Acenaphthylene asymmetric alpha-diimine chemical intermediates, methods of making and using the same

Abstract

This invention discloses a acenaphthene-bisasymmetric α-diimide chemical intermediate, a catalyst prepared from it, the intermediate itself, a method for preparing the catalyst, and its applications. Using 2,4,6-tri-tert-butylaniline as a raw material, a acenaphthene-bisasymmetric α-diimide chemical intermediate with the structure shown in formula (I) is obtained in the presence of a catalyst. Compared with existing technologies, this invention uses readily available, inexpensive, and easily stored 2,4,6-tri-tert-butylaniline as a reaction raw material instead of expensive and demanding 2,4-di-tert-butylaniline, effectively reducing the raw material procurement threshold and overall production costs, and simplifying storage conditions. The method of this invention uses readily available raw materials, is low-cost, simple to operate, and has a high yield, making it suitable for industrial-scale production.

Description

Technical Field

[0001] This invention relates to the field of chemical synthesis technology, and more specifically, to a acenaphthene-bisasymmetric α-diimine chemical intermediate, its preparation method, and its application. Background Technology

[0002] Acenathoine biasymmetric α-diimine is an important chemical ligand or intermediate. As a core raw material, it can be used to synthesize high-value metal complex catalysts and special compounds for pharmaceutical and other fields.

[0003] Based on a related collaborative research and development project, this invention often requires the use of this compound as a key raw material. The inventors have innovatively developed a synthetic process route for this intermediate.

[0004] Generally, based on chemical reaction principles and formulas, the synthesis of acenaphthene-bisasymmetric α-diimine intermediates can be achieved using 2,4-di-tert-butylaniline as a direct starting material. However, in practice, the inventors found that while 2,4-di-tert-butylaniline is commercially available, its market price is relatively high, and the substance requires stringent storage conditions (such as low temperature, protection from light, and inert gas protection), making long-term preservation difficult. This presents a significant obstacle to the synthesis of acenaphthene-bisasymmetric α-diimine intermediates: high raw material acquisition costs and significant storage difficulties.

[0005] To address the issues of high raw material acquisition costs and storage difficulties, those skilled in the art might attempt to synthesize 2,4-di-tert-butylaniline themselves. However, this would undoubtedly prolong the overall synthetic route, increasing process complexity and production costs.

[0006] Therefore, there is an urgent need to find low-cost and easy-to-store raw materials for the synthesis of ethyleneacenaphthene biasymmetric α-diimine chemical intermediates. Summary of the Invention

[0007] To address the aforementioned technical problems, the inventors innovatively employed 2,4,6-tri-tert-butylaniline as a reactant. Compared to 2,4-di-tert-butylaniline used in conventional approaches, 2,4,6-tri-tert-butylaniline offers significant comprehensive advantages: its market price is far lower (only about 1 / 7 to 1 / 10 of the latter), its storage conditions are more flexible (no need for low-temperature or inert gas protection, room temperature sealed storage is sufficient), and its market supply is stable and procurement is convenient. 2,4,6-tri-tert-butylaniline differs from 2,4-di-tert-butylaniline in molecular structure. Due to the strong stereoshiking effect of the two ortho-tert-butyl groups, the reactivity of the nitrogen atom and aromatic ring of 2,4,6-tri-tert-butylaniline is significantly reduced. However, the inventors of this application unexpectedly discovered that when 2,4,6-tri-tert-butylaniline is used as a raw material for ketamine condensation reactions, the ortho-tert-butyl substituents are removed, even under conventional ketamine condensation conditions. This enabled 2,4,6-tri-tert-butylaniline to successfully substitute for 2,4-di-tert-butylaniline in the reaction and generate the target product—ethyleneacenaphthene biasymmetric α-diimide chemical intermediate.

[0008] This discovery provides a novel technical route for the synthesis of acenaphthenic bisasymmetric α-diimine chemical intermediates, effectively avoiding the problems of high raw material costs, demanding storage conditions, and unstable supply associated with using 2,4-di-tert-butylaniline. No existing technology discloses any technical solution for preparing acenaphthenic bisasymmetric α-diimine chemical intermediates using 2,4,6-tri-tert-butylaniline as a raw material. Therefore, developing a method for the efficient and reliable synthesis of acenaphthenic bisasymmetric α-diimine chemical intermediates based on 2,4,6-tri-tert-butylaniline is of great significance for reducing dependence on 2,4-di-tert-butylaniline, lowering production costs, simplifying storage conditions, and ultimately achieving stable and economical preparation of this intermediate.

