Preparation method of tetra (ethyl methyl amino) hafnium

Abstract

The invention relates to a preparation method of tetra (ethyl methyl amino) hafnium, which comprises the following steps: (1) mixing a hydrocarbon solvent and an alkali metal compound, and adding methylethyl amine for reaction; and (2) adding hafnium tetrachloride into the reaction liquid in the step (1), and reacting to obtain the tetra (ethyl methyl amino) hafnium, the alkali metal compound is sodium hydride or potassium hydride. According to the preparation method, a preparation method of tetra (ethyl methyl amino) hafnium in the prior art is optimized, raw materials are easy to obtain, the reaction danger is reduced, the reaction convenience is improved, meanwhile, the obtained target product has high yield and purity, and industrial large-scale production is facilitated.

Description

Technical Field

[0001] The invention relates to the technical field of organic synthesis, and in particular to a method for preparing tetrakis(ethylmethylamino)hafnium. Background Art

[0002] With the development of microelectronics technology, in order to improve the integration of integrated circuits, increase the operating speed and reduce energy consumption, the characteristic size of integrated circuits has been continuously reduced, the size of MOS transistors, which are the basic devices, has been continuously reduced, and the operating voltage has been continuously reduced. After the thickness of the traditional SiO2 gate dielectric layer is reduced to the nanometer level, its leakage degree increases sharply with the decrease in thickness, which seriously affects the reliability and power consumption of the integrated circuit. Therefore, a material with a high dielectric constant is urgently needed to replace SiO2 to promote the development of microelectronics technology.

[0003] After research, it was found that hafnium oxide, as a material with a high dielectric constant, when used as a gate dielectric layer, can obtain a gate dielectric layer with a larger physical thickness under the same equivalent gate oxide layer thickness, thereby greatly improving the gate leakage phenomenon; in addition, it also has high thermal stability, avoiding the reaction of high dielectric constant materials with Si substrates at high temperatures. HfCl4 is the earliest precursor material studied for the preparation of hafnium oxide, but this material will generate a large amount of hydrochloric acid during actual application, which will not only corrode the surface of the silicon substrate, but also damage the corresponding CVD or ALD instruments. In addition, the vapor pressure of HfCl4 at the same temperature is small, so its use efficiency in equipment such as ALD is low.

[0004] Tetrakis(ethylmethylamino)hafnium is a new type of precursor material for preparing hafnium oxide. It is liquid at room temperature, very sensitive to air and moisture, highly reactive, and soluble in low-polarity solvents such as n-hexane. It avoids the generation of hydrochloric acid during use and has a high vapor pressure, so it is currently widely used in CVD and ALD research fields.

[0005] At present, there are three main methods for synthesizing tetra(ethylmethylamino)hafnium reported in the literature: the first method is to disperse hafnium tetrachloride in toluene, then add methylethylamine, add butyl lithium at low temperature to react, and then distill under reduced pressure to obtain the product; the second method is to first generate the lithium salt of methylethylamine in tetrahydrofuran, then add hafnium tetrachloride, and distill under reduced pressure to obtain the product; the third method is to first add n-butyl lithium to a n-hexane solution of methylethylamine at low temperature to obtain the lithium salt of methylethylamine, then add hafnium tetrachloride, and distill under reduced pressure to obtain the product. The first and second methods require the use of toluene or tetrahydrofuran, both solvents not only have certain biological toxicity, but also tetrahydrofuran will compete with lithium salt for coordination, resulting in a low product yield. In addition, all three methods require the use of butyl lithium, and butyl lithium, as a hazardous chemical, will immediately burn or even explode in the air, increasing the danger of production; in addition, butyl lithium is generally dissolved in n-hexane, thus limiting the maximum reaction amount under the same volume container.

[0006] Therefore, it is of great significance to provide a method for preparing tetrakis(ethylmethylamino)hafnium which is economical, safe, easy to operate and suitable for industrial production. Summary of the invention

[0007] In order to solve the above technical problems, the purpose of the present invention is to provide a method for preparing tetrakis(ethylmethylamino)hafnium. The present invention mainly optimizes the existing production process of tetrakis(ethylmethylamino)hafnium. By replacing the strongly alkaline hydrogenation reagent n-butyllithium with an alkali metal compound, not only the safety and convenience of the reaction are increased, but also the reaction rate is faster, and the obtained target product has a higher yield and purity.

