Novel synthesis method of tris (dimethylamino) cyclopentadienyl hafnium

Abstract

The invention provides a synthesis method of tris (dimethylamino) cyclopentadienyl hafnium, which comprises the following steps: reacting hafnium tetrachloride with sodium dimethylamino at a first temperature under the protection of inert gas to form an intermediate; heating and settling, cooling to a second temperature, dropwise adding cyclopentadiene, and filtering, distilling and purifying to obtain a target product. According to the method, high yield and high purity are achieved by optimizing the raw material ratio and controlling the dropwise adding temperature and the use amount of cyclopentadiene. The byproduct sodium chloride is large in particle and easy to filter, the post-treatment process is remarkably simplified, and the process safety, controllability and industrial adaptability are improved.

Description

Technical Field

[0001] The present invention relates to the field of organic chemical synthesis, and in particular to a novel synthesis method of tris(dimethylamino)cyclopentadienyl hafnium. Background Art

[0002] Hafnium tris(dimethylamino)cyclopentadienyl is a class of hafnium complexes with significant application value in organometallic chemistry. They are widely used in atomic layer deposition (ALD) and chemical vapor deposition (CVD) processes in semiconductor manufacturing and can also serve as catalyst precursors in a variety of organic transformation reactions. The development of high-performance thin film materials and efficient catalytic systems has placed higher demands on high-purity, scalable synthesis technologies for these compounds. Summary of the Invention

[0003] In the prior art, typical synthesis methods for tris(dimethylamino)cyclopentadienyl hafnium often involve reacting hafnium tetrachloride with lithium dimethylamide (LiNMe2) to produce an intermediate, which then undergoes a coordination reaction with cyclopentadiene. For example, patent CN119684373A discloses a method for directly reacting lithium dimethylamide with hafnium tetrachloride by reacting n-butyllithium with dimethylamine. Patent CN117186136A achieves some success in improving product yield and purity by optimizing the addition rate and reflux conditions of lithium dimethylamide and a zirconium source. However, this method has significant technical drawbacks. First, the byproduct lithium chloride (LiCl) during the reaction is a fine, granular solid that is difficult to effectively remove through conventional filtration methods. Additional steps such as centrifugation and adsorption purification are often required, increasing process complexity and equipment burden, and easily creating operational bottlenecks in continuous or scaled-up production. Secondly, this type of method generally adopts a step-by-step synthesis route, which requires the separation and purification of intermediates. The operation is cumbersome and time-consuming. In addition, improper handling of intermediates can easily cause fluctuations in the yield of the target product and affect batch stability.

[0004] Therefore, there is an urgent need to provide a new synthesis process with a more optimized reagent system, a simpler operating process, milder reaction conditions, and suitability for industrial production.

[0005] In view of this, the present invention provides a method for synthesizing tris(dimethylamino)cyclopentadienyl hafnium, comprising the following steps:

[0006] Step 1: Under the protection of an inert gas, hafnium tetrachloride and an organic solvent solution of sodium dimethylamide are mixed and reacted at a first temperature, and then returned to room temperature and stirred to form a reaction system; Step 2: Raise the temperature to allow the solid in the reaction system of step 1 to settle, then cool to a second temperature and dropwise add cyclopentadiene. After the dropwise addition is complete, return the temperature to room temperature, filter, distill, and purify by vacuum distillation to obtain tris(dimethylamino)cyclopentadienyl hafnium.

[0007] In some specific embodiments, the molar ratio of sodium dimethylamide to hafnium tetrachloride in step 1 is 3:1 to 4:1.

[0008] In some specific embodiments, the molar ratio of sodium dimethylamide to hafnium tetrachloride in step 1 is 3:1, 3.1:1, 3.2:1, 3.3:1, 3.4:1, 3.5:1, 3.6:1, 3.7:1, 3.8:1, 3.9:1 or 4:1.

