A method for preparing pentamethylcyclopentadienyl titanium trichloride

Abstract

The application discloses a preparation method of pentamethylcyclopentadienyl titanium trichloride, relates to the technical field of organic metal compound and olefin polymerization catalyst precursor preparation, and comprises the following steps: S1, under the protection of dry inert gas, dry chlorinated hydrocarbon solvent and titanium tetrachloride are added into a reactor provided with a stirring device, a temperature control device and a tail gas leading-out pipeline. The tail gas leading-out pipeline is in communication with a condenser, an online HCl detection unit and an external absorption unit in sequence, and the external absorption unit is isolated from the reactor liquid phase. S2, pentamethylcyclopentadiene feed liquid is divided into start-up feed and feedback feed. Pentamethylcyclopentadiene and titanium tetrachloride form η 5 The process of the pentamethylcyclopentadienyl titanium species is accompanied by HCl generation. The continuous removal of HCl from the liquid-gas system can reduce the HCl partial pressure on the product side and promote the direct coordination process.

Description

Technical Field

[0001] This invention relates to the field of preparation technology of organometallic compounds and olefin polymerization catalyst precursors, specifically a method for preparing pentamethylcyclopentadienyl titanium trichloride. Background Technology

[0002] Pentamethylcyclopentadienyltitanium trichloride, usually denoted as Cp TiCl3, where Cp Indicates η 5 -C5(CH3)5 is an important precursor for the preparation of monotitanium catalysts, syndiotactic polystyrene catalytic systems, and other organotitanium derivatives. This compound is sensitive to water and substances containing active hydrogen, and its preparation is easily affected by local ligand excess, reduction side reactions, and impurities introduced during post-processing.

[0003] Existing methods typically involve first converting pentamethylcyclopentadiene into the corresponding metal salt using n-butyllithium, potassium metal, potassium hydride, or Grignard reagents, and then reacting it with titanium tetrachloride. Another approach involves first preparing pentamethylcyclopentadienyltrimethylsilane, and then obtaining Cp via silyl transfer. TiCl3. For example, CN101077879A involves a ligand silylation process involving n-butyllithium and trimethylchlorosilane; EP0639579B1 involves a combination of cyclopentadienyl magnesium halides, low-valent titanium salts, and organohalide oxidants. These methods can produce the target compound, but they suffer from the high risk of strong bases or active metal reagents, lengthy steps, numerous salt byproducts, and a heavy burden of intermediate separation.

[0004] Direct coordination substitution of pentamethylcyclopentadiene with titanium tetrachloride can reduce intermediates and salt byproducts. However, this reaction releases HCl, and the accumulation of HCl in the liquid phase can alter the coordination equilibrium and affect the reaction rate due to mass transfer conditions. Judging the endpoint solely by a fixed reaction time or reactor temperature cannot distinguish between "the reaction is complete" and "the HCl signal in the tail gas decreases due to temporary limitations in gas-liquid mass transfer." Furthermore, single-pass or constant-rate feeding may result in excessively high local ligand concentrations, increasing the production of bispentamethylcyclopentadienyl titanium byproducts or other difficult-to-separate components. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a method for preparing pentamethylcyclopentadienyl titanium trichloride, wherein pentamethylcyclopentadiene reacts with titanium tetrachloride to form η 5 The formation of HCl is accompanied by the formation of -pentamethylcyclopentadienyl titanium species. Continuously removing HCl from the liquid-gas system can reduce the partial pressure of HCl on the product side and promote the direct coordination process.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a method for preparing pentamethylcyclopentadienyl titanium trichloride, comprising the following steps: S1. Under the protection of a dry inert gas, add dry chlorinated hydrocarbon solvent and titanium tetrachloride to a reactor equipped with a stirring device, a temperature control device, and a tail gas outlet pipeline. The tail gas outlet pipeline is connected in sequence to a condenser, an online HCl detection unit, and an external absorption unit, which is isolated from the liquid phase of the reactor.

[0007] S2. The pentamethylcyclopentadiene feed solution is divided into start-up feed and feedback feed. Start-up feed, comprising 10%–25% of the total amount of pentamethylcyclopentadiene, is added at -5–10°C, followed by raising the temperature to 25–45°C. During the feedback feed, dry inert gas flows through the gas phase space at a constant reference flow rate. The feedback feed rate and reaction temperature are adjusted based on the online HCl signal, controlling the normalized instantaneous HCl carry-out rate to 0.001–0.020 min. - ¹. The molar ratio of titanium tetrachloride to pentamethylcyclopentadiene is 1:1.03 to 1.07.

[0008] S3. After the feedback feed is completed, the system temperature is raised to 70–86°C, and a dry inert gas is used to sweep the reactor gas phase space in a single pass. The HCl-containing tail gas is condensed and then subjected to online detection and external absorption; when the cumulative amount of HCl carried out is 0.78–1.02 times the initial amount of titanium tetrachloride, and the normalized instantaneous HCl carry-out rate does not exceed 8 × 10⁻⁶, the HCl is effectively absorbed. -4 min - ¹The reaction is terminated after at least 10 minutes.

[0009] S4. Under inert gas protection, filter and concentrate under reduced pressure, add a nonpolar antisolvent and crystallize by programmed cooling, filter, wash and vacuum dry to obtain Cp. TiCl3. No alkali metals, alkali metal hydrides, alkyl lithiums, Grignard reagents, nitrogen-containing organic bases, trialkyl halosilanes, or pentamethylcyclopentadienyltrialkylsilanes are added to the reaction solutions in steps S1 to S3.

[0010] Preferably, the dry chlorinated hydrocarbon solvent is a mixed solvent composed of 1,2-dichloroethane and chlorobenzene in a volume ratio of 4:1 to 9:1, with a water content not exceeding 8 ppm; the concentration of titanium tetrachloride in step S1 is 0.08 to 0.16 mol / L. This mixed solvent balances the heat transfer and carry-out capacity of 1,2-dichloroethane and the solubility buffering effect of chlorobenzene on products and intermediate species at around 78 to 84°C.

[0011] Preferably, the concentration of pentamethylcyclopentadiene in the feed solution is 0.20–0.50 mol / L, the molar ratio of titanium tetrachloride to pentamethylcyclopentadiene is 1:1.045–1.065, and the feedback feed time is 90–180 min. The initial feed accounts for 15%–22%, and is added within 10–25 min at -3–3°C, held at this temperature for 10–30 min, and then raised to 30–42°C for feedback feed.

[0012] The normalized instantaneous HCl carryover rate is calculated as rHCl = Qg × yHCl / n0, where Qg is the molar flow rate of the tail gas after condensation (mol / min); yHCl is the molar fraction of HCl in the tail gas; and n0 is the initial amount of titanium tetrachloride. During the feedback feed, rHCl is preferably controlled between 0.003 and 0.012 min. - ¹, The online data acquisition interval is no more than 10 s. When rHCl is continuously higher than 0.012 min for 30 seconds. - ¹When the feed rate is reduced by 20%–50% and the temperature is lowered by 3–8°C; when rHCl remains below 0.003 min for 3 consecutive minutes. - ¹And before the feeding is finished, the feedback feeding speed will be increased by 10% to 30% and the temperature will be increased by 2 to 5°C, and the temperature will not exceed 45°C after the increase.

[0013] Preferably, the condenser temperature is -15 to 0°C, and a polytetrafluoroethylene (PTFE) demister unit is installed between the condenser and the online detection unit; the online detection unit is a tunable diode laser absorption HCl detection unit. The first absorber is filled with an 8% to 15% sodium hydroxide aqueous solution, and the second absorber is filled with a 5% to 10% sodium bicarbonate aqueous solution. The gas discharged from the second absorber is not returned to the reactor.

[0014] Preferably, step S3 is maintained at 78–84°C, and the scavenging rate of the dry inert gas is 0.05–0.20 vvm, that is, the standard volume introduced per minute is 0.05–0.20 times the volume of the reaction liquid. The cumulative HCl carryover ratio is calculated as XHCl = ∫(Qg × yHCl)dt / n0. When XHCl is not less than 0.85 and rHCl is not more than 3 × 10 -4 min - ¹The reaction is terminated after 15–30 minutes.

[0015] Preferably, in step S4, the reaction solution is first cooled to 55–65°C, and then filtered through a polytetrafluoroethylene filter medium with a pore size of 0.5–2 μm under positive pressure of an inert gas. It is then concentrated to 25%–40% of the original reaction solution volume at 30–45°C and an absolute pressure of 5–20 kPa, and 3–5 times the volume of the concentrated solution of dry n-heptane or methylcyclohexane is added. The programmed cooling includes: starting at 20–30°C, cooling to 0–5°C at a rate of 0.2–0.8°C / min and holding for 0.5–1.5 h, then cooling to -15 to -5°C at a rate of 0.1–0.5°C / min and holding for 1–3 h. After filtration, the solution is washed twice with the non-polar anti-solvent described above at a rate of 0.5–1.5 mL per gram of wet filter cake each time, and then dried at 25–40°C and an absolute pressure not exceeding 2 kPa for 4–10 h.

