Method for preparing (cyclopentadienyl) tris (dimethylamino) hafnium by using nuclear magnetic control
By monitoring the synthesis process of (cyclopentadienyl)tris(dimethylamino)hafnium using NMR detection signals and determining the reaction progress using the ratio of characteristic peaks, the problem of difficulty in monitoring the reaction process in existing technologies has been solved, and high-yield and high-purity product production has been achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- YUANZHAN MATERIAL TECHNOLOGY (TAIZHOU) CO LTD
- Filing Date
- 2026-01-05
- Publication Date
- 2026-05-01
AI Technical Summary
Existing methods for synthesizing (cyclopentadienyl)tris(dimethylamino)hafnium cannot effectively monitor the reaction process, resulting in problems such as low yield and safety hazards in post-processing.
The method of preparing (cyclopentadienyl)tris(dimethylamino)hafnium using NMR involves using NMR detection signals to determine the reaction progress, and using the ratio of the integral area of characteristic peak A to characteristic peak B to guide the termination and treatment of the reaction, ensuring the completeness and safety of the reaction.
It improved the safety of the production process, the conversion rate of raw materials, and the purity of products, while reducing safety risks and increasing production efficiency.
Smart Images
Figure CN121949415A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of fine chemical technology, specifically to a method for the controlled preparation of (cyclopentadienyl)tris(dimethylamino)hafnium using nuclear magnetic resonance (NMR). Background Technology
[0002] In advanced integrated circuit manufacturing, especially since the 45nm technology node, high-k hafnium oxide (HfO2) thin films have become a revolutionary material replacing traditional silicon dioxide (SiO2) gate dielectrics. Its high dielectric constant (k≈20-25) allows for the use of thicker physical layers while maintaining the same equivalent oxide thickness (EOT), effectively suppressing gate leakage current caused by quantum tunneling and solving the bottleneck problems of chip power consumption and heat generation. The "High-k / metal gate" technology, integrating HfO2 with metal gates (such as TiN), is one of the core changes driving the continuation of Moore's Law and propelling semiconductor processes towards 28nm and more advanced nodes.
[0003] Currently, the mainstream industrial process for preparing high-performance HfO2 thin films is atomic layer deposition (ALD), which places extremely high demands on the purity, stability, and volatility of the precursor source. (Cyclopentadienyl)tris(dimethylamino)hafnium has become a key hafnium-based ALD precursor due to its suitable reactivity, volatility, and thermal stability.
[0004] Among various techniques for preparing hafnium oxide thin films, atomic layer deposition (ALD) is widely used due to its excellent uniformity, conformality, and controllable thickness. (Cyclopentadienyl)tris(dimethylamino)hafnium (CpHf(NMe2)3) is a precursor source for ALD hafnium oxide. Currently, the synthesis of this precursor is typically carried out using a multi-step method. A typical process route is as follows: first, hafnium tetrachloride (HfCl4) is reacted with excess dimethylamine (HNMe2) to prepare the intermediate tetra(dimethylamino)hafnium (Hf(NMe2)4); subsequently, this intermediate is further reacted with cyclopentadiene (C5H5) to obtain the target product CpHf(NMe2)3. However, this synthetic route involves multiple reaction steps and is accompanied by the generation of various highly reactive organometallic intermediates and byproducts, such as lithium dimethylamino (LiNMe2) and cyclopentadienyl lithium (C5H5Li). These substances are extremely sensitive to air and moisture, and may spontaneously combust upon exposure to air, posing a significant safety hazard.
[0005] Furthermore, the entire synthesis reaction is extremely sensitive to parameters such as feed ratio, feeding rate, reactant concentration, stirring efficiency, and reaction temperature. Fluctuations in any condition can lead to incomplete reaction, resulting in the unconsumed highly reactive substances remaining in the reaction system. If these residual reactive substances enter subsequent reactor residues or filter residues along with the reactants, they will pose serious safety hazards in post-processing stages such as separation, washing, drying, and even waste disposal, greatly increasing the safety burden and risk management difficulty of the process. In traditional production processes, the degree of reaction completion is usually judged by empirical reaction time control or endpoint sampling analysis (such as gas chromatography), but these methods have obvious lag, are destructive, and cannot reflect the true content of reactive substances in the reactor in real time.
