Synthesis method of tri (isopropyl cyclopentadienyl) lanthanum

Abstract

The invention discloses a synthetic method of tris (isopropyl cyclopentadienyl) lanthanum. The synthetic method comprises the following steps: preparing a lanthanum trichloride tetrahydrofuran complex; synthesis of isopropyl cyclopentadiene is carried out; and synthesis of tri (isopropyl cyclopentadienyl) lanthanum. According to the technical scheme, the lanthanum trichloride tetrahydrofuran complex is prepared firstly and then reacts with lithium dimethylamino and isopropyl cyclopentadiene in sequence, and the target product is obtained. Reaction raw materials are simple and easy to obtain, operation is convenient, the safety coefficient is high, the yield is high, and the method is suitable for industrial large-scale production.

Description

Technical Field

[0001] The present invention relates to the technical field of chemical synthesis, and more specifically, to a method for synthesizing tri(isopropylcyclopentadienyl)lanthanum. Background Art

[0002] With the continuous advancement of semiconductor process technology, it is expected that the size of components will continue to shrink in order to reduce costs and increase production capacity. However, since the thickness of the gate oxide layer has reached its limit, the leakage current is too large due to direct tunneling current, which makes the components unacceptable. Therefore, it is urgent to find high dielectric materials to replace silicon dioxide. Lanthanum oxide thin film, as a high dielectric material, has gradually come into people's view.

[0003] Many methods for preparing lanthanum oxide thin films have been reported, including electron beam evaporation, magnetron sputtering, arc ion plating, chemical vapor deposition (CVD), atomic layer deposition (ALD), etc. Among them, the atomic layer deposition method (ALD) has been increasingly recognized due to its self-limiting characteristics and excellent three-dimensional structural conformality.

[0004] Common lanthanum precursors include lanthanum tris(cyclopentadienyl) lanthanum, lanthanum acetylacetonate, lanthanum tris(bis(trimethylsilyl)amino) lanthanum, lanthanum tris(2,2,6,6-tetramethyl-3,5-heptanedione) lanthanum, lanthanum tris(isopropylcyclopentadienyl) lanthanum, etc. Since lanthanum tris(cyclopentadienyl) lanthanum, lanthanum acetylacetonate, lanthanum tris(bis(trimethylsilyl)amino) lanthanum, lanthanum tris(2,2,6,6-tetramethyl-3,5-heptanedione) lanthanum are solid at room temperature, have low reactivity, require very high temperatures during use, and are prone to sublimation and block the source bottle, these compounds are not very ideal ALD precursors. However, lanthanum tris(isopropylcyclopentadienyl) lanthanum is a liquid at room temperature and is widely used due to its higher vapor pressure and better thermal stability. However, there are few reports on the synthesis of lanthanum tris(isopropylcyclopentadienyl) lanthanum. Therefore, it is necessary to find a synthetic route with simple process, convenient operation, high yield, and suitable for factory scale-up. Summary of the invention

[0005] 1. Technical issues to be resolved In view of the problems existing in the prior art, the present invention provides a method for synthesizing tri(isopropylcyclopentadienyl)lanthanum to solve the technical problems mentioned in the background technology.

[0006] (II) Technical solution To achieve the above object, the present invention provides the following technical solution: a method for synthesizing tri(isopropylcyclopentadienyl)lanthanum, comprising the following steps: Step 1: Preparation of lanthanum trichloride tetrahydrofuran complex; Step 2: Synthesis of isopropylcyclopentadiene; Step 3: Synthesis of tri(isopropylcyclopentadienyl)lanthanum.

[0007] The present invention is further configured as follows: in the step 1, metal lanthanum (50 g, 0.36 mol), methanol (40.4 g, 1.26 mol) and 1 liter of tetrahydrofuran are sequentially added to a 2000 ml reaction bottle under a nitrogen atmosphere, and trimethylsilyl chloride (136.9 g, 1.26 mol) is added dropwise. After the addition is completed, the mixture is stirred at room temperature for 12 hours, filtered in anhydrous and oxygen-free conditions, washed with n-hexane, and dried to obtain a lanthanum trichloride tetrahydrofuran complex LaCl3(THF) X 98.2g, elemental analysis and lanthanum content determination of the product, obtained X≈1, yield 86%.

