CN113929885B - Composite catalyst and application thereof in preparation of glycolide - Google Patents
Composite catalyst and application thereof in preparation of glycolide Download PDFInfo
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- CN113929885B CN113929885B CN202111213592.1A CN202111213592A CN113929885B CN 113929885 B CN113929885 B CN 113929885B CN 202111213592 A CN202111213592 A CN 202111213592A CN 113929885 B CN113929885 B CN 113929885B
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G63/00—Macromolecular compounds obtained by reactions forming a carboxylic ester link in the main chain of the macromolecule
- C08G63/02—Polyesters derived from hydroxycarboxylic acids or from polycarboxylic acids and polyhydroxy compounds
- C08G63/06—Polyesters derived from hydroxycarboxylic acids or from polycarboxylic acids and polyhydroxy compounds derived from hydroxycarboxylic acids
- C08G63/08—Lactones or lactides
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G63/00—Macromolecular compounds obtained by reactions forming a carboxylic ester link in the main chain of the macromolecule
- C08G63/78—Preparation processes
- C08G63/82—Preparation processes characterised by the catalyst used
- C08G63/823—Preparation processes characterised by the catalyst used for the preparation of polylactones or polylactides
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
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- Y02P20/52—Improvements relating to the production of bulk chemicals using catalysts, e.g. selective catalysts
Abstract
The invention relates to a composite catalyst and application thereof in preparation of glycolide. The preparation method provided by the invention utilizes the stability and moderate Lewis acidity of 4,4' -xylyl phenyl methyl carbonium tetrafluoroborate and coordinates with a cocatalyst to catalyze the dealcoholization and polycondensation reaction of methyl glycolate, and then catalyzes the cracking and cyclization reaction of the methyl glycolate under the high-temperature and high-vacuum environment to prepare glycolide. The glycolide prepared by the catalyst for catalyzing the polycondensation and the cracking cyclization of the methyl glycolate has the characteristics of high purity, high yield, low viscosity of cracking cyclization substrates and no coking.
Description
Technical Field
The invention belongs to the field of glycolide synthesis catalysts, and particularly relates to a catalyst for catalyzing polycondensation of methyl glycolate and cyclization and cracking of poly methyl glycolate formed by polycondensation to generate glycolide and a method for preparing glycolide by using the catalyst.
Background
Polyglycolide (abbreviated as PGA, also known as polyglycolic acid, polyglycolic acid ester) has a main chain structure as follows:
the main chain structure has completely degradable ester chemical groups, the degradation speed is high under the action of hydrolysis and the like, and finally degraded products in nature are carbon dioxide and water, so that the material is considered as an ideal completely biodegradable high polymer material. PGA may be a polymer obtained by ring-opening polymerization of glycolide or by direct polycondensation of glycolic acid (ester). However, since it is relatively difficult to obtain PGA having a relative molecular mass of one hundred thousand or more by the conventional direct polycondensation method, the most mature method for producing PGA is to synthesize glycolide by cyclization of glycolic acid (ester) and then produce polyglycolic acid by ring-opening polymerization of glycolide, as shown in the following formula:
the cost of glycolide as a core material for the preparation of PGA and its copolymers has been one of the important factors that restrict the application of PGA. Methyl glycolate can be obtained through a coal chemical industry route, and is a relatively cheap chemical raw material. Therefore, if a highly efficient catalyst can be developed and a suitable process can be used to produce glycolide from methyl glycolate, it is expected that the production cost of PGA can be greatly reduced.
Patent publication No. CN112469704A reports a process for preparing glycolide products from poly (methyl glycolate) or products thereof. The method takes the polyglycolic acid methyl ester as a raw material, adopts an all-metal compound catalyst, firstly hydrolyzes the polyglycolic acid methyl ester, then polymerizes the polyglycolic acid methyl ester, and then carries out pyrolysis (the term "pyrolysis" is the same as the term "cracking cyclization", "cracking" or "depolymerization" in the invention) under high temperature and high vacuum by matching with a viscosity reducer, thereby solving the problems that a depolymerization substrate is easy to carbonize and has high viscosity and the yield of crude glycolide is low in the glycolide generation process. However, this method has a problem that the process flow is long, the addition of a viscosity-reducing agent causes inconvenience in the recovery of the substrate, and the inclusion of free acids in glycolide causes an increase in cost.
Patent publication No. CN 111548339A reports a method for preparing glycolide by polycondensation and depolymerization of glycolates by using common tin, antimony and zinc metal compounds as catalysts. However, the method needs complex equipment to solve the problems of low purity of crude glycolide in the preparation process and easy coking in the depolymerization process. And the polycondensation process of the glycolate needs a vacuum environment, and has certain requirements on polycondensation equipment.
Methyl glycolate can generate polymerization reaction under the catalysis of certain Lewis acid to generate poly-methyl glycolate, but few related reports exist about special catalysts which are specially used for preparing glycolide by firstly polymerizing methyl glycolate and then depolymerizing (cracking cyclization).
