Method for synthesizing indenyl titanium trichloride catalyst by one-step method

Abstract

The invention discloses a method for synthesizing an indenyl titanium trichloride catalyst by a one-step method, and belongs to the field of organic synthesis.The method comprises the steps that in the inert gas atmosphere, tetraethyl titanate and an organic solvent 1 are added, indene is added at the room temperature, a heating reaction is conducted, the temperature is reduced to the room temperature after the reaction, trimethylchlorosilane is added, a reaction is conducted at the room temperature, the solvent is removed under reduced pressure, and the indenyl titanium trichloride catalyst is obtained. And adding an organic solvent 2, mixing, filtering, concentrating and recrystallizing to obtain the indenyl titanium trichloride catalyst. The invention provides a one-step synthesis method for synthesizing an indenyl titanium trichloride catalyst. The method is simple to operate, short in production period, high in yield and suitable for industrial production, and avoids dangerous materials.

Description

Technical Field

[0001] The invention belongs to the technical field of organic synthesis, and in particular relates to a one-step method for synthesizing an indenyl titanium trichloride catalyst. Background Art

[0002] Polyolefins are widely used due to their excellent mechanical properties, low price, and ease of processing, making them the most produced synthetic polymer material. Olefin polymerization catalysts can precisely control the structure and properties of polyolefins and are therefore considered the core technology of the polyolefin industry. Indenyltitanium trichloride is an excellent olefin polymerization catalyst. Its structure is shown below:

[0003]

[0004] Under the activation of methylaluminoxane cocatalyst, indenyl titanium trichloride catalyzes the highly syndiotactic selective polymerization of styrene, with an activity of up to ten to the seventh power, obtaining a syndiotacticity greater than 98%, making it one of the most efficient syndiotactic styrene polymerization catalyst systems (Macromolecules, 1993, 26, 5822-5823). Under the activation of alkyl aluminum, indenyl titanium trichloride can catalyze the copolymerization of ethylene with α-olefins and diolefins to obtain crosslinkable polyolefin elastomeric materials (CN 118005833A). Except for directly using as a catalyst, one of the chlorine can also be replaced by other ligands to prepare a series of derivatives. CN 113788862A reports the use of bisphenol A to replace chlorine to obtain a binuclear titanium catalyst. In ethylene / cycloolefin copolymerization, binuclear metallocene compounds can improve catalytic activity and cycloolefin monomer insertion rate. CN 115651011A reports that bicyclo[2.2.1]heptane-2-ol is used to replace chlorine. The resulting catalyst is suitable for homopolymerization of ethylene and α-olefins, and copolymerization of ethylene with α-olefins / cycloolefins. It can efficiently prepare polyolefin materials such as polyethylene, polyolefin elastomers, and cycloolefin copolymers.

[0005] The main synthesis methods of the catalyst are:

[0006] A: Three-step method. Indene reacts with butyl lithium to produce indenyl lithium in 99% yield; indenyl lithium reacts with trimethylsilyl chloride and distills to obtain trimethylsilyl indene intermediate in 85% yield; the intermediate reacts with titanium tetrachloride to produce indenyl titanium trichloride in 97% yield (Journal of Organometallic Chemistry, 1996, 519, 21-28).

[0007]

[0008] B: Two-step method. Indene reacts with butyl lithium and then trimethylsilyl chloride to obtain a trimethylsilylindene intermediate in 61% yield. This intermediate then reacts with titanium tetrachloride to obtain indenyltitanium trichloride in 79.9% yield (Journal of Organometallic Chemistry, 1996, 519, 21-28).

[0009]

[0010] Method A: (1) The synthesis process requires butyl lithium, which is a flammable substance. (2) The three-step reaction is cumbersome and requires a long production cycle. The production process involves the separation of active intermediates. (3) The yield is low, with the first step yield being 99%, the second step yield being 85%, and the third step yield being 97%, for a total yield of 81%.

[0011] Method B: (1) The synthesis requires butyl lithium, a flammable substance. (2) The two-step reaction is optimized based on Method A, combining the first and second steps to avoid the separation of the active intermediate, but the yield drops sharply. (3) The yield is low, with the first step yielding 61% and the second step yielding 79.9%. The overall yield is 49%.

[0012] Therefore, existing synthesis methods involve multiple steps, are cumbersome to operate, have long manufacturing cycles, low yields, and high production costs. Furthermore, the use of hazardous materials makes them difficult to scale up for production. Summary of the Invention

[0013] Purpose of the invention: In view of the defects and shortcomings of the existing technology, the present invention provides a one-step method for synthesizing indenyl titanium trichloride catalyst. The method is simple to operate, has a short production cycle, avoids hazardous materials, has a high yield, and is suitable for industrial production.