[0008] The present invention is further configured as follows: in the step 2, sodium hydroxide (120g, 3.0mol) and 1.5 liters of DMSO are added to a 10L multi-mouth reaction bottle under a nitrogen atmosphere, the temperature is lowered to 0°C, cyclopentadiene monomer (244.6g, 3.7mol) is added dropwise to the reaction system, the system turns dark red, the addition is completed, the temperature is slowly restored to room temperature and stirring is continued for 1 hour, 2-bromopropane (350g, 2.85mol) is added dropwise to the system, the addition is completed, the temperature is slowly restored to room temperature and stirring is continued for 12 hours, dilute hydrochloric acid (40mLHCl, 400mL water) is continued to be added dropwise to the system, the addition is completed, the system turns into an orange-yellow turbid liquid, filtered, separated, the organic phase is dried with anhydrous sodium sulfate, filtered, and distilled under reduced pressure, the vacuum degree is controlled at 10-15Torr, 166.5g of the internal temperature 24°C fraction is collected, and the purity is 98% using gas chromatography. The yield is 54%.

[0009] The present invention is further configured as follows: in the step 3, lanthanum trichloride tetrahydrofuran complex (38.1 g, 0.12 mol) and 800 ml of tetrahydrofuran are added to a 2000 ml reaction bottle under a nitrogen atmosphere, the temperature is lowered to 0°C, and 300 ml of lithium dimethylamide (18.7 g, 0.366 mol) of tetrahydrofuran solvent is added dropwise under stirring. After the addition is completed, the room temperature is slowly restored and stirring is continued for 12 hours, and then isopropylcyclopentadiene (45.4 g, 0.42 mol) is added dropwise to the system. After the addition is completed, the system is heated to 40°C and the reaction is continued for 8 hours. After the reaction is completed, the solvent is drained, toluene is added for extraction, filtration is performed, and the filtrate is distilled under reduced pressure to obtain 44.8 grams of a viscous yellow liquid with a yield of 81%.

[0010] (III) Beneficial effects Compared with the prior art, the present invention provides a method for synthesizing tri(isopropylcyclopentadienyl)lanthanum, which has the following beneficial effects: The technical problem to be solved by the present invention is to provide a preparation method of a tri(isopropylcyclopentadienyl)lanthanum complex precursor, the whole process operation conditions are convenient; the raw material source is wide and cheap, the product yield is high, and the process stability is good; the product metal purity is high, and the requirements for the metal purity of the product in the semiconductor field are met. The technical scheme first prepares a lanthanum trichloride tetrahydrofuran complex, and then reacts with lithium dimethylamine and isopropylcyclopentadiene in sequence to obtain a target product. The reaction raw materials are simple and easy, the operation is convenient, the safety factor is high, and the yield is high. It is suitable for industrialized amplification production. DETAILED DESCRIPTION

[0012] Example: The synthesis method of tri(isopropylcyclopentadienyl)lanthanum comprises the following steps: Step 1: Preparation of lanthanum trichloride tetrahydrofuran complex Lanthanum metal (50 g, 0.36 mol), methanol (40.4 g, 1.26 mol) and 1 liter of tetrahydrofuran were added to a 2000 ml reaction bottle in a nitrogen atmosphere, and trimethylsilyl chloride (136.9 g, 1.26 mol) was added dropwise. After the addition was completed, the mixture was stirred at room temperature for 12 hours, filtered in anhydrous and oxygen-free conditions, washed with n-hexane, and dried to obtain 98.2 g of lanthanum trichloride tetrahydrofuran complex LaCl3(THF)X. The product was subjected to elemental analysis and lanthanum content determination, and X≈1 was obtained, with a yield of 86%. Elemental analysis results: C: 14.99, H: 2.61. La content: 43.45%.

