CN101020747A - Double function catalyst for synthesizing polycarbonate - Google Patents

Abstract

The invention relates to a highly active catalyst for synthesizing polycarbonate by catalytically activating carbon dioxide and alkylene oxide. The catalyst is a tetradentate Schiff base metal complex containing a functionalized group, which has dual functions, that is, contains both an electrophilic center and a nucleophilic center in the same molecule. The electrophilic center comes from the metal ion in the Schiff base metal complex, and the nucleophilic center comes from the quaternary ammonium or phosphonium salt connected to the benzene ring in the complex. The bifunctional catalyst can efficiently catalyze the polymerization reaction of carbon dioxide and alkylene oxide to prepare polycarbonate under milder conditions and lower catalyst concentration. The catalytic efficiency reaches 10 ⁶ grams of polymer/mole of catalyst, the molecular weight of the polymer is adjustable within the range of 10 ³ to 10 ⁵ , the molecular weight distribution is less than 2, the alternating structure exceeds 97%, and it can be degraded into small molecular compounds under certain conditions.

Description

Bifunctional catalysts for polycarbonate synthesis

technical field

The invention relates to a catalyst for synthesizing polycarbonate, in particular to a highly active single-component bifunctional catalyst for synthesizing polycarbonate by catalytically activating carbon dioxide and alkylene oxide.

Background technique

Carbon dioxide is the main gas that causes the greenhouse effect, and it is also one of the most abundant carbon sources on earth. The chemical fixation of carbon dioxide is an important research field of green chemistry. Among them, a main direction of utilizing carbon dioxide is to prepare polycarbonate by copolymerizing it with alkylene oxide under the action of a catalyst. The high polymer can be photodegraded and biodegraded; meanwhile, it has excellent performance of blocking oxygen and water. Therefore, polycarbonate can be used as engineering plastics, biodegradable non-polluting materials, disposable medical and food packaging materials, adhesives, and composite materials.

At present, there are many patent reports on the preparation of polycarbonate by copolymerization of carbon dioxide and alkylene oxide at home and abroad. For example, US patents US3585168, US3900424 and US3953383 use alkyl zinc-based two-component catalysts to obtain polycarbonate, polyurethane and polyether with a molecular weight higher than 20,000. Japanese published patents JP02142824 and JP02575199 use porphyrin complexes to catalyze carbon dioxide and alkylene oxide to synthesize polycarbonate, and the catalytic efficiency reaches 10 ³ to 10 ⁴ grams of polymer per mole of catalyst, but the molecular weight of the polymer is only about 5000, and the reaction time requires More than 10 days. Chinese patent application number CN89100701.6 and CN91109459.8 disclose the bimetallic catalytic system of polymer load anion coordination, also can obtain the catalytic efficiency of 10 ⁴ gram polymers/mole catalyst, but carrier is difficult to with the polycarbonate of generation separate. Chinese patent application numbers CN98125654.6, CN00136189.9 and CN03105023.9 report that the three-way catalyst system of alkyl zinc/glycerol/rare earth salt is used to prepare polycarbonate with a molecular weight higher than 20,000, and the alternating structure is greater than 95%. In U.S. Patent US6133402 and J.Am.Chem.Soc., (2002,124,14284), Coates described a highly active single-site organozinc catalyst, which has a catalytic activity of catalyzing the reaction of carbon dioxide and propylene oxide up to 235 moles of product/mole of catalyst per hour, polypropylene carbonate with a molecular weight between 20,000 and 40,000 and a narrow distribution is obtained, but 13 to 25% of cyclic propylene carbonate by-products are also produced simultaneously. In our previous patent application (Chinese patent application number: CN200410021316.5), it has been reported that a two-component catalytic system composed of a tetradentate Schiff base metal complex and a quaternary ammonium salt or a quaternary phosphonium salt can be used in a relatively mild Catalyzing the reaction of carbon dioxide and alkylene oxide under the conditions to synthesize polycarbonate with high selectivity, and the catalytic efficiency reaches 10 ⁵ grams of polymer/mole of catalyst.

The above methods for preparing polycarbonate mostly have low catalyst activity, long reaction time, and high pressure, requiring organic solvents; accompanied by the production of cyclic carbonate by-products or low carbonate units in the polymerization product; catalysts and reaction in the reaction system The molar ratio of the substrate is high; the separation of the product and the catalyst is difficult and other problems.