[0006] Therefore, there is an urgent need for an intermediate control method that can monitor the content of key active substances in the synthesis of (cyclopentadienyl)tris(dimethylamino)hafnium in real time or near real time and accurately judge the reaction progress. This method is of great industrial demand and technical value for improving the inherent safety level of the entire production process, ensuring the efficient conversion of raw materials, and ultimately obtaining high-purity products. Summary of the Invention
[0007] To address the problems of low yield and high safety risks in post-processing caused by the inability to effectively monitor the reaction process in existing (cyclopentadienyl)tris(dimethylamino)hafnium synthesis methods, this invention provides a method for the controlled preparation of (cyclopentadienyl)tris(dimethylamino)hafnium using nuclear magnetic resonance (NMR). By taking intermediate samples and testing NMR, the NMR detection signal is used to determine the reaction progress and guide further optimization, greatly improving the safety of the production process, the conversion rate of raw materials, and the purity of the product.
[0008] Specifically, the following technical solutions are provided: This invention provides a method for preparing (cyclopentadienyl)tris(dimethylamino)hafnium using nuclear magnetic resonance (NMR), comprising the following steps: S1. Hafnium tetrachloride was reacted with cyclopentadiene and dimethylamine in the presence of n-butyllithium and n-hexane under reflux. After a preset reaction time, the supernatant was taken and its 1H NMR spectrum was detected. S2. Calculate the ratio 'a' of the integrated areas of characteristic peak A and characteristic peak B based on the obtained 1H NMR spectrum, and determine whether 'a' is within the target range. Perform the following operations: If the value of a is within the target range, terminate the reaction, separate the liquid phase, and collect the crude product by distillation. If the value of a is greater than the maximum value of the target range, add cyclopentadiene to the reaction system and continue the reaction until the ratio of the integral area of characteristic peak A to characteristic peak B in the 1H NMR spectrum of the reaction supernatant falls within the target range, then terminate the reaction, separate the liquid phase, and collect the crude product by distillation. If the value of a is less than the minimum value of the target range, continue the reaction until the ratio of the integral area of characteristic peak A to characteristic peak B in the 1H NMR spectrum of the reaction supernatant falls within the target range, then terminate the reaction, separate the liquid phase, and collect the crude product by distillation. The chemical shift of characteristic peak A is 2.96 ppm, and the chemical shift of characteristic peak B is 2.20 ppm; the chemical shifts of characteristic peaks A and B are corrected for using an internal standard (deuterated benzene). The target range is 1.4-1.6.
[0009] This invention addresses the practical requirements of the (cyclopentadienyl)tris(dimethylamino)hafnium production process regarding safety, yield, and purity. It proposes a central control method by correlating detection data and reaction results during the reaction process, as detailed below: (1) Determination of characteristic peaks: When the reaction reaches a certain time, the detection data is measured by the NMR spectrum of the reaction liquid. The NMR of the mixture is seriously interfered with each other and the displacement is large. The characteristic peaks with small interference and high correlation with the reaction results are selected.
[0010] (2) Determination of indicators that can be used to measure reaction results: Yield: The active substance is mainly converted into a product or by-product. If the conversion is more complete, the yield will be higher.
[0011] Purity: The percentage of (cyclopentadienyl)tris(dimethylamino)hafnium in the crude product. The crude product typically contains impurities tetra(dimethylamino)hafnium (TDMAH) and di(cyclopentadienyl)di(dimethylamino)hafnium (Cp). 2Hf (NMe2)2).
[0012] The temperature rise of the reactor residue: During the production process, with a fixed amount of raw materials, the higher the product yield, the less active material there is, and the lower the temperature rise of the reactor residue when exposed to air within a certain time. Conversely, the lower the product yield, the more active material there is, and the higher the temperature rise of the reactor residue when exposed to air within a certain time.