[0009] One of the objectives of this invention is to provide a method for preparing a acenaphthenic asymmetric α-diimine chemical intermediate. This method uses 2,4,6-tri-tert-butylaniline as a starting material to successfully synthesize the target product, thereby overcoming the shortcomings of the prior art that uses 2,4-di-tert-butylaniline, such as high raw material cost, harsh storage conditions and unstable supply, and achieving low-cost, high-efficiency and stable preparation of the chemical intermediate.

[0010] A second objective of this invention is to provide a acenaphthene-asymmetric α-diimine chemical intermediate, the chemical formula and structural formula of which are shown in formula (I):

[0011] A third objective of this invention is to provide a method for preparing the intermediate shown in formula (I) above, comprising the following steps: 1) Acenathoquinone reacts with aniline containing a sterically hindered substituent via a ketamine condensation reaction to yield the compound shown in formula (III):

[0012] 2) The compound shown in formula (III) reacts with 2,4,6-tri-tert-butylaniline via a ketamine condensation reaction to yield the intermediate shown in formula (I):

[0013] In some embodiments, the solvent used in step 1) above is selected from at least one of toluene, acetonitrile, acetic acid and anhydrous ethanol, preferably at least one of toluene and acetonitrile.

[0014] In some embodiments, the catalyst used in step 1) above is selected from at least one of p-toluenesulfonic acid and acetic acid.

[0015] In some embodiments, in step 1) above, the ratio of the catalyst, acenaphthoquinone, aniline with a large sterically hindered substituent, and solvent is 0.1-0.15 mmol: 1-1.1 mmol: 1-1.4 mmol: 5-10 mL.

[0016] In some implementations, the reaction time for step 1) above is 2-8 hours, preferably 3-6 hours.

[0017] In some embodiments, step 1) above further includes column chromatography of the product in a silica gel column using a mixed solvent of dichloromethane and petroleum ether or a mixed solvent of petroleum ether and ethyl acetate as eluent to obtain the product shown in formula (III).

[0018] In some embodiments, in step 2) above, the ratio of reactant (III), 2,4,6-tritert-butylaniline, zinc chloride and solvent is 0.5-1 mmol: 1.0-1.5 mmol: 1.0-1.5 mmol: 3-5 mL.

[0019] In some embodiments, the reaction temperature of step 2) above is selected from 110-120°C.

[0020] In some embodiments, the reaction time of step 2) above is selected from 20 min to 1 h, preferably 30 min to 40 min.

[0021] In some implementations, step 2) above further includes the following steps: After the reaction was complete, the reaction solution was cooled and filtered, and washed three times with isopropyl ether. The solid was dissolved in dichloromethane until clear and transparent, and 20 ml of hydrated potassium oxalate aqueous solution (0.15 mol / L) was added. The mixture was stirred vigorously for 30 min until a white precipitate of zinc oxalate appeared. The layers were separated, and the organic layer was washed three times with deionized water. The product was dried with anhydrous magnesium sulfate, filtered, rotary evaporated, and dried. The product was eluented with a mixture of dichloromethane and petroleum ether or a mixture of petroleum ether and ethyl acetate in a silica gel column to obtain the product shown in formula (I).

[0022] A fourth objective of this invention is to provide a method for preparing a catalyst of formula (II) using an intermediate shown in formula (I), comprising the following steps: under an inert gas atmosphere, complexing the intermediate compound shown in formula (I) with one of ethylene glycol dimethyl ether nickel dibromide, ethylene glycol dimethyl ether nickel dichloride, or nickel dichloride hexahydrate to obtain the catalyst of formula (II) of this invention. In the structural formula of the catalyst of this invention, X is chlorine or bromine. In one embodiment of this invention, X is selected as bromine. In another embodiment of this invention, X is chlorine.

[0023] In one embodiment of the present invention, under a nitrogen atmosphere, the compound shown in formula (I) is used as a ligand, and the nickel-containing compound complexed with the ligand is selected as nickel dimethyl ether dibromide (DME)NiBr2, wherein the molar ratio of the ligand to (DME)NiBr2 is 1:1-1.2, preferably 1:1.1; the solvent used is dichloromethane, the reaction temperature is 15-35℃, preferably 25℃, and the reaction time is 8-30 hours, preferably 16-24 hours.