[0016] Compared with the prior art, the present invention provides a method for preparing pentamethylcyclopentadienyl titanium trichloride, which has the following beneficial effects: pentamethylcyclopentadiene reacts with titanium tetrachloride to form η 5 The formation of HCl is accompanied by the formation of -pentamethylcyclopentadienyl titanium species. Continuously removing HCl from the liquid-gas system can reduce the partial pressure of HCl on the product side and promote the direct coordination process; external absorption also avoids contact between the alkaline absorbent and the water-sensitive titanium complex.

[0017] The initial feed establishes a detectable reaction response, and the feed feedback is then used to characterize the instantaneous conversion / deacidification load per unit titanium feed using rHCl. A constant carrier gas reference allows the concentration signal to be converted into a molar carryover rate; the linkage between feed rate and temperature suppresses local ligand excess and exothermic peaks. The cumulative amount of XHCl reflects the overall reaction extent, while the instantaneous rate reflects the tail-end reaction near the endpoint. The combination of both can eliminate false endpoints caused by mass transfer fluctuations when using the instantaneous signal alone.

[0018] Mixed chlorinated hydrocarbons, inert heat filtration, controlled concentration, and two-stage programmed cooling collectively reduce the entrainment of unreacted ligands and diligand byproducts by crystals, resulting in crystals with a more easily filtered particle size. This allows for improved yield, purity, filtration performance, and batch consistency without the use of highly hazardous strong bases and silicon-based transfer reagents. Attached Figure Description

[0019] Figure 1 The image shows the 1H NMR spectrum of the pentamethylcyclopentadienyl titanium trichloride prepared in Example 3.

[0020] Figure 2 The image shows the carbon NMR spectrum of the pentamethylcyclopentadienyl titanium trichloride prepared in Example 3.

[0021] Figure 3 The image shows the high-resolution X-ray photoelectron spectra of titanium and chlorine in the pentamethylcyclopentadienyl titanium trichloride prepared in Example 3.

[0022] Figure 4 This is a field emission scanning electron microscope image of the product crystal obtained in Example 3. Detailed Implementation

[0023] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0024] Please see Figures 1-4 This invention provides a technical solution for preparing pentamethylcyclopentadienyl titanium trichloride: The structural formula of pentamethylcyclopentadienyl titanium trichloride is CpTiCl3, where Cp represents η. 5 -C5(CH3)5. This compound contains an η... 5 -Pentamethylcyclopentadienyl ligand, belonging to the semi-sandwich type of monotitanium cinnamate organic complexes. The term "monocathocene compound" as used in this article refers to compounds containing an η- 5 -Titanium complexes with cyclopentadienyl or substituted ligands thereof. Hereinafter referred to as "target organotitanium complexes" or "target products".

[0025] Cp H represents pentamethylcyclopentadiene, Cp TiCl3 represents pentamethylcyclopentadienyl titanium trichloride. All reactors, pipelines, filters, and receiving containers in contact with the reaction solution were dried and purged with nitrogen or argon. Titanium tetrachloride, Cp H, 1,2-dichloroethane, chlorobenzene, n-heptane, and methylcyclohexane were all anhydrous products; the solvent moisture content was determined by the following method.

[0026] The online HCl detection unit uses traceable HCl / nitrogen standard gases for zero-point, range, and linearity calibration. A condenser recovers chlorinated hydrocarbon vapors, and a PTFE demister reduces droplet interference with optical detection. Qg is obtained from a calibrated mass flow meter and HCl volume fraction; the carrier gas reference flow rate remains stable within the same batch.

[0027] In the examples, 0.1000 mol titanium tetrachloride corresponds to Cp The theoretical mass of TiCl3 is 28.945 g. All separation yields were corrected for quantitative NMR purity: Y = m × P / (n0 × M) × 100%, where m is the mass of the dried product, P is the quantitative NMR mass fraction, and M is the Cpp. The molar mass of TiCl3 is 289.45 g / mol.

[0028] Example 1 S1. After drying the 3 L jacketed glass reactor, stirrer, metering pump, jacketed temperature controller, and exhaust gas pipeline, purge with nitrogen three times while maintaining a slight positive pressure. The exhaust gas pipeline is connected in sequence to a condenser, a PTFE demister, a tunable diode laser absorption HCl detection unit, a first absorber, and a second absorber. The absorbed gas does not return to the reactor. The first absorber contains an 8% (w / w) sodium hydroxide aqueous solution, and the second absorber contains a 5% (w / w) sodium bicarbonate aqueous solution. A dry solvent with a water content of 8 ppm is added to the reactor, consisting of 1000 mL of 1,2-dichloroethane and 250 mL of chlorobenzene, with a volume ratio of 4:1. Then, 18.97 g (0.1000 mol) of titanium tetrachloride is added to bring the initial titanium tetrachloride concentration to 0.08 mol / L.

[0029] S2. Prepare a feed solution of 14.03 g pentamethylcyclopentadiene with a concentration of 0.2 mol / L and a total volume of 515 mL; the molar ratio of titanium tetrachloride to pentamethylcyclopentadiene is 1:1.030. First, add a start-up feed containing 10% of the total amount of pentamethylcyclopentadiene at -5℃ over 30 min, and maintain this temperature for 10 min. Then, adjust the system to 25℃, and flow dry nitrogen through the gas phase space at a constant standard flow rate of 20 mL / min, adding the remaining feedback feed over 600 min. During the feedback period, adjust the feed rate and temperature according to the online HCl signal to keep rHCl between 0.003 and 0.005 min. - ¹. The process record is as follows: No abnormal threshold correction was triggered during the feedback feeding stage. The online data acquisition interval is 5 seconds.

[0030] S3. After the feedback feed is completed, the system temperature is raised to 70°C, and the dry nitrogen scavenging rate is set to 0.05 vvm, corresponding to a standard volumetric flow rate of approximately 88 mL / min for this batch. The condenser temperature is -15°C, and the condensed tail gas undergoes demisting, online monitoring, and two-stage external absorption. Qg is the molar flow rate of the condensed tail gas, yHCl is the HCl mole fraction, and n0 is 0.1000 mol. The instantaneous rate is calculated using rHCl = Qg × yHCl / n0, and the cumulative carryover ratio is calculated using XHCl = ∫(Qg × yHCl)dt / n0. This batch continues to react for approximately 240 min after the feedback feed is completed, reaching XHCl = 0.78, and rHCl not exceeding 8.0 × 10⁻⁶. -4 min - ¹The reaction was stopped after 10 minutes.

[0031] S4. Cool the reaction solution to 55°C and filter it through a 0.5 μm PTFE filter medium under positive nitrogen pressure. Concentrate the filtrate to 25% of the original reaction solution volume at 30°C and 5 kPa absolute pressure. Add three times the volume of dry n-heptane to the concentrated solution, first adjust to 20°C, then lower to 0°C at 0.2°C / min and hold for 0.5 h, then lower to -15°C at 0.1°C / min and hold for 1 h. After filtration, wash twice with the same antisolvent at -10°C at a rate of 0.5 mL per gram of wet filter cake each time, and vacuum dry at 25°C and an absolute pressure not exceeding 2 kPa for 4 h.

[0032] 20.7 g of dark red to reddish-brown crystals were obtained. The separation yield, corrected for quantitative NMR purity, was 69.8%, and the quantitative NMR purity was 97.6%. ¹H NMR (400 MHz, anhydrous CDCl3) δ 2.39 (s, 15H); ¹³C NMR (100 MHz, anhydrous CDCl3) δ 138.04, 14.59. No alkali metals, alkali metal hydrides, alkyllithium, Grignard reagents, nitrogen-containing organic bases, trialkylhalosilanes, or pentamethylcyclopentadienyltrialkylsilanes were added in steps S1 to S3.

[0033] Example 2 S1. After drying the 3 L jacketed glass reactor, stirrer, metering pump, jacketed temperature controller, and exhaust gas pipeline, purge with nitrogen three times while maintaining a slight positive pressure. The exhaust gas pipeline is connected in sequence to a condenser, a PTFE demister, a tunable diode laser absorption HCl detection unit, a first absorber, and a second absorber. The absorbed gas does not return to the reactor. The first absorber contains an 8% (w / w) sodium hydroxide aqueous solution, and the second absorber contains a 5% (w / w) sodium bicarbonate aqueous solution. A dry solvent with a water content of 8 ppm is added to the reactor, consisting of 1000 mL of 1,2-dichloroethane and 250 mL of chlorobenzene, with a volume ratio of 4:1. Then, 18.97 g (0.1000 mol) of titanium tetrachloride is added to bring the initial titanium tetrachloride concentration to 0.08 mol / L.