[0009] In some specific embodiments, the molar ratio of sodium dimethylamide in step 1 to cyclopentadiene in step 2 is 3:1 to 5:1.

[0010] In some specific embodiments, the molar ratio of sodium dimethylamide to hafnium tetrachloride in step 1 is 3:1, 3.1:1, 3.2:1, 3.3:1, 3.4:1, 3.5:1, 3.6:1, 3.7:1, 3.8:1, 3.9:1, 4:1, 4.1:1, 4.2:1, 4.3:1, 4.4:1, 4.5:1, 4.6:1, 4.7:1, 4.8:1, 4.9:1 or 5:1.

[0011] In some specific embodiments, the molar ratio of hafnium tetrachloride in step 1 to cyclopentadiene in step 2 is 1.1:1 to 1.3:1.

[0012] In some specific embodiments, the molar ratio of hafnium tetrachloride in step 1 to cyclopentadiene in step 2 is 1.1:1, 1.2:1 or 1.3:1.

[0013] In some specific embodiments, the inert gas in step 1 is selected from at least one of nitrogen, argon and helium.

[0014] In some specific embodiments, the inert gas in step 1 is nitrogen.

[0015] In some specific embodiments, the organic solvent in step 1 is selected from at least one of toluene, tetrahydrofuran, diethyl ether and n-hexane, preferably toluene.

[0016] In some specific embodiments, the organic solvent in step 1 is toluene.

[0017] In some specific embodiments, the first temperature in step 1 is -20°C to 0°C.

[0018] In some specific embodiments, the first temperature in step 1 is -20°C, -19°C, -18°C, -17°C, -16°C, -15°C, -14°C, -13°C, -12°C, -11°C, -10°C, -9°C, -8°C, -7°C, -6°C, -5°C, -4°C, -3°C, -2°C, -1°C or 0°C.

[0019] In some specific embodiments, the second temperature in step 2 is -20°C to -10°C.

[0020] In some specific embodiments, the second temperature in step 2 is -20°C, -19°C, -18°C, -17°C, -16°C, -15°C, -14°C, -13°C, -12°C, -11°C or -10°C.

[0021] In some specific embodiments, the amount of cyclopentadiene used in step 2 is 0.7 to 1.0 equivalents.

[0022] In some specific embodiments, the amount of cyclopentadiene used in step 2 is 0.8 equivalents, 0.85 equivalents or 0.9 equivalents.

[0023] In some specific embodiments, the vacuum degree of the reduced pressure distillation in step 2 is 0.05-0.5 mmHg.

[0024] In some specific embodiments, the vacuum degree of the reduced pressure distillation in step 2 is 0.05 mmHg, 0.1 mmHg, 0.15 mmHg, 0.2 mmHg, 0.25 mmHg, 0.3 mmHg, 0.35 mmHg, 0.4 mmHg, 0.45 mmHg, or 0.5 mmHg.

[0025] In some specific embodiments, the heating temperature of the reduced pressure distillation in step 2 is 80-100°C.

[0026] In some specific embodiments, the heating temperature for the reduced pressure distillation in step 2 is 80°C, 81°C, 82°C, 83°C, 84°C, 85°C, 86°C, 87°C, 88°C, 89°C, 90°C, 91°C, 92°C, 93°C, 94°C, 95°C, 96°C, 97°C, 98°C, 99°C or 100°C.

[0027] Beneficial effects: Compared with traditional methods, the method provided by the present invention significantly improves yield (71% in Example 1). The generated byproduct, sodium chloride, is large particles that can be directly separated by conventional sand core filtration, avoiding the difficulty in filtering lithium chloride produced by using lithium dimethylamide. Furthermore, the post-processing steps are simplified, improving the overall process's industrial adaptability and ease of operation.