[0024] The fifth objective of this invention is to provide a catalyst composition for catalyzing olefin polymerization, the composition comprising a main catalyst and a co-catalyst, wherein the main catalyst is selected from the catalyst shown in formula (II), the co-catalyst is selected from at least one of alkylaluminum chloride, alkylaluminum and aluminoxane, and the olefin is ethylene or propylene.

[0025] In a preferred embodiment, the catalyst composition comprises a main catalyst and a co-catalyst, wherein the main catalyst is selected from the catalyst shown in formula (II), the co-catalyst is selected from at least one of alkylaluminum chloride, alkylaluminum and aluminoxane, and the olefin is ethylene or propylene.

[0026] In one embodiment, in the above catalyst composition, the aluminum oxane is methylaluminoxane (MAO), modified methylaluminoxane (MMAO), ethylaluminoxane, or isobutylaluminoxane.

[0027] In one embodiment, in the above catalyst composition, the alkylaluminum is trimethylaluminum, triethylaluminum, triisobutylaluminum, tri-n-hexylaluminum, or tri-n-octylaluminum.

[0028] In one embodiment, in the above catalyst composition, the alkylaluminum chloride is diethylaluminum chloride, sesqui-diethylaluminum chloride, or ethylaluminum dichloride.

[0029] Considering the effectiveness and cost of the co-catalyst, in a preferred embodiment, the co-catalyst is alkyl aluminum chloride.

[0030] In a preferred embodiment, when the co-catalyst is alkylaluminum chloride, the molar ratio of metallic aluminum in alkylaluminum chloride to metallic nickel in the catalyst is referred to as the aluminum-nickel ratio, and the aluminum-nickel ratio ranges from 50 to 2000:1.

[0031] The sixth objective of this invention is to provide the application of the catalyst shown in formula (I) in the catalytic polymerization of ethylene and propylene to prepare polyethylene.

[0032] Compared with the prior art, the acenaphthene-bisasymmetric α-diimine chemical intermediate and its synthesis method provided by the present invention have the following beneficial effects: 1) Raw material costs are significantly reduced, and storage conditions are greatly simplified. This invention addresses the problems of high cost and demanding storage conditions associated with 2,4-di-tert-butylaniline, a key starting material in existing synthetic routes, by innovatively employing the structural analog 2,4,6-tri-tert-butylaniline as an alternative starting material. 2,4,6-tri-tert-butylaniline is a conventional chemical product with a stable market supply, and its price is significantly lower than that of 2,4-di-tert-butylaniline. Furthermore, its storage requirements are less stringent, requiring only sealed, cool, and dry storage. This alternative significantly reduces the raw material procurement threshold and overall production cost of the acenaphthene-bisasymmetric α-diimine chemical intermediate, demonstrating excellent economic applicability and making it more suitable for industrial-scale production.

[0033] 2) The reaction conditions are mild and the operation is simple. The method of this invention does not rely on complex reaction equipment or harsh reaction conditions (such as extreme environments like high pressure) and can be successfully implemented in conventional reactors. The synthetic route is rationally designed, the steps are simple, and the technical requirements for operators are low, reducing the difficulty of process control and improving production efficiency.

[0034] 3) Simple post-processing and high yield The reaction system exhibits good selectivity and few side reactions, and the purification and separation process of the target product, acenaphthene-bisasymmetric α-diimine, is simple and easy to perform. The method of this invention can achieve an ideal product yield (up to 48.7%), avoiding product loss caused by cumbersome post-processing steps and further improving the overall synthesis efficiency. Detailed Implementation

[0035] The present invention will be further described below with reference to specific embodiments, but the present invention is not limited to the following embodiments.

[0036] Example 1, Preparation of Compound (III): Toluenesulfonic acid (0.34 g, 2 mmol) was added to a toluene (150 mL) solution of 2,6-bis(diphenylmethyl)-4-methylaniline (8.8 g, 20 mmol) and acenaphthene (3.64 g, 20 mmol), and the mixture was refluxed for 6 h. The solvent was removed, and the residue was subjected to silica gel column chromatography with a 2:1 volume ratio of dichloromethane and petroleum ether to obtain an intermediate of Formula (III) with a mass of 11.2 g, yield: 93.0%.