[0008] To achieve this object, the present invention adopts the following technical solutions:

[0009] In a first aspect, the present invention provides a method for preparing tetrakis(ethylmethylamino)hafnium, the preparation method comprising the following steps:

[0010] (1) mixing a hydrocarbon solvent and an alkali metal compound, and adding methylethylamine to carry out a reaction;

[0011] (2) adding hafnium tetrachloride to the reaction solution in step (1) to carry out a reaction to obtain the tetrakis(ethylmethylamino)hafnium;

[0012] The alkali metal compound is sodium hydride or potassium hydride.

[0013] The synthetic route of the preparation method provided by the present invention is as follows:

[0014]

[0015] The preparation method of tetrakis(ethylmethylamino)hafnium provided by the present invention adopts a specific alkali metal compound to replace n-butyllithium in the traditional preparation method, which not only increases the safety and convenience of the reaction, but also enables the obtained tetrakis(ethylmethylamino)hafnium to have a high yield and purity.

[0016] In the present invention, the use of sodium hydride or potassium hydride, a specific alkali metal compound, reduces the risk of the reaction and improves the convenience of the reaction; and both sodium hydride and potassium hydride are solid powders and do not need to be prepared into corresponding solutions, so the reaction feed amount under the same volume container can be increased, which is conducive to large-scale industrial production; at the same time, when the two react with methylethylamine, an extremely low temperature is not required, and -10°C can meet the requirements, thereby reducing energy consumption.

[0017] Preferably, the hydrocarbon solvent in step (1) comprises C5-C 12 Alkanes (for example, C5 alkanes, C6 alkanes, C7 alkanes, C8 alkanes, C9 alkanes, C 10 Alkanes, C 11 Alkanes or C 12 Alkanes), C6-C 14 Aromatic hydrocarbons (e.g., C6 aromatic hydrocarbons, C9 aromatic hydrocarbons, 10 Aromatics, C 12 Aromatic or C 14 Aromatics, etc.).

[0018] Preferably, the hydrocarbon solvent in step (1) comprises any one of n-pentane, n-hexane, n-heptane, benzene or toluene, or a combination of at least two thereof, preferably n-pentane, n-hexane or n-heptane, and more preferably n-hexane.

[0019] The hydrocarbon solvent used in the present invention is preferably n-pentane, n-hexane and n-heptane, which not only reduces the reaction cost, but also has non-coordination and is non-toxic to the human body.

[0020] Preferably, the molar ratio of the hydrocarbon solvent to the alkali metal compound in step (1) is (0.5-2):1, for example, it can be 0.7:1, 0.9:1, 1:1, 1.1:1, 1.2:1, 1.3:1, 1.4:1, 1.5:1, 1.6:1, 1.7:1 or 1.8:1, etc.

[0021] Preferably, the mixing in step (1) is carried out under stirring.

[0022] Preferably, the system is cooled before adding the methylethylamine in step (1).

[0023] Preferably, the cooling is to -78°C to -10°C, for example, -78°C, -70°C, -65°C, -60°C, -50°C, -40°C, -30°C, -20°C or -10°C.

[0024] Preferably, the methylethylamine in step (1) is added dropwise at constant pressure.

[0025] In the present invention, the addition of methylethylamine by constant pressure dropwise addition is beneficial to controlling the temperature of the reaction system, which can not only avoid the risk of generating by-products due to local heat accumulation, but also enable the raw materials to fully contact and react, thereby improving the yield.

[0026] Preferably, during the addition of methylethylamine in step (1), the system temperature is controlled below 5°C.

[0027] Preferably, the molar ratio of the methylethylamine to the alkali metal compound in step (1) is (1-4):1, for example, it can be 1:1, 1.12:1, 1.15:1, 1.18:1, 1.2:1, 1.5:1, 2:1, 3:1 or 4:1, and more preferably (1-1.2):1.

[0028] In the present invention, the specific molar ratio of methylethylamine to the alkali metal compound is beneficial to improving the yield of the target product. When the molar ratio of the two is (1-1.2):1, the best technical effect is achieved. If the molar ratio of the two is lower than 1:1, the alkali metal compound will not react completely, resulting in the inability to completely replace the chlorine atoms in the hafnium tetrachloride, thereby resulting in a low yield of the product. If the molar ratio of the two is higher than 1.2:1, excess methylethylamine will increase the viscosity of the reaction system, hinder the collection of the product, and reduce the yield.

[0029] Preferably, the reaction temperature in step (1) is -78°C to -10°C, for example, -78°C, -70°C, -65°C, -60°C, -50°C, -40°C, -30°C, -20°C or -10°C.