Carbocations are ions of a positively charged carbon atom that are generally unstable and highly reactive because they do not have 8 electrons to satisfy the octagon rule. The carbonium ion is an sp2 hybridized plane at the carbon center of the carbonium ion, has an empty P orbital with positive charge, and can be used for receiving electrons. Thus, carbenium is a potential Lewis acid organic molecular catalyst. However, triphenylcarbenium ion has unusual stability and strong Lewis acidity due to its unique structure. And the Lewis acidity of the triphenylcarbenium ion can be adjusted by changing the electron cloud density on the aromatic ring. For carbenium ions, the more electron donating groups on the aromatic ring, the more Lewis acidic the compound is. Compared with the conventional metal Lewis acid catalyst, the adjustability of Lewis acidity of the carbenium ion is a remarkable advantage, so that the carbenium ion has obvious advantages in certain synthesis fields which are sensitive to the Lewis acidity of the catalyst.
The invention content is as follows:
aiming at the defects of the prior art, the invention aims to provide a catalyst, a preparation method of the catalyst and catalytic application of the catalyst in a glycolide preparation method, so as to solve the problems of more side reactions, easy coking and carbonization of a substrate, low product purity and complex process equipment in the conventional preparation of glycolide from methyl glycolate.
Technical scheme
The invention provides a catalyst which takes triphenyl carbonium ions as a main catalyst, and the catalyst is used for the catalytic application of preparing glycolide from methyl glycolate, and a method for synthesizing glycolide by applying the catalyst.
A method for preparing a composite catalyst, comprising the steps of:
(1) adding the measured ethyl benzoate and p-methylphenyl magnesium bromide into anhydrous tetrahydrofuran, refluxing for 3h at 70-80 ℃, and providing for the step (2).
(2) And dropwise adding an ammonium chloride aqueous solution in an ice bath to quench the reaction, and then carrying out liquid separation to obtain an organic phase.
(3) Evaporating the organic phase obtained in the step (2) to dryness at 120-160 ℃ by using a rotary evaporator to obtain a viscous yellow oily substance, namely 4,4' -dimethyl triphenyl carbinol.
(4) Dissolving the 4,4' -dimethyl triphenyl carbinol obtained in the step (3) in ether, stirring and slowly dripping the tetrafluoroboric acid ether solution (HBF) 4 50 percent by mass) of the total amount of the sodium tetrafluoroborate, generating yellow precipitates, and drying the precipitates to obtain the 4,4' -xylyl phenyl methyl carbonium tetrafluoroborate.
(5) And (3) compounding the 4,4' -xylyl phenyl methyl carbonium tetrafluoroborate obtained in the step (4) and zinc oxide serving as a cocatalyst according to a certain proportion to obtain the composite catalyst.
In the step (1), the mol ratio of the ethyl benzoate to the p-methylphenyl magnesium bromide is 1:2 to 1:4.
in the step (2), the ratio of the mol amount of ammonium chloride contained in the dropwise added ammonium chloride aqueous solution to the mol amount of methyl phenyl magnesium bromide is 1:1 to 2:1
In the step (3), the mol amount of the tetrafluoroboric acid contained in the dropwise added tetrafluoroboric acid diethyl ether solution is 1 to 2 times of the mol amount of 4,4' -dimethyltriphenylmethanol.
In the step (5), the mass ratio of the 4,4' -xylyl phenyl methyl carbonium tetrafluoroborate to the zinc oxide is 1:1 to 4:1.
in the step (5), the 4,4' -xylyl phenyl methyl carbonium tetrafluoroborate has a structural formula shown in the following figure
A composite catalyst prepared by the method of any one of claims 1 to 5.
The use of the catalyst in the preparation of glycolide from methyl glycolate is characterized in that: firstly, methyl glycolate and the catalyst are stirred and mixed in a reaction kettle, and react for a period of time at 140-230 ℃ under normal pressure environment to obtain methyl glycolate oligomer, and then the methyl glycolate oligomer is subjected to cracking cyclization reaction at 230-245 ℃ under vacuum 50-500 Pa (absolute pressure) environment to generate glycolide.
Specifically, the method comprises the following reaction steps:
polycondensation reaction of methyl glycolate: taking a certain amount of methyl glycolate into a reaction kettle, then adding the composite catalyst prepared by the invention into the reaction kettle, and starting stirring, wherein the dosage of the catalyst is 0.5-1% of the mass of the methyl glycolate. Then, the temperature is raised to 140 ℃ N 2 Reacting for 2-4 h under the protection of normal pressure, and heating to 180 ℃ to obtain N 2 Reacting for 4-6 h under the protection of normal pressure, and finally heating to 230 ℃ N 2 The reaction is carried out for 2 to 4 hours under the protection of normal pressure, thus completing the polycondensation reaction of the methyl glycolate and obtaining the low molecular weight poly-methyl glycolate.
Depolymerization and cyclization reaction: the reaction vessel is evacuated to 50 to 500Pa (absolute pressure) at all times, and heated to obtain glycolide by a depolymerization cyclization reaction of low molecular weight poly (methyl glycolate) at high temperature under high vacuum. The temperature control process comprises the following steps: keeping the temperature in the reaction kettle at 230 ℃ and reacting for 1-2 h; heating to 240 ℃ and reacting for 1-2 h; finally, the temperature is raised to 245 ℃ for reaction for 0.5 to 1 hour.