[0013] Therefore, the final degree of completion of the reaction can be judged by the yield and the temperature rise of the residue in the reactor.
[0014] (3) Relationship between characteristic peaks and reaction results: Through numerous experiments and comparisons of the relationship between various signal peaks in the NMR spectrum of the reaction supernatant after the preset reaction time and the self-heating of the reactor residue and product yield, the inventors screened out characteristic peaks A (signal peak of (cyclopentadienyl)tris(dimethylamino)hafnium) and B (signal peak of the intermediate product combining TDMAH and cyclopentadiene) with strong correlation and low interference. They found that when the ratio of the integral area of characteristic peak A to characteristic peak B in the 1H NMR spectrum of the reaction supernatant is within a specific range (1.4-1.6), it indicates that the reaction has been basically completed. Filtration and distillation can then be performed, and the residual active substances in the filter residue and still residue are basically fully consumed, allowing for safe quenching and recovery, while obtaining the target product with high purity and high yield. When the ratio of the two is too large (e.g., greater than 1.6), it indicates that the reaction system lacks reactive cyclopentadiene (cyclopentadiene deteriorates significantly during the reaction). Adding cyclopentadiene can further improve the yield and reduce still residue. When the ratio of the two is too small (e.g., less than 1.4), it indicates that cyclopentadiene has not fully reacted. Extending the reaction time can further improve the yield and reduce still residue.
[0015] Furthermore, in step S1, the preset time is preferably 12-20 h, such as 16 h, 18 h, etc. If the reaction time is too short, the reaction will be incomplete, and hafnium chloride will be converted into the intermediate product tetra(dimethylamino)hafnium. However, if the reaction time is too long, the byproduct bis(cyclopentadienyl)bis(dimethylamino)hafnium will be formed. Preferably, the preset time is set to within 12-20 h.
[0016] Further, in step S1, n-butyllithium is first mixed with n-hexane, dimethylamine is slowly added, and then hafnium tetrachloride is added for a first heating and reflux reaction for 6-10 h. After the reaction is completed, the temperature is lowered, and then cyclopentadiene is added for a second heating and reflux reaction for 6-10 h. Preferably, the dimethylamine is added within 1-3 h.
[0017] Further, in step S1, the molar ratio of hafnium tetrachloride to cyclopentadiene, dimethylamine, n-butyllithium, and n-hexane is 1:(1-1.5):(4-6):(4-5):(10-20), for example, 1:1:4:4:10.
[0018] Further, in step S1, the temperature of the first heating reflux reaction is 50-65 ℃, for example 60 ℃; the temperature of the second heating reflux reaction is 50-65 ℃, for example 60 ℃.
[0019] Furthermore, in step S1, after taking the supernatant, part of the solvent is removed (by desolvation under reduced pressure until more than half of the reaction solution has evaporated), and then the 1H NMR spectrum is detected to avoid cyclopentadiene affecting the test accuracy.
[0020] Further, in step S2, the target range is 4.4-4.6, more preferably 4.45-4.55.
[0021] Furthermore, in step S2, when the value of a is greater than the maximum value of the target range, cyclopentadiene is added to the reaction system to continue the reaction. The duration of the continued reaction is 1-4 hours, for example, 1 hour, 2 hours, 3 hours, 4 hours, etc.
[0022] Furthermore, in step S2, when the value of a is less than the minimum value of the target range, the reaction continues for a period of 1-4 hours, such as 1 hour, 2 hours, 3 hours, 4 hours, etc.
[0023] Furthermore, in step S2, the purity (mass purity) of the crude product is greater than 93%, and the yield is greater than 84%.