[0030] The step (1) in the preparation method provided by the present invention has a wide reaction temperature range and can be adjusted according to actual production conditions; at the same time, the specific temperature range indicates that the preparation method does not require extremely low temperatures during the preparation process, and -10°C can meet the requirements, thereby reducing energy consumption.

[0031] Preferably, the reaction time of step (1) is 4 to 24 h, for example, 4.5 h, 5 h, 5.5 h, 6 h, 6.5 h, 7 h, 7.5 h, 8 h, 10 h, 15 h or 20 h, etc., preferably 4-12 h, more preferably 4 to 8 h.

[0032] Preferably, the molar ratio of the alkali metal compound in step (1) to the hafnium tetrachloride in step (2) is (4-8):1, for example, 4:1, 4.1:1, 4.2:1, 4.3:1, 4.4:1, 4.5:1, 5:1, 6:1, 7:1 or 8:1, and more preferably (4.1-4.4):1.

[0033] In the present invention, the specific molar ratio of the alkali metal compound to the hafnium tetrachloride is beneficial to improving the yield of the obtained target product. When the molar ratio of the two is (4.1-4.4):1, the best technical effect is achieved. If the molar ratio of the two is lower than 4.1:1, the metal salt generated in the first stage cannot completely replace the chlorine atoms in the hafnium tetrachloride, resulting in a low product yield. If the molar ratio of the two is higher than 4.4:1, the excess metal salt cannot react. Because it is solid, it will wrap part of the product during the product collection process, and it will also cause uneven heating of the product, resulting in a low product yield.

[0034] Preferably, the hafnium tetrachloride in step (2) is added in batches, more preferably in three batches.

[0035] The constant pressure drop method for adding hafnium tetrachloride in the present invention is beneficial to controlling the temperature of the reaction system, which can not only avoid the risk of generating by-products due to local heat accumulation, but also enable the raw materials to fully contact and react, thereby improving the yield.

[0036] Preferably, during the addition of hafnium tetrachloride in step (2), the temperature of the reaction system is controlled below 10°C.

[0037] Preferably, the reaction in step (2) includes a first stage reaction and a second stage reaction.

[0038] Preferably, the first stage reaction is a low temperature reaction.

[0039] Preferably, the temperature of the low-temperature reaction is not higher than 10°C, more preferably -10°C to 10°C, for example, it can be -10°C, -8°C, -5°C, -2°C, 0°C, 2°C, 5°C, 8°C or 10°C.

[0040] Preferably, the low-temperature reaction time is 4 to 24 h, for example, 6 h, 8 h, 10 h, 12 h, 15 h, 18 h, 20 h or 22 h, etc., preferably 4 to 15 h, more preferably 4 to 10 h.

[0041] Preferably, the second stage reaction is a reflux reaction.

[0042] Preferably, the reflux reaction time is 4 to 18 h, for example, 4.5 h, 5 h, 7 h, 8 h, 9 h, 10 h, 12 h, 14 h or 16 h, etc., more preferably 4 to 14 h.

[0043] Preferably, the reaction in step (1) and the reaction in step (2) are both carried out under a protective gas atmosphere;

[0044] Preferably, the protective gas includes any one of nitrogen, argon or helium, or a combination of at least two of them.

[0045] Preferably, after the reaction in step (2) is completed, the hydrocarbon solvent is first removed by distillation under normal pressure, and then the fraction at 130°C / 4 mmHg is collected by distillation under reduced pressure to obtain the tetrakis(ethylmethylamino)hafnium.

[0046] In the specific preparation method provided by the present invention, after the synthesis reaction is completed, there is no need to filter out the corresponding inorganic salts, and the desired target product can be obtained by directly performing atmospheric distillation and reduced pressure distillation, which simplifies the experimental operation and improves the production efficiency.