Advantageous effects
The catalyst provided by the invention can greatly improve the conversion rate of methyl glycolate into crude glycolide, and the obtained crude glycolide has higher purity. On the one hand, 4' -ditolyl phenyl methyl carbonium tetrafluoroborate has moderate Lewis acidity and can show good compatibility with the auxiliary catalyst zinc oxide; on the other hand, 4' -ditolylphenylmethyl carbenium as a phenyl carbenium has higher stability than a general carbenium.
Drawings
FIG. 1-nuclear magnetic hydrogen spectrum of tolylbenzhydryl carbonium tetrafluoroborate
FIG. 2, 4' -ditolyl phenyl methyl carbonium ion tetrafluoroborate nuclear magnetic hydrogen spectrum
FIG. 3 ' 4',4' -Trimethylphenylmethyl carbonium tetrafluoroborate nuclear magnetic hydrogen spectrogram
Detailed Description
The following detailed description is given for the purpose of illustration, but it is to be understood that the invention is not limited to the specific embodiments disclosed, and that various insubstantial changes and modifications can be made by one skilled in the art based on the teachings of the invention described above.
Except where specifically stated, the apparatus and methods used in the present invention are those commonly used in the art. Glycolide purity test method: the obtained crude glycolide was mixed, crushed and mixed uniformly by a crusher, and then sampled, and the melting point of glycolide was measured by a DSC apparatus (hitachi, model DSC 7020). The purity is evaluated by the melting point of glycolide, the higher the melting point the higher the purity. The specific DSC test method comprises the following steps: taking a proper amount of glycolide sample, and heating glycolide to 90 ℃ from 40 ℃ at a heating rate of 5 ℃/min. The nuclear magnetic test method comprises the following steps: after dissolving the sample in 0.5-0.6 ml of deuterated reagent, the sample is transferred into a nuclear magnetic tube, and the synthesized carbenium tetrafluoroborate is characterized by performing nuclear magnetic resonance hydrogen spectrum analysis on a nuclear magnetic resonance apparatus (Bruker Avance AV-400, switzerland Bruker).
Example 1
1.1 preparation of the catalyst
(1) The metered amount of ethyl benzoate (30 mmol) and p-methylphenylmagnesium bromide (60 mmol) were added to 60ml of anhydrous tetrahydrofuran and refluxed at 70 ℃ for 3 hours.
(2) An aqueous ammonium chloride solution (containing 30mmol of ammonium chloride) was added dropwise to the reaction mixture in an ice bath to quench the reaction, followed by liquid separation to obtain an organic phase.
(3) And (3) evaporating the organic phase obtained in the step (2) to dryness at 120 ℃ by using a rotary evaporator to obtain a viscous yellow oily substance, namely 4,4' -dimethyl triphenyl carbinol (5.76g, 20mmol).
(4) Dissolving the 4,4' -dimethyl triphenyl carbinol obtained in the step (3) in ether, stirring and slowly dripping the tetrafluoroboric acid ether solution (HBF) 4 50 percent of the weight percentage content and 40mmol HBF 4 ) Yellow precipitate is generated, and the precipitate is washed and dried to obtain the 4,4' -xylyl phenyl methyl carbonium tetrafluoroborate (4.9)2g)。
(5) And (3) compounding the 4,4' -xylyl phenyl methyl carbonium tetrafluoroborate obtained in the step (4) with zinc oxide serving as a cocatalyst according to a mass ratio of 4.
1.2 preparation method of glycolide:
taking 200g of methyl glycolate into a reaction kettle, then adding 1g of composite catalyst into the reaction kettle, starting stirring, heating to 140 ℃ and raising the temperature to N 2 Reacting for 4 hours under the protection of normal pressure, and then heating to 180 ℃ N 2 Reacting for 4 hours under the protection of normal pressure, and finally, heating to 230 ℃ N 2 The reaction is carried out for 2h under the protection of normal pressure, thus completing the polycondensation reaction of the methyl glycolate and obtaining the low molecular weight poly-methyl glycolate. Vacuumizing the reaction kettle to 50Pa (absolute pressure), heating to enable low molecular weight poly (methyl glycolate) to undergo cracking cyclization reaction, collecting the extracted glycolide in the process, and opening a bottom valve of the reaction kettle to discharge a cracking substrate. The heating process of the cracking cyclization reaction comprises the following steps: keeping the temperature in the reaction kettle at 230 ℃ and reacting for 1h; heating to 240 ℃ and reacting for 1h; and finally, heating to 245 ℃ for reaction for 1h, collecting the extracted glycolide, and opening a bottom valve of the reaction kettle to discharge a cracking substrate.
The measurement and test results of the collected glycolide are shown in Table 1
Example 2
2.1 preparation of the catalyst
(1) The metered amount of ethyl benzoate (30 mmol) and p-methylphenylmagnesium bromide (120 mmol) were added to 60ml of anhydrous tetrahydrofuran and refluxed at 70 ℃ for 3 hours.