[0024] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention provides a method for the controlled preparation of (cyclopentadienyl)tris(dimethylamino)hafnium using nuclear magnetic resonance (NMR). By taking intermediate samples and testing NMR, the content of active substances can be effectively monitored using NMR detection signals to determine the reaction progress and guide further optimization. This method greatly improves the safety of the production process, the conversion rate of raw materials, and the purity of the product, and has important application value in the actual production of (cyclopentadienyl)tris(dimethylamino)hafnium. Attached Figure Description
[0025] Figure 1 The structural diagram of (cyclopentadienyl)tris(dimethylamino)hafnium; Figure 2 Production route diagram for (cyclopentadienyl)tris(dimethylamino)hafnium; Figure 3 The 1H NMR spectrum of (cyclopentadienyl)tris(dimethylamino)hafnium prepared in Example 1. Detailed Implementation
[0026] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments described are not intended to limit the present invention.
[0027] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the specification of this invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The terms “comprising” or “including” used in this invention may also be replaced with the closed form “is” or “consisting of”. Example 1
[0028] This embodiment relates to the preparation of (cyclopentadienyl)tris(dimethylamino)hafnium, and the specific operation is as follows: (1) At room temperature, n-butyllithium and n-hexane were added sequentially to the reactor, followed by slow addition of dimethylamine over 2 hours. Then, hafnium tetrachloride was added, and the mixture was refluxed at 60 °C for 6 hours. Finally, cyclopentadiene was added at room temperature, and the mixture was refluxed at 60 °C for 6 hours. The molar ratio of hafnium tetrachloride to cyclopentadiene, dimethylamine, n-butyllithium, and n-hexane was 1:1:4:4:10. A small amount of supernatant was taken from the sampling port of the reactor and transferred to a Schlenk flask. A solvent removal device was connected to remove more than half of the solvent. The 1H NMR spectrum of the residual liquid was tested, as shown in the figure. Figure 3 As shown, the integral area ratio 'a' of characteristic peak A with a chemical shift of 2.96 ppm and characteristic peak B with a chemical shift of 2.20 ppm is 1.51:1; the integral area ratio 'b' of characteristic peak A with a chemical shift of 6.0 ppm and characteristic peak B with a chemical shift of 2.20 ppm is 0.28:1.
[0029] (2) The remaining reaction liquid in the reactor is filtered to remove the solid precipitate through a filtration device. The filtrate is then desolventized under reduced pressure and distilled to obtain the product.
[0030] The yield, purity, and contents of impurities TDMAZ and Cp2Hf(NMe2)2 of the target product were calculated using the 1H NMR spectrum of the test product. The test results were: yield 89%, purity 97%, TDMAZ content 1.3%, and Cp2Hf(NMe2)2 content 1.7%.
[0031] In addition, remove the solids from the filter, place them in a fume hood, insert a thermometer, and observe the temperature change. Generally, the temperature will rise to the highest temperature within 0.5-1.5 hours. Record the temperature value, which is the highest temperature of the reactor residue. In this embodiment, the highest temperature of the reactor residue is 27 ℃. Example 2
[0032] This embodiment relates to the preparation of (cyclopentadienyl)tris(dimethylamino)hafnium, which is completely consistent with the operation in Example 1, but the test results of steps (1) and (2) are different, as follows: (1) The operation was the same as in Example 1. The nuclear magnetic resonance hydrogen spectrum of the residual liquid was tested, and the integral area ratio a of the characteristic peak A with a chemical shift of 2.96 ppm and the characteristic peak B with a chemical shift of 2.20 ppm was calculated to be 1.71:1; the integral area ratio b of the characteristic peak A with a chemical shift of 6.0 ppm and the characteristic peak B with a chemical shift of 2.20 ppm was calculated to be 0.31:1.
[0033] (2) The operation is the same as in Example 1, and the product is obtained.
[0034] The yield, purity, and contents of impurities TDMAH and Cp2Hf(NMe2)2 of the target product were calculated using the 1H NMR spectrum of the test product. The test results were: yield 82%, purity 91%, TDMAH content 7.9%, and Cp2Hf(NMe2)2 content 1.1%.
