H), -2.87(s, 2H); the identification results show that: four (4- Chlorophenyl) porphyrin has a structure shown in formula X;

At 25°C, under the protection of _N2 , 20 mL of dry dichloromethane and 0.75 g of tetrakis (4-chlorophenyl) porphyrin (1 mmol) were added to a 50 mL round-bottomed three-neck flask, and after stirring until the solid was completely solvent, 1.5 mL of Diethylaluminum chloride solution (1mol/L n-hexane solution, 1.5eq) was stirred for 1h; the above-mentioned liquid was distilled off under reduced pressure to remove the solvent, and the resulting crude product was separated by a chromatographic column [stationary phase: aluminum oxide; mobile phase: Dichloromethane; Elution phase: dichloromethane/methanol (volume ratio)=10:1], obtain tetrakis (4-chlorophenyl) porphyrin aluminum chloride, product conversion rate 94.3%; The present invention is to the obtained tetrakis (4-Chlorophenyl) porphyrin aluminum chloride was tested by proton nuclear magnetic resonance, and the test results were: ¹ H NMR (300MHz, DMSO), δ: 9.08 (s, 8H), 8.12 (d, J = 9.0Hz, 8H), 8.04(d, J=9.0Hz, 8H); the identification results show that tetrakis(4-chlorophenyl)porphyrin aluminum chloride has the structure shown in formula II;

At 25°C, 20 mL of acetone and 0.81 g of tetrakis(4-chlorophenyl) porphyrin aluminum chloride (1 mmol) were added to a 100 mL round-bottomed three-necked flask, and 20 mL of silver p-toluenesulfonate (0.29 g, 1.05 eq) acetonitrile solution, stirred for 12h, the above-mentioned liquid was distilled off under reduced pressure to remove the solvent, dissolved in methanol and filtered under reduced pressure, and the solvent was removed by distillation under reduced pressure to obtain tetrakis (4-chlorophenyl) porphyrin aluminum (axial OTs), and the product was transformed into The yield is 74.6%; the present invention carries out the proton nuclear magnetic resonance spectrum test to the obtained tetrakis (4-chlorophenyl) porphyrin aluminum (axial OTs), and the test result is: ¹ H NMR (300MHz, DMSO), δ: 9.03(s ,8H), 8.12(d, J=9.0Hz, 8H), 8.03(d, J=9.0Hz, 8H), 7.41(d, J=9.0Hz, 2H), 7.08(d, J=9.0Hz, 2H ); The test results show that the obtained tetrakis (4-chlorophenyl) porphyrin aluminum (axial OTs) has a structure shown in formula III.

Example 2

At 25°C, add 800mL of dry dichloromethane, 3.7g of 4-bromobenzaldehyde (20mmol), 1.4mL of pyrrole (20mmol) into a 1000mL three-necked round-bottomed flask under the protection of _N2 , stir until the solid is completely dissolved, then add 3.7 mL of trifluoroacetic acid (50 mmol, 2.5 eq) was stirred for 1 h, then 9.08 g of DDQ (2.3-dichloro-5,6-dicyano-1,4-benzoquinone) was added and stirred for 1 h. The above liquid was filtered under reduced pressure, the solvent was distilled off under reduced pressure, and the obtained crude product was separated by chromatographic column [stationary phase: aluminum oxide; mobile phase: dichloromethane/petroleum ether (volume ratio)=2:1] to obtain four (4-bromophenyl) porphyrin, the product conversion rate is 19.5%; the present invention carries out proton nuclear magnetic resonance spectrum test to the obtained tetrakis (4-bromophenyl) porphyrin, and the test result is: ¹ H NMR (300MHz, CDCl3) ,δ:8.84(s,8H),8.06(d,J＝9.0Hz,8H),7.91(d,J＝9.0Hz,8H),-2.86(s,2H); test results show that: four (4- Bromophenyl) porphyrin has structure shown in formula XI;

At 25°C, under the protection of _N2 , 20 mL of dry dichloromethane and 0.9 g of tetrakis (4-bromophenyl) porphyrin (1 mmol) were added to a 50 mL round-bottomed three-necked flask, and after stirring until the solid was completely solvent, 1.5 mL of Diethylaluminum chloride solution (1mol/L n-hexane solution, 1.5eq) was stirred for 1h; the above-mentioned liquid was distilled off under reduced pressure to remove the solvent, and the resulting crude product was separated by a chromatographic column [stationary phase: aluminum oxide; mobile phase: Dichloromethane; Elution phase: dichloromethane/methanol (volume ratio)=10:1], obtain tetrakis (4-bromophenyl) porphyrin aluminum chloride, product conversion rate 93.5%; The present invention is to the obtained tetrakis (4-Bromophenyl) porphyrin aluminum chloride was tested by proton nuclear magnetic resonance, and the test results were: ¹ H NMR (300MHz, DMSO), δ: 9.05 (s, 8H), 8.15 (d, J = 9.0Hz, 8H), 8.05 (d, J=9.0Hz, 8H); test results show that tetrakis(4-bromophenyl)porphyrin aluminum chloride has the structure shown in formula IV;

