阅读说明：本技术 一种高活性催化乙烯聚合的配合物及其制备方法 (High-activity complex for catalyzing ethylene polymerization and preparation method thereof ) 是由 徐毓敏 于 2021-01-13 设计创作，主要内容包括：本发明公开一种高活性催化乙烯聚合的配合物及其制备方法；该配合物在亚胺氮原子芳环的邻位引入柔性基团取代基和刚性基团取代基,刚柔性基团相互配合,有效的调节金属中心的位置和乙烯插入的速度,同时,在亚胺氮原子芳环的对位引入供电子的甲氧基和在配体的骨架上引入供电子取代基甲氧基,使催化剂的供电性增强,有利于稳定金属活性中心,提高了催化剂的催化活性和热稳定性。(The invention discloses a complex for catalyzing ethylene polymerization with high activity and a preparation method thereof; according to the complex, a flexible group substituent and a rigid group substituent are introduced to the ortho position of an imine nitrogen atom aromatic ring, rigid and flexible groups are matched with each other, the position of a metal center and the speed of inserting ethylene are effectively adjusted, meanwhile, an electron-donating methoxy group is introduced to the para position of the imine nitrogen atom aromatic ring and an electron-donating substituent methoxy group is introduced to a ligand framework, so that the power supply performance of the catalyst is enhanced, the metal active center is stabilized, and the catalytic activity and the thermal stability of the catalyst are improved.)

1. A diimine palladium catalyst, wherein the diimine palladium catalyst has a structure represented by formula (I):

2. the process for preparing a diimine palladium catalyst (I) according to claim 1, which comprises the steps of:

(1) mixing 4, 4-dimethoxy acenaphthenequinone and 2, 6-dipropyl-4-methoxyaniline suspension in an inert gas atmosphere, stirring and refluxing for 6-12 h at 90 ℃, cooling the obtained reaction liquid to room temperature, filtering, collecting precipitate, washing and drying to obtain a diimine ligand;

(2) under the conditions of nitrogen atmosphere and room temperature, dissolving diimine ligand and (COD) PdMeCl in an organic solvent, and stirring for reaction for a period of time to obtain the diimine palladium catalyst.

3. The process for preparing a diimine palladium complex (I) according to claim 2, which is characterized in that: in the step (1), the molar ratio of the 4, 4-dimethoxy acenaphthenequinone to the 2, 6-dipropyl-4-methoxyaniline is 1: 2.2-2.5.

4. The process for preparing a diimine palladium complex (I) according to claim 2, which is characterized in that: in step (1), the solvents used for the reaction are acetonitrile and acetic acid.

5. The process for preparing a diimine palladium complex (I) according to claim 2, which is characterized in that: in step (2), the molar ratio of the diimine ligand to (COD) PdMeCl is 1: 1.2.

6. The process for preparing a diimine palladium complex (I) according to claim 2, which is characterized in that: in step (2), the organic solvent is dichloromethane.

7. The process for preparing a diimine palladium complex (I) according to claim 2, which is characterized in that: in the step (2), the reaction time is 12-18 hours.

8. Use of the diimine palladium complex (I) of claim 1 as a catalyst in the polymerization of ethylene.

9. The use according to claim 8, wherein the polymerization time is 4 to 10 hours, the polymerization temperature is 30 ℃ and the polymerization pressure is 0.2 atm.

Technical Field

The invention belongs to the field of olefin catalytic polymerization, and particularly relates to a complex for catalyzing ethylene polymerization with high activity and a preparation method thereof.

Background

Polyethylene is a polyolefin material with great application potential, and compared with common polyolefin materials, the high temperature resistance, the electrical property, the optical property, the mechanical property and the like of polyethylene are more excellent. The method is mainly used for manufacturing medical appliances (such as syringes), physical and chemical experimental appliances, special feeders for electronic cookers, baking plates, release paper, heat-resistant wire coatings and the like.