[0035] In addition, remove the solids from the filter, place them in a fume hood, insert a thermometer, and observe the temperature change. Generally, the temperature will rise to the highest temperature within 0.5-1.5 hours. Record the temperature value, which is the highest temperature of the reactor residue. In this embodiment, the highest temperature of the reactor residue is 32 ℃. Example 3
[0036] This embodiment relates to the preparation of (cyclopentadienyl)tris(dimethylamino)hafnium, which is completely consistent with the operation in Example 1, but the test results of steps (1) and (2) are different, as follows: The operation was the same as in Example 1. The 1H NMR spectrum of the residual liquid was tested, and the integral area ratio 'a' of characteristic peak A with a chemical shift of 2.96 ppm and characteristic peak B with a chemical shift of 2.20 ppm was calculated to be 1.65:1; the integral area ratio 'b' of characteristic peak A with a chemical shift of 6.0 ppm and characteristic peak B with a chemical shift of 2.20 ppm was calculated to be 0.31:1.
[0037] (1) The operation is the same as in Example 1, and the product is obtained.
[0038] (2) The yield, purity, content of impurity TDMAH and impurity Cp2Hf(NMe2)2 of the target product were calculated by nuclear magnetic hydrogen spectrum of the test product. The test results were: yield 86%, purity 94%, content of TDMAH 4.7%, and content of Cp2Hf(NMe2)2 1.3%.
[0039] In addition, remove the solids from the filter, place them in a fume hood, insert a thermometer, and observe the temperature change. Generally, the temperature will rise to the highest temperature within 0.5-1.5 hours. Record the temperature value, which is the highest temperature of the reactor residue. In this embodiment, the highest temperature of the reactor residue is 29 ℃. Example 4
[0040] This embodiment relates to the preparation of (cyclopentadienyl)tris(dimethylamino)hafnium, which is completely consistent with the operation in Example 1, but the test results of steps (1) and (2) are different, as follows: (1) The operation was the same as in Example 1. The nuclear magnetic resonance hydrogen spectrum of the residual liquid was tested, and the integral area ratio a of the characteristic peak A with a chemical shift of 2.96 ppm and the characteristic peak B with a chemical shift of 2.20 ppm was calculated to be 1.44:1; the integral area ratio b of the characteristic peak A with a chemical shift of 6.0 ppm and the characteristic peak B with a chemical shift of 2.20 ppm was calculated to be 0.28:1.
[0041] (2) The operation is the same as in Example 1, and the product is obtained.
[0042] The yield, purity, and contents of impurities TDMAH and Cp2Hf(NMe2)2 of the target product were calculated using the 1H NMR spectrum of the test product. The test results were: yield 88%, purity 96%, TDMAH content 1.2%, and Cp2Hf(NMe2)2 content 2.8%.
[0043] In addition, remove the solids from the filter, place them in a fume hood, insert a thermometer, and observe the temperature change. Generally, the temperature will rise to the highest temperature within 0.5-1.5 hours. Record the temperature value, which is the highest temperature of the reactor residue. In this embodiment, the highest temperature of the reactor residue is 27 ℃. Example 5
[0044] This embodiment relates to the preparation of (cyclopentadienyl)tris(dimethylamino)hafnium, which is completely consistent with the operation in Example 1, but the test results of steps (1) and (2) are different, as follows: (1) The operation was the same as in Example 1. The nuclear magnetic resonance hydrogen spectrum of the residual liquid was tested, and the integral area ratio a of the characteristic peak A with a chemical shift of 2.96 ppm and the characteristic peak B with a chemical shift of 2.20 ppm was calculated to be 1.22:1; the integral area ratio b of the characteristic peak A with a chemical shift of 6.0 ppm and the characteristic peak B with a chemical shift of 2.20 ppm was calculated to be 0.23:1.
[0045] (2) The operation is the same as in Example 1, and the product is obtained.
[0046] The yield, purity, and contents of impurities TDMAH and Cp2Hf(NMe2)2 of the target product were calculated using the 1H NMR spectrum of the test product. The test results were: yield 85%, purity 93%, TDMAH content 1.0%, and Cp2Hf(NMe2)2 content 6.0%.