Contents of the invention

The technical problem to be solved by the present invention is to provide a monomolecular bifunctional catalyst that selectively catalyzes the reaction of carbon dioxide and alkylene oxide to prepare polycarbonate with high molecular weight and high alternating structure under low catalyst concentration and relatively mild reaction conditions.

The technical scheme of the invention is a bifunctional catalyst system tetradentate Schiff base metal complex for synthesizing polycarbonate, and its molecule contains quaternary ammonium salt or quaternary phosphonium salt group. The metal ion in the Schiff base metal complex has electrophilic properties, and the quaternary ammonium salt or phosphonium salt connected to the benzene ring has nucleophilic properties, which can be prepared by catalyzing the reaction of carbon dioxide and alkylene oxide at low concentration Polycarbonate material in alternating structure. The difference from our previously reported two-component catalyst system (Chinese patent application number: CN200410021316.5) is that the catalyst of the present invention is a single component, and its molecular structure contains both an electrophilic center and a nucleophilic center. The bifunctional catalyst has the following structural features:

or

or

In the formula, M is Fe ³⁺ , Co ³⁺ , Ni ³⁺ , Cr ³⁺ , Mn ³⁺ , Al ³⁺ or Ru ³⁺ trivalent metal ion; R ₁ and R ₂ are H, CH ₃ , -( CH) ₄ -, -(CH ₂ ) ₄ -, CH ₂ CH ₃ or Ph; R ₄ and R ₅ are H, C ₁ to C ₆ alkyl; R ₆ is C ₁ to C ₆ alkyl or Ph; n 0 to 10; Z is nitrogen or phosphorus; X, Y are F-1, Cl ^-1 , Br ^-1 , I ^-1 , NO ₃ ^-1 , CH ₃ COO ^-1 , CCl ₃ COO ^-1 , CF ₃ COO ^-1 , ClO ₄ ^-1 , BF ₄ ^-1 , BPh ₄ ^-1 , N ₃ ^-1 , p-toluate, p-toluenesulfonate, o-nitrophenol oxygen, p-nitro Phenol oxide, m-nitrophenol oxide, 2,4-dinitrophenol oxide, 3,5-dinitrophenol oxide, 2,4,6-trinitrophenol oxide, 3,5-dichlorophenol oxide , 3,5-difluorophenoloxy, 3,5-bis-trifluoromethylphenoloxy or pentafluorophenoloxy anion.

In the bifunctional catalyst structure, the metal ion is coordinated with a tetradentate Schiff base ligand obtained by reacting salicylaldehyde containing a quaternary ammonium salt or a quaternary phosphonium salt group with a diamine or triamine compound. Diamine compounds are ethylenediamine, 1,2-propylenediamine, 1,3-propylenediamine, 1,2-butanediamine, 2,3-butanediamine, cyclohexanediamine, o-phenylenediamine or diphenylethylenediamine. The triamine compound is diethylenetriamine.

When using the bifunctional catalyst provided by the invention, the molar ratio of catalyst and _alkylene oxide in the reaction system is 1: 2000 to 1: 200000, the CO pressure is 0.1 to 6.0 MPa, and the reaction temperature is 10 to 100 ° C. 48 hours.

The general structural formula of the reactant alkylene oxide used when preparing polycarbonate is:

或

or

Wherein R ₁ and R ₂ are H, CH ₃ , CH ₂ Cl, CH ₂ CH ₃ , CH ₂ (CH ₂ ) _n CH ₃ or CH ₂ (CH ₂ ) _n CHCH ₂ , wherein n is 1-12.

The method for preparing polycarbonate provided by the present invention has the following effects and benefits:

(1) At low catalyst concentration, it still has high catalytic activity;

(2) The reaction conditions are relatively mild and the process is simple;

(3) High catalyst activity and high selectivity of polymerization products;

(4) The alternating structure in the polycarbonate product is higher than 97%, and the molecular weight distribution is narrow;

(5) No need to add any organic solvent.

Detailed ways

Specific embodiments of the present invention will be described in detail below in conjunction with technical solutions.