[0047] Preferably, the preparation method of tetrakis(ethylmethylamino)hafnium specifically comprises the following steps:

[0048] (1) Under a protective gas atmosphere, a hydrocarbon solvent and an alkali metal compound are mixed in a molar ratio of (0.9-1.8):1, the temperature is lowered to -78°C to -10°C, methylethylamine is added dropwise at a constant pressure, the system temperature is controlled to be below 5°C, and the reaction is carried out at -78°C to -10°C for 4 to 24 hours;

[0049] The alkali metal compound is sodium hydride or potassium hydride;

[0050] The hydrocarbon solvent includes C5-C 12 Alkanes, C6-C 14 Aromatics;

[0051] The molar ratio of the methylethylamine to the alkali metal compound is (1-4):1;

[0052] (2) adding hafnium tetrachloride to the reaction solution in step (1) in batches, controlling the temperature of the reaction system to be lower than 10° C., after the addition of hafnium tetrachloride is completed, subjecting the reaction system to a low-temperature reaction for 4 to 24 hours under a protective gas atmosphere, and then subjecting the reaction system to a reflux reaction for 4 to 18 hours. After the reaction is completed, firstly removing the hydrocarbon solvent by atmospheric distillation, and then subjecting the fraction to reduced pressure distillation at 130° C. / 4 mmHg to obtain the tetrakis(ethylmethylamino)hafnium;

[0053] The molar ratio of the alkali metal compound in step (1) to the hafnium tetrachloride in step (2) is (4-8):1;

[0054] The temperature of the low-temperature reaction in step (2) is not higher than 10°C.

[0055] Compared with the prior art, the present invention has at least the following beneficial effects:

[0056] (1) The preparation method of tetrakis(ethylmethylamino)hafnium provided by the present invention adopts a specific alkali metal compound to replace n-butyllithium in the traditional preparation method, which not only increases the safety and convenience of the reaction, but also enables the yield of tetrakis(ethylmethylamino)hafnium to reach 94%, and the purity reaches 98.8%;

[0057] (2) The present invention optimizes the preparation method of tetrakis(ethylmethylamino)hafnium in the prior art, and the raw materials are easily available, which not only reduces the risk of the reaction, but also improves the convenience of the reaction. At the same time, the target product has a higher yield and purity, which is conducive to industrial large-scale production. DETAILED DESCRIPTION

[0058] For the convenience of understanding the present invention, the present invention lists the following embodiments. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0059] Example 1

[0060] This embodiment provides a method for preparing tetrakis(ethylmethylamino)hafnium, the method comprising the following steps:

[0061] (1) Under N2 atmosphere, sodium hydride (106 g, 4.42 mol) and 1 L of n-hexane were added to a 5 L reactor, the temperature was lowered to -10°C, and methylethylamine (287 g, 4.86 mol) was slowly dripped into the reactor through a constant pressure dropping funnel, during which the temperature change of the system was kept within 5°C. After the addition was completed, the reaction was carried out at -10°C for 8 h;

[0062] (2) Add hafnium tetrachloride powder (329 g, 1.03 mol) into the reactor in three batches through a solid sampler, control the temperature of the reaction system to be below 10°C, and react at -10°C for 4 h under N2 atmosphere, followed by reflux reaction for 14 h. After the reaction, replace the apparatus with an atmospheric distillation apparatus, evaporate n-hexane at 70°C, and obtain a mixture of the product and an inorganic salt. Then replace the apparatus with a vacuum distillation apparatus, collect the fraction at 130°C / 4 mmHg, and obtain 396 g of colorless liquid tetrakis(ethylmethylamino)hafnium.

[0063] The NMR characterization data of the compound tetrakis(ethylmethylamino)hafnium are as follows:

[0064] 1H NMR (400MHz, toluene-d8): δ3.82 (q, J=7.1Hz, 8H), 3.57 (s, 12H), 1.75 (t, J=7.1Hz, 12H).

[0065] Example 2

[0066] This embodiment provides a method for preparing tetrakis(ethylmethylamino)hafnium, the method comprising the following steps:

[0067] (1) Under N2 atmosphere, sodium hydride (183 g, 7.63 mol) and 1 L of n-hexane were added to a 5 L reactor, the temperature was lowered to -10°C, and methylethylamine (496 g, 8.39 mol) was slowly dripped into the reactor through a constant pressure dropping funnel, during which the temperature change of the system was kept within 5°C. After the addition was completed, the reaction was carried out at -10°C for 8 h;

[0068] (2) Add hafnium tetrachloride powder (568 g, 1.77 mol) into the reactor in three batches through a solid sampler, control the temperature of the reaction system to be below 10°C, and react at 10°C for 10 h under a N2 atmosphere, followed by reflux reaction for 4 h. After the reaction, replace the apparatus with an atmospheric distillation apparatus, evaporate n-hexane at 70°C, and obtain a mixture of the product and an inorganic salt. Subsequently, replace the apparatus with a vacuum distillation apparatus, collect the fraction at 130°C / 4 mmHg, and obtain 472 g of colorless liquid tetrakis(ethylmethylamino)hafnium.