[0047] In addition, remove the solids from the filter, place them in a fume hood, insert a thermometer, and observe the temperature change. Generally, the temperature will rise to the highest temperature within 0.5-1.5 hours. Record the temperature value, which is the highest temperature of the reactor residue. In this embodiment, the highest temperature of the reactor residue is 28 ℃. Example 6
[0048] This embodiment relates to the preparation of (cyclopentadienyl)tris(dimethylamino)hafnium, which is completely consistent with the operation in Example 1, but the test results of steps (1) and (2) are different, as follows: (1) The operation was the same as in Example 1. The nuclear magnetic resonance hydrogen spectrum of the residual liquid was tested, and the integral area ratio a of the characteristic peak A with a chemical shift of 2.96 ppm and the characteristic peak B with a chemical shift of 2.20 ppm was calculated to be 1.07:1; the integral area ratio b of the characteristic peak A with a chemical shift of 6.0 ppm and the characteristic peak B with a chemical shift of 2.20 ppm was calculated to be 0.21:1.
[0049] (2) The operation is the same as in Example 1, and the product is obtained.
[0050] The yield, purity, and contents of impurities TDMAH and Cp2Hf(NMe2)2 of the target product were calculated using the 1H NMR spectrum of the test product. The test results were: yield 81%, purity 88%, TDMAH content 0.9%, and Cp2Hf(NMe2)2 content 11.1%.
[0051] In addition, remove the solids from the filter, place them in a fume hood, insert a thermometer, and observe the temperature change. Generally, the temperature will rise to the highest temperature within 0.5-1.5 hours. Record the temperature value, which is the highest temperature of the reactor residue. In this embodiment, the highest temperature of the reactor residue is 31 ℃. Example 7
[0052] This embodiment relates to the preparation of (cyclopentadienyl)tris(dimethylamino)hafnium, which differs from Example 1 in that: after testing the 1H NMR spectrum of the residual liquid in step (1), 0.1 equivalent of cyclopentadiene is added to the reaction vessel and the reaction continues for 3 h, as follows: (1) At room temperature, n-butyllithium and n-hexane were added sequentially to the reactor, followed by slow addition of dimethylamine, which was expected to take 2 hours. Then, hafnium tetrachloride was added, and the mixture was refluxed at 60 °C for 6 hours. Finally, cyclopentadiene was added at room temperature, and the mixture was refluxed at 60 °C for 6 hours. The molar ratio of hafnium tetrachloride to cyclopentadiene, dimethylamine, n-butyllithium, and n-hexane was 1:1:4:4:10. A small amount of supernatant was taken out through the sampling port of the reactor and transferred to a Schlenk flask. The flask was then connected to a solvent removal device to remove more than half of the solvent. The 1H NMR spectrum of the residual liquid was tested. The integral area ratio (a) of characteristic peak A (chemical shift 2.96 ppm) to characteristic peak B (chemical shift 2.20 ppm) was calculated to be 2.01:1, and the integral area ratio (b) of characteristic peak A (chemical shift 6.0 ppm) to characteristic peak B (chemical shift 2.20 ppm) was calculated to be 0.35:1. Then, 0.1 equivalents of cyclopentadiene were added to the reactor, and the reaction continued for 3 hours. A small amount of supernatant was then taken out through the sampling port of the reactor and transferred to a Schlenk flask. A solvent removal device was connected to remove more than half of the solvent. The 1H NMR spectrum of the residual liquid was tested again. The integral area ratio (a) of characteristic peak A (chemical shift 2.96 ppm) to characteristic peak B (chemical shift 2.20 ppm) was calculated to be 1.62:1, and the integral area ratio (b) of characteristic peak A (chemical shift 6.0 ppm) to characteristic peak B (chemical shift 2.20 ppm) was calculated to be 0.30:1.
[0053] (2) The operation is the same as in Example 1, and the product is obtained.
[0054] The yield, purity, and contents of impurities TDMAH and Cp2Hf(NMe2)2 of the target product were calculated using the 1H NMR spectrum of the test product. The test results were: yield 85%, purity 95%, TDMAH content 1.4%, and Cp2Hf(NMe2)2 content 3.6%.