[0013] Step 2: Synthesis of isopropylcyclopentadiene Under nitrogen atmosphere, sodium hydroxide (120g, 3.0mol) and 1.5L DMSO were added to a 10L multi-mouth reaction bottle, and the temperature was lowered to 0°C. Cyclopentadiene monomer (244.6g, 3.7mol) was added dropwise to the reaction system, and the system turned dark red. After the addition was completed, the temperature was slowly restored to room temperature and continued to stir for 1 hour. 2-bromopropane (350g, 2.85mol) was added dropwise to the system, and the temperature was slowly restored to room temperature and continued to stir for 12 hours. Dilute hydrochloric acid (40mLHCl, 400mL water) was continued to be added dropwise to the system, and after the addition was completed, the system turned into an orange-yellow turbid liquid, filtered, separated, the organic phase was dried with anhydrous sodium sulfate, filtered, and distilled under reduced pressure. The vacuum degree was controlled at 10-15Torr. 166.5g of the fraction with an internal temperature of 24°C was collected, and the purity was 98% by gas chromatography. The yield was 54%.

[0014] Step 3: Synthesis of tri(isopropylcyclopentadienyl)lanthanum Lanthanum trichloride tetrahydrofuran complex (38.1 g, 0.12 mol) and 800 ml tetrahydrofuran were added to a 2000 ml reaction bottle under nitrogen atmosphere, cooled to 0°C, and 300 ml of lithium dimethylamide (18.7 g, 0.366 mol) in tetrahydrofuran solvent was added dropwise with stirring. After the addition was completed, the room temperature was slowly restored and stirring was continued for 12 hours. Then, isopropylcyclopentadiene (45.4 g, 0.42 mol) was added dropwise to the system. After the addition was completed, the system was heated to 40°C and the reaction was continued for 8 hours. After the reaction was completed, the solvent was drained, toluene was added for extraction, filtered, and the filtrate was distilled under reduced pressure to obtain 44.8 g of a viscous yellow liquid with a yield of 81%.

[0015] 1HNMR (C6D6): 6.04 (m, 6H), 5.98 (m, 6H), 2.75 (m, 3H), 1.09 (d, 18H).

[0016] The purity of the product was tested using inductively coupled plasma mass spectrometry (ICP-MS), and the results showed that the metal purity of the product was 4N.

[0017] Comparative Example 1: Unlike step 2, in this example, sodium hydroxide is replaced with potassium hydroxide. Under nitrogen atmosphere, 85% potassium hydroxide (940.7 g, 14.25 mol) and 5.0 liters of DMSO were added to a 10L multi-mouth reaction bottle, and the temperature was lowered to 0°C. Cyclopentadiene monomer (244.6 g, 3.7 mol) was added dropwise to the reaction system, and the system turned dark red. After the addition was completed, the temperature was slowly restored to room temperature and stirring was continued for 1 hour. 2-Bromopropane (350 g, 2.85 mol) was added dropwise to the system. After the addition was completed, the temperature was slowly restored to room temperature and stirring was continued for 12 hours. Dilute hydrochloric acid (180 mL HCl, 1800 mL water) was continued to be added dropwise to the system. After the addition was completed, the system turned into an orange-yellow turbid liquid, filtered, separated, the organic phase was dried over anhydrous sodium sulfate, filtered, and distilled under reduced pressure. The vacuum degree was controlled at 10-15 Torr. 144.9 g of the fraction with an internal temperature of 24°C was collected. The purity was 97% using gas chromatography, and the yield was 47%.