(2) An aqueous ammonium chloride solution (containing 240mmol of ammonium chloride) was added dropwise to the mixture in an ice bath to quench the reaction, followed by liquid separation to obtain an organic phase.
(3) And (3) evaporating the organic phase obtained in the step (2) to dryness at 160 ℃ by using a rotary evaporator to obtain a viscous yellow oily substance, namely 4,4' -dimethyltriphenylmethanol (7.49g, 26mmol).
(4) Dissolving the 4,4' -dimethyl triphenyl carbinol obtained in the step (3) in ether, stirring and slowly dripping the tetrafluoroboric acid ether solution (HBF) 4 50 percent of the weight percentage content and 26mmol HBF 4 ) Yellow precipitate is formed, and the precipitate is washed and driedThus, 4' -ditolylphenylmethylcarbenonium tetrafluoroborate (5.40 g) was obtained.
(5) And (3) compounding the 4,4' -ditolyl phenyl methyl carbonium tetrafluoroborate obtained in the step (4) with zinc oxide serving as a cocatalyst according to the mass ratio of 1.
2.2 preparation method of glycolide:
taking 200g of methyl glycolate into a reaction kettle, then adding 2g of composite catalyst into the reaction kettle, starting stirring, heating to 140 ℃ and raising the temperature to N 2 Reacting for 2 hours under the protection of normal pressure, and then heating to 180 ℃ N 2 Reacting for 6h under the protection of normal pressure, and finally, heating to 230 ℃ N 2 The reaction is carried out for 2 to 4 hours under the protection of normal pressure, thus completing the polycondensation reaction of the methyl glycolate and obtaining the low molecular weight poly-methyl glycolate. Vacuumizing the reaction kettle to 150Pa (absolute pressure), heating to enable low molecular weight poly (methyl glycolate) to undergo cracking cyclization reaction, collecting the extracted glycolide in the process, and opening a bottom valve of the reaction kettle to discharge a cracking substrate. The heating process of the cracking cyclization reaction comprises the following steps: keeping the temperature in the reaction kettle at 230 ℃ and reacting for 2 hours; heating to 240 ℃ and reacting for 1h; finally, the temperature is raised to 245 ℃ for reaction for 0.5h.
The measurement and test results of the collected glycolide are shown in Table 1
Example 3
3.1 preparation of the catalyst
(1) The metered amount of ethyl benzoate (30 mmol) and p-methylphenylmagnesium bromide (80 mmol) are introduced into 60ml of anhydrous tetrahydrofuran and refluxed at 70 ℃ for 3 hours.
(2) An aqueous ammonium chloride solution (containing 120mmol of ammonium chloride) was added dropwise to the reaction mixture in an ice bath to quench the reaction, followed by liquid separation to obtain an organic phase.
(3) And (3) evaporating the organic phase obtained in the step (2) to dryness at 140 ℃ by using a rotary evaporator to obtain a viscous yellow oily substance, namely 4,4' -dimethyl triphenyl carbinol (7.78g, 27mmol).
(4) Dissolving the 4,4' -dimethyl triphenyl carbinol obtained in the step (3) in ether, stirring and slowly dripping the tetrafluoroboric acid ether solution (HBF) 4 50 percent of the weight percentage of the HBF and 30mmol of HBF 4 ) Yellow precipitate is generated, and the precipitate is washed and dried to obtain the productTo 4,4' -ditolylphenylmethylcarbenonium tetrafluoroborate (5.83 g).
(5) And (5) compounding the 4,4' -xylyl phenyl methyl carbonium tetrafluoroborate obtained in the step (4) with a promoter zinc oxide according to the mass ratio of 3.
3.2 preparation method of glycolide:
taking 200g of methyl glycolate into a reaction kettle, then adding 2g of composite catalyst into the reaction kettle, starting stirring, heating to 140 ℃ and raising the temperature to N 2 Reacting for 4 hours under the protection of normal pressure, and then heating to 180 ℃ N 2 Reacting for 4 hours under the protection of normal pressure, and finally, heating to 230 ℃ N 2 The reaction is carried out for 4 hours under the protection of normal pressure, thus completing the polycondensation reaction of the methyl glycolate and obtaining the low molecular weight poly-methyl glycolate. Vacuumizing the reaction kettle to 500Pa (absolute pressure), heating to enable low molecular weight poly (methyl glycolate) to undergo cracking cyclization reaction, collecting the extracted glycolide in the process, and opening a bottom valve of the reaction kettle to discharge a cracking substrate. The heating process of the cracking cyclization reaction comprises the following steps: keeping the temperature in the reaction kettle at 230 ℃ and reacting for 2 hours; heating to 240 ℃ for reaction for 2h; and finally, heating to 245 ℃ for reaction for 1h, collecting the extracted glycolide, and opening a bottom valve of the reaction kettle to discharge a cracking substrate.