[0037] Example 2, Preparation of Chemical Intermediate of Formula (I): Zinc chloride (0.20 g, 1.5 mmol) was added to a solution of 2,4,6-tri-tert-butylaniline (0.392 g, 1.5 mmol) and compound of Formula (III) (0.603 g, 1 mmol) in acetic acid (5 mL). The mixture was heated to 110-120 °C and reacted for 30 min. After cooling and filtration, the mixture was washed three times with isopropyl ether. The solid was dissolved in dichloromethane until clear and transparent. 20 mL of hydrated potassium oxalate solution (0.15 mol / L) was added, and the mixture was stirred vigorously for 30 min until a white precipitate of zinc oxalate appeared. The mixture was separated, and the organic layer was washed three times with deionized water. The solution was dried using anhydrous magnesium sulfate, filtered, and dried again by rotary evaporation. Silica gel column chromatography was performed using a mixed solvent of dichloromethane and petroleum ether in a volume ratio of 4:1 to obtain the intermediate of Formula (I) with a mass of 0.414 g and a yield of 52.36%.

[0038] Example 3, Preparation of catalyst of formula (II): Under a nitrogen atmosphere, ligand of formula (I) (0.158 g, 0.2 mmol) and (DME)NiBr2 (0.062 g, 0.2 mmol) were dissolved in 20 mL of dichloromethane and stirred at room temperature for 24 hours. The dichloromethane was dried under vacuum, and the solution was washed three times with 20 mL of diethyl ether each time. The diethyl ether was then dried under vacuum to obtain catalyst of formula (II), 0.190 g, with a yield of 94.1%.

[0039] The following examples illustrate catalytic ethylene polymerization: Example 4: Ethylene pressure polymerization was carried out under anhydrous and oxygen-free conditions. The ethylene pressure was 0.7 MPa, and the polymerization temperature was 40 °C. 1 L of heptane was poured into a 2000 mL stainless steel reactor, followed by the injection of 1.5 mL of a 2.0 mol / L toluene solution of diethylaluminum chloride, a co-catalyst. 2 μmol of catalyst (II) was dissolved in 10 mL of toluene solution and injected. The ethylene pressure was increased to 0.7 MPa, and the mixture was stirred. After reacting for half an hour, the polymer solution was poured into an acidified ethanol solution for sedimentation. The polymer was filtered, washed several times with acidified ethanol, and dried under vacuum at 60 °C to constant weight. 2.7 g of polymer was then weighed. The catalytic activity was 2.7 × 10⁻⁶. 6 gPE[mol(Ni)h] -1 The weight-average molecular weight of the polymer product is 1.48 × 10⁻⁶. 6 g / mol, polydispersity index of 2.89, and branching degree of 98.

Claims

1. The acenaphthene-bisasymmetric α-diimine chemical intermediate shown in formula (Ⅰ): 。 2. The catalyst shown in formula (II): in, X is chlorine or bromine.

3. A method for preparing formula (I) according to claim 1, characterized in that, Using 2,4,6-tri-tert-butylaniline as a raw material, the chemical intermediate of acenaphthene-bisasymmetric α-diimine is obtained, which includes the following steps: 1) Acenathoquinone reacts with aniline containing a sterically hindered substituent via a ketamine condensation reaction to yield the compound shown in formula (III): ； 2) The compound shown in formula (III) reacts with 2,4,6-tri-tert-butylaniline via a ketamine condensation reaction to yield the intermediate shown in formula (I): 。 4. A method for preparing the catalyst according to claim 2, comprising the following steps: under inert gas protection, complexing the intermediate according to claim 1 with one of ethylene glycol dimethyl ether nickel dibromide, ethylene glycol dimethyl ether nickel dichloride, or nickel dichloride hexahydrate to obtain the catalyst according to claim 2.

5. A catalyst composition for catalyzing olefin polymerization, characterized in that, It comprises a main catalyst and a co-catalyst, wherein the main catalyst is selected from the catalyst according to claim 2, wherein the co-catalyst is selected from at least one of alkylaluminum chloride, alkylaluminum or aluminoxane, and the olefin is ethylene or propylene.

6. The application of the catalyst according to claim 2 in the catalytic polymerization of ethylene and propylene to prepare polyethylene and polypropylene.

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