The development and application of polyethylene catalysts is a major breakthrough in the field of olefin polymerization catalysts after traditional Ziegler-Natta catalysts, which makes the research of polyethylene catalysts enter a rapidly developing stage. The homogeneous phase polyethylene catalyst has high activity, needs large catalyst consumption and high production cost, and the obtained polymer has no granular shape and cannot be used in a polymerization process of a slurry method or a gas phase method which is widely applied. An effective method for overcoming the above problems is to carry out a supporting treatment of the soluble polyethylene catalyst. At present, a great number of research reports on N, N-diimine palladium catalysts are available. In order to deeply research an N, N-diimine palladium catalyst system and promote the further development of the N, N-diimine palladium catalyst and polyolefin industry, the invention provides a complex for catalyzing ethylene polymerization with high activity and a preparation method thereof.

Disclosure of Invention

The invention aims to provide a diimine palladium catalyst, wherein the ortho position of the catalyst is substituted by benzhydryl, the para position of the catalyst is a methoxy substituent group for electron effect, and a framework contains the methoxy substituent group.

Another object of the present invention is to provide a process for producing the above diimine palladium complex.

Still another object of the present invention is to provide the use of the above diimine palladium complex in the polymerization of ethylene.

The above purpose of the invention is realized by the following technical scheme:

a diimine palladium complex having the formula (I):

the diimine palladium catalyst has higher reaction activity, is applied to the polymerization reaction of ethylene, has mild reaction conditions, and does not need to carry out the polymerization reaction under the harsh anhydrous and anaerobic conditions; flexible group substituent and rigid group substituent are introduced to the ortho position of the imine nitrogen atom aromatic ring, the rigid group and the flexible group are matched with each other, the position of the metal center and the speed of inserting ethylene are effectively adjusted, meanwhile, the methoxy group for supplying electrons is introduced to the para position of the imine nitrogen atom aromatic ring and the methoxy group for supplying electron substituent is introduced to the skeleton of the ligand, so that the power supply performance of the catalyst is enhanced, the metal active center is stabilized, and the catalytic activity and the thermal stability of the catalyst are improved.

A preparation method of a diimine palladium complex comprises the following steps:

1. mixing 4, 4-dimethoxy acenaphthenequinone and 2, 6-dipropyl-4-methoxyaniline suspension in an inert gas atmosphere, stirring and refluxing for 6-12 h at 90 ℃, cooling the obtained reaction liquid to room temperature, filtering, collecting precipitate, washing and drying to obtain the diimine ligand.

Wherein the molar ratio of 4, 4-dimethoxy acenaphthenequinone to 2, 6-dipropyl-4-methoxyaniline is 1: 2.2-2.5.

Wherein, the solvent used in the reaction is acetonitrile and acetic acid.

2. Under the conditions of nitrogen atmosphere and room temperature, dissolving diimine ligand and (COD) PdMeCl in an organic solvent, and stirring for reaction for a period of time to obtain the diimine palladium catalyst.

Wherein the molar ratio of the diimine ligand to the (COD) PdMeCl is 1: 1.2.

Wherein the organic solvent is dichloromethane.

Wherein the reaction time is 12-18 hours.

The synthesis reaction formula is as follows:

the invention also provides the application of the diimine palladium complex serving as a catalyst in ethylene polymerization.

The diimine palladium complex serving as an ethylene polymerization catalyst can be used for preparing polyethylene under the conditions that the polymerization time is 4-10 h, the polymerization temperature is 30 ℃ and the polymerization pressure is 0.2 atm.

Compared with the prior art, the invention has the following advantages and beneficial effects:

according to the complex, a flexible group substituent and a rigid group substituent are introduced to the ortho position of an imine nitrogen atom aromatic ring, rigid and flexible groups are matched with each other, the position of a metal center and the speed of inserting ethylene are effectively adjusted, meanwhile, an electron-donating methoxy group is introduced to the para position of the imine nitrogen atom aromatic ring and an electron-donating substituent methoxy group is introduced to a ligand framework, so that the power supply performance of the catalyst is enhanced, the metal active center is stabilized, and the catalytic activity and the thermal stability of the catalyst are improved.