The measurement and test results of the collected glycolide are shown in Table 1
Example 4
4.1 preparation of the catalyst
Same as example 3
4.2 preparation method of glycolide:
taking 200g of methyl glycolate into a reaction kettle, then adding 2g of composite catalyst into the reaction kettle, starting stirring, heating to 140 ℃ and raising the temperature to N 2 Reacting for 4 hours under the protection of normal pressure, and then heating to 180 ℃ N 2 Reacting for 4 hours under the protection of normal pressure, and finally, heating to 230 ℃ N 2 The reaction is carried out for 4 hours under the protection of normal pressure, thus completing the polycondensation reaction of the methyl glycolate and obtaining the low molecular weight poly-methyl glycolate. Vacuumizing the reaction kettle to 100Pa (absolute pressure), heating to enable low molecular weight poly (methyl glycolate) to undergo cracking cyclization reaction, collecting the extracted glycolide in the process, and opening a bottom valve of the reaction kettle to discharge a cracking substrate. Cleavage cyclizationThe heating process of the reaction is as follows: keeping the temperature in the reaction kettle at 230 ℃ and reacting for 2 hours; heating to 240 ℃ for reaction for 2h; and finally, heating to 245 ℃ for reaction for 1h, collecting the extracted glycolide, and opening a bottom valve of the reaction kettle to discharge a cracking substrate.
The measurement and test results of the collected glycolide are shown in Table 1
Example 5
5.1 preparation of the catalyst
Same as example 3
4.2 preparation method of glycolide: (the amount of the composite catalyst is slightly larger)
Taking 200g of methyl glycolate into a reaction kettle, then adding 4g of composite catalyst into the reaction kettle, starting stirring, heating to 140 ℃ and raising the temperature to N 2 Reacting for 4 hours under the protection of normal pressure, and then heating to 180 ℃ N 2 Reacting for 4 hours under the protection of normal pressure, and finally, heating to 230 ℃ N 2 The reaction is carried out for 4h under the protection of normal pressure, thus completing the polycondensation reaction of methyl glycolate and obtaining low molecular weight poly-methyl glycolate. Vacuumizing the reaction kettle to 100Pa (absolute pressure), heating to enable low molecular weight poly (methyl glycolate) to undergo cracking cyclization reaction, collecting the extracted glycolide in the process, and opening a bottom valve of the reaction kettle to discharge a cracking substrate. The heating process of the cracking cyclization reaction comprises the following steps: keeping the temperature in the reaction kettle at 230 ℃ and reacting for 2 hours; heating to 240 ℃ for reaction for 2h; and finally, heating to 245 ℃ for reaction for 1h, collecting the extracted glycolide, and opening a bottom valve of the reaction kettle to discharge a cracking substrate.
The measurement and test results of the collected glycolide are shown in Table 1
Example 6
6.1 preparation of the catalyst
(1) The metered amount of ethyl benzoate (30 mmol) and p-methylphenylmagnesium bromide (100 mmol) were added to 60ml of anhydrous tetrahydrofuran and refluxed at 70 ℃ for 3 hours.
(2) An aqueous ammonium chloride solution (containing 150mmol of ammonium chloride) was added dropwise to the reaction mixture in an ice bath to quench the reaction, followed by liquid separation to obtain an organic phase.
(3) And (3) evaporating the organic phase obtained in the step (2) to dryness at 140 ℃ by using a rotary evaporator to obtain a viscous yellow oily substance, namely 4,4' -dimethyl triphenyl carbinol (7.20g, 25mmol).
(4) Dissolving the 4,4' -dimethyl triphenyl carbinol obtained in the step (3) in ether, stirring and slowly dripping the tetrafluoroboric acid ether solution (HBF) 4 50 percent of the weight percentage of the HBF powder and 40mmol of HBF 4 ) Yellow precipitate was formed, and the precipitate was washed and dried to obtain 4,4' -ditolyl phenyl methyl carbonium tetrafluoroborate (5.36 g).
(5) And (3) compounding the 4,4' -ditolyl phenyl methyl carbonium tetrafluoroborate obtained in the step (4) with zinc oxide serving as a cocatalyst according to the mass ratio of 2.
6.2 preparation method of glycolide:
adding 200g of methyl glycolate into a reaction kettle, then adding 1.6g of composite catalyst into the reaction kettle, starting stirring, heating to 140 ℃ and raising the temperature to N 2 Reacting for 2 hours under the protection of normal pressure, and then heating to 180 ℃ N 2 Reacting for 4 hours under the protection of normal pressure, and finally, heating to 230 ℃ N 2 The reaction is carried out for 3h under the protection of normal pressure, thus completing the polycondensation reaction of the methyl glycolate and obtaining the low molecular weight poly-methyl glycolate. Vacuumizing the reaction kettle to 200Pa (absolute pressure), heating to enable low molecular weight poly (methyl glycolate) to undergo cracking cyclization reaction, collecting the extracted glycolide in the process, and opening a bottom valve of the reaction kettle to discharge a cracking substrate. The heating process of the cracking cyclization reaction comprises the following steps: keeping the temperature in the reaction kettle at 230 ℃ and reacting for 2 hours; heating to 240 ℃ and reacting for 1h; and finally, heating to 245 ℃ for reaction for 0.5h, collecting the extracted glycolide, and opening a bottom valve of the reaction kettle to discharge a cracking substrate.