[0034] S2. Prepare a feed solution of 14.24 g pentamethylcyclopentadiene with a concentration of 0.2 mol / L and a total volume of 522.5 mL; the molar ratio of titanium tetrachloride to pentamethylcyclopentadiene is 1:1.045. First, add a start-up feed containing 15% of the total amount of pentamethylcyclopentadiene at -3℃ over 10 min, and maintain this temperature for 10 min. Then, adjust the system to 30℃, and flow dry nitrogen through the gas phase space at a constant standard flow rate of 30 mL / min, adding the remaining feedback feed over 180 min. During the feedback period, adjust the feed rate and temperature according to the online HCl signal to keep rHCl between 0.003 and 0.005 min. -¹. The process record is as follows: rHCl = 0.0124 min once. - ¹And after 30 seconds, the feed rate is reduced by 20% and the temperature is lowered by 3°C; rHCl = 0.0028 min at one time. - ¹The feed rate was increased by 10% and the temperature was raised by 2°C for 3 consecutive minutes. The online data acquisition interval was 5 seconds.

[0035] S3. After the feedback feed is completed, the system temperature is raised to 78°C, and the dry nitrogen scavenging rate is set to 0.05 vvm, corresponding to a standard volumetric flow rate of approximately 89 mL / min for this batch. The condenser temperature is -15°C, and the condensed tail gas undergoes demisting, online monitoring, and two-stage external absorption. Qg is the molar flow rate of the condensed tail gas, yHCl is the HCl mole fraction, and n0 is 0.1000 mol. The instantaneous rate is calculated using rHCl = Qg × yHCl / n0, and the cumulative carryover ratio is calculated using XHCl = ∫(Qg × yHCl)dt / n0. This batch continues to react for approximately 180 min after the feedback feed is completed, reaching XHCl = 0.85, and rHCl not exceeding 3.0 × 10⁻⁶. -4 min - ¹The reaction was stopped after 15 minutes.

[0036] S4. Cool the reaction solution to 55°C and filter it through a 0.5 μm PTFE filter medium under positive nitrogen pressure. Concentrate the filtrate to 25% of the original reaction solution volume at 30°C and 5 kPa absolute pressure. Add three times the volume of dry n-heptane to the concentrated solution, first adjust to 20°C, then lower to 0°C at 0.2°C / min and hold for 0.5 h, then lower to -15°C at 0.1°C / min and hold for 1 h. After filtration, wash twice with the same antisolvent at -10°C at a rate of 0.5 mL per gram of wet filter cake each time, and vacuum dry at 25°C and an absolute pressure not exceeding 2 kPa for 4 h.

[0037] 23.57 g of dark red to reddish-brown crystals were obtained. The separation yield, corrected for quantitative NMR purity, was 80.2%, and the quantitative NMR purity was 98.5%. ¹H NMR (400 MHz, anhydrous CDCl3) δ 2.39 (s, 15H); ¹³C NMR (100 MHz, anhydrous CDCl3) δ 138.04, 14.59. No alkali metals, alkali metal hydrides, alkyllithium, Grignard reagents, nitrogen-containing organic bases, trialkylhalosilanes, or pentamethylcyclopentadienyltrialkylsilanes were added in steps S1 to S3.

[0038] Example 3 S1. After drying the 2 L jacketed glass reactor, stirrer, metering pump, jacketed temperature controller, and exhaust gas pipeline, purge with nitrogen three times while maintaining a slight positive pressure. The exhaust gas pipeline is connected in sequence to the condenser, PTFE demister, tunable diode laser absorption HCl detection unit, first absorber, and second absorber. The absorbed gas does not return to the reactor. The first absorber contains an 11.5% (w / w) sodium hydroxide aqueous solution, and the second absorber contains a 7.5% (w / w) sodium bicarbonate aqueous solution. A dry solvent with a water content of 4 ppm is added to the reactor, consisting of 722.2 mL of 1,2-dichloroethane and 111.1 mL of chlorobenzene, with a volume ratio of 6.5:1. Then, 18.97 g (0.1000 mol) of titanium tetrachloride is added to bring the initial titanium tetrachloride concentration to 0.12 mol / L.

[0039] S2. Prepare a feed solution of 14.37 g pentamethylcyclopentadiene with a concentration of 0.35 mol / L and a total volume of 301.4 mL; the molar ratio of titanium tetrachloride to pentamethylcyclopentadiene is 1:1.055. First, add a start-up feed containing 18.5% of the total amount of pentamethylcyclopentadiene at 0℃ over 18 min, and maintain this temperature for 20 min. Then, adjust the system to 36℃, and flow dry nitrogen through the gas phase space at a constant standard flow rate of 50 mL / min, adding the remaining feedback feed over 135 min. During the feedback period, adjust the feed rate and temperature according to the online HCl signal to keep rHCl between 0.006 and 0.009 min. - ¹. The process record is as follows: rHCl = 0.0135 min once. - ¹And for 30 consecutive seconds, reduce the feed rate by 35% and lower the temperature by 5.5℃; rHCl = 0.0025 min at a time. - ¹The feed rate was increased by 20% and the temperature was raised by 3.5°C for 3 consecutive minutes. The online data acquisition interval was 5 seconds.

[0040] S3. After the feedback feed is completed, the system temperature is raised to 81°C, and the dry nitrogen scavenging rate is set to 0.125 vvm, corresponding to a standard volumetric flow rate of approximately 142 mL / min for this batch. The condenser temperature is -7.5°C. The condensed tail gas undergoes demisting, online monitoring, and two-stage external absorption. Qg is the molar flow rate of the condensed tail gas, yHCl is the HCl mole fraction, and n0 is 0.1000 mol. The instantaneous rate is calculated using rHCl = Qg × yHCl / n0, and the cumulative carryover ratio is calculated using XHCl = ∫(Qg × yHCl)dt / n0. This batch continues to react for approximately 105 min after the feedback feed is completed, reaching XHCl = 0.935, and rHCl not exceeding 1.5 × 10⁻⁶. -4 min - ¹The reaction was stopped after 23 minutes.

[0041] S4. Cool the reaction solution to 60°C and filter it through a 1.25 μm PTFE filter medium under positive nitrogen pressure. Concentrate the filtrate to 32.5% of the original reaction solution volume at 37.5°C and 12.5 kPa absolute pressure. Add 4 times the volume of the concentrated solution of dry methylcyclohexane, adjust the temperature to 25°C, lower it to 2.5°C at 0.5°C / min and hold for 1 h, then lower it to -10°C at 0.3°C / min and hold for 2 h. After filtration, wash twice with the same antisolvent at -5°C at a rate of 1 mL per gram of wet filter cake each time, and vacuum dry at 32.5°C and an absolute pressure not exceeding 1 kPa for 7 h.

[0042] 26.08 g of dark red to reddish-brown crystals were obtained. The separation yield, corrected for quantitative NMR purity, was 89.4%, and the quantitative NMR purity was 99.2%. ¹H NMR (400 MHz, anhydrous CDCl3) δ 2.39 (s, 15H); ¹³C NMR (100 MHz, anhydrous CDCl3) δ 138.04, 14.59. No alkali metals, alkali metal hydrides, alkyllithium, Grignard reagents, nitrogen-containing organic bases, trialkylhalosilanes, or pentamethylcyclopentadienyltrialkylsilanes were added in steps S1 to S3.

[0043] Example 4 S1. After drying the 2 L jacketed glass reactor, stirrer, metering pump, jacketed temperature controller, and exhaust gas pipeline, purge with argon three times while maintaining a slight positive pressure. The exhaust gas pipeline is sequentially connected to a condenser, a PTFE demister, a tunable diode laser absorption HCl detection unit, a first absorber, and a second absorber. The absorbed gas does not return to the reactor. The first absorber contains a 15% (w / w) sodium hydroxide aqueous solution, and the second absorber contains a 10% (w / w) sodium bicarbonate aqueous solution. A dry solvent with a water content of 2 ppm is added to the reactor, consisting of 562.5 mL of 1,2-dichloroethane and 62.5 mL of chlorobenzene, with a volume ratio of 9:1. Then, 18.97 g (0.1000 mol) of titanium tetrachloride is added to bring the initial titanium tetrachloride concentration to 0.16 mol / L.

[0044] S2. Prepare a feed solution of 14.51 g pentamethylcyclopentadiene with a concentration of 0.5 mol / L and a total volume of 213 mL; the molar ratio of titanium tetrachloride to pentamethylcyclopentadiene is 1:1.065. First, add a start-up feed containing 22% of the total amount of pentamethylcyclopentadiene at 3℃ over 25 min, and maintain this temperature for 30 min. Then, adjust the system to 42℃, and flow dry argon through the gas phase space at a constant standard volume flow rate of 80 mL / min, adding the remaining feedback feed over 90 min. During the feedback period, adjust the feed rate and temperature according to the online HCl signal to keep rHCl between 0.010 and 0.012 min. - ¹. The process was recorded as follows: rHCl = 0.0150 min once. - ¹And after 30 seconds, the feed rate is reduced by 50% and the temperature is lowered by 8°C; rHCl = 0.0022 min at a time. - ¹The feed rate was increased by 30% and the temperature was raised by 5°C for 3 consecutive minutes, and the temperature did not exceed 45°C after the increase. The online data acquisition interval was 5 seconds.