[0055] In addition, remove the solids from the filter, place them in a fume hood, insert a thermometer, and observe the temperature change. Generally, the temperature will rise to the highest temperature within 0.5-1.5 hours. Record the temperature value, which is the highest temperature of the reactor residue. In this embodiment, the highest temperature of the reactor residue is 28 ℃. Example 8
[0056] This embodiment relates to the preparation of (cyclopentadienyl)tris(dimethylamino)hafnium, which differs from Example 1 in that: after testing the 1H NMR spectrum of the residual liquid in step (1), the reaction continues for 3 h, as follows: (1) At room temperature, n-butyllithium and n-hexane were added sequentially to the reactor, followed by slow addition of dimethylamine, which was expected to take 2 hours. Then, hafnium tetrachloride was added, and the mixture was refluxed at 60 °C for 6 hours. Finally, cyclopentadiene was added at room temperature, and the mixture was refluxed at 60 °C for 6 hours. The molar ratio of hafnium tetrachloride to cyclopentadiene, dimethylamine, n-butyllithium, and n-hexane was 1:1:4:4:10. A small amount of supernatant was taken out through the sampling port of the reactor and transferred to a Schlenk flask. The flask was then connected to a solvent removal device to remove more than half of the solvent. The 1H NMR spectrum of the residual liquid was tested. The integral area ratio (a) of characteristic peak A (chemical shift 2.96 ppm) to characteristic peak B (chemical shift 2.20 ppm) was calculated to be 1.03:1, and the integral area ratio (b) of characteristic peak A (chemical shift 6.0 ppm) to characteristic peak B (chemical shift 2.20 ppm) was calculated to be 0.20:1. The reaction was continued for 3 hours. A small amount of supernatant was then taken through the sampling port of the reactor and transferred to a Schlenk flask. A solvent removal device was connected to remove more than half of the solvent. The 1H NMR spectrum of the residual liquid was tested again. The integral area ratio (a) of characteristic peak A (chemical shift 2.96 ppm) to characteristic peak B (chemical shift 2.20 ppm) was calculated to be 1.44:1, and the integral area ratio (b) of characteristic peak A (chemical shift 6.0 ppm) to characteristic peak B (chemical shift 2.20 ppm) was calculated to be 0.27:1.
[0057] (2) The operation is the same as in Example 1, and the product is obtained.
[0058] The yield, purity, and contents of impurities TDMAH and Cp2Hf(NMe2)2 of the target product were calculated using the 1H NMR spectrum of the test product. The test results were: yield 87%, purity 94%, TDMAH content 1.1%, and Cp2Hf(NMe2)2 content 4.9%.
[0059] In addition, remove the solids from the filter, place them in a fume hood, insert a thermometer, and observe the temperature change. Generally, the temperature will rise to the highest temperature within 0.5-1.5 hours. Record the temperature value, which is the highest temperature of the reactor residue. In this embodiment, the highest temperature of the reactor residue is 27 ℃.
[0060] The ratio a of characteristic peak A (chemical shift of 2.96 ppm) to characteristic peak B (chemical shift of 2.20 ppm), the ratio b of chemical shift of 6.0 ppm to chemical shift of 2.20 ppm, the target yield, purity, impurity content, and highest temperature of residue in the 1H NMR spectrum of the reaction supernatant before solid-phase filtration in the above embodiments, as well as the target yield, purity, impurity content, and highest temperature of residue in the reactor, are summarized in Table 1 below.
[0061] Table 1
[0062] As shown in Table 1, within the range of (1.07-1.71):1, the yield and purity initially increase and then decrease with increasing value of a. Furthermore, the maximum temperature at the reactor residue initially decreases and then increases with increasing value of a. When the value of a is in the range of 1.4-1.6, the yield and purity of the target product are relatively high, and the maximum temperature at the reactor residue is relatively low, with 1.51:1 being more preferable. The yield, purity, and maximum temperature at the reactor residue of the target product are not significantly correlated with the value of b. This is because the value of a is calculated from the ratio of the peaks at 2.96 and 2.20 ppm. These two positions are close, and the integral area per unit hydrogen is similar, better matching the actual molar ratio. In the value of b, 6.0 ppm is too far from 2.20 ppm, and the difference in the integral area per unit hydrogen is too large, failing to match the molar ratio and thus not effectively reflecting the actual reaction progress.