The measurement and test results of the collected glycolide are shown in Table 1
Example 7
7.1 preparation of the catalyst
(1) The metered amounts of ethyl benzoate (30 mmol) and p-methylphenylmagnesium bromide (80 mmol) are introduced into 60ml of anhydrous tetrahydrofuran and refluxed at 70 ℃ for 3h.
(2) An aqueous ammonium chloride solution (containing 120mmol of ammonium chloride) was added dropwise to the reaction mixture in an ice bath to quench the reaction, followed by liquid separation to obtain an organic phase.
(3) And (3) evaporating the organic phase obtained in the step (2) to dryness at 140 ℃ by using a rotary evaporator to obtain a viscous yellow oily substance, namely 4,4' -dimethyl triphenyl carbinol (7.78g, 27mmol).
(4) Dissolving the 4,4' -dimethyl triphenyl carbinol obtained in the step (3) in ether, stirring and slowly dripping the tetrafluoroboric acid ether solution (HBF) 4 50 percent of the weight percentage of the HBF and 30mmol of HBF 4 ) Yellow precipitate was formed, and the precipitate was washed and dried to obtain 4,4' -ditolyl phenyl methyl carbonium tetrafluoroborate (5.83 g).
(5) 4,4' -xylyl phenyl methyl carbonium tetrafluoroborate obtained in the step (4) is not subjected to compound treatment and is directly used as a catalyst special for preparing glycolide from methyl glycolate.
7.2 preparation method of glycolide:
adding 200g of methyl glycolate into a reaction kettle, then adding 1g of 4,4' -xylyl phenyl methyl carbonium tetrafluoroborate into the reaction kettle, starting stirring, heating to 140 ℃ and raising the temperature to N 2 Reacting for 4 hours under the protection of normal pressure, and then heating to 180 ℃ N 2 Reacting for 4 hours under the protection of normal pressure, and finally, heating to 230 ℃ N 2 The reaction is carried out for 4h under the protection of normal pressure, thus completing the polycondensation reaction of methyl glycolate and obtaining low molecular weight poly-methyl glycolate. Vacuumizing the reaction kettle to 500Pa (absolute pressure), heating to enable low molecular weight poly (methyl glycolate) to undergo cracking cyclization reaction, collecting the extracted glycolide in the process, and opening a bottom valve of the reaction kettle to discharge a cracking substrate. The heating process of the cracking cyclization reaction comprises the following steps: keeping the temperature in the reaction kettle at 230 ℃ and reacting for 2 hours; heating to 240 ℃ for reaction for 2h; and finally, heating to 245 ℃ for reaction for 1h, collecting the extracted glycolide, and opening a bottom valve of the reaction kettle to discharge a cracking substrate.
The measurement and test results of the collected glycolide are shown in Table 1
Comparative example 1
Preparing a catalyst:
(1) a metered amount of benzophenone (30 mmol) and p-methylphenylmagnesium bromide (80 mmol) are added to 60ml of anhydrous tetrahydrofuran and refluxed at 70 ℃ for 3h.
(2) An aqueous ammonium chloride solution (containing 120mmol of ammonium chloride) was added dropwise to the reaction mixture in an ice bath to quench the reaction, followed by liquid separation to obtain an organic phase.
(3) And (3) evaporating the organic phase obtained in the step (2) to dryness at 140 ℃ by using a rotary evaporator to obtain a viscous yellow oily substance, namely the 4-methyl triphenyl methanol (5.6 g,20.4 mmol).
(4) Dissolving the 4-methyl triphenyl carbinol obtained in the step (3) in ether, stirring and slowly dropwise adding the tetrafluoroboric acid ether solution (HBF) 4 50 percent of the weight percentage content and 30mmol HBF 4 ) Yellow precipitate was formed, and the precipitate was washed and dried to obtain 4-tolyldiphenylmethylcarbapentanium tetrafluoroborate (5.05 g).
(5) And (5) compounding the 4-tolyl diphenyl methyl carbonium tetrafluoroborate obtained in the step (4) with a cocatalyst zinc oxide according to a mass ratio of 3.
The preparation method of glycolide comprises the following steps:
taking 200g of methyl glycolate into a reaction kettle, then adding 2g of composite catalyst into the reaction kettle, starting stirring, heating to 140 ℃ and raising the temperature to N 2 Reacting for 4 hours under the protection of normal pressure, and then heating to 180 ℃ N 2 Reacting for 4 hours under the protection of normal pressure, and finally, heating to 230 ℃ N 2 The reaction is carried out for 4h under the protection of normal pressure, thus completing the polycondensation reaction of methyl glycolate and obtaining low molecular weight poly-methyl glycolate. Vacuumizing the reaction kettle to 100Pa (absolute pressure), heating to enable low molecular weight poly (methyl glycolate) to undergo cracking cyclization reaction, collecting the extracted glycolide in the process, and opening a bottom valve of the reaction kettle to discharge a cracking substrate. The heating process of the cracking cyclization reaction comprises the following steps: keeping the temperature in the reaction kettle at 230 ℃ and reacting for 2 hours; heating to 240 ℃ for reaction for 2h; and finally, heating to 245 ℃ for reaction for 1h, collecting the extracted glycolide, and opening a bottom valve of the reaction kettle to discharge a cracking substrate.