[0045] S3. After the feedback feed is completed, the system temperature is raised to 84°C, and the purging rate of drying argon gas is set to 0.2 vvm, corresponding to a standard volumetric flow rate of approximately 168 mL / min for this batch. The condenser temperature is 0°C, and the condensed tail gas undergoes demisting, online monitoring, and two-stage external absorption. Qg is the molar flow rate of the condensed tail gas, yHCl is the molar fraction of HCl, and n0 is 0.1000 mol. The instantaneous rate is calculated using rHCl = Qg × yHCl / n0, and the cumulative carry-over ratio is calculated using XHCl = ∫(Qg × yHCl)dt / n0. This batch continues to react for approximately 75 min after the feedback feed is completed, reaching XHCl = 1.02, and rHCl is not higher than 0.5 × 10⁻⁶. -4 min - ¹The reaction was stopped after 30 minutes.

[0046] S4. Cool the reaction solution to 65°C and filter it through a 2 μm PTFE filter medium under positive argon pressure. Concentrate the filtrate to 40% of the original reaction solution volume at 45°C and 20 kPa absolute pressure. Add 5 times the volume of dry n-heptane to the concentrated solution, adjust the temperature to 30°C, lower it to 5°C at 0.8°C / min and hold for 1.5 h, then lower it to -5°C at 0.5°C / min and hold for 3 h. After filtration, wash twice with the same antisolvent at 0°C at a rate of 1.5 mL per gram of wet filter cake each time, and vacuum dry at 40°C and an absolute pressure not exceeding 2 kPa for 10 h.

[0047] 26.34 g of dark red to reddish-brown crystals were obtained. The separation yield, corrected for quantitative NMR purity, was 90.1%, and the quantitative NMR purity was 99%. ¹H NMR (400 MHz, anhydrous CDCl3) δ 2.39 (s, 15H); ¹³C NMR (100 MHz, anhydrous CDCl3) δ 138.04, 14.59. No alkali metals, alkali metal hydrides, alkyllithium, Grignard reagents, nitrogen-containing organic bases, trialkylhalosilanes, or pentamethylcyclopentadienyltrialkylsilanes were added in steps S1 to S3.

[0048] Example 5 S1. After drying the 2 L jacketed glass reactor, stirrer, metering pump, jacketed temperature controller, and exhaust gas pipeline, purge with argon three times while maintaining a slight positive pressure. The exhaust gas pipeline is connected in sequence to a condenser, a PTFE demister, a tunable diode laser absorption HCl detection unit, a first absorber, and a second absorber. The absorbed gas does not return to the reactor. The first absorber contains a 15% (w / w) sodium hydroxide aqueous solution, and the second absorber contains a 10% (w / w) sodium bicarbonate aqueous solution. A dry solvent with a water content of 8 ppm is added to the reactor, consisting of 562.5 mL of 1,2-dichloroethane and 62.5 mL of chlorobenzene, with a volume ratio of 9:1. Then, 18.97 g (0.1000 mol) of titanium tetrachloride is added to bring the initial titanium tetrachloride concentration to 0.16 mol / L.

[0049] S2. Prepare a feed solution of 14.58 g of pentamethylcyclopentadiene with a concentration of 0.5 mol / L and a total volume of 214 mL; the molar ratio of titanium tetrachloride to pentamethylcyclopentadiene is 1:1.070. First, add a start-up feed containing 25% of the total amount of pentamethylcyclopentadiene at 10℃ over 20 min, and maintain this temperature for 10 min. Then, adjust the system to 45℃, and flow dry argon through the gas phase space at a constant standard flow rate of 100 mL / min, adding the remaining feedback feed over 45 min. During the feedback period, adjust the feed rate and temperature according to the online HCl signal to keep rHCl between 0.016 and 0.020 min. - ¹. The process record is as follows: No abnormal threshold correction was triggered during the feedback feeding stage. The online data acquisition interval is 5 seconds.

[0050] S3. After the feedback feed is completed, the system temperature is raised to 86°C, and the purging rate of drying argon gas is set to 0.2 vvm, corresponding to a standard volumetric flow rate of approximately 168 mL / min for this batch. The condenser temperature is 0°C, and the condensed tail gas undergoes demisting, online monitoring, and two-stage external absorption. Qg is the molar flow rate of the condensed tail gas, yHCl is the molar fraction of HCl, and n0 is 0.1000 mol. The instantaneous rate is calculated using rHCl = Qg × yHCl / n0, and the cumulative carry-over ratio is calculated using XHCl = ∫(Qg × yHCl)dt / n0. This batch continues to react for approximately 90 min after the feedback feed is completed, reaching XHCl = 1.02, and rHCl is not higher than 8.0 × 10⁻⁶. -4 min - ¹The reaction was stopped after 10 minutes.

[0051] S4. Cool the reaction solution to 65°C and filter it through a 2 μm PTFE filter medium under positive argon pressure. Concentrate the filtrate to 40% of the original reaction solution volume at 45°C and 20 kPa absolute pressure. Add 5 times the volume of the concentrated solution of dry methylcyclohexane, adjust the temperature to 30°C, lower it to 5°C at 0.8°C / min and hold for 1.5 h, then lower it to -5°C at 0.5°C / min and hold for 3 h. After filtration, wash twice with the same antisolvent at 0°C at a rate of 1.5 mL per gram of wet filter cake, and vacuum dry at 40°C and an absolute pressure not exceeding 2 kPa for 10 h.

[0052] 24.2 g of dark red to reddish-brown crystals were obtained. The separation yield, corrected for quantitative NMR purity, was 82%, and the quantitative NMR purity was 98.1%. ¹H NMR (400 MHz, anhydrous CDCl3) δ 2.39 (s, 15H); ¹³C NMR (100 MHz, anhydrous CDCl3) δ 138.04, 14.59. No alkali metals, alkali metal hydrides, alkyllithium, Grignard reagents, nitrogen-containing organic bases, trialkylhalosilanes, or pentamethylcyclopentadienyltrialkylsilanes were added in steps S1 to S3.

[0053] Unless otherwise stated, all comparative examples are the same as in Example 3.

[0054] Comparative Example 1 The only difference was that the feedback feeding stage was changed to a constant feed rate of 135 min; the online detection, inert carrier gas, S3 scavenging, dual endpoints and other conditions were the same as in Example 3.

[0055] S1. After drying the 2 L jacketed glass reactor, stirrer, metering pump, jacketed temperature controller, and exhaust gas pipeline, purge with nitrogen three times while maintaining a slight positive pressure. The exhaust gas pipeline is connected in sequence to the condenser, PTFE demister, tunable diode laser absorption HCl detection unit, first absorber, and second absorber. The absorbed gas does not return to the reactor. The first absorber contains an 11.5% (w / w) sodium hydroxide aqueous solution, and the second absorber contains a 7.5% (w / w) sodium bicarbonate aqueous solution. A dry solvent with a water content of 4 ppm is added to the reactor, consisting of 722.2 mL of 1,2-dichloroethane and 111.1 mL of chlorobenzene, with a volume ratio of 6.5:1. Then, 18.97 g (0.1000 mol) of titanium tetrachloride is added to bring the initial titanium tetrachloride concentration to 0.12 mol / L.

[0056] S2. Prepare a feed solution of 14.37 g pentamethylcyclopentadiene with a concentration of 0.35 mol / L and a total volume of 301.4 mL; the molar ratio of titanium tetrachloride to pentamethylcyclopentadiene is 1:1.055. First, add a start-up feed containing 18.5% of the total amount of pentamethylcyclopentadiene at 0℃ over 18 min, and maintain this temperature for 20 min. Then, adjust the system to 36℃, and flow dry nitrogen through the gas phase space at a constant standard flow rate of 50 mL / min, adding the remaining feedback feed over 135 min. During the feedback process, rHCl is recorded online, but not as a feedback control variable. The process recording is as follows: only the online HCl signal is recorded; the feed rate or temperature is not adjusted. The online data acquisition interval is 5 s.

[0057] S3. After the feedback feed is completed, the system temperature is raised to 81°C, and the dry nitrogen scavenging rate is set to 0.125 vvm, corresponding to a standard volumetric flow rate of approximately 142 mL / min for this batch. The condenser temperature is -7.5°C. The condensed tail gas undergoes demisting, online monitoring, and two-stage external absorption. Qg is the molar flow rate of the condensed tail gas, yHCl is the HCl mole fraction, and n0 is 0.1000 mol. The instantaneous rate is calculated using rHCl = Qg × yHCl / n0, and the cumulative carryover ratio is calculated using XHCl = ∫(Qg × yHCl)dt / n0. This batch continues to react for approximately 105 min after the feedback feed is completed, reaching XHCl = 0.935, and rHCl not exceeding 1.5 × 10⁻⁶. -4 min - ¹The reaction was stopped after 23 minutes.