Example 1

In a stainless steel autoclave with an effective volume of 200ml, add in the following order at ambient temperature: 0.1 mmol of tetradentate Schiff base cobalt complex (X, Y are 2,4-dinitrophenol oxyanions; R ₌ R ₂ = H; R ₃ is tert-butyl; R ₄ and R ₅ are methyl; R ₆ is n-butyl; n is 2; Z is nitrogen; the quaternary ammonium salt group is at the 5th position of the benzene ring) And 1 mole of propylene oxide, and then carbon dioxide gas and maintain a constant pressure of 2.0MPa. Control the temperature at 50°C, react under magnetic stirring for 6 hours, slowly release unreacted carbon dioxide in the autoclave, collect unreacted propylene oxide in a cold trap at -20°C, and then add a certain amount of methanol/chloroform mixture The polymer was dissolved, and then a large amount of ether was added to precipitate polycarbonate. It was filtered, washed several times with ether, and dried in vacuo to constant weight to obtain 37 g of polypropylene carbonate as a white solid. The average molecular weight of the polymer was determined by gel permeation chromatography to be 53800, and the molecular weight distribution was 1.27; the ¹ H-NMR was measured by a Varian INOVA-400MHz nuclear magnetic resonance instrument, and its alternating structure was found to exceed 99%.

Example 2

In the same equipment used in Example 1, under the same conditions, only the diamine skeleton in the tetradentate Schiff base cobalt complex was changed from ethylenediamine (ie R ₁ =R ₂ =H) to cyclohexanedi Amines (ie R ₁ , R ₂ are -(CH ₂ ) ₄ -)). After reacting at 50° C. for 6 hours, 39 g of polypropylene carbonate was obtained with a molecular weight of 62,000 and a molecular weight distribution of 1.33, and the carbonate units in the polymer exceeded 99%.

Example 3

In the same equipment used in Example 1, under the same conditions, only the diamine skeleton in the tetradentate Schiff base cobalt complex was changed from ethylenediamine (ie R ₁ =R ₂ =H) to phthalic diamine Amines (ie R ₁ , R ₂ are -(CH) ₄ -)). After reacting at 50° C. for 6 hours, 38 g of polypropylene carbonate was obtained, the molecular weight was 59400, the molecular weight distribution was 1.29, and the carbonate units in the polymer exceeded 99%.

Example 4

In the same equipment used in Example 1, under the same conditions, only the quaternary ammonium salt group on the benzene ring of the complex in the tetradentate Schiff base cobalt complex is changed from the 5-position to the 3-position, and the tert-butyl Changed from 3 digits to 5 digits. After reacting at 50° C. for 6 hours, 31 g of polypropylene carbonate was obtained, the molecular weight was 52300, the molecular weight distribution was 1.17, and the carbonate units in the polymer exceeded 99%.

Example 5

In the same equipment used in Example 1, under the same conditions, only the tert-butyl group at the 3-position of the complex benzene ring in the tetradentate Schiff base cobalt complex is also changed to be the same as that at the 5-position. containing quaternary ammonium salt groups. After reacting at 50° C. for 6 hours, 48 grams of polypropylene carbonate was obtained, the molecular weight was 46200, the molecular weight distribution was 1.41, and the carbonate units in the polymer exceeded 99%.

Example 6

Under the same equipment and same catalyst conditions as used in Example 1, only the reaction temperature was changed from 50°C to 25°C. After reacting at this temperature for 24 hours, 51 g of polypropylene carbonate was obtained, the molecular weight was 75100, the molecular weight distribution was 1.21, and the carbonate units in the polymer exceeded 99%.

Example 7

Under the same equipment and same catalyst conditions as used in Example 1, only the reaction temperature was changed from 50°C to 75°C. After reacting at this temperature for 2 hours, 41 g of polypropylene carbonate was obtained, the molecular weight was 43800, the molecular weight distribution was 1.28, and the carbonate units in the polymer exceeded 99%.

Example 8

Under the same equipment and the same catalyst conditions as used in Example 1, just change the molar ratio of catalyst to propylene oxide from 1: 10000 to 1: 20000. After reacting at 50° C. for 12 hours, 35 grams of polypropylene carbonate was obtained with a molecular weight of 91800 and a molecular weight distribution of 1.24, and the carbonate units in the polymer exceeded 99%.

Example 9

Under the same equipment and the same catalyst conditions used in Example 1, the reaction pressure was only increased from 2.0MPa to 5.0MPa. After reacting at 50° C. for 6 hours, 31 g of polypropylene carbonate was obtained with a molecular weight of 40800 and a molecular weight distribution of 1.19, and the carbonate units in the polymer exceeded 99%.

Example 10

Under the same equipment and same catalyst conditions as used in Example 1, except that 1,2-butylene oxide was used instead of propylene oxide. After reacting at 50° C. for 10 hours, 35 grams of polycarbonate was obtained, the molecular weight of which was 61400, the molecular weight distribution was 1.38, and the carbonate units in the polymer exceeded 99%.