At 25°C, add 50mL of dichloromethane, 1.0g of tetrakis(4-bromophenyl)porphyrin aluminum chloride (1mmol) and 1.03g of NaBr into a 100mL round-bottomed three-neck flask, stir for 24h and filter, and the filtrate is decompressed The solvent was distilled off to obtain aluminum tetrakis(4-bromophenyl)porphyrin (axial Br), and the conversion rate of the product was 80.3%. In the present invention, the obtained tetrakis(4-bromophenyl)porphyrin aluminum (axial Br) is tested by proton nuclear magnetic resonance spectrum, and the test result is: ¹ H NMR (300MHz, DMSO), δ: 9.03 (s, 8H), 8.14 (d, J=9.0Hz, 8H), 8.05 (d, J=9.0Hz, 8H). The test results show that tetrakis(4-bromophenyl)aluminum porphyrin (axial Br) has the structure shown in formula V.

Example 3

Add 800mL of dry dichloromethane, 2.7g of 4-methoxybenzaldehyde (20mmol), and 1.4mL of pyrrole (20mmol) into a 1000mL round-bottomed three-neck flask at 25°C under the protection of _N2 , and stir until the solids are completely dissolved , added 3.7mL trifluoroacetic acid (50mmol, 2.5eq) and stirred for 1h, then added 9.08g DDQ (2.3-dichloro-5,6-dicyano-1,4-benzoquinone) and stirred for 1h. The above liquid was filtered under reduced pressure, the solvent was distilled off under reduced pressure, and the obtained crude product was separated by chromatographic column [stationary phase: aluminum oxide; mobile phase: dichloromethane/petroleum ether (volume ratio)=2:1] to obtain four (4-methoxyphenyl) porphyrin, the product conversion rate is 17.5%. The present invention carries out proton nuclear magnetic resonance spectrum test to obtained tetrakis (4-methoxyphenyl) porphyrin, and test result is: ¹ H NMR (300MHz, DMSO), δ: 8.88 (s, 8H), 8.13 (d, J=9Hz, 8H), 7.29(d, J=9Hz, 8H), 4.10(m, 12H), -2.84(s, 2H); test results show that: four (4-methoxyphenyl) porphyrin has Structure shown in formula XII;

At 25°C, under the protection of _N2 , 20mL of dry dichloromethane and 0.73g of tetrakis(4-methoxyphenyl)porphyrin (1mmol) were added to a 50mL round-bottomed three-neck flask, stirred until the solid was completely solvent-free, and then added 1.5mL diethylaluminum chloride solution (1mol/L n-hexane solution, 1.5eq) was stirred for 1h. The above liquid was distilled off under reduced pressure to remove the solvent, and the obtained crude product was separated by a chromatographic column [stationary phase: aluminum oxide; mobile phase: dichloromethane; eluent phase: dichloromethane/methanol (volume ratio) = 10:1] , to obtain tetrakis(4-methoxyphenyl)porphyrin aluminum chloride, the product conversion rate is 90.1%. The present invention carries out the proton nuclear magnetic resonance spectrum test to the obtained tetrakis (4-methoxyphenyl) porphyrin aluminum chloride, and the test result is: ¹ H NMR (300MHz, DMSO), δ: 8.46-8.59 (s, 16H) , 7.53 (d, 8H, J=9.0Hz), 4.16 (s, 12H); test results show that tetrakis (4-methoxyphenyl) porphyrin aluminum chloride has the structure shown in formula VI;

At 25°C, 20 mL of acetone and 0.80 g of tetrakis(4-methoxyphenyl)porphyrin aluminum chloride (1 mmol) were added to a 100 mL round-bottomed three-neck flask, and 20 mL of silver p-toluenesulfonate (0.29 g, 1.05eq) of acetonitrile solution, stirred for 12h, the above-mentioned liquid was distilled off under reduced pressure to remove the solvent, dissolved in methanol, filtered under reduced pressure, and removed by distillation under reduced pressure to obtain tetrakis(4-methoxyphenyl)porphyrin aluminum (axial OTs) , The product conversion rate is 74.3%. In the present invention, the obtained tetrakis (4-methoxyphenyl) porphyrin aluminum (axial OTs) is tested by proton nuclear magnetic resonance spectrum, and the test result is: ¹ H NMR (300MHz, DMSO), δ: 9.03 (s, 8H ), 8.14 (d, J=9.0Hz, 8H), 8.05 (d, J=9.0Hz, 8H), 7.45 (d, J=9.0Hz, 2H), 7.10 (d, J=9.0Hz, 2H).