[0069] Example 3

[0070] This embodiment provides a method for preparing tetrakis(ethylmethylamino)hafnium, the method comprising the following steps:

[0071] (1) Under N2 atmosphere, sodium hydride (200 g, 8.33 mol) and 1 L of n-hexane were added to a 5 L reactor, the temperature was lowered to -20°C, and methylethylamine (542 g, 9.17 mol) was slowly dripped into the reactor through a constant pressure dropping funnel, during which the temperature change of the system was kept within 5°C. After the addition was completed, the reaction was carried out at -20°C for 8 h;

[0072] (2) Add hafnium tetrachloride powder (620 g, 1.94 mol) into the reactor in three batches through a solid sampler, control the temperature of the reaction system to be below 10°C, and react at 0°C for 10 h under a N2 atmosphere, followed by reflux reaction for 8 h. After the reaction, replace the apparatus with an atmospheric distillation apparatus, evaporate n-hexane at 70°C, and obtain a mixture of the product and an inorganic salt. Subsequently, replace the apparatus with a vacuum distillation apparatus, collect the fraction at 130°C / 4 mmHg, and obtain 644 g of colorless liquid tetra(ethylmethylamino)hafnium.

[0073] Example 4

[0074] This embodiment provides a method for preparing tetrakis(ethylmethylamino)hafnium, the method comprising the following steps:

[0075] (1) Under N2 atmosphere, sodium hydride (146 g, 6.08 mol) and 1 L of n-hexane were added to a 5 L reactor, and the temperature was lowered to -78°C. Ethyl methylamine (396 g, 6.70 mol) was slowly dripped into the reactor through a constant pressure dropping funnel, and the temperature of the system was kept within 5°C. After the addition was completed, the reaction was carried out at -78°C for 8 h.

[0076] (2) Add hafnium tetrachloride powder (453 g, 1.41 mol) to the reactor in three batches through a solid sampler, control the temperature of the reaction system to be below 10°C, and react at -10°C for 4 h under N2 atmosphere, followed by reflux reaction for 14 h. After the reaction, replace the apparatus with an atmospheric distillation apparatus, evaporate n-hexane at 70°C, and obtain a mixture of the product and an inorganic salt. Subsequently, replace the apparatus with a vacuum distillation apparatus, collect the fraction at 130°C / 4 mmHg, and obtain 534 g of colorless liquid tetrakis(ethylmethylamino)hafnium.

[0077] Example 5

[0078] This embodiment provides a method for preparing tetrakis(ethylmethylamino)hafnium, the method comprising the following steps:

[0079] (1) Under N2 atmosphere, sodium hydride (148 g, 6.17 mol) and 1 L of n-pentane were added to a 5 L reactor, and the temperature was lowered to -60°C. Methylethylamine (547 g, 9.25 mol) was slowly dripped into the reactor through a constant pressure dropping funnel, and the temperature of the system was kept within 5°C. After the addition was completed, the reaction was carried out at -60°C for 4 h.

[0080] (2) Add hafnium tetrachloride powder (494 g, 1.54 mol) into the reactor in three batches through a solid sampler, control the temperature of the reaction system to be below 10°C, and react at -5°C for 7 hours under a N2 atmosphere, followed by reflux reaction for 11 hours. After the reaction, replace the apparatus with an atmospheric distillation apparatus, evaporate n-pentane at 60°C, and obtain a mixture of the product and an inorganic salt. Subsequently, replace the apparatus with a vacuum distillation apparatus, collect the fraction at 130°C / 4 mmHg, and obtain 545 g of colorless liquid tetra(ethylmethylamino)hafnium.

[0081] Example 6

[0082] This embodiment provides a method for preparing tetrakis(ethylmethylamino)hafnium, the method comprising the following steps:

[0083] (1) Under N2 atmosphere, potassium hydride (132 g, 3.29 mol) and 1 L of n-hexane were added to a 5 L reactor, the temperature was lowered to -40°C, and methylethylamine (389 g, 6.58 mol) was slowly dripped into the reactor through a constant pressure dropping funnel, during which the temperature of the system was kept within 5°C. After the addition was completed, the reaction was carried out at -40°C for 6 h;

[0084] (2) Add hafnium tetrachloride powder (211 g, 0.66 mol) into the reactor in three batches through a solid sampler, control the temperature of the reaction system to be below 10°C, and react at 0°C for 10 h under N2 atmosphere, followed by reflux reaction for 6 h. After the reaction, replace the apparatus with an atmospheric distillation apparatus, evaporate n-hexane at 70°C, and obtain a mixture of the product and an inorganic salt. Then replace the apparatus with a vacuum distillation apparatus, collect the fraction at 130°C / 4 mmHg, and obtain 206 g of colorless liquid tetra(ethylmethylamino)hafnium.