Example 11

Under the same equipment and same catalyst conditions as used in Example 1, except that ethylene oxide was used instead of propylene oxide. After reacting at 50° C. for 6 hours, 32 grams of polycarbonate was obtained, the molecular weight was 44400, the molecular weight distribution was 1.41, and the carbonate units in the polymer exceeded 99%.

Example 12

In the same equipment used in Example 1, under the same conditions, only the metal ion in the tetradentate Schiff base metal complex is changed from cobalt to chromium, and X and Y in the complex are changed from 2,4-dinitro The phenol oxygen anion was changed to NO ₃ ^- anion. After reacting at 50° C. for 24 hours, 29 g of polypropylene carbonate was obtained, the molecular weight was 102,000, the molecular weight distribution was 1.37, and the carbonate unit in the polymer was 99%.

Example 13

In the same equipment used in Example 1, under the same conditions, only the metal ion in the tetradentate Schiff base metal complex is changed from cobalt to aluminum, and X and Y in the complex are changed from 2,4-dinitro The phenol oxyanion was changed to Cl ^- anion. After reacting at 50° C. for 24 hours, 17 g of polypropylene carbonate was obtained with a molecular weight of 32,000, a molecular weight distribution of 1.59, and 97% of carbonate units in the polymer.

Example 14

In the same equipment used in Example 1, under the same conditions, just R in the tetradentate Schiff base cobalt complex is changed from n _- butyl to phenyl, and Z is changed from nitrogen to phosphorus. After reacting at 50° C. for 6 hours, 34 g of polypropylene carbonate was obtained with a molecular weight of 63,700, a molecular weight distribution of 1.21, and 99% of carbonate units in the polymer.

Example 15

In the same equipment used in Example 13, under the same conditions, just change X, Y in the tetradentate Schiff base cobalt complex from 2,4-dinitrophenol oxyanion to Cl ^- anion. After reacting at 50° C. for 6 hours, 29 g of polypropylene carbonate was obtained with a molecular weight of 51,000, a molecular weight distribution of 1.38, and 99% of carbonate units in the polymer.

Claims (7)

1. the dual-function catalyst that is used for polycarbonate synthesis is characterized in that this catalyzer is the tetradentate schiff base metal complexes, and contains quaternary ammonium salt Huo quaternary alkylphosphonium salt group in the molecule; Wherein, M is Fe ³⁺, Co ³⁺, Ni ³⁺, Cr ³⁺, Mn ³⁺, Al ³⁺Or Ru ³⁺X is F ^-1, Cl ^-1, Br ^-1, I ^-1, NO ₃ ^-1, CH ₃COO ^-1, CCl ₃COO ^-1, CF ₃COO ^-1, ClO ₄ ^-1, BF ₄ ^-1, BPh ₄ ^-1, N ₃ ^-1, p-methylbenzoic acid root, p-methyl benzenesulfonic acid root, ONP oxygen, right-nitrophenols oxygen ,-nitrophenols oxygen, 2,2, 4-dinitrophenol oxygen, 3,5-dinitrophenol(DNP) oxygen, 2,4,6-trinitrophenol oxygen, 3,5-chlorophenesic acid oxygen, 3,5-difluorophenol oxygen, 3,5-di-trifluoromethyl phenol oxygen or pentafluranol negative oxygen ion.

2. the dual-function catalyst that is used for polycarbonate synthesis according to claim 1 is characterized in that the structure of this tetradentate schiff base metal complexes is:

In the formula: R ₁, R ₂Be H, CH ₃,-(CH) ₄-,-(CH ₂) ₄-, CH ₂CH ₃Or Ph; R ₃Be H, C ₁～C ₆Alkyl, C ₁～C ₆Alkoxyl group, Cl, Br or NO ₂Group; R ₄, R ₅Be H, C ₁～C ₆Alkyl; R ₆Be C ₁～C ₆Alkyl or Ph; N is 0～10; Z is elemental nitrogen or phosphorus; Y is F ^-1, Cl ^-1, Br ^-1, I ^-2, NO ₃ ^-1, CH ₃COO ^-1, CCl ₃COO ^-1, CF ₃COO ^-1, ClO ₄ ^-1, BF ₄ ^-1, BPh ₄ ^-1, N ₃ ^-1, p-methylbenzoic acid root, p-methyl benzenesulfonic acid root, ONP oxygen, right-nitrophenols oxygen ,-nitrophenols oxygen, 2,2, 4-dinitrophenol oxygen, 3,5-dinitrophenol(DNP) oxygen, 2,4,6-trinitrophenol oxygen, 3,5-chlorophenesic acid oxygen, 3,5--fluorophenol oxygen, 3,5-di-trifluoromethyl phenol oxygen or pentafluranol negative oxygen ion.