Example 4

Add 800mL of dry dichloromethane, 3.5g of 2,4-dichlorobenzaldehyde (20mmol), and 1.4ml of pyrrole (20mmol) into a 1000mL three-necked round-bottomed flask at 25°C under the protection of _N2 , and stir until the solids are completely dissolved , added 3.7mL trifluoroacetic acid (50mmol, 2.5eq) and stirred for 1h, then added 9.08g DDQ (2.3-dichloro-5,6-dicyano-1,4-benzoquinone) and stirred for 3h. The above liquid was filtered under reduced pressure, the solvent was distilled off under reduced pressure, and the obtained crude product was separated by chromatographic column [stationary phase: aluminum oxide; mobile phase: dichloromethane/petroleum ether (volume ratio)=2:1] to obtain four (2,4-dichlorophenyl) porphyrin, the product conversion rate is 16.8%. In the present invention, the obtained tetrakis(2,4-dichlorophenyl)porphyrin is tested by proton nuclear magnetic resonance spectrum, and the test result is: ¹ H NMR (300MHz, CDCl3), δ: 8.15-7.98 (m, 4H), 7.89 -7.85 (m, J=9.0Hz, 4H), 7.67-7.61 (m, 4H), -2.76 (s, 2H); test results show that: the obtained tetrakis (2,4-dichlorophenyl) porphyrin has Structure shown in formula XIII;

At 25°C, under the protection of _N2 , 20 mL of dry dichloromethane and 1.0 g of tetrakis(2,4-dichlorophenyl) porphyrin (1 mmol) were added to a 50 mL round-bottomed three-necked flask, and stirred until the solid was completely solvent-free. Add 1.5mL diethylaluminum chloride solution (1mol/L n-hexane solution, 1.5eq) and stir for 1h. The above liquid was distilled off under reduced pressure to remove the solvent, and the obtained crude product was separated by a chromatographic column [stationary phase: aluminum oxide; mobile phase: dichloromethane; eluent phase: dichloromethane/methanol (volume ratio) = 10:1] , and tetrakis(2,4-dichlorophenyl)porphyrin aluminum aluminum chloride was obtained, and the product conversion rate was 98.8%. In the present invention, the obtained tetrakis (2,4-dichlorophenyl) porphyrin aluminum aluminum chloride is tested by proton nuclear magnetic resonance spectrum, and the test result is: ¹ H NMR (300MHz, DMSO), δ: 8.95 (s, 8H) , 8.28 (m, 8H), 7.92 (m, 4H); test results show that tetrakis(2,4-dichlorophenyl) porphyrin aluminum aluminum chloride has the structure shown in formula VII.

Example 5

Add 500mL of propionic acid into a 1000mL round-bottomed three-neck flask, stir and heat to boiling, add 29.3g of 2,4,6-trichlorobenzaldehyde (0.14mol), 10mL of freshly steamed pyrrole (0.14mol) and stir to reflux for 30min. After stopping the reaction, cool to room temperature, continue to cool with ice water for 4h, and filter with suction. Wash with methanol to colorless, and wash with hot water until neutral to obtain tetrakis(2,4,6-trichlorophenyl)porphyrin with a conversion rate of 11.3%. The present invention conducts ultraviolet-visible spectrum analysis (UV-vis) on the obtained tetrakis(2,4,6-trichlorophenyl)porphyrin, and the analysis result is: UV-vis (nm): 424,513,556,588,658.

In the present invention, the obtained tetrakis(2,4,6-trichlorophenyl)porphyrin is tested by proton nuclear magnetic resonance spectrum, and the test result is: ¹ H NMR (300MHz, CDCl3), δ: 8.84 (s, 8H), 8.06 (d, J=9.0Hz, 8H), 7.91(d, J=9.0Hz, 8H), -2.86(s, 2H); test results show: tetrakis (2,4,6-trichlorophenyl) porphyrin Has the structure shown in formula XIV;

At 25°C, under the protection of _N2 , 20 mL of dry dichloromethane and 1.03 g of tetrakis (2,4,6-trichlorophenyl) porphyrin (1 mmol) were added into a 50 mL round-bottomed three-necked flask, and stirred until the solid was completely dissolved. After that, add 1.5mL diethylaluminum chloride solution (1mol/L n-hexane solution, 1.5eq) and stir for 1h, distill the above liquid under reduced pressure to remove the solvent, and the obtained crude product is separated by chromatographic column [stationary phase: di Aluminum; Mobile phase: dichloromethane; Elution phase: dichloromethane/methanol (volume ratio)=10:1], obtain tetrakis (2,4,6-trichlorophenyl) porphyrin aluminum aluminum chloride, product The conversion rate is 91.2%. The present invention carries out ultraviolet-visible spectrum analysis (UV-vis) to the obtained tetrakis (2,4,6-trichlorophenyl) porphyrin aluminum aluminum chloride, and the analysis result is: UV-vis (nm): 370,419, 508,650. Ultraviolet-visible light spectrum analysis shows that tetrakis(2,4,6-trichlorophenyl)porphyrin aluminum aluminum chloride has the structure shown in formula VIII.