[0085] Example 7

[0086] This embodiment provides a method for preparing tetrakis(ethylmethylamino)hafnium, the method comprising the following steps:

[0087] (1) Under N2 atmosphere, sodium hydride (167 g, 6.96 mol) and 1 L of benzene were added to a 5 L reactor, cooled to -20°C, and methylethylamine (1645 g, 27.8 mol) was slowly dripped into the reactor through a constant pressure dropping funnel, during which the temperature of the system was kept within 5°C. After the addition was completed, the reaction was carried out at -20°C for 12 h;

[0088] (2) Add hafnium tetrachloride powder (278 g, 0.87 mol) into the reactor in three batches through a solid sampler, control the temperature of the reaction system to be lower than 10°C, and react at 5°C for 15 hours under N2 atmosphere, followed by reflux reaction for 4 hours. After the reaction, replace the device with a normal pressure distillation device, evaporate benzene at 85°C, and obtain a mixture of product and inorganic salt. Then replace the device with a vacuum distillation device, collect the fraction at 130°C / 4 mmHg, and obtain 240 g of colorless liquid tetrakis(ethylmethylamino)hafnium.

[0089] Example 8

[0090] This embodiment provides a method for preparing tetrakis(ethylmethylamino)hafnium. The preparation method is different from that of Example 1 only in that methylethylamine (287 g, 4.86 mol) is adjusted to methylethylamine (235 g, 3.98 mol) in step (1), and other raw materials, contents and methods are the same as those of Example 1.

[0091] Example 9

[0092] This embodiment provides a method for preparing tetrakis(ethylmethylamino)hafnium. The preparation method is different from that of Example 1 only in that methylethylamine (287 g, 4.86 mol) is adjusted to methylethylamine (261 g, 4.42 mol) in step (1), and other raw materials, contents and methods are the same as those of Example 1.

[0093] Example 10

[0094] This embodiment provides a method for preparing tetrakis(ethylmethylamino)hafnium. The preparation method is different from that of Example 1 only in that methylethylamine (287 g, 4.86 mol) is adjusted to methylethylamine (313 g, 5.31 mol) in step (1), and other raw materials, contents and methods are the same as those of Example 1.

[0095] Embodiment 11

[0096] This embodiment provides a method for preparing tetrakis(ethylmethylamino)hafnium. The preparation method is different from that of Example 1 only in that methylethylamine (287 g, 4.86 mol) is adjusted to methylethylamine (339 g, 5.75 mol) in step (1), and other raw materials, contents and methods are the same as those of Example 1.

[0097] Example 12

[0098] This embodiment provides a method for preparing tetrakis(ethylmethylamino)hafnium. The preparation method is different from that of Example 1 only in that hafnium tetrachloride (329 g, 1.03 mol) is adjusted to hafnium tetrachloride (363 g, 1.13 mol) in step (2). Other raw materials, contents and methods are the same as those of Example 1.

[0099] Example 13

[0100] This embodiment provides a method for preparing tetrakis(ethylmethylamino)hafnium. The preparation method is different from that of Example 1 only in that hafnium tetrachloride (329 g, 1.03 mol) is adjusted to hafnium tetrachloride (354 g, 1.11 mol) in step (2). Other raw materials, contents and methods are the same as those of Example 1.

[0101] Embodiment 14

[0102] This embodiment provides a method for preparing tetrakis(ethylmethylamino)hafnium. The preparation method is different from that of Embodiment 1 only in that hafnium tetrachloride (329 g, 1.03 mol) is adjusted to hafnium tetrachloride (336 g, 1.05 mol) in step (2). Other raw materials, contents and methods are the same as those of Embodiment 1.

[0103] Embodiment 15

[0104] This embodiment provides a method for preparing tetrakis(ethylmethylamino)hafnium. The preparation method is different from that of Embodiment 1 only in that hafnium tetrachloride (329 g, 1.03 mol) is adjusted to hafnium tetrachloride (322 g, 1 mol) in step (2). Other raw materials, contents and methods are the same as those of Embodiment 1.