[0028] The method provided by the present invention controls the addition amount and dropwise addition temperature of cyclopentadiene, effectively suppresses the occurrence of side reactions while achieving complete reaction, significantly improves the yield and purity of the product, and simultaneously has good reaction controllability and process safety, and is suitable for stable scale-up production under industrial conditions. DETAILED DESCRIPTION

[0029] In order to enable those skilled in the art to better understand the technical solutions of the present invention, some non-limiting embodiments are further disclosed below to further illustrate the present invention in detail.

[0030] Explanation of terms: (1) Room temperature: The temperature of the indoor environment, which is the temperature range that people can feel comfortable in their daily activities without additional heating or cooling. It is usually understood to be between 20 and 25 degrees Celsius.

[0031] (2) One-pot reaction: A chemical reaction strategy in which reactants undergo multiple steps of reaction in a single reactor to improve reaction efficiency.

[0032] (3) Vacuum distillation: A distillation method carried out under conditions of reduced ambient pressure.

[0033] (4) Hafnium tetrachloride: A weak Lewis acid that can form adducts ZrCl4·PCl5 and ZrCl4·2PCl5 with phosphorus pentachloride, or hexachlorozirconate with alkali metal or alkaline earth metal chlorides.

[0034] (5) Sodium dimethylamide: an organic ammonium salt, commonly used as a condensing agent and reducing agent in organic synthetic chemistry, and is often used in the synthesis of amino acids and peptide compounds.

[0035] (6) Cyclopentadiene: It is used in pesticides as an intermediate of tetrachlorocyclopentane in the synthesis of insecticides chlordane and endosulfan. It can also be used as an intermediate in the production of insecticide imidacloprid. In addition, it is mainly used in the resin industry, synthetic rubber, etc.

[0036] Example 1 Under nitrogen, hafnium tetrachloride (100 g, 0.312 mol) was weighed and added portionwise to a solution of sodium dimethylamide in toluene (1.25 mol, 1.25 L), maintaining the temperature between -20°C and -10°C. After addition, the mixture was slowly returned to room temperature and stirred for 12 hours. After the reaction, the temperature was raised to 50°C to allow the solids in the reaction system to settle. The temperature was then lowered to -20°C, and cyclopentadiene (17.5 g, 0.265 mol) was added dropwise to the reaction system, maintaining the temperature between -20°C and -10°C. After the addition was complete, the mixture was slowly returned to room temperature. The reaction system was directly filtered through a frit to remove the generated inorganic salts, and the filtrate was collected. The solvent was removed from the filtrate by atmospheric distillation to obtain the crude product. The crude product was then distilled under reduced pressure at a vacuum of 0.1 mmHg and a heating temperature of 90°C. The fraction with a top temperature of 60-65°C was collected, which was tris(dimethylamino)cyclopentadienylhafnium, 82.2 g, with a yield of 71%.

[0037] Example 2 Under nitrogen, hafnium tetrachloride (100 g, 0.312 mol) was weighed and added portionwise to a solution of sodium dimethylamide in toluene (1.25 mol, 1.25 L), maintaining the temperature between -20°C and -10°C. After addition, the mixture was slowly returned to room temperature and stirred for 12 hours. After the reaction, the temperature was raised to 50°C to allow the solids in the reaction system to settle. The temperature was then lowered to -20°C, and cyclopentadiene (16.5 g, 0.25 mol) was added dropwise to the reaction system, maintaining the temperature between -20°C and -10°C. After the addition was complete, the mixture was slowly returned to room temperature. The reaction system was directly filtered through a frit to remove the generated inorganic salts, and the filtrate was collected. The solvent was removed from the filtrate by atmospheric distillation to obtain the crude product. The crude product was then distilled under reduced pressure at a vacuum of 0.1 mmHg and a heating temperature of 90°C. The fraction with a top temperature of 60-65°C was collected, which was tris(dimethylamino)cyclopentadienylhafnium, 75.2 g, with a yield of 65%.