[0014] Technical solution: In order to achieve the above object, the present invention provides a one-step method for synthesizing indenyl titanium trichloride catalyst, comprising the following steps:

[0015] Under an inert gas atmosphere, titanate or tetrakis(dimethylamino)titanium and organic solvent 1 are added, indene is added at room temperature, and after the addition is complete, heating is carried out to react. After the reaction, the temperature is cooled to room temperature, trimethylchlorosilane is added, and after the addition is complete, the temperature is cooled to room temperature. After the solvent is removed under reduced pressure, organic solvent 2 is added, mixed, filtered, concentrated, and recrystallized to obtain an indenyl titanium trichloride catalyst.

[0016] Wherein, the inert gas atmosphere is nitrogen or argon atmosphere.

[0017] Wherein, the organic solvent 1 is anhydrous toluene or anhydrous xylene.

[0018] Wherein, the molar ratio of the titanate or tetrakis(dimethylamino)titanium to indene is 1:1-1:1.3.

[0019] Preferably, the molar ratio of the titanate or tetrakis(dimethylamino)titanium to indene is 157:162.

[0020] The heating reaction is carried out by heating the temperature to 70-80° C. for 2-3 hours.

[0021] Preferably, the heating reaction is carried out by heating the temperature to 70° C. for 3 hours.

[0022] Wherein, the molar ratio of tetraethyl titanate to trimethylchlorosilane is 1:6-1:6.5.

[0023] Wherein, the molar ratio of tetraethyl titanate to trimethylchlorosilane is 157:960.

[0024] The addition of trimethylsilyl chloride is followed by reaction at room temperature for 2-3 hours.

[0025] Wherein, the organic solvent 2 is anhydrous n-hexane, anhydrous n-pentane or anhydrous n-heptane.

[0026] The one-step method for synthesizing an indenyl titanium trichloride catalyst of the present invention has the following general reaction formula:

[0027]

[0028] This invention proposes a novel one-step method for synthesizing indenyl titanium trichloride catalysts. Through route design and reaction condition screening, using commercially available raw materials, the three-step reaction is reduced to a single step. This method avoids the use of hazardous materials such as butyl lithium and the separation of reactive intermediates, while also making the reaction conditions milder and post-processing simpler, thereby increasing the yield from 50-80% to 94.7%.

[0029] In the synthesis method of the present invention, the raw materials, raw material ratio, and reaction conditions are all very important. Any change in the conditions will lead to a significant decrease in yield. Compared with the prior art, the present invention simplifies the synthesis of the indenyl titanium trichloride catalyst, reduces reaction risk and manufacturing costs, and improves yield and production efficiency. The present invention not only does not require intermediate separation, but also achieves a high overall yield.

[0030] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages:

[0031] The invention provides a one-step method for synthesizing an indenyl titanium trichloride catalyst. The method is simple to operate, short in production cycle, avoids hazardous materials, has high yield, and is suitable for industrial production.

[0032] The method of the present invention not only simplifies the synthesis method of the indenyl titanium trichloride catalyst, reduces the reaction risk and manufacturing cost, but also improves the yield and production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is the NMR spectrum of indenyltitanium trichloride. DETAILED DESCRIPTION

[0034] The present invention will be further described below with reference to the embodiments.

[0035] The experimental methods described in the examples are conventional methods unless otherwise specified; the materials, reagents, etc. used in the examples are all commercially available unless otherwise specified.

[0036] Example 1

[0037] Under nitrogen atmosphere, tetraethyl titanate (35.5 g, 157 mmol) and 138 mL of anhydrous toluene were added to a Schlenk flask. At room temperature, indene (18.83 g, 162 mmol) was added, and after the addition, the temperature was raised to 70°C and reacted for 3 hours. After cooling to room temperature, trimethylsilyl chloride (104 g, 960 mmol) was added, and after the addition, the temperature was raised to 70°C and reacted for 2 hours. After removing the solvent under reduced pressure, 120 mL of anhydrous n-hexane was added and mixed, filtered, concentrated to 60 mL, and recrystallized at -30°C to obtain a deep red product, indenyl titanium trichloride (39.69 g, 94.7%). The NMR spectrum is as follows: Figure 1 shown.

[0038] 1 H NMR (C6D6): δ=7.13(2H,m),6.82(2H,m),6.32(2H,d),6.21(1H,t).

[0039]

[0040] Example 2

[0041] Under a nitrogen atmosphere, tetramethyl titanate (27.6 g, 157 mmol) and 150 mL of anhydrous toluene were added to a Schlenk flask. At room temperature, indene (18.83 g, 162 mmol) was added and the mixture was heated to 70°C for 3 hours. After cooling to room temperature, trimethylsilyl chloride (104 g, 960 mmol) was added and the mixture was allowed to react at room temperature for 2 hours. After removing the solvent under reduced pressure, 120 mL of anhydrous n-hexane was added, mixed, filtered, concentrated to 60 mL, and recrystallized at -30°C to obtain the deep red product, indenyltitanium trichloride (38.26 g, 91.3%).