The measurement and test results of the collected glycolide are shown in Table 1
Comparative example 2
Preparing a catalyst:
(1) the metered amounts of ethyl terephthalate (26 mmol) and p-methylphenylmagnesium bromide (66 mmol) were added to 60ml of anhydrous tetrahydrofuran and refluxed at 70 ℃ for 3h.
(2) An aqueous ammonium chloride solution (containing 120mmol of ammonium chloride) was added dropwise in an ice bath to quench the reaction, followed by liquid separation to obtain an organic phase.
(3) And (3) evaporating the organic phase obtained in the step (2) to dryness at 140 ℃ by using a rotary evaporator to obtain a viscous yellow oily substance, namely 4,4' -trimethyltriphenylmethanol (5.2g, 17.2mmol).
(4) Dissolving the 4,4' -trimethyltriphenylmethanol obtained in the step (3) in diethyl ether, stirring and slowly dropwise adding a tetrafluoroboric acid diethyl ether solution (HBF) 4 50 percent of the weight percentage of the nano-particles and 17.2mmolHBF 4 ) A yellow precipitate was formed, and the precipitate was washed and dried to obtain 4-tolyldiphenylmethylcarbapentanium tetrafluoroborate (5.82 g).
(5) And (3) compounding the 4,4' -tritolyl methyl carbonium tetrafluoroborate obtained in the step (4) with a cocatalyst zinc oxide according to the mass ratio of 3.
The preparation method of glycolide comprises the following steps:
taking 200g of methyl glycolate into a reaction kettle, then adding 2g of composite catalyst into the reaction kettle, starting stirring, heating to 140 ℃ and raising the temperature to N 2 Reacting for 4 hours under the protection of normal pressure, and then heating to 180 ℃ N 2 Reacting for 4 hours under the protection of normal pressure, and finally, heating to 230 ℃ N 2 The reaction is carried out for 4h under the protection of normal pressure, thus completing the polycondensation reaction of methyl glycolate and obtaining low molecular weight poly-methyl glycolate. Vacuumizing the reaction kettle to 100Pa (absolute pressure), heating to enable low molecular weight poly (methyl glycolate) to undergo cracking cyclization reaction, collecting the extracted glycolide in the process, and opening a bottom valve of the reaction kettle to discharge a cracking substrate. The heating process of the cracking cyclization reaction comprises the following steps: keeping the temperature in the reaction kettle at 230 ℃ and reacting for 2 hours; heating to 240 ℃ and reacting for 2h; and finally, heating to 245 ℃ for reaction for 1h, collecting the extracted glycolide, and opening a bottom valve of the reaction kettle to discharge a cracking substrate.
The measurement and test results of the collected glycolide are shown in Table 1
Comparative example 3
Adding 200g of methyl glycolate into a reaction kettle, then adding 2g of zinc oxide into the reaction kettle, starting stirring, heating to 140 ℃ and raising the temperature to N 2 Reacting for 4 hours under the protection of normal pressure, and then heating to 180 ℃ N 2 Reacting for 4 hours under the protection of normal pressure, and finally, heating to 230 ℃ N 2 Protection ofThe reaction is carried out for 4h under normal pressure, thus completing the polycondensation reaction of the methyl glycolate and obtaining the low molecular weight poly-methyl glycolate. Vacuumizing the reaction kettle to 100Pa (absolute pressure), heating to enable low molecular weight poly (methyl glycolate) to undergo cracking cyclization reaction, collecting the extracted glycolide in the process, and opening a bottom valve of the reaction kettle to discharge a cracking substrate. The heating process of the cracking cyclization reaction comprises the following steps: keeping the temperature in the reaction kettle at 230 ℃ and reacting for 2 hours; heating to 240 ℃ and reacting for 2h; and finally, heating to 245 ℃ for reaction for 1h, collecting the extracted glycolide, and opening a bottom valve of the reaction kettle to discharge a cracking substrate.
The measurement and test results of the collected glycolide are shown in Table 1
Comparative example 4
Taking 200g of methyl glycolate into a reaction kettle, then adding 2g of stannous chloride into the reaction kettle, starting stirring, heating to 140 ℃ and raising the temperature to N 2 Reacting for 4 hours under the protection of normal pressure, and then heating to 180 ℃ N 2 Reacting for 4 hours under the protection of normal pressure, and finally, heating to 230 ℃ N 2 The reaction is carried out for 4 hours under the protection of normal pressure, thus completing the polycondensation reaction of the methyl glycolate and obtaining the low molecular weight poly-methyl glycolate. Vacuumizing the reaction kettle to 100Pa (absolute pressure), heating to enable low molecular weight poly (methyl glycolate) to undergo cracking cyclization reaction, collecting the extracted glycolide in the process, and opening a bottom valve of the reaction kettle to discharge a cracking substrate. The heating process of the cracking cyclization reaction comprises the following steps: keeping the temperature in the reaction kettle at 230 ℃ and reacting for 2 hours; heating to 240 ℃ and reacting for 2h; and finally, heating to 245 ℃ for reaction for 1h, collecting the extracted glycolide, and opening a bottom valve of the reaction kettle to discharge a cracking substrate.