[0038] Example 3 Under nitrogen, hafnium tetrachloride (100 g, 0.312 mol) was weighed and added portionwise to a solution of sodium dimethylamide in toluene (1.25 mol, 1.25 L), maintaining the temperature between -20°C and -10°C. After addition, the mixture was slowly returned to room temperature and stirred for 12 hours. After the reaction, the temperature was raised to 50°C to allow the solids in the reaction system to settle. The temperature was then lowered to -20°C, and cyclopentadiene (16.5 g, 0.25 mol) was added dropwise to the reaction system, maintaining the temperature between -20°C and -10°C. After the addition was complete, the mixture was slowly returned to room temperature. The reaction system was directly filtered through a frit to remove the generated inorganic salts, and the filtrate was collected. The solvent was removed from the filtrate by atmospheric distillation to obtain the crude product. The crude product was then distilled under reduced pressure at a vacuum of 0.1 mmHg and a heating temperature of 90°C. The fraction with a top temperature of 60-65°C was collected, which was tris(dimethylamino)cyclopentadienylhafnium, 72.9 g, with a yield of 63%.

[0039] Example 4 Under nitrogen, hafnium tetrachloride (100 g, 0.312 mol) was weighed and added portionwise to a solution of sodium dimethylamide in toluene (1.25 mol, 1.25 L), maintaining the temperature between -20°C and -10°C. After addition, the mixture was slowly returned to room temperature and stirred for 12 hours. After the reaction, the temperature was raised to 50°C to allow the solids in the reaction system to settle. The temperature was then lowered to -20°C, and cyclopentadiene (18.6 g, 0.281 mol) was added dropwise to the reaction system, maintaining the temperature between -20°C and -10°C. After the addition was complete, the mixture was slowly returned to room temperature. The reaction system was directly filtered through a frit to remove the generated inorganic salts, and the filtrate was collected. The solvent was removed from the filtrate by atmospheric distillation to obtain the crude product. The crude product was then distilled under reduced pressure at a vacuum of 0.1 mmHg and a heating temperature of 90°C. The fraction with a top temperature of 60-65°C was collected, which was tris(dimethylamino)cyclopentadienylhafnium, 78.7 g, with a yield of 68%.

[0040] Example 5 Under nitrogen, hafnium tetrachloride (100 g, 0.312 mol) was weighed and added portionwise to a solution of sodium dimethylamide in toluene (1.25 mol, 1.25 L), maintaining the temperature between -20°C and -10°C. After addition, the mixture was slowly returned to room temperature and stirred for 12 hours. After the reaction, the temperature was raised to 50°C to allow the solids in the reaction system to settle. The temperature was then lowered to -20°C, and cyclopentadiene (16.5 g, 0.25 mol) was added dropwise to the reaction system, maintaining the temperature between -20°C and -10°C. After the addition was complete, the mixture was slowly returned to room temperature. The reaction system was directly filtered through a frit to remove the generated inorganic salts, and the filtrate was collected. The solvent was removed from the filtrate by atmospheric distillation to obtain the crude product. The crude product was then distilled under reduced pressure at a vacuum of 0.1 mmHg and a heating temperature of 90°C. The fraction with a top temperature of 60-65°C was collected, which was tris(dimethylamino)cyclopentadienylhafnium, 71.8 g, with a yield of 62%.

[0041] Example 6 Under nitrogen, weigh hafnium tetrachloride (100 g, 0.312 mol) and add it portionwise to a solution of sodium dimethylamide in toluene (1.25 mol, 1.25 L). Maintain the temperature between -10°C and 0°C. After addition, slowly return the mixture to room temperature and stir for 12 hours. After the reaction, raise the temperature to 50°C to allow the solids in the reaction system to settle. Then, cool the temperature to -10°C and add cyclopentadiene (17.5 g, 0.265 mol) dropwise to the reaction system, maintaining the temperature between -10°C and 0°C. After the addition is complete, slowly return the mixture to room temperature. Filter the reaction system directly through a frit to remove the generated inorganic salts, and collect the filtrate. Distill the filtrate under atmospheric pressure to remove the solvent and obtain the crude product. The crude product was then distilled under reduced pressure at a vacuum of 0.1 mmHg and a heating temperature of 90°C. The fraction with a top temperature of 60-65°C was collected, which was tris(dimethylamino)cyclopentadienylhafnium, 78.7 g, with a yield of 68%.