[0058] S4. Cool the reaction solution to 60°C and filter it through a 1.25 μm PTFE filter medium under positive nitrogen pressure. Concentrate the filtrate to 32.5% of the original reaction solution volume at 37.5°C and 12.5 kPa absolute pressure. Add 4 times the volume of the concentrated solution of dry methylcyclohexane, adjust the temperature to 25°C, lower it to 2.5°C at 0.5°C / min and hold for 1 h, then lower it to -10°C at 0.3°C / min and hold for 2 h. After filtration, wash twice with the same antisolvent at -5°C at a rate of 1 mL per gram of wet filter cake each time, and vacuum dry at 32.5°C and an absolute pressure not exceeding 1 kPa for 7 h.

[0059] 24.52 g of dark red to reddish-brown crystals were obtained. The separation yield, corrected for quantitative NMR purity, was 82%, and the quantitative NMR purity was 96.8%. ¹H NMR (400 MHz, anhydrous CDCl3) δ 2.39 (s, 15H); ¹³C NMR (100 MHz, anhydrous CDCl3) δ 138.04, 14.59. No alkali metals, alkali metal hydrides, alkyllithium, Grignard reagents, nitrogen-containing organic bases, trialkylhalosilanes, or pentamethylcyclopentadienyltrialkylsilanes were added in steps S1 to S3.

[0060] Comparative Example 2 The only difference is that the active scavenging volume in step S3 is changed from 0.125 vvm to 0 vvm, while retaining the micro-positive pressure nitrogen protection and the same exhaust gas absorption pipeline; all other conditions are the same as in Example 3.

[0061] S1. After drying the 2 L jacketed glass reactor, stirrer, metering pump, jacketed temperature controller, and exhaust gas pipeline, purge with nitrogen three times while maintaining a slight positive pressure. The exhaust gas pipeline is connected in sequence to the condenser, PTFE demister, tunable diode laser absorption HCl detection unit, first absorber, and second absorber. The absorbed gas does not return to the reactor. The first absorber contains an 11.5% (w / w) sodium hydroxide aqueous solution, and the second absorber contains a 7.5% (w / w) sodium bicarbonate aqueous solution. A dry solvent with a water content of 4 ppm is added to the reactor, consisting of 722.2 mL of 1,2-dichloroethane and 111.1 mL of chlorobenzene, with a volume ratio of 6.5:1. Then, 18.97 g (0.1000 mol) of titanium tetrachloride is added to bring the initial titanium tetrachloride concentration to 0.12 mol / L.

[0062] S2. Prepare a feed solution of 14.37 g pentamethylcyclopentadiene with a concentration of 0.35 mol / L and a total volume of 301.4 mL; the molar ratio of titanium tetrachloride to pentamethylcyclopentadiene is 1:1.055. First, add a start-up feed containing 18.5% of the total amount of pentamethylcyclopentadiene at 0℃ over 18 min, and maintain this temperature for 20 min. Then, adjust the system to 36℃, and flow dry nitrogen through the gas phase space at a constant standard flow rate of 50 mL / min, adding the remaining feedback feed over 135 min. During the feedback period, adjust the feed rate and temperature according to the online HCl signal to keep rHCl between 0.006 and 0.009 min. - ¹. The process record is as follows: rHCl = 0.0135 min once. - ¹And for 30 consecutive seconds, reduce the feed rate by 35% and lower the temperature by 5.5℃; rHCl = 0.0025 min at a time. - ¹The feed rate was increased by 20% and the temperature was raised by 3.5°C for 3 consecutive minutes. The online data acquisition interval was 5 seconds.

[0063] S3. After the feedback feed is completed, the system temperature is raised to 81°C, and the dry nitrogen scavenging rate is set to 0 vvm, corresponding to a standard volumetric flow rate of approximately 0 mL / min for this batch. The condenser temperature is -7.5°C. The condensed tail gas undergoes demisting, online monitoring, and two-stage external absorption. Qg is the molar flow rate of the condensed tail gas, yHCl is the HCl mole fraction, and n0 is 0.1000 mol. The instantaneous rate is calculated using rHCl = Qg × yHCl / n0, and the cumulative carryover ratio is calculated using XHCl = ∫(Qg × yHCl)dt / n0. This batch continues to react for approximately 320 min after the feedback feed is completed, reaching XHCl = 0.935, and rHCl not exceeding 1.5 × 10⁻⁶. -4 min - ¹The reaction was stopped after 23 minutes.

[0064] S4. Cool the reaction solution to 60°C and filter it through a 1.25 μm PTFE filter medium under positive nitrogen pressure. Concentrate the filtrate to 32.5% of the original reaction solution volume at 37.5°C and 12.5 kPa absolute pressure. Add 4 times the volume of the concentrated solution of dry methylcyclohexane, adjust the temperature to 25°C, lower it to 2.5°C at 0.5°C / min and hold for 1 h, then lower it to -10°C at 0.3°C / min and hold for 2 h. After filtration, wash twice with the same antisolvent at -5°C at a rate of 1 mL per gram of wet filter cake each time, and vacuum dry at 32.5°C and an absolute pressure not exceeding 1 kPa for 7 h.

[0065] 23.22 g of dark red to reddish-brown crystals were obtained. The separation yield, corrected for quantitative NMR purity, was 77.1%, and the quantitative NMR purity was 96.1%. ¹H NMR (400 MHz, anhydrous CDCl3) δ 2.39 (s, 15H); ¹³C NMR (100 MHz, anhydrous CDCl3) δ 138.04, 14.59. No alkali metals, alkali metal hydrides, alkyllithium, Grignard reagents, nitrogen-containing organic bases, trialkylhalosilanes, or pentamethylcyclopentadienyltrialkylsilanes were added in steps S1 to S3.

[0066] Comparative Example 3 Simply change the reaction endpoint to rHCl not exceeding 1.5 × 10⁻⁶. -4 min - ¹The process was continued for 23 minutes and then ended. The cumulative HCl carry-out ratio was not required. All other conditions were the same as in Example 3.

[0067] S1. After drying the 2 L jacketed glass reactor, stirrer, metering pump, jacketed temperature controller, and exhaust gas pipeline, purge with nitrogen three times while maintaining a slight positive pressure. The exhaust gas pipeline is connected in sequence to the condenser, PTFE demister, tunable diode laser absorption HCl detection unit, first absorber, and second absorber. The absorbed gas does not return to the reactor. The first absorber contains an 11.5% (w / w) sodium hydroxide aqueous solution, and the second absorber contains a 7.5% (w / w) sodium bicarbonate aqueous solution. A dry solvent with a water content of 4 ppm is added to the reactor, consisting of 722.2 mL of 1,2-dichloroethane and 111.1 mL of chlorobenzene, with a volume ratio of 6.5:1. Then, 18.97 g (0.1000 mol) of titanium tetrachloride is added to bring the initial titanium tetrachloride concentration to 0.12 mol / L.

[0068] S2. Prepare a feed solution of 14.37 g pentamethylcyclopentadiene with a concentration of 0.35 mol / L and a total volume of 301.4 mL; the molar ratio of titanium tetrachloride to pentamethylcyclopentadiene is 1:1.055. First, add a start-up feed containing 18.5% of the total amount of pentamethylcyclopentadiene at 0℃ over 18 min, and maintain this temperature for 20 min. Then, adjust the system to 36℃, and flow dry nitrogen through the gas phase space at a constant standard flow rate of 50 mL / min, adding the remaining feedback feed over 135 min. During the feedback period, adjust the feed rate and temperature according to the online HCl signal to keep rHCl between 0.006 and 0.009 min. - ¹. The process record is as follows: rHCl = 0.0135 min once. - ¹And for 30 consecutive seconds, reduce the feed rate by 35% and lower the temperature by 5.5℃; rHCl = 0.0025 min at a time. -¹The feed rate was increased by 20% and the temperature was raised by 3.5°C for 3 consecutive minutes. The online data acquisition interval was 5 seconds.

[0069] S3. After the feedback feed is completed, the system temperature is raised to 81°C, and the dry nitrogen scavenging rate is set to 0.125 vvm, corresponding to a standard volumetric flow rate of approximately 142 mL / min for this batch. The condenser temperature is -7.5°C. The condensed tail gas undergoes demisting, online monitoring, and two-stage external absorption. Qg is the molar flow rate of the condensed tail gas, yHCl is the HCl mole fraction, and n0 is 0.1000 mol. The instantaneous rate is calculated using rHCl = Qg × yHCl / n0, and the cumulative carry-over ratio is calculated using XHCl = ∫(Qg × yHCl)dt / n0. This batch continues to react for approximately 55 min after the feedback feed is completed; the online record shows that XHCl = 0.72 at this time, but XHCl is not used as the endpoint condition; it is only considered as an endpoint condition when rHCl is not higher than 1.5 × 10⁻⁶. -4 min - ¹The reaction was stopped after 23 minutes.