[0042] Example 3

[0043] Under a nitrogen atmosphere, tetraisopropyl titanate (44.62 g, 157 mmol) and 200 mL of anhydrous toluene were added to a Schlenk flask. At room temperature, indene (18.83 g, 162 mmol) was added and the temperature was raised to 70°C for 3 hours. After cooling to room temperature, trimethylsilyl chloride (104 g, 960 mmol) was added and the temperature was raised to room temperature for 2 hours. After removing the solvent under reduced pressure, 120 mL of anhydrous n-hexane was added, mixed, filtered, concentrated to 60 mL, and recrystallized at -30°C to obtain the deep red product, indenyltitanium trichloride (37.9 g, 90.5%).

[0044] Comparative Example 1

[0045] The method of Example 1 was adopted, except that the temperature was raised to 70° C. for reaction for 3 hours instead of room temperature for reaction for 3 hours, to obtain a deep red product, indenyltitanium trichloride (10.7 g, 25.5%).

[0046] Comparative Example 2

[0047] The method of Example 1 was adopted, except that the temperature was raised to 150°C for 3 hours instead of 70°C for 3 hours. The yield of the deep red product indenyltitanium trichloride was also less than 30%, which was a significant decrease in yield.

[0048] Comparative Example 3

[0049] The method of Example 1 was adopted, except that the molar ratio of tetraethyl titanate to trimethylsilyl chloride was changed from 157:960 to 157:157, and the yield of the deep red product indenyltitanium trichloride (4.8 g, 11.4%) was significantly reduced.

[0050] Comparative Example 4

[0051] The method of Example 1 was adopted, except that the molar ratio of tetraethyl titanate to trimethylsilyl chloride was changed from 157:960 to 157:1099. The yield of the deep red product indenyltitanium trichloride was also less than 50%, and the yield decreased significantly.

[0052] Comparative Example 5

[0053] The method of Example 1 was adopted, except that the molar ratio of tetraethyl titanate to indene was changed from 157:162 to 157:110. The yield of the deep red product indenyl titanium trichloride was less than 50%, which was a significant decrease in yield.

[0054] Comparative Example 6

[0055] The method of Example 1 was adopted, except that the molar ratio of tetraethyl titanate to indene was changed from 157:162 to 157:235. The yield of the deep red product indenyl titanium trichloride was less than 50%, which was a significant decrease in yield.

Claims

1. A one-step method for synthesizing an indenyl titanium trichloride catalyst, characterized in that: The steps include: In an inert gas atmosphere, titanate or tetrakis(dimethylamino)titanium and organic solvent 1 are added, indene is added at room temperature, heated to react, cooled to room temperature after the reaction, trimethylsilyl chloride is added, reacted at room temperature, the solvent is removed under reduced pressure, organic solvent 2 is added, mixed, filtered, concentrated and recrystallized to obtain an indenyl titanium trichloride catalyst.

2. The method for synthesizing an indenyl titanium trichloride catalyst in one step according to claim 1, wherein: The inert gas atmosphere is nitrogen or argon atmosphere.

3. The method for synthesizing indenyl titanium trichloride catalyst by one-step method according to claim 1, characterized in that: The titanate is tetraethyl titanate, tetramethyl titanate or tetraisopropyl titanate.

4. The method for synthesizing an indenyl titanium trichloride catalyst in one step according to claim 1, wherein: The organic solvent 1 is anhydrous toluene or anhydrous xylene.

5. The method for synthesizing indenyl titanium trichloride catalyst by one-step method according to claim 1, characterized in that: The molar ratio of the titanate or tetrakis(dimethylamino)titanium to indene is preferably 1:1-1:1.

3.

6. The method for synthesizing an indenyl titanium trichloride catalyst in one step according to claim 1, wherein: The heating reaction is carried out by heating the temperature to 70-80° C. for 2-3 hours.

7. The method for synthesizing an indenyl titanium trichloride catalyst in one step according to claim 1, wherein: The molar ratio of the titanate or tetrakis(dimethylamino)titanium to trimethylchlorosilane is 1:6-1:6.

5.

8. The method for synthesizing an indenyl titanium trichloride catalyst in one step according to claim 1, wherein: The trimethylsilyl chloride was added and reacted at room temperature for 2-3 hours.

9. The method for synthesizing an indenyl titanium trichloride catalyst in one step according to claim 1, wherein: The organic solvent 2 is anhydrous n-hexane, anhydrous n-pentane or anhydrous n-heptane.

10. A one-step method for synthesizing an indenyl titanium trichloride catalyst, characterized in that: The general reaction formula of the method is preferably as follows:

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