Mono-titanocene complex as well as preparation method and application thereof

Abstract

The invention provides a mono-titanocene complex as well as a preparation method and application thereof. According to the mono-titanocene complex, methylene bridged diarylboronic acid is adopted as an auxiliary ligand, the electrophilicity of titanium metal is improved through the strong electron withdrawing effect of boron oxygen, coordination insertion of styrene monomers is facilitated, and then the chain growth rate is increased. Meanwhile, through the steric effect of an auxiliary ligand of methylene bridged diarylboronic acid, a catalytic active center can be stabilized and a chain transfer reaction can be inhibited, so that high-molecular-weight syndiotactic polystyrene can be prepared with high activity and can catalyze syndiotactic polymerization of styrene with high activity. Tests show that the mono-titanocene complex provided by the invention is used as a catalyst, the activity is high, and the ash content of a product is as low as 18 ppm.

Description

Technical Field

[0001] This invention belongs to the field of olefin polymerization catalysts, specifically relating to a monocyclic titanium complex, its preparation method, and its application. Background Technology

[0002] Syntactic polystyrene (sPS) is a semi-crystalline polymer with a melting point as high as 270℃ and a fast crystallization rate. It has excellent properties such as high crystallinity, low density, heat resistance, and good chemical corrosion resistance, and has been widely used in the automotive industry, instrument metal housings, food containers, and electronic components.

[0003] Syndiotactic polystyrene, as an engineering resin, is generally obtained by the polymerization of styrene monomers catalyzed by a catalyst. The activity of the catalyst affects the purity and ash content of the syndiotactic polystyrene product, thus influencing its performance and applications. Furthermore, the molecular weight of the syndiotactic polystyrene product has a significant impact on its final properties; the molecular weight of the polymer is generally between 100,000 and 500,000.

[0004] Currently, catalysts used for the catalytic preparation of sPS mainly include monocyclic titanium-based catalysts or rare earth catalysts. Monocyclic titanium-based catalysts consist of a single cyclic ring structure, a metal center, and auxiliary ligands, exhibiting a specific monocyclic ring coordination structure. Activated by a co-catalyst alkyl aluminum compound (such as MAO), the resulting monocyclic titanium-based catalyst possesses characteristics such as a well-defined structure, a single active center, designable catalyst structure, and high polymerization reactivity, making it the most mature catalyst for the industrial production of sPS. However, current monocyclic titanium-based catalyst systems often require the use of excess alkyl aluminum co-catalysts for activation. During polymerization, chain transfer caused by excess alkyl aluminum results in a typically low molecular weight product, rarely exceeding 500,000. Summary of the Invention

[0005] In view of this, the purpose of this invention is to provide a monocyclic titanium-ceramic complex, its preparation method, and its application. The monocyclic titanium-ceramic complex uses methylene-bridged diarylboronic acid as an auxiliary ligand, whose steric hindrance effect can stabilize the catalytic active center and inhibit chain transfer reactions, enabling the highly active preparation of high molecular weight, syndiotactic polystyrene.

[0006] To achieve this objective, the present invention adopts the following technical solution:

[0007] In a first aspect, the present invention provides a monotitanium complex having the structure of Formula I:

[0008] Formula I;

[0009] Wherein, Cp' is selected from substituted or unsubstituted cyclopentadienyl, substituted or unsubstituted indenyl, or substituted or unsubstituted fluorenyl.

[0010] Preferably, the substituted group in the substituted or unsubstituted cyclopentadienyl, substituted or unsubstituted indenyl, or substituted or unsubstituted fluorenyl is selected from C1 to C6 alkyl groups, such as methyl, ethyl, propyl, or butyl.

[0011] Preferably, Cp' is selected from cyclopentadienyl (C5H5) - ), pentamethylcyclopentadienyl ([C5(CH3)5] - ), tetramethylcyclopentadienyl ([C5H(CH3)4] - ), 1,2,3-trimethylcyclopentadienyl ([C5H