Example 6

Add 0.1 mmol of complex 1, 0.1 mmol of cocatalyst bistriphenylphosphine ammonium chloride (PPNCl) and 1 mol of propylene oxide into a 500 mL autoclave that has been pre-treated for dehydration and oxygen removal, and quickly pass through The _CO2 supply line with the function of adjustment is filled into the kettle with _CO2 until the pressure is 2.0 MPa, and the temperature is controlled at 70 °C and stirred for 4 hours. Collect unreacted epoxide in a cold trap at -20°C, then add a certain amount of dichloromethane to the kettle to dissolve the copolymerization mixture, then add a certain amount of methanol to precipitate polycarbonate, and the precipitated polymer is washed with methanol After washing, the washed copolymer was vacuum-dried to constant weight to obtain 18 g of white polypropylene carbonate, TOF=441h ^-1 . In the present invention, the number average molecular weight of the polymer measured by gel permeation chromatography is 73000g/mol, and the molecular weight distribution is 1.13; ¹ H-NMR analysis results show that the by-product of cyclic carbonate is less than 2.0%, and the carbonate unit in the polymer The content is higher than 98%.

Example 7

Add 0.5mmol of complex 2, 0.25mmol of 4-dimethylaminopyridine (DMAP) and 1mol of propylene oxide into a 500mL high-pressure reactor that has been pre-treated to remove water and oxygen, and quickly pass through the _CO2 with pressure adjustment function Fill the kettle with _CO2 to 6.0MPa from the supply line, control the temperature at 80°C and stir the reaction for 1 hour. After the polymerization reaction, cool the reactor to room temperature, slowly release the carbon dioxide, and collect it in a cold trap at -20°C Unreacted epoxide. Then add a certain amount of dichloromethane into the kettle to dissolve the copolymerization mixture, then add a certain amount of methanol to precipitate polycarbonate, the precipitated polymer is washed with methanol, and the washed copolymer is vacuum-dried to constant weight to obtain 17g polypropylene carbonate, TOF=333h ^-1 , the polymer number average molecular weight measured by gel permeation chromatography is 34000g/mol, the molecular weight distribution is 1.12, ¹ H-NMR analysis results show that the cyclic carbonate by-product is less than 2.0%, the content of carbonate units in the polymer is higher than 98%.

Example 8

Add 0.01mmol of complex 3, 0.01mmol of bistriphenylphosphine ammonium bromide (PPNBr) and 2mol of propylene oxide into a 500mL autoclave that has been pre-treated to remove water and oxygen, and quickly pass through Fill the reactor with CO ₂ to 1.0MPa through the CO ₂ supply line, control the temperature at 90°C and stir for 12 hours. After the polymerization reaction is over, cool the reactor to room temperature, slowly release the carbon dioxide, and cool at -20°C Collect the unreacted epoxide in the trap, then add a certain amount of dichloromethane into the kettle to dissolve the copolymerization mixture, then add a certain amount of methanol to precipitate polycarbonate, the precipitated polymer is washed with methanol, and after washing The copolymer was vacuum-dried to constant weight to obtain 29 g of polypropylene carbonate, TOF=441h ^-1 . According to the present invention, the number average molecular weight of the polymer measured by gel permeation chromatography is 159200, and the molecular weight distribution is 1.15. The ¹ H-NMR analysis results show that the cyclic carbonate by-product is less than 3.0%, and the carbonate unit content in the polymer is higher than 97%.

Example 9

Add 0.2mmol of complex 1, 0.1mmol of tetrabutylammonium bromide and 1mol of propylene oxide into a 500mL high-pressure reactor that has been pre-treated to remove water and oxygen, and quickly pass the _CO2 supply line with pressure adjustment function to the reactor. Fill the interior with _CO2 to 2.0MPa, control the temperature at 100°C and stir the reaction for 2 hours. After the polymerization reaction is completed, cool the reactor to room temperature, slowly release the carbon dioxide, and collect unreacted carbon dioxide in a cold trap at -20°C. Then add a certain amount of dichloromethane into the kettle to dissolve the copolymerization mixture, then add a certain amount of methanol to precipitate polycarbonate, the precipitated polymer is washed with methanol, and the washed copolymer is vacuum-dried to Constant weight was obtained to obtain 31g of white polypropylene carbonate, TOF=760h ^-1 . According to the present invention, the number-average molecular weight of the polymer measured by gel permeation chromatography is 102000, and the molecular weight distribution is 1.17. The 1H-NMR analysis results show that the by-product of cyclic carbonate is less than 8.0%, and the content of carbonate units in the polymer is higher than 97%. %.

Example 10

Add 0.1mmol of complex 1, 0.4mmol of bistriphenylphosphine ammonium chloride and 1mol of propylene oxide into a 500mL autoclave that has been pre-treated to remove water and oxygen, and quickly pass through the _CO2 supply line with pressure adjustment function Fill the kettle with _CO2 to 0.1MPa, control the temperature at 20°C and stir the reaction for 8 hours. After the polymerization reaction is over, cool the reactor to room temperature, and slowly release the carbon dioxide. Then add a certain amount of dichloromethane into the kettle to dissolve the copolymerization mixture, then add a certain amount of methanol to precipitate polycarbonate, the precipitated polymer is washed with methanol, and the washed copolymer is vacuum Dry to constant weight to obtain 11 g of white polypropylene carbonate, TOF=135h ^-1 . According to the present invention, the number-average molecular weight of the polymer measured by gel permeation chromatography is 53500, and the molecular weight distribution is 1.12. ¹ H-NMR analysis results show that the cyclic carbonate by-product is less than 1.0%, and the carbonate unit content in the polymer is higher than 99%.