[0042] Example 7 Under nitrogen, hafnium tetrachloride (100 g, 0.312 mol) was weighed and added portionwise to a solution of sodium dimethylamide in toluene (1.25 mol, 1.25 L). The temperature was maintained between -20°C and -10°C. After the addition was complete, the mixture was slowly returned to room temperature and stirred for 12 hours. After the reaction was complete, the temperature was raised to 50°C to allow the solids in the reaction system to settle. The temperature was then lowered to 0°C, and cyclopentadiene (17.5 g, 0.265 mol) was added dropwise to the reaction system, maintaining the temperature between 0°C and 10°C. After the addition was complete, the mixture was slowly returned to room temperature. The reaction system was directly filtered through a frit to remove the generated inorganic salts, and the filtrate was collected. The solvent was removed from the filtrate by atmospheric distillation to obtain the crude product. The crude product was then distilled under reduced pressure at a vacuum of 0.1 mmHg and a heating temperature of 90°C. The fraction with a top temperature of 60-65°C was collected, which was tris(dimethylamino)cyclopentadienylhafnium, 70.6 g, with a yield of 61%.

[0043] Example 8 Under nitrogen, hafnium tetrachloride (100 g, 0.312 mol) was weighed and added portionwise to a solution of sodium dimethylamide in toluene (0.936 mol, 0.936 L), maintaining the temperature between -20°C and -10°C. After addition, the mixture was slowly returned to room temperature and stirred for 12 hours. After the reaction, the temperature was raised to 50°C to allow the solids in the reaction system to settle. The temperature was then lowered to -20°C, and cyclopentadiene (17.5 g, 0.265 mol) was added dropwise to the reaction system, maintaining the temperature between -20°C and -10°C. After the addition was complete, the mixture was slowly returned to room temperature. The reaction system was directly filtered through a frit to remove the generated inorganic salts, and the filtrate was collected. The solvent was removed from the filtrate by atmospheric distillation to obtain the crude product. The crude product was then distilled under reduced pressure at a vacuum of 0.1 mmHg and a heating temperature of 90°C. The fraction with a top temperature of 60-65°C was collected, which was tris(dimethylamino)cyclopentadienylhafnium, 77.5 g, with a yield of 67%.

[0044] Example 9 Under nitrogen, weigh hafnium tetrachloride (100 g, 0.312 mol) and add it portionwise to a solution of sodium dimethylamide in tetrahydrofuran (1.25 mol, 1.25 L). Maintain the temperature between -20°C and -10°C. After addition, slowly return the mixture to room temperature and stir for 12 hours. After the reaction, raise the temperature to 50°C to allow the solids in the reaction system to settle. Then, cool the temperature to -20°C and add cyclopentadiene (17.5 g, 0.265 mol) dropwise to the reaction system, maintaining the temperature between -20°C and -10°C. After the addition is complete, slowly return the mixture to room temperature. Filter the reaction system directly through a frit to remove the generated inorganic salts, and collect the filtrate. Distill the filtrate under atmospheric pressure to remove the solvent to obtain the crude product. The crude product was then distilled under reduced pressure at a vacuum of 0.1 mmHg and a heating temperature of 90°C. The fraction with a top temperature of 60-65°C was collected, which was tris(dimethylamino)cyclopentadienylhafnium, 76.4 g, with a yield of 66%.