Drawings

FIG. 1 is a single crystal structural diagram of a diimine palladium complex prepared in example 2 of this invention.

Detailed Description

The present invention will be described in further detail with reference to specific examples, which are not intended to limit the present invention in any manner. Reagents, methods and apparatus used in the present invention are conventional in the art unless otherwise indicated.

The structural formula of the diimine palladium complex is as follows:

in the following examples, the number average molecular weight of the polyethylene prepared was measured by gel permeation chromatography.

Example 1

This example provides a diimine ligand, which is synthesized as follows.

Under nitrogen atmosphere, 4, 4-dimethoxy acenaphthenequinone (3.0mmol) is suspended in acetonitrile (40mL), 2, 6-dipropyl-4-methoxyaniline (6.6mmol) is suspended in acetic acid (16mL), and then the two mixed liquids are mixed; the mixture is stirred vigorously at 90 ℃ and reacts for 12 hours to become a reddish brown solution; subsequently, the solution was cooled to room temperature, and the yellow precipitate was collected by filtration; the solid was washed with acetonitrile and dried under vacuum to give a yellow powder, the diimine ligand, in 75.3% yield.

Example 2

This example provides a palladium diimine catalyst, which is synthesized as follows.

Under nitrogen protection, 20mL of diimine ligand (0.5mmol), (COD) PdMeCl (0.6mmol) and dichloromethane were added to a Schlenk flask with a mouth, stirred at room temperature for 12 hours, and then the solvent was evaporated at room temperature under reduced pressure to about 5mL, and 20mL of n-hexane was added, at which time a large amount of precipitate was generated. Filtration through a G4 filter ball and washing of the precipitate with 3X 10mL of n-hexane followed by vacuum drying gave the diimine palladium catalyst as a yellow solid in 71.9% yield.

Example 3

This example provides a polyethylene prepared as follows.

A magnetic stir bar was placed in a 100mL round bottom flask and heated under vacuum with an infrared lamp at 150 ℃ for 3h, then cooled to room temperature. The flask was pressurized to 0.1MPa of ethylene and pumped three times. 28mL of toluene was added to the reactor under 0.2MPa of ethylene pressure at 30 ℃ with continuous stirring for 5min, and then 5. mu. mol of diimine palladium catalyst dissolved in 2mL of methylene chloride was added to the reaction flask via a syringe to start the reaction. Ethylene was continuously fed during the reaction to maintain the ethylene pressure at 0.02MPa, and the reaction temperature was controlled in the polymerization experiment using an external water bath. After 4h polymerization time had been reached, 2mL of triethylsilane were added to terminate the polymerization. Removing the solvent in the mixture by rotary evaporation, and centrifuging to remove the palladium black; the product was purified by column chromatography and then constant weight at 75 ℃ in vacuo. 5.36g of polyethylene having a number-average molecular weight of 35369g mol were obtained^-1The molecular weight distribution was 1.30 and the degree of branching was 203 branches/1000C.

Example 4

This example provides a polyethylene prepared as follows.

The polymerization conditions were the same as in example 3, the reaction time being 6h instead of 4 h. 5.34g of polyethylene with a number-average molecular weight of 30634g mol are obtained^-1The molecular weight distribution was 1.21 and the degree of branching was 216 branches/1000C.

Example 5

This example provides a polyethylene prepared as follows.

The polymerization conditions were the same as in example 3, the reaction time being 8h instead of 4 h. 6.34g of polyethylene having a number-average molecular weight of 29671g mol were obtained^-1The molecular weight distribution was 1.28 and the degree of branching was 221 branches/1000C.

Example 6

This example provides a polyethylene prepared as follows.

The polymerization conditions were the same as in example 3, and the reaction time was 10h instead of 4 h. 6.87g of polyethylene having a number-average molecular weight of 28697g mol were obtained^-1The molecular weight distribution was 1.32 and the degree of branching was 230 branches/1000C.

From examples 3 to 6, it can be seen that the diimine palladium complex prepared by the invention has high catalytic activity at 30 ℃ when used for catalyzing ethylene polymerization.