Example 11

Add 0.05mmol of complex 1, 0.2mmol of bistriphenylphosphine ammonium chloride and 1mol of propylene oxide into a 500mL autoclave that has been pre-treated to remove water and oxygen, and quickly pass through the _CO2 supply line with pressure adjustment function Fill the kettle with _CO2 to 8.0MPa, control the temperature at 120°C and stir the reaction for 6 hours. After the polymerization reaction, cool the reactor to room temperature, slowly release the carbon dioxide, and collect the untreated carbon dioxide in a cold trap at -20°C. Reactive epoxides. Then add a certain amount of dichloromethane into the kettle to dissolve the copolymerization mixture, then add a certain amount of methanol to precipitate polycarbonate, the precipitated polymer is washed with methanol, and the washed copolymer is vacuum-dried to constant weight to obtain 39g of white polypropylene carbonate, TOF=1274h ^-1 . According to the present invention, the number-average molecular weight of the polymer measured by gel permeation chromatography is 125600, and the molecular weight distribution is 1.15. ¹ H-NMR analysis results show that the cyclic carbonate by-product is less than 10.0%, and the carbonate unit content in the polymer is higher than 96%.

Example 12

Add 0.5mmol of complex 1, 0.25mmol of bistriphenylphosphine ammonium bromide and 1mol of epoxycyclohexane into a 500mL autoclave that has been pre-treated to remove water and oxygen, and quickly pass through the CO with pressure adjustment function. _2. Fill the kettle with _CO2 to 2.0MPa through the supply line, and control the temperature at 120°C to stir the reaction for 2 hours. After the polymerization reaction, cool the reactor to room temperature, slowly release the carbon dioxide, and at the same time place it in a cold trap at -20°C Collect the unreacted epoxide, then add a certain amount of dichloromethane into the kettle to dissolve the copolymerization mixture, then add a certain amount of methanol to precipitate polycarbonate, and wash the precipitated polymer with methanol. After washing, the copolymerization The product was vacuum-dried to constant weight to obtain 79g of white polycarbonate, TOF=5563h ^-1 . According to the present invention, the number-average molecular weight of the polymer measured by gel permeation chromatography is 98000, and the molecular weight distribution is 1.18. ¹ H-NMR analysis results show that the cyclic carbonate by-product is less than 1.0%, and the carbonate unit content in the polymer is higher than 99%.

Example 13

Add 0.1mmol of complex 1, 0.1mmol of bistriphenylphosphine ammonium chloride and 1mol of epichlorohydrin into a 500mL autoclave that has been pre-treated to remove water and oxygen, and quickly pass through the CO ₂ Fill the kettle with _CO2 to 2.0MPa from the supply line, control the temperature at 100°C and stir the reaction for 4 hours. After the polymerization reaction, cool the reactor to room temperature, slowly release the carbon dioxide, and collect it in a cold trap at -20°C Unreacted epoxide; then add a certain amount of dichloromethane to the kettle to dissolve the copolymer mixture, then add a certain amount of methanol to precipitate polycarbonate, the precipitated polymer is washed with methanol, and the washed copolymer Vacuum dried to constant weight to obtain 36g of white polypropylene carbonate with TOF value=661h ^-1 . According to the present invention, the number-average molecular weight of the polymer measured by gel permeation chromatography is 107,000, and the molecular weight distribution is 1.18. ¹ H-NMR analysis results show that the cyclic carbonate by-product is less than 4.0%, and the carbonate unit content in the polymer is higher than 97%.

Example 14

Add 0.1mmol of complex 1, 0.1mmol of bistriphenylphosphine ammonium chloride and 1mol of a mixture of propylene oxide and cyclohexane oxide into a 500mL autoclave that has been pre-treated to remove water and oxygen, and quickly pass through The _CO2 supply line with pressure adjustment function fills the kettle with _CO2 to 2.0MPa, controls the temperature at 110°C and stirs the reaction for 4 hours. Collect the unreacted epoxide in a cold trap at -20°C; then add a certain amount of dichloromethane to the kettle to dissolve the copolymerization mixture, then add a certain amount of methanol to precipitate polycarbonate, and the precipitated polymer is washed with methanol After washing, the washed copolymer was vacuum-dried to constant weight to obtain 49 g of white polypropylene carbonate, TOF=1004h ^-1 . According to the present invention, the number-average molecular weight of the polymer measured by gel permeation chromatography is 121500, and the molecular weight distribution is 1.16. The ¹ H-NMR analysis results show that the by-product of cyclic carbonate is less than 8.0%, and the content of carbonate units in the polymer is higher than 96%.