[0070] S4. Cool the reaction solution to 60°C and filter it through a 1.25 μm PTFE filter medium under positive nitrogen pressure. Concentrate the filtrate to 32.5% of the original reaction solution volume at 37.5°C and 12.5 kPa absolute pressure. Add 4 times the volume of the concentrated solution of dry methylcyclohexane, adjust the temperature to 25°C, lower it to 2.5°C at 0.5°C / min and hold for 1 h, then lower it to -10°C at 0.3°C / min and hold for 2 h. After filtration, wash twice with the same antisolvent at -5°C at a rate of 1 mL per gram of wet filter cake each time, and vacuum dry at 32.5°C and an absolute pressure not exceeding 1 kPa for 7 h.

[0071] 22.98 g of dark red to reddish-brown crystals were obtained. The separation yield, corrected for quantitative NMR purity, was 76.5%, and the quantitative NMR purity was 96.4%. ¹H NMR (400 MHz, anhydrous CDCl3) δ 2.39 (s, 15H); ¹³C NMR (100 MHz, anhydrous CDCl3) δ 138.04, 14.59. No alkali metals, alkali metal hydrides, alkyllithium, Grignard reagents, nitrogen-containing organic bases, trialkylhalosilanes, or pentamethylcyclopentadienyltrialkylsilanes were added in steps S1 to S3.

[0072] Comparative Example 4 The only difference was that the 1,2-dichloroethane / chlorobenzene mixed solvent was replaced with 833.3 mL of single 1,2-dichloroethane, while maintaining the initial concentration of titanium tetrachloride at 0.12 mol / L; all other conditions were the same as in Example 3.

[0073] S1. After drying the 2 L jacketed glass reactor, stirrer, metering pump, jacketed temperature controller, and exhaust gas pipeline, purge with nitrogen three times while maintaining a slight positive pressure. The exhaust gas pipeline is connected in sequence to the condenser, PTFE demister, tunable diode laser absorption HCl detection unit, first absorber, and second absorber. The absorbed gas does not return to the reactor. The first absorber contains an 11.5% (w / w) sodium hydroxide aqueous solution, and the second absorber contains a 7.5% (w / w) sodium bicarbonate aqueous solution. A dry solvent with a water content of 4 ppm is added to the reactor, including 833.3 mL of 1,2-dichloroethane and 0 mL of chlorobenzene, with the volume composition recorded as 1,2-dichloroethane alone; then 18.97 g (0.1000 mol) of titanium tetrachloride is added to make the initial titanium tetrachloride concentration 0.12 mol / L.

[0074] S2. Prepare a feed solution of 14.37 g pentamethylcyclopentadiene with a concentration of 0.35 mol / L and a total volume of 301.4 mL; the molar ratio of titanium tetrachloride to pentamethylcyclopentadiene is 1:1.055. First, add a start-up feed containing 18.5% of the total amount of pentamethylcyclopentadiene at 0℃ over 18 min, and maintain this temperature for 20 min. Then, adjust the system to 36℃, and flow dry nitrogen through the gas phase space at a constant standard flow rate of 50 mL / min, adding the remaining feedback feed over 135 min. During the feedback period, adjust the feed rate and temperature according to the online HCl signal to keep rHCl between 0.006 and 0.009 min. - ¹. The process record is as follows: rHCl = 0.0135 min once. - ¹And for 30 consecutive seconds, reduce the feed rate by 35% and lower the temperature by 5.5℃; rHCl = 0.0025 min at a time. - ¹The feed rate was increased by 20% and the temperature was raised by 3.5°C for 3 consecutive minutes. The online data acquisition interval was 5 seconds.

[0075] S3. After the feedback feed is completed, the system temperature is raised to 81°C, and the dry nitrogen scavenging rate is set to 0.125 vvm, corresponding to a standard volumetric flow rate of approximately 142 mL / min for this batch. The condenser temperature is -7.5°C. The condensed tail gas undergoes demisting, online monitoring, and two-stage external absorption. Qg is the molar flow rate of the condensed tail gas, yHCl is the HCl mole fraction, and n0 is 0.1000 mol. The instantaneous rate is calculated using rHCl = Qg × yHCl / n0, and the cumulative carryover ratio is calculated using XHCl = ∫(Qg × yHCl)dt / n0. This batch continues to react for approximately 105 min after the feedback feed is completed, reaching XHCl = 0.935, and rHCl not exceeding 1.5 × 10⁻⁶. -4 min - ¹The reaction was stopped after 23 minutes.

[0076] S4. Cool the reaction solution to 60°C and filter it through a 1.25 μm PTFE filter medium under positive nitrogen pressure. Concentrate the filtrate to 32.5% of the original reaction solution volume at 37.5°C and 12.5 kPa absolute pressure. Add 4 times the volume of the concentrated solution of dry methylcyclohexane, adjust the temperature to 25°C, lower it to 2.5°C at 0.5°C / min and hold for 1 h, then lower it to -10°C at 0.3°C / min and hold for 2 h. After filtration, wash twice with the same antisolvent at -5°C at a rate of 1 mL per gram of wet filter cake each time, and vacuum dry at 32.5°C and an absolute pressure not exceeding 1 kPa for 7 h.

[0077] 25.29 g of dark red to reddish-brown crystals were obtained. The separation yield, corrected for quantitative NMR purity, was 85.7%, and the quantitative NMR purity was 98.1%. ¹H NMR (400 MHz, anhydrous CDCl3) δ 2.39 (s, 15H); ¹³C NMR (100 MHz, anhydrous CDCl3) δ 138.04, 14.59. No alkali metals, alkali metal hydrides, alkyllithium, Grignard reagents, nitrogen-containing organic bases, trialkylhalosilanes, or pentamethylcyclopentadienyltrialkylsilanes were added in steps S1 to S3.

[0078] Comparative Example 5 The only difference was that the two-stage cooling process was changed to directly lower the temperature from 25°C to -10°C within 15 minutes and hold it at that temperature for 2 hours; the type and amount of antisolvent and all other conditions were the same as in Example 3.

[0079] S1. After drying the 2 L jacketed glass reactor, stirrer, metering pump, jacketed temperature controller, and exhaust gas pipeline, purge with nitrogen three times while maintaining a slight positive pressure. The exhaust gas pipeline is connected in sequence to the condenser, PTFE demister, tunable diode laser absorption HCl detection unit, first absorber, and second absorber. The absorbed gas does not return to the reactor. The first absorber contains an 11.5% (w / w) sodium hydroxide aqueous solution, and the second absorber contains a 7.5% (w / w) sodium bicarbonate aqueous solution. A dry solvent with a water content of 4 ppm is added to the reactor, consisting of 722.2 mL of 1,2-dichloroethane and 111.1 mL of chlorobenzene, with a volume ratio of 6.5:1. Then, 18.97 g (0.1000 mol) of titanium tetrachloride is added to bring the initial titanium tetrachloride concentration to 0.12 mol / L.

[0080] S2. Prepare a feed solution of 14.37 g pentamethylcyclopentadiene with a concentration of 0.35 mol / L and a total volume of 301.4 mL; the molar ratio of titanium tetrachloride to pentamethylcyclopentadiene is 1:1.055. First, add a start-up feed containing 18.5% of the total amount of pentamethylcyclopentadiene at 0℃ over 18 min, and maintain this temperature for 20 min. Then, adjust the system to 36℃, and flow dry nitrogen through the gas phase space at a constant standard flow rate of 50 mL / min, adding the remaining feedback feed over 135 min. During the feedback period, adjust the feed rate and temperature according to the online HCl signal to keep rHCl between 0.006 and 0.009 min. - ¹. The process record is as follows: rHCl = 0.0135 min once. - ¹And for 30 consecutive seconds, reduce the feed rate by 35% and lower the temperature by 5.5℃; rHCl = 0.0025 min at a time. - ¹The feed rate was increased by 20% and the temperature was raised by 3.5°C for 3 consecutive minutes. The online data acquisition interval was 5 seconds.

[0081] S3. After the feedback feed is completed, the system temperature is raised to 81°C, and the dry nitrogen scavenging rate is set to 0.125 vvm, corresponding to a standard volumetric flow rate of approximately 142 mL / min for this batch. The condenser temperature is -7.5°C. The condensed tail gas undergoes demisting, online monitoring, and two-stage external absorption. Qg is the molar flow rate of the condensed tail gas, yHCl is the HCl mole fraction, and n0 is 0.1000 mol. The instantaneous rate is calculated using rHCl = Qg × yHCl / n0, and the cumulative carryover ratio is calculated using XHCl = ∫(Qg × yHCl)dt / n0. This batch continues to react for approximately 105 min after the feedback feed is completed, reaching XHCl = 0.935, and rHCl not exceeding 1.5 × 10⁻⁶. -4 min - ¹The reaction was stopped after 23 minutes.