The measurement and test results of the collected glycolide are shown in Table 1
TABLE 1 glycolide yield and test results statistics table
As can be seen from a comparison of examples with comparative examples 1 and 2, the Lewis acidity of the catalyst has a large influence on the melting point of glycolide obtained and the yield of glycolide. The carbonium borate of comparative example 1 has one less methyl group compared to the carbonium borate of the examples, whereas the carbonium borate of comparative example 2 has one more methyl group. Methyl as an electron donating group, and a change in the amount will also directly affect the Lewis acidity of the carbenium borate. The carbonium ion borate adopted by the composite catalyst special for preparing glycolide by methyl glycolate is 4,4' -ditolyl phenyl methyl carbonium ion tetrafluoroborate, has moderate Lewis acidity, and is just suitable for prepolymerization of methyl glycolate and depolymerization reaction of low molecular weight methyl glycolate.
It can be seen from the comprehensive examples and comparative examples that the composite catalyst specially used for preparing glycolide from methyl glycolate has higher melting point and yield in the preparation of glycolide by polycondensation and cracking cyclization of methyl glycolate, and the cracking substrate has low viscosity, no coking, easy residue discharge and industrial production. Meanwhile, the invention also shows that the special composite catalyst for preparing glycolide from methyl glycolate has higher selectivity and conversion rate, and is a special catalyst with excellent performance.
Claims (6)
1. A method for preparing a composite catalyst for preparing glycolide from methyl glycolate is characterized by comprising the following steps:
2. the method of claim 1, wherein the step of
In (1), theThe mol ratio of the ethyl benzoate to the p-methylphenyl magnesium bromide is 1:2 to 1:4.
3. the method of claim 1, wherein the steps are as follows
Wherein the ratio of the mol amount of ammonium chloride contained in the dropwise added ammonium chloride aqueous solution to the mol amount of methylphenylmagnesium bromide is 1:1 to 2:1.
4. the method of claim 1, wherein the step of
Wherein the molar amount of tetrafluoroboric acid contained in the dropwise added tetrafluoroboric acid diethyl ether solution is 1 to 2 times of the molar amount of 4,4' -dimethyltriphenylmethanol.
5. The method of claim 4, wherein the step of
The 4,4' -ditolyl phenyl methyl carbonium tetrafluoroborate has the structural formula shown as the following figure:
6. use of the composite catalyst obtained by the production method according to claim 1 for producing glycolide from methyl glycolate, wherein: firstly, stirring and mixing methyl glycolate and the composite catalyst obtained by the preparation method of claim 1 in a reaction kettle, reacting for a while at 140-230 ℃ under normal pressure to obtain methyl glycolate oligomer, and then performing ring cleavage reaction on the methyl glycolate oligomer at 230-245 ℃ under vacuum absolute pressure of 50-500Pa to obtain glycolide.
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Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1999019378A1 (en) * | 1997-10-13 | 1999-04-22 | Kureha Kagaku Kogyo K.K. | Processes for producing polyhydroxy carboxylic acid and glycolide |
| WO2016090710A1 (en) * | 2014-12-09 | 2016-06-16 | 天津久联科技有限公司 | Method for preparing phenyl bis (2,4,6-trimethyl benzoyl) phosphine oxide |
| CN106459281A (en) * | 2014-05-22 | 2017-02-22 | 切弗朗菲利浦化学公司 | Dual catalyst systems for producing polymers with a broad molecular weight distribution and a uniform short chain branch distribution |
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Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1999019378A1 (en) * | 1997-10-13 | 1999-04-22 | Kureha Kagaku Kogyo K.K. | Processes for producing polyhydroxy carboxylic acid and glycolide |
| CN106459281A (en) * | 2014-05-22 | 2017-02-22 | 切弗朗菲利浦化学公司 | Dual catalyst systems for producing polymers with a broad molecular weight distribution and a uniform short chain branch distribution |
| WO2016090710A1 (en) * | 2014-12-09 | 2016-06-16 | 天津久联科技有限公司 | Method for preparing phenyl bis (2,4,6-trimethyl benzoyl) phosphine oxide |
Non-Patent Citations (2)
| Title |
|---|
| 四氢呋喃均聚醚催化研究进展;孙亚斌等;《化学推进剂与高分子材料》;20040425;第第2期卷(第02期);第7-12页 * |
| 固体超强酸催化合成乙醇酸甲酯;陈栋梁等;《天然气化工(C1化学与化工)》;20001030(第05期);第5-7页 * |
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