Example 15

Add 0.1mmol of complex 4, 0.1mmol of bistriphenylphosphine ammonium chloride and 1mol of propylene oxide into a 500mL high-pressure reactor that has been pre-treated to remove water and oxygen, and quickly pass through the _CO2 supply line with pressure adjustment function Fill the kettle with _CO2 to 2.0MPa, control the temperature at 100°C and stir the reaction for 4 hours. After the polymerization reaction is over, cool the reactor to room temperature, and slowly release the carbon dioxide. Then add a certain amount of dichloromethane to the kettle to dissolve the copolymerization mixture, then add a certain amount of methanol to precipitate polycarbonate, the precipitated polymer is washed with methanol, and the washed copolymer is vacuum Dry to constant weight to obtain 32g of white polypropylene carbonate, TOF=784h ^-1 . According to the present invention, the number-average molecular weight of the polymer measured by gel permeation chromatography is 75000, and the molecular weight distribution is 1.14. ¹ H-NMR analysis results show that the cyclic carbonate by-product is less than 6.0%, and the carbonate unit content in the polymer is higher than 97%.

Example 16

Add 0.1mmol of complex 5, 0.1mmol of bistriphenylphosphine ammonium chloride and 1mol of propylene oxide into a 500mL autoclave that has been pre-treated to remove water and oxygen, and quickly pass through the _CO2 supply line with pressure adjustment function Fill the kettle with _CO2 to 2.0MPa, control the temperature at 90°C and stir the reaction for 4 hours. After the polymerization reaction is over, cool the reactor to room temperature, slowly release the carbon dioxide, and collect untreated carbon dioxide in a -20°C cold trap Then add a certain amount of dichloromethane to the kettle to dissolve the copolymerization mixture, then add a certain amount of methanol to precipitate polycarbonate, the precipitated polymer is washed with methanol, and the washed copolymer is vacuum Dry to constant weight to obtain 37g of white polypropylene carbonate, TOF=906h ^-1 . According to the present invention, the number-average molecular weight of the polymer measured by gel permeation chromatography is 101000, and the molecular weight distribution is 1.17. ¹ H-NMR analysis results show that the cyclic carbonate by-product is less than 5.0%, and the carbonate unit content in the polymer is higher than 96%.

Example 17

Add 0.1mmol of complex 6, 0.1mmol of bistriphenylphosphine ammonium chloride and 1mol of propylene oxide into a 500mL autoclave that has been pre-treated to remove water and oxygen, and quickly pass through the _CO2 supply line with pressure adjustment function Fill the kettle with _CO2 to 4.0MPa, control the temperature at 90°C and stir for 1 hour. After the polymerization reaction, cool the reactor to room temperature, slowly release the carbon dioxide, and collect the untreated carbon dioxide in a cold trap at -20°C. Then add a certain amount of dichloromethane to the kettle to dissolve the copolymerization mixture, then add a certain amount of methanol to precipitate polycarbonate, the precipitated polymer is washed with methanol, and the washed copolymer is vacuum Dry to constant weight to obtain 14g of white polypropylene carbonate, TOF=1372h ^-1 . According to the present invention, the number-average molecular weight of the polymer measured by gel permeation chromatography is 111000, and the molecular weight distribution is 1.17. ¹ H-NMR analysis results show that the by-product of cyclic carbonate is less than 4.0%, and the content of carbonate units in the polymer is higher than 97%.

Example 18

Add 0.05mmol of complex 7, 0.1mmol of bistriphenylphosphine ammonium chloride and 1mol of propylene oxide into a 500mL autoclave that has been pre-treated to remove water and oxygen, and quickly pass through the _CO2 supply line with pressure adjustment function Fill the kettle with _CO2 to 2.0MPa, control the temperature at 100°C and stir the reaction for 4 hours. After the polymerization reaction is over, cool the reactor to room temperature, and slowly release the carbon dioxide. Then add a certain amount of dichloromethane to the kettle to dissolve the copolymerization mixture, then add a certain amount of methanol to precipitate polycarbonate, the precipitated polymer is washed with methanol, and the washed copolymer is vacuum Dry to constant weight to obtain 39g of white polypropylene carbonate, TOF=1911h ^-1 . According to the present invention, the number-average molecular weight of the polymer measured by gel permeation chromatography is 156,000, and the molecular weight distribution is 1.15. ¹ H-NMR analysis results show that the cyclic carbonate by-product is less than 8.0%, and the content of carbonate units in the polymer is higher than 97%.

Example 19

Add 0.05mmol of complex 3, 0.1mmol of bistriphenylphosphine ammonium chloride and 1mol of propylene oxide to a 500mL autoclave that has been pre-treated to remove water and oxygen, and at the same time add 100mL of polycarbonate good solvent II Chloromethane, quickly fill the reactor with CO ₂ to 4.0MPa through the CO ₂ supply line with pressure adjustment function, control the temperature at 90°C and stir for 8 hours. After the polymerization reaction is completed, cool the reactor to room temperature and slowly release Remove carbon dioxide, and collect unreacted epoxides and solvents in a cold trap at -20°C; then add a certain amount of methylene chloride to the kettle to dissolve the copolymerization mixture, and then add a certain amount of methanol to precipitate polycarbonate. The precipitated polymer was washed with methanol, and the washed copolymer was vacuum-dried to constant weight to obtain 45 g of white polypropylene carbonate, TOF=1103 h ^-1 . According to the present invention, the number-average molecular weight of the polymer measured by gel permeation chromatography is 198,000, and the molecular weight distribution is 1.15. The ¹ H-NMR analysis results show that the cyclic carbonate by-product is less than 4.0%, and the carbonate unit content in the polymer is higher than 97%.