3. the dual-function catalyst that is used for polycarbonate synthesis according to claim 1 is characterized in that the structure of this tetradentate schiff base metal complexes is:

In the formula: R ₁, R ₂Be H, CH ₃,-(CH) ₄-,-(CH ₂) ₄-, CH ₂CH ₃Or Ph; R ₃Be H, C ₁～C ₆Alkyl, C ₁～C ₆Alkoxyl group, Cl, Br or NO ₂Group; R ₄, R ₅Be H, C ₁～C ₆Alkyl; R ₆Be C ₁～C ₆Alkyl or Ph; N is 0～10; Z is elemental nitrogen or phosphorus; Y is F ^-1, Cl ^-1, Br ^-1, I ^-1, NO ₃ ^-1, CH ₃COO ^-1, CCl ₃COO ^-1, CF ₃COO ^-1, ClO ₄ ^-1, BF ₄ ^-1, BPh ₄ ^-1, N ₃ ^-1, p-methylbenzoic acid root, p-methyl benzenesulfonic acid root, ONP oxygen, right-nitrophenols oxygen ,-nitrophenols oxygen, 2,2, 4-dinitrophenol oxygen, 3,5-dinitrophenol(DNP) oxygen, 2,4,6-trinitrophenol oxygen, 3,5-chlorophenesic acid oxygen, 3,5-difluorophenol oxygen, 3,5-di-trifluoromethyl phenol oxygen or pentafluranol negative oxygen ion.

4. the dual-function catalyst that is used for polycarbonate synthesis according to claim 1 is characterized in that the structure of this tetradentate schiff base metal complexes is:

In the formula: R ₁, R ₂Be H, CH ₃,-(CH) ₄-,-(CH ₂) ₄-, CH ₂CH ₃Or Ph; R ₄, R ₅Be H, C ₁～C ₆Alkyl; R ₆Be C ₁～C ₆Alkyl or Ph; N is 0～10; Z is elemental nitrogen or phosphorus; Y is F ^-1, Cl ^-1, Br ^-1, I ^-1, NO ₃ ^-1, CH ₃COO ^-1, CCl ₃COO ^-1, CF ₃COO ^-1, ClO ₄ ^-1, BF ₄ ^-1, BPh ₄ ^-1, N ₃ ^-1, p-methylbenzoic acid root, p-methyl benzenesulfonic acid root, ONP oxygen, right-nitrophenols oxygen ,-nitrophenols oxygen, 2,2, 4-dinitrophenol oxygen, 3,5-dinitrophenol(DNP) oxygen, 2,4,6-trinitrophenol oxygen, 3,5-chlorophenesic acid oxygen, 3,5-difluorophenol oxygen, 3,5-di-trifluoromethyl phenol oxygen or pentafluranol negative oxygen ion.

5. according to each described dual-function catalyst that is used for polycarbonate synthesis of claim 1-4, it is characterized in that part in the tetradentate schiff base metal complexes is to be made by the salicylic aldehyde that contains quaternary ammonium salt or quaternary alkylphosphonium salt group and diamines or the reaction of three aminated compoundss; Diamine compounds is a quadrol, 1,2-propylene diamine, 1,3-propylene diamine, 1,2-butanediamine, 2,3-butanediamine, cyclohexanediamine, O-Phenylene Diamine or diphenyl ethylene diamine; Three aminated compoundss are diethylenetriamines.

6. method of using the described dual-function catalyst polycarbonate synthesis of claim 1, it is characterized in that being used for catalysis carbonic acid gas and epoxy alkane prepared in reaction polycarbonate, application rights requires each described dual-function catalyst of 2-4, and temperature of reaction is 10～100 ℃, CO ₂Pressure is 0.1～6.0MPa, and the mol ratio of catalyzer and epoxy alkane is 1: 2000 to 1: 200000, reacts 1～48 hour.

7. a kind of method of using the described dual-function catalyst polycarbonate synthesis of claim 1 according to claim 6 is characterized in that as the general structure of reactant epoxy alkane being:

R wherein ₁, R ₂Be H, CH ₃, CH ₂Cl, CH ₂CH ₃, CH ₂(CH ₂) _nCH ₃Or CH ₂(CH ₂) _nCHCH ₂, wherein n is 1～12.