[0082] S4. Cool the reaction solution to 60°C and filter it through a 1.25 μm PTFE filter medium under positive nitrogen pressure. Concentrate the filtrate to 32.5% of the original reaction solution volume at 37.5°C and 12.5 kPa absolute pressure. Add 4 times the volume of the concentrated solution of dry methylcyclohexane, and directly lower the system from 25°C to -10°C within 15 min and maintain the temperature for 2 h. After filtration, wash twice with the same antisolvent at -5°C at a rate of 1 mL per gram of wet filter cake each time, and vacuum dry at 32.5°C and an absolute pressure not exceeding 1 kPa for 7 h.

[0083] 26.52 g of dark red to reddish-brown crystals were obtained. The separation yield, corrected for quantitative NMR purity, was 88.8%, and the quantitative NMR purity was 96.9%. ¹H NMR (400 MHz, anhydrous CDCl3) δ 2.39 (s, 15H); ¹³C NMR (100 MHz, anhydrous CDCl3) δ 138.04, 14.59. No alkali metals, alkali metal hydrides, alkyllithium, Grignard reagents, nitrogen-containing organic bases, trialkylhalosilanes, or pentamethylcyclopentadienyltrialkylsilanes were added in steps S1 to S3.

[0084] Test methods In accordance with GB / T 27417-2017 "Guidelines for Conformity Assessment and Validation of Chemical Analysis Methods" and GB / T 32465-2015 "Requirements for Validation and Internal Quality Control of Chemical Analysis Methods", the selectivity, linearity, accuracy, precision, limit of detection, limit of quantitation and measurement uncertainty were verified.

[0085] Quantitative NMR purity: Samples were prepared with anhydrous CDCl3 in a dry glove box, using calibrated ferrocene as an internal standard; 400 MHz, 298 K, relaxation delay 30 s, 64 scans. The method was validated according to GB / T 27417-2017 and GB / T 32465-2015; linearity R² not less than 0.999, recovery rate 98%–102%, repeatability RSD not higher than 1.5%.

[0086] Moisture content: The Karl Fischer coulometric method was used with headspace furnace injection, and the procedure was performed according to GB / T 6283-2008 "Determination of Moisture Content in Chemical Products - Karl Fischer Method (General Method)"; blank and spiked recovery were used to eliminate sample reaction interference.

[0087] Crystal particle size D50: Dispersed in dry n-heptane under nitrogen-sealed conditions, the volume median particle size D50 was determined according to GB / T 19077-2024 "Particle size analysis by laser diffraction". Each sample was measured in parallel three times.

[0088] The online TDLAS result for HCl online quantity verification is calibrated with standard gas; the tail gas is quantitatively absorbed within a specified time and measured according to HJ 549-2016 "Determination of Hydrogen Chloride in Ambient Air and Exhaust Gas by Ion Chromatography", and the Qg×yHCl integral value is verified.

[0089] Filtration time: Using a 50 mm diameter, 0.45 μm polytetrafluoroethylene filter membrane of the same batch, 20.0 g wet filter cake equivalent slurry was filtered at an absolute pressure of 20 kPa and a slurry temperature of -10℃. The time required for the continuous dripping of filtrate to end was recorded; each sample was tested in triplicate.

[0090] Residual Cp H and dual-ligand byproducts: characteristic peaks of quantitative NMR were used for separation and integration, and qualitative verification was performed by LC-MS; the selectivity, spike recovery and repeatability of the quantitative method were verified according to GB / T 27417-2017 and GB / T 32465-2015.

[0091] Unless otherwise stated, each analytical result is the average of three parallel determinations. Yields and purity are rounded to one decimal place, and results for trace impurities and HCl emissions are rounded to the appropriate significant figures according to the method's quantification capability.

[0092] Table 1

[0093] Table 2

[0094] Table 3

[0095] Compared to Example 3, Comparative Example 1, which only eliminated HCl feedback regulation, saw a decrease in yield from 89.4% to 82.0%, a decrease in purity from 99.2% to 96.8%, and an increase in the percentage of dual-ligand byproducts from 0.12% to 1.18%. This indicates that the online signal is not merely used for recording, but rather to limit local ligand loading by linking feed and temperature, thereby reducing side reactions.

[0096] In Comparative Example 2, with S3 active scavenging removed, the reaction time after the feedback feed required to achieve the same endpoint was extended from 105 min to 320 min, resulting in a yield decrease to 77.1% and residual Cp. H increased to 1.30%. This result indicates that only when external HCl absorption is combined with a single-pass inert scavenging gas can the partial pressure of HCl in the gas phase be continuously reduced and the tail reaction improved.

[0097] Comparative Example 3, with the cumulative HCl criterion removed, showed that XHCl was only 0.720 when the instantaneous rate reached the threshold, indicating premature termination due to a temporary decrease in mass transfer; its yield was 76.5%, and the residual Cp... H is 1.45%. Example 3 requires both XHCl and rHCl to meet certain conditions, thereby enabling the differentiation between the true endpoint and the transient low signal.

[0098] The contribution of the mixed solvent. In Comparative Example 4, the 1,2-dichloroethane / chlorobenzene mixed solvent was replaced with an equal volume of single 1,2-dichloroethane, resulting in a yield and purity of 85.7% and 98.1%, respectively, lower than the 89.4% and 99.2% of Example 3. The mixed solvent has a buffering effect on the dissolution state and organic vapor condensation load in the high-temperature range, which is beneficial for maintaining a more stable HCl carryover signal.

[0099] Comparative Example 5 used a single rapid cooling process, and its crude separation yield was close to that of Example 3, but the purity decreased from 99.2% to 96.9%, the D50 decreased from 146 μm to 43 μm, and the filtration time increased from 10.2 min to 32.5 min. The two-stage cooling program was not a typical post-processing parameter, but rather a way to control nucleation and crystal growth, reduce the entrainment of mother liquor and unreacted ligands, and simultaneously improve filterability.

[0100] Depend on Figure 1 As can be seen, the product obtained in Example 3 exhibits a major singlet near a chemical shift δ 2.39 ppm. The integral of this peak corresponds to 15 hydrogens, which are attributed to the protons of the five equivalent methyl groups in the pentamethylcyclopentadienyl ligand. The five groups of methyl protons show only one major resonance signal, indicating that the five methyl groups are in a nearly equivalent chemical environment, interacting with the pentamethylcyclopentadienyl ligand at an η-coefficient. 5 The form is consistent with the symmetrical structure formed after coordination of the titanium center. Figure 1 The signal near δ 7.26 ppm is a residual peak of deuterated chloroform, and the signal at δ 0.00 ppm is an internal standard peak of tetramethylsilane; neither belongs to the target product. This demonstrates the presence of a pentamethylcyclopentadienyl structure in a highly symmetric coordination environment within the product and helps determine the residual status of unreacted pentamethylcyclopentadiene.

[0101] Depend on Figure 2 As can be seen, the product obtained in Example 3 exhibits a major carbon signal near δ 138.04 ppm, which belongs to the five equivalent ring carbons in the pentamethylcyclopentadienyl ligand; another major carbon signal appears near δ 14.59 ppm, which belongs to the methyl carbon in the five equivalent methyl groups. The product mainly presents two types of carbon chemical environments, indicating that the five ring carbons and the five methyl carbons are in approximately equivalent coordination environments. The triplet near δ 77.16 ppm in the figure is the deuterated chloroform solvent peak, and the signal at δ 0.00 ppm is the tetramethylsilane internal standard peak. This further proves that a pentamethylcyclopentadienyl ligand structure with high symmetry has been formed in the product, rather than the starting state retaining multiple non-equivalent carbon environments in the uncoordinated pentamethylcyclopentadiene.

[0102] Figure 3 The image shows the high-resolution X-ray photoelectron spectra of titanium and chlorine in the pentamethylcyclopentadienyl titanium trichloride prepared in Example 3. Figure 3 The Ti 2p spectrum in Figure (a) shows spin-orbit double peaks of Ti 2p3 / 2 and Ti 2p1 / 2. The two peaks have reasonable splitting energies, area relationships and peak width characteristics. Their binding energy range is consistent with high-valence titanium species in chlorine coordination environment. Figure 3The Cl 2p spectrum in Figure (b) shows a doublet of Cl 2p3 / 2 and Cl 2p1 / 2, and its binding energy range is consistent with the metal-chlorine coordination state. The simultaneous appearance of Ti 2p and Cl 2p signals indicates that titanium and chlorine in a coordinated state are present on the product surface.

[0103] Depend on Figure 4 As can be seen, the product obtained in Example 3 mainly presents as blocky or short prismatic crystals with distinct edges. Relatively continuous crystal faces can be observed on the crystal surface, and most crystal outlines are relatively complete. The crystals are mainly stacked naturally and in mechanical contact, with only a small amount of fine particles adhering to the surface. No severe agglomeration structure formed by a large amount of loose microparticles was observed. This indicates that the antisolvent addition and programmed cooling crystallization process used in Example 3 are beneficial to the gradual nucleation and crystal growth of the target product, which can reduce the fine powder generated by rapid crystallization and improve crystal integrity and particle size uniformity.

[0104] In summary, feedback feeding, single-pass deacidification, and dual endpoints affect local reaction load, reaction equilibrium / mass transfer, and endpoint reliability, respectively, and these three factors are sequentially linked. Mixed solvents and programmed crystallization further transform reaction control into separable, high-purity crystals. The above single-factor comparisons demonstrate that each constraint contributes practically to the technical effect, and the complete combination is not merely an arbitrary juxtaposition of conventional process parameters.

[0105] The above are merely specific embodiments of the present invention, but the technical features of the present invention are not limited thereto. Any simple changes, equivalent substitutions, or modifications made based on the present invention to solve essentially the same technical problems and achieve essentially the same technical effects are all covered within the protection scope of the present invention.

Claims

1. A method for preparing pentamethylcyclopentadienyl titanium trichloride, characterized in that: Includes the following steps: S1. Under the protection of dry inert gas, dry chlorinated hydrocarbon solvent and titanium tetrachloride are added to a reactor equipped with a stirring device, a temperature control device and a tail gas outlet pipeline; the tail gas outlet pipeline is connected in sequence to a condenser, an online HCl detection unit and an external absorption unit, and the external absorption unit is isolated from the liquid phase of the reactor. S2. The feed solution, consisting of pentamethylcyclopentadiene and the dry chlorinated hydrocarbon solvent, is divided into a start-up feed and a feedback feed. A start-up feed, comprising 10%–25% of the total amount of pentamethylcyclopentadiene in the feed solution, is added at -5–10°C. The reaction system is then raised to 25–45°C. During the addition of the remaining feedback feed, a dry inert gas flows through the reactor's gas phase space at a constant reference flow rate. The feedback feed rate and reaction temperature are adjusted based on the HCl signal measured by the online HCl detection unit, controlling the normalized instantaneous HCl carry-out rate to 0.001–0.020 min. - ¹; The normalized instantaneous HCl carry-out rate is defined as the amount of HCl carried out by the tail gas per unit time and per unit initial amount of titanium tetrachloride; wherein, the molar ratio of titanium tetrachloride to pentamethylcyclopentadiene is 1:1.03 to 1.

07. S3. After the feedback feed is completed, the reaction system is heated to 70-86°C, and a dry inert gas is used to perform a single-pass scavenging of the reactor's gas phase space. The escaping HCl-containing tail gas is condensed and then subjected to online detection and external absorption. When the cumulative amount of HCl carried out is 0.78-1.02 times the initial amount of titanium tetrachloride, and the normalized instantaneous HCl carry-out rate does not exceed 8 × 10⁻⁶, the reaction proceeds to the next stage. -4 min - ¹The reaction was stopped after lasting for at least 10 minutes to obtain a reaction solution containing pentamethylcyclopentadienyl titanium trichloride; S4. The reaction solution is filtered and concentrated under reduced pressure under inert gas protection. A non-polar antisolvent is added to the resulting concentrate, and the solution is cooled to crystallize. The solution is then filtered, washed, and dried under vacuum to obtain pentamethylcyclopentadienyl titanium trichloride. In steps S1 to S3, no alkali metals, alkali metal hydrides, alkyl lithiums, Grignard reagents, nitrogen-containing organic bases, trialkyl halosilanes, or pentamethylcyclopentadienyl trialkylsilanes are added to the reaction solution.

2. The method for preparing pentamethylcyclopentadienyl titanium trichloride according to claim 1, characterized in that: The dry chlorinated hydrocarbon solvent is a mixed solvent composed of 1,2-dichloroethane and chlorobenzene in a volume ratio of 4:1 to 9:1, and the water content of the mixed solvent is not higher than 8 ppm; the concentration of titanium tetrachloride in the system obtained in step S1 is 0.08 to 0.16 mol / L.

3. The method for preparing pentamethylcyclopentadienyl titanium trichloride according to claim 1, characterized in that: The concentration of pentamethylcyclopentadiene in the feed solution is 0.20–0.50 mol / L, the molar ratio of titanium tetrachloride to pentamethylcyclopentadiene is 1:1.045–1.065, and the addition time of the feedback feed is 90–180 min.

4. The method for preparing pentamethylcyclopentadienyl titanium trichloride according to claim 1, characterized in that: The pentamethylcyclopentadiene in the start-up feed accounts for 15% to 22% of the total amount of pentamethylcyclopentadiene in the feed liquid; the start-up feed is added at -3 to 3°C over 10 to 25 minutes, and after addition, the temperature is maintained for 10 to 30 minutes, and then the reaction system is raised to 30 to 42°C and the feedback feed is added.

5. The method for preparing pentamethylcyclopentadienyl titanium trichloride according to claim 1, characterized in that: The initial amount of titanium tetrachloride and the amount of HCl carried out by the exhaust gas per unit time are calculated as rHCl = Qg × yHCl / n0; where rHCl is the normalized instantaneous HCl carry-out rate in min. - ¹, Qg is the molar flow rate of the condensed tail gas in mol / min, yHCl is the molar fraction of HCl in the tail gas, and n0 is the initial amount of titanium tetrachloride in step S1; during the addition of the feedback feed, rHCl is controlled at 0.003–0.012 min. - ¹, the data acquisition interval of the online HCl detection unit is no more than 10 s.

6. The method for preparing pentamethylcyclopentadienyl titanium trichloride according to claim 1, characterized in that: During the aforementioned feedback feed, when rHCl is continuously above 0.012 min for 30 s. - ¹When the feedback feed rate is reduced by 20%–50%, and the reaction temperature is reduced by 3–8°C; when rHCl remains below 0.003 min for 3 consecutive mins. - ¹When the feedback feed has not been fully added, the feedback feed rate is increased by 10% to 30%, and the reaction temperature is increased by 2 to 5°C, with the increased reaction temperature not exceeding 45°C.

7. The method for preparing pentamethylcyclopentadienyl titanium trichloride according to claim 1, characterized in that: The condenser has a condensation temperature of -15 to 0°C. A polytetrafluoroethylene (PTFE) demisting unit is provided between the condenser and the online HCl detection unit. The online HCl detection unit is a tunable diode laser absorption HCl detection unit. The external absorption unit includes a first absorber and a second absorber arranged in sequence. The first absorber contains an 8% to 15% sodium hydroxide aqueous solution, and the second absorber contains a 5% to 10% sodium bicarbonate aqueous solution. The gas discharged through the second absorber does not return to the reactor.

8. The method for preparing pentamethylcyclopentadienyl titanium trichloride according to claim 1, characterized in that: In step S3, the reaction system is maintained at 78–84°C. The scavenging rate of the dry inert gas is 0.05–0.20 vvm, meaning the standard volume of dry inert gas introduced per minute is 0.05–0.20 times the volume of the reaction liquid. The cumulative HCl carry-out ratio is calculated as XHCl = ∫(Qg × yHCl)dt / n0. When XHCl is not less than 0.85 and rHCl is not more than 3 × 10⁻⁶, the scavenging rate is determined. -4 min - ¹The reaction is terminated after 15–30 minutes.

9. The method for preparing pentamethylcyclopentadienyl titanium trichloride according to claim 1, characterized in that: In step S4, the reaction solution is first cooled to 55-65°C and filtered through a polytetrafluoroethylene filter medium with a pore size of 0.5-2 μm under positive pressure of an inert gas. The filtrate is then concentrated to 25%-40% of the original reaction solution volume at 30-45°C and an absolute pressure of 5-20 kPa. Then, dry n-heptane or dry methylcyclohexane with a volume of 3-5 times that of the concentrated solution is added as the non-polar antisolvent.

10. The method for preparing pentamethylcyclopentadienyl titanium trichloride according to claim 1, characterized in that: The programmed cooling crystallization process includes: first, adjusting the system after adding the non-polar antisolvent to 20–30°C, then cooling it to 0–5°C at a rate of 0.2–0.8°C / min and holding it at that temperature for 0.5–1.5 h, then cooling it to -15–-5°C at a rate of 0.1–0.5°C / min and holding it at that temperature for 1–3 h; after filtration, washing it twice with the non-polar antisolvent at -10–0°C at a rate of 0.5–1.5 mL per gram of wet filter cake each time, and then vacuum drying it for 4–10 h at 25–40°C and an absolute pressure not exceeding 2 kPa.

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