Example 20

Add 0.05mmol of complex 4, 0.1mmol of bistriphenylphosphine ammonium chloride and 1mol of propylene oxide to a 500mL autoclave that has been pre-treated to remove water and oxygen, and add 100mL of polycarbonate poor solvent n-hexane Alkanes, quickly fill the reactor with CO ₂ to 4.0MPa through the CO ₂ supply line with pressure adjustment function, control the temperature at 90°C and stir for 8 hours, after the polymerization reaction is completed, cool the reactor to room temperature, and slowly release Carbon dioxide, while collecting unreacted epoxy and solvent in a cold trap at -20°C; then add a certain amount of dichloromethane to the kettle to dissolve the copolymerization mixture, then add a certain amount of methanol to precipitate polycarbonate, and precipitate The obtained polymer was washed with methanol, and the washed copolymer was vacuum-dried to constant weight to obtain 37g of white polypropylene carbonate, TOF=906h ^-1 . According to the present invention, the number average molecular weight of the polymer measured by gel permeation chromatography is 135,000 g/mol, and the molecular weight distribution is 1.15. ¹ H-NMR analysis results show that the cyclic carbonate by-product is less than 3.0%, and the content of carbonate units in the polymer is higher than 97%.

comparative example

Add 600 mL propionic acid to a 1000 mL three-neck round bottom flask, stir and heat to boiling. Extract 11.2 mL (0.16 mol) and 16.0 mL (0.16 mol) of redistilled pyrrole and benzaldehyde, respectively, and add them to boiling propionic acid, and continue to reflux for 30 minutes. After the reaction stops, cool to room temperature and continue cooling with ice water. Filtrate with suction to obtain a dark purple precipitate, wash with methanol until the filtrate is colorless, and then wash with hot distilled water until the filtrate is neutral to obtain a purple crystal. The crude product continues to be recrystallized from chloroform/methanol to obtain the tetraphenylporphyrin ligand, and the yield is about 23%. The present invention carries out a proton nuclear magnetic resonance spectrum test on the obtained tetraphenylporphyrin ligand, and the test result is : ¹ H NMR (300 MHz, CDCl3), δ: 8.87 (s, 8H), 8.12-8.25 (m, 8H), 7.74-7.80 (m, 12H), -2.75 (s, 2H). The test results show that the tetraphenylporphyrin ligand has the structure shown in formula XV:

Formula XV;

Under the protection of nitrogen, add 1 mmol of fully dried tetraphenylporphyrin ligand (TPPH2) into a pre-dried three-necked flask with a stirring magnet, draw 20 mL of dichloromethane into the reaction flask with a syringe, stir at a constant speed, and use Slowly add 0.16mL diethylaluminum chloride (Et2AlCl) dropwise into a dry syringe; after stirring at room temperature for 1 hour, pump out the dichloromethane first with a water pump, and then fully dry it with an oil pump under heating conditions to obtain purple crystals that are tetrachloride. Phenylporphyrin aluminum chloride (TPPAlCl), the yield rate is 94.3%. The present invention carries out hydrogen nuclear magnetic resonance spectrum test on the obtained tetraphenylporphyrin aluminum chloride, and the test result is: ¹ HNMR (300MHz, CDCl ₃ ), δ: 8.56-8.67 (m, 16H), 7.93-8.08 (m, 12H). The test results show that tetraphenylporphyrin aluminum chloride has the structure shown in formula XVI, which is denoted as complex 8:

Formula XVI;

Add 0.1 mmol of complex 8, 0.1 mmol of bistriphenylphosphine ammonium chloride and 1 mol of propylene oxide into a 500 mL autoclave that has been pre-treated to remove water and oxygen, and quickly pass through the _CO supply line with pressure adjustment function Fill the kettle with _CO2 to 2.0MPa, control the temperature at 70°C and stir the reaction for 4 hours. After the polymerization reaction is over, cool the reactor to room temperature, slowly release the carbon dioxide, and collect untreated carbon dioxide in a cold trap at -20°C. Then add a certain amount of dichloromethane into the kettle to dissolve the copolymerization mixture, then add a certain amount of methanol to precipitate polycarbonate, the precipitated polymer is washed with methanol, and the washed copolymer is vacuum Dry to constant weight to obtain 8 g of white polypropylene carbonate, TOF=196h ^-1 . The number-average molecular weight of the polymer measured by gel permeation chromatography is 22200, and the molecular weight distribution is 1.15. ¹ H-NMR analysis results show that the cyclic carbonate by-product is less than 22.4%, and the carbonate unit content in the polymer is higher than 97%. .