[0045] Based on Examples 1-9, the cyclopentadiene feed equivalent and its addition temperature significantly influence the yield of the target product. Controlling the cyclopentadiene dosage near the stoichiometric ratio, particularly preferably 0.85 equivalents, effectively avoids side reactions and improves reaction selectivity. Simultaneously, controlling the addition temperature within the low temperature range of -20°C to -10°C not only helps suppress impurity formation but also ensures controllability and safety of the reaction. The coordinated optimization of these process conditions significantly improves the yield and purity of tris(dimethylamino)cyclopentadienyl hafnium, demonstrating clear technical advantages and industrial application value.

[0046] Comparative Example 1 Under nitrogen, hafnium tetrachloride (100 g, 0.312 mol) was weighed and added portionwise to a solution of lithium dimethylamide in toluene (1.25 mol, 1.25 L), maintaining the temperature between -20°C and -10°C. After addition, the mixture was slowly returned to room temperature and stirred for 12 hours. After the reaction, the temperature was raised to 50°C to allow the solids in the reaction system to settle. The temperature was then lowered to -20°C, and cyclopentadiene (17.5 g, 0.265 mol) was added dropwise to the reaction system, maintaining the temperature between -20°C and -10°C. After the addition was complete, the mixture was slowly returned to room temperature. The reaction system was directly filtered through a frit to remove the generated inorganic salts, and the filtrate was collected. The solvent was removed from the filtrate by atmospheric distillation to obtain the crude product. The crude product was then distilled under reduced pressure at a vacuum of 0.1 mmHg and a heating temperature of 90°C. The fraction with a top temperature of 60-65°C was collected, which was tris(dimethylamino)cyclopentadienylhafnium, 63.7 g, with a yield of 55%.

[0047] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for synthesizing tris(dimethylamino)cyclopentadienyl hafnium, characterized in that: The steps include: Step 1: Under the protection of an inert gas, hafnium tetrachloride and an organic solvent solution of sodium dimethylamide are mixed and reacted at a first temperature, and then returned to room temperature and stirred to form a reaction system; Step 2: Raise the temperature to allow the solid in the reaction system of step 1 to settle, then cool to a second temperature and dropwise add cyclopentadiene. After the dropwise addition is complete, return the temperature to room temperature, filter, distill, and purify by vacuum distillation to obtain tris(dimethylamino)cyclopentadienyl hafnium.

2. The synthesis method according to claim 1, wherein In the step 1, the molar ratio of sodium dimethylamide to hafnium tetrachloride is 3:1 to 4:1, preferably 4:

1.

3. The synthesis method according to claim 1, wherein The molar ratio of sodium dimethylamide in step one to cyclopentadiene in step two is 3:1 to 5:1, preferably 4.7:1; and / or the molar ratio of hafnium tetrachloride in step one to cyclopentadiene in step two is 1.1:1 to 1.3:1, preferably 1.2:

1.

4. The synthesis method according to claim 1, characterized in that In step 1, the inert gas is selected from at least one of nitrogen, argon and helium, preferably nitrogen.

5. The synthesis method according to claim 1, characterized in that In the step 1, the organic solvent is selected from at least one of toluene, tetrahydrofuran, diethyl ether and n-hexane, preferably toluene.

6. The synthesis method according to claim 1, characterized in that The first temperature in step 1 is -20°C to 0°C, preferably -10°C.

7. The synthesis method according to claim 1, characterized in that The second temperature in the step 2 is -20°C to -10°C, preferably -20°C.

8. The synthesis method according to claim 1, characterized in that The amount of cyclopentadiene used in step 2 is 0.8 to 0.9 equivalents, preferably 0.85 equivalents.

9. The synthesis method according to claim 1, characterized in that The vacuum degree of the reduced pressure distillation in step 2 is 0.05-0.5 mmHg, preferably 0.1 mmHg.

10. The synthesis method according to claim 1, characterized in that The heating temperature for the reduced pressure distillation in step 2 is 80-100°C, preferably 90°C.

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