[0063] Therefore, it can be seen that by detecting and calculating the ratio 'a' of the areas of specific characteristic peaks, the present invention can effectively monitor the content of active substances, judge the reaction process, and guide further optimization, which greatly improves the safety of the production process, the raw material conversion rate, and the product purity.
[0064] The above-described embodiments are merely preferred embodiments provided to fully illustrate the present invention, and the scope of protection of the present invention is not limited thereto. Equivalent substitutions or modifications made by those skilled in the art based on the present invention are all within the scope of protection of the present invention. The scope of protection of the present invention is defined by the claims.
Claims
1. A method for the controlled preparation of (cyclopentadienyl)tris(dimethylamino)hafnium using nuclear magnetic resonance (NMR), characterized in that, Includes the following steps: S1. Hafnium tetrachloride was reacted with cyclopentadiene and dimethylamine in the presence of n-butyllithium and n-hexane under reflux. After a preset reaction time, the supernatant was taken and its 1H NMR spectrum was detected. S2. Calculate the ratio 'a' of the integrated areas of characteristic peak A and characteristic peak B based on the obtained 1H NMR spectrum, and determine whether 'a' is within the target range. Perform the following operations: If the value of a is within the target range, terminate the reaction, separate the liquid phase, and collect the crude product by distillation. If the value of a is greater than the maximum value of the target range, add cyclopentadiene to the reaction system and continue the reaction until the ratio of the integral area of characteristic peak A to characteristic peak B in the 1H NMR spectrum of the reaction supernatant falls within the target range, then terminate the reaction, separate the liquid phase, and collect the crude product by distillation. If the value of a is less than the minimum value of the target range, continue the reaction until the ratio of the integral area of characteristic peak A to characteristic peak B in the 1H NMR spectrum of the reaction supernatant falls within the target range, then terminate the reaction, separate the liquid phase, and collect the crude product by distillation. The chemical shift of characteristic peak A is 2.96 ppm, and the chemical shift of characteristic peak B is 2.20 ppm; The target range is 1.4-1.
6.
2. The method according to claim 1, characterized in that, In step S1, the preset time is 12-20 h.
3. The method according to claim 1, characterized in that, In step S1, n-butyllithium and n-hexane are first mixed, dimethylamine is slowly added, and then hafnium tetrachloride is added for the first heating and reflux reaction for 6-10 h. After the reaction is completed, the temperature is lowered, and then cyclopentadiene is added for the second heating and reflux reaction for 6-10 h.
4. The method according to claim 1 or 3, characterized in that, In step S1, the molar ratio of hafnium tetrachloride to cyclopentadiene, dimethylamine, n-butyllithium, and n-hexane is 1:(1-1.5):(4-6):(4-5):(10-20).
5. The method according to claim 3, characterized in that, In step S1, the temperature of the first heating reflux reaction is 50-65 °C; The temperature of the second heating reflux reaction is 50-65 ℃.
6. The method according to claim 1, characterized in that, In step S1, after taking the supernatant, some solvent is removed, and then the 1H NMR spectrum is detected.
7. The method according to claim 1, characterized in that, In step S2, the target range is 1.45-1.
55.
8. The method according to claim 1, characterized in that, In step S2, when the value of a is greater than the maximum value of the target range, cyclopentadiene is added to the reaction system to continue the reaction, and the continued reaction time is 1-4 h.
9. The method according to claim 1, characterized in that, In step S2, when the value of a is less than the minimum value of the target range, the reaction continues for 1-4 hours.
10. The method according to claim 1, characterized in that, In step S2, the purity of the crude product is greater than 94%, and the yield is greater than 86%.