Known from above embodiment, the present invention provides a kind of preparation method of polycarbonate, comprises the following steps: under the effect of co-catalyst and co-catalyst, carry out copolymerization reaction with carbon dioxide and epoxide, obtain polycarbonate; The main catalyst is an aluminum porphyrin complex, and the aluminum porphyrin complex has a structure shown in formula I; the cocatalyst includes one or more of quaternary ammonium salts, quaternary phosphorus salts and organic bases; the main catalyst The ratio of the substance to the cocatalyst is 1:0.2-4. Compared with the prior art, the preparation method provided by the present invention adopts the aluminum porphyrin complex as the main catalyst, and adjusts the electronic environment of the metal active center aluminum by changing the substituent, so that it can perform in the copolymerization reaction of carbon dioxide and epoxide higher activity. In addition, the main catalyst used in the preparation method provided by the present invention also has high product selectivity in the copolymerization reaction, and the obtained polymerization product has a high molecular weight. The experimental results show that: when the aluminum porphyrin complex provided by the invention is used to catalyze carbon dioxide and epoxy compounds to carry out the polymerization reaction, the conversion number (TOF) of the catalytic system can reach up to 5563h ^-1 ; The product is less than 10.0%, and the carbonate unit content is higher than 96%. The number average molecular weight of the prepared polycarbonate is 34000g/mol-198000g/mol.

The above is only a preferred embodiment of the present invention, it should be pointed out that for those skilled in the art, without departing from the principle of the present invention, some improvements and modifications can also be made, and these improvements and modifications are also It should be regarded as the protection scope of the present invention.

Claims (9)

1. A preparation method for polycarbonate, comprising the following steps: Under the action of the main catalyst and the co-catalyst, the carbon dioxide and the epoxide are copolymerized to obtain polycarbonate; The main catalyst is an aluminum porphyrin complex, and the aluminum porphyrin complex has a structure shown in formula I: In formula _I , the R is selected from halogen, aliphatic group, substituted aliphatic group, substituted heteroaliphatic group, aryl, substituted aryl or substituted heteroaryl; _The R2 and _R3 are independently selected from hydrogen, halogen, aliphatic group, substituted aliphatic group, substituted heteroaliphatic group, aryl group, substituted aryl group or substituted heteroaryl group; The Y is halogen, -NO ₃ , CH ₃ COO-, CCl ₃ COO-, CF ₃ COO-, ClO ₄ -, BF ₄ -, BPh ₄ -, -CN, -N ₃ , p-toluic acid root, p-toluenesulfonate, o-nitrophenol oxyanion, p-nitrophenol oxyanion, m-nitrophenol oxyanion, 2,4-dinitrophenol oxyanion, 3,5-dinitrophenol oxyanion anion, 2,4,6-trinitrophenoloxyanion, 3,5-dichlorophenoloxyanion, 3,5-difluorophenoloxyanion, 3,5-di-trifluoromethylphenoloxyanion or penta Fluorophenol oxygen anion; The promoter includes one or more of quaternary ammonium salts, quaternary phosphorus salts and organic bases; The mass ratio of the main catalyst and the cocatalyst is 1:0.2～4; The epoxides include ethylene oxide, propylene oxide, 1,2-butylene oxide, cyclohexane, cyclopentane, epichlorohydrin glycidyl methacrylate, methyl glycidyl One or more of glyceryl ether, phenyl glycidyl ether and styrene alkylene oxide. 2. preparation method according to claim 1, is characterized in that, described cocatalyst comprises tetraethylammonium bromide, tetrabutylammonium bromide, tetrabutylammonium chloride, tetrabutylammonium bisulfate, bis One of triphenylphosphine ammonium chloride, bistriphenylphosphine ammonium bromide, bistriphenylphosphine nitroamine, 4-dimethylaminopyridine and γ-chloropropylmethyldimethoxysilane or Various. 3. The preparation method according to claim 1, characterized in that the molar ratio of the aluminum porphyrin complex to the epoxide is 1:2000-200000. 4. The preparation method according to claim 1, characterized in that the pressure of the carbon dioxide is 0.1MPa˜8MPa. 5. The preparation method according to claim 1, characterized in that, the temperature of the copolymerization reaction is 20°C-120°C. 6. The preparation method according to claim 1, characterized in that, the time of the copolymerization reaction is 1h-12h. 7. preparation method according to claim 1, is characterized in that, described R ₁ is selected from the aliphatic group of halogen or replacement; The R ₂ and R ₃ are independently selected from hydrogen, halogen or aliphatic groups. 8. The preparation method according to claim 7, wherein said R ₁ is selected from -Cl, -Br or -OCH ₃ ; The R ₂ and R ₃ are independently selected from hydrogen, -Cl, -Br or -CH ₃ . 9. The preparation method according to claim 1, characterized in that, the Y is -Cl, -Br or p-toluenesulfonate.