[0018] Comparative Example 2: Different from step 3, this example directly uses lanthanum trichloride instead of lanthanum trichloride tetrahydrofuran complex to participate in the reaction Lanthanum trichloride (29.4 g, 0.12 mol) and 800 ml of tetrahydrofuran were added to a 2000 ml reaction bottle under a nitrogen atmosphere, and 300 ml of a tetrahydrofuran solution of isopropylcyclopentadienyl sodium (48.4 g, 0.372 mol) was added dropwise under stirring. After the addition was completed, the mixture was heated to reflux and the reaction was continued for 24 hours. After the reflux was completed, the solvent was drained, toluene was added for extraction, and the mixture was filtered. The solvent was drained from the filtrate to obtain a black viscous yellow liquid. The target product could not be obtained by distillation under reduced pressure. This may be because the water content of commercially available lanthanum trichloride was too high, resulting in the failure of the reaction.

[0019] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for synthesizing tri(isopropylcyclopentadienyl)lanthanum, characterized in that: The following steps are involved: Step 1: Preparation of lanthanum trichloride tetrahydrofuran complex; Step 2: Synthesis of isopropylcyclopentadiene; Step 3: Synthesis of tri(isopropylcyclopentadienyl)lanthanum.

2. The method for synthesizing tri(isopropylcyclopentadienyl)lanthanum according to claim 1, characterized in that: In the step 1, lanthanum metal (50 g, 0.36 mol), methanol (40.4 g, 1.26 mol) and 1 liter of tetrahydrofuran were added to a 2000 ml reaction bottle in a nitrogen atmosphere, and trimethylsilyl chloride (136.9 g, 1.26 mol) was added dropwise. After the addition was completed, the mixture was stirred at room temperature for 12 hours, filtered in anhydrous and oxygen-free conditions, washed with n-hexane, and dried to obtain lanthanum trichloride tetrahydrofuran complex LaCl3(THF) X 98.2g, elemental analysis and lanthanum content determination of the product, obtained X≈1, yield 86%.

3. The method for synthesizing tri(isopropylcyclopentadienyl)lanthanum according to claim 2, characterized in that: In the step 2, sodium hydroxide (120 g, 3.0 mol) and 1.5 liters of DMSO were added to a 10L multi-mouth reaction bottle under a nitrogen atmosphere, and the temperature was lowered to 0°C. Cyclopentadiene monomer (244.6 g, 3.7 mol) was added dropwise to the reaction system, and the system turned dark red. After the addition was completed, the temperature was slowly restored to room temperature and stirring was continued for 1 hour. 2-bromopropane (350 g, 2.85 mol) was added dropwise to the system. After the addition was completed, the temperature was slowly restored to room temperature and stirring was continued for 12 hours. Dilute hydrochloric acid (40 mL HCl, 400 mL water) was continued to be added dropwise to the system. After the addition was completed, the system turned into an orange-yellow turbid liquid, filtered, separated, the organic phase was dried over anhydrous sodium sulfate, filtered, and distilled under reduced pressure. The vacuum degree was controlled at 10-15 Torr. 166.5 g of a fraction with an internal temperature of 24°C was collected. The purity was 98% and the yield was 54% as detected by gas chromatography.

4. The method for synthesizing tri(isopropylcyclopentadienyl)lanthanum according to claim 2, characterized in that: In the step 3, lanthanum trichloride tetrahydrofuran complex (38.1 g, 0.12 mol) and 800 ml of tetrahydrofuran are added to a 2000 ml reaction bottle under a nitrogen atmosphere, the temperature is lowered to 0° C., 300 ml of lithium dimethylamide (18.7 g, 0.366 mol) in tetrahydrofuran solvent is added dropwise under stirring, and after the addition is completed, the room temperature is slowly restored and stirring is continued for 12 hours, and then isopropylcyclopentadiene (45.4 g, 0.42 mol) is added dropwise to the system, and after the addition is completed, the system is heated to 40° C. and the reaction is continued for 8 hours. After the reaction is completed, the solvent is drained, toluene is added for extraction, and the mixture is filtered. The filtrate is distilled under reduced pressure to obtain 44.8 g of a viscous yellow liquid with a yield of 81%.