[0105] Example 16

[0106] This embodiment provides a method for preparing tetrakis(ethylmethylamino)hafnium. The preparation method is different from that of Embodiment 1 only in that hafnium tetrachloride (329 g, 1.03 mol) is adjusted to hafnium tetrachloride (314 g, 0.98 mol) in step (2). Other raw materials, contents and methods are the same as those of Embodiment 1.

[0107] Comparative Example 1

[0108] This comparative example provides a method for preparing tetrakis(ethylmethylamino)hafnium, the preparation method differing from that of Example 1 only in that in step (1), sodium hydride (106 g, 4.42 mol) is replaced with lithium hydride (35.1 g, 4.42 mol), and other raw materials, contents and methods are the same as those of Example 1.

[0109] Comparative Example 2

[0110] This comparative example provides a method for preparing tetrakis(ethylmethylamino)hafnium, the preparation method differing from that of Example 1 only in that sodium hydride (106 g, 4.42 mol) is replaced with sodium ethoxide (300 g, 4.42 mol) in step (1), and other raw materials, contents and methods are the same as those of Example 1.

[0111] Comparative Example 3

[0112] This comparative example provides a method for preparing tetrakis(ethylmethylamino)hafnium, the preparation method differing from that of Example 1 only in that sodium hydride (106 g, 4.42 mol) is replaced with potassium tert-butoxide (496 g, 4.42 mol) in step (1), and other raw materials, contents and methods are the same as those of Example 1.

[0113] Comparative Example 4

[0114] This comparative example provides a method for preparing tetrakis(ethylmethylamino)hafnium, the preparation method differing from that of Example 1 only in that in step (1), sodium hydride (106 g, 4.42 mol) is replaced by potassium hydroxide (248 g, 4.42 mol), and other raw materials, contents and methods are the same as those of Example 1.

[0115] Comparative Example 5

[0116] This comparative example provides a method for preparing tetrakis(ethylmethylamino)hafnium, the preparation method differing from that of Example 1 only in that sodium hydride (106 g, 4.42 mol) is replaced with cesium fluoride (672 g, 4.42 mol) in step (1), and other raw materials, contents and methods are the same as those of Example 1.

[0117] Comparative Example 6

[0118] This comparative example provides a method for preparing tetrakis(ethylmethylamino)hafnium, the preparation method differing from that of Example 1 only in that sodium hydride (106 g, 4.42 mol) is replaced by sodium carbonate (469 g, 4.42 mol) in step (1), and other raw materials, contents and methods are the same as those of Example 1.

[0119] Comparative Example 7

[0120] This comparative example provides a method for preparing tetrakis(ethylmethylamino)hafnium, the preparation method differing from that of Example 1 only in that sodium hydride (106 g, 4.42 mol) is replaced by sodium amide (173 g, 4.42 mol) in step (1), and other raw materials, contents and methods are the same as those of Example 1.

[0121] Comparative Example 8

[0122] This comparative example provides a method for preparing tetrakis(ethylmethylamino)hafnium, the preparation method differing from Example 1 only in that in step (1), sodium hydride (106 g, 4.42 mol) is replaced with a 2M tetrahydrofuran solution of lithium diisopropylamide (2.21 L), and other raw materials, contents and methods are the same as those in Example 1.

[0123] The yield and purity of the product tetrakis(ethylmethylamino)hafnium obtained in the above Examples 1-16 and Comparative Examples 1-8 are shown in Table 1.

[0124] Table 1

[0125]

[0126]

[0127] The test results show that:

[0128] (1) It can be seen from Examples 1-16 that the preparation method of tetrakis(ethylmethylamino)hafnium provided by the present invention adopts a specific alkali metal compound to replace n-butyllithium in the traditional preparation method, which not only increases the safety and convenience of the reaction, but also makes the obtained tetrakis(ethylmethylamino)hafnium have a high yield of up to 94% and a purity of up to 98.8%.

[0129] (2) By comparing Example 1 with Comparative Examples 1-8, it can be seen that the selection of a specific alkali metal compound in the technical solution of the present invention can obtain the target product tetrakis(ethylmethylamino)hafnium with a higher yield and purity.

[0130] In summary, the present invention optimizes the preparation method of tetrakis(ethylmethylamino)hafnium in the prior art, and the raw materials are easily available, which not only reduces the risk of the reaction, but also improves the convenience of the reaction. At the same time, the target product has a higher yield and purity, which is conducive to industrial large-scale production.

[0131] The applicant declares that the above is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention shall fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for preparing tetrakis(ethylmethylamino)hafnium, characterized in that: The preparation method comprises the following steps: (1) mixing a hydrocarbon solvent and an alkali metal compound, and adding methylethylamine to carry out a reaction; (2) adding hafnium tetrachloride to the reaction solution in step (1) to carry out a reaction to obtain the tetrakis(ethylmethylamino)hafnium; The alkali metal compound is sodium hydride or potassium hydride.

2. The preparation method according to claim 1, characterized in that: The hydrocarbon solvent in step (1) includes C5-C 12 Alkanes, C6-C 14 Aromatics; Preferably, the hydrocarbon solvent in step (1) comprises any one of n-pentane, n-hexane, n-heptane, benzene or toluene, or a combination of at least two thereof, and n-hexane is more preferably used; Preferably, the mixing in step (1) is carried out under stirring.

3. The preparation method according to claim 1 or 2, characterized in that: In step (1), the system is cooled before adding the methylethylamine; Preferably, the cooling is to -78°C to -10°C; Preferably, the methylethylamine in step (1) is added dropwise at constant pressure; Preferably, during the addition of methylethylamine in step (1), the system temperature is controlled below 5°C; Preferably, the molar ratio of methylethylamine to the alkali metal compound in step (1) is (1-4):1, more preferably (1-1.2):

1.

4. The preparation method according to any one of claims 1 to 3, characterized in that The reaction temperature in step (1) is -78°C to -10°C; Preferably, the reaction time of step (1) is 4 to 24 hours, more preferably 4 to 8 hours.

5. The preparation method according to any one of claims 1 to 4, characterized in that: The molar ratio of the alkali metal compound in step (1) to the hafnium tetrachloride in step (2) is (4-8):1, and more preferably (4.1-4.4):

1.

6. The preparation method according to any one of claims 1 to 5, characterized in that: The hafnium tetrachloride in step (2) is added in batches, more preferably in three batches; Preferably, during the addition of hafnium tetrachloride in step (2), the temperature of the reaction system is controlled below 10°C.

7. The preparation method according to any one of claims 1 to 5, characterized in that: The reaction in step (2) includes a first-stage reaction and a second-stage reaction; Preferably, the first stage reaction is a low temperature reaction; Preferably, the temperature of the low-temperature reaction is not higher than 10°C, more preferably -10°C to 10°C; Preferably, the low temperature reaction time is 4 to 24 hours, more preferably 4 to 10 hours; Preferably, the second stage reaction is a reflux reaction; Preferably, the reflux reaction time is 4 to 18 hours, more preferably 4 to 14 hours.

8. The preparation method according to any one of claims 1 to 7, characterized in that: The reaction in step (1) and the reaction in step (2) are both carried out under a protective gas atmosphere; Preferably, the protective gas includes any one of nitrogen, argon or helium, or a combination of at least two of them.

9. The preparation method according to any one of claims 1 to 8, characterized in that: After the reaction in step (2) is completed, the hydrocarbon solvent is first removed by distillation under normal pressure, and then the fraction at 130°C / 4mmHg is collected by distillation under reduced pressure to obtain the tetrakis(ethylmethylamino)hafnium.

10. The preparation method according to any one of claims 1 to 9, characterized in that: The preparation method specifically comprises the following steps: (1) In a protective gas atmosphere, a hydrocarbon solvent and an alkali metal compound are mixed, the temperature is lowered to -78°C to -10°C, methylethylamine is added dropwise at a constant pressure, the system temperature is controlled to be below 5°C, and the reaction is carried out at -78°C to -10°C for 4 to 24 hours; The alkali metal compound is sodium hydride or potassium hydride; The hydrocarbon solvent includes C5-C 12 Alkanes, C6-C 14 Aromatics; The molar ratio of the methylethylamine to the alkali metal compound is (1-4):1; (2) adding hafnium tetrachloride to the reaction solution in step (1) in batches, controlling the temperature of the reaction system to be lower than 10° C., after the addition of hafnium tetrachloride is completed, subjecting the reaction system to a low-temperature reaction for 4 to 24 hours under a protective gas atmosphere, and then subjecting the reaction system to a reflux reaction for 4 to 18 hours. After the reaction is completed, firstly removing the hydrocarbon solvent by atmospheric distillation, and then subjecting the fraction to reduced pressure distillation at 130° C. / 4 mmHg to obtain the tetrakis(ethylmethylamino)hafnium; The molar ratio of the alkali metal compound in step (1) to the hafnium tetrachloride in step (2) is (4-8):1; The temperature of the low-temperature reaction in step (2) is not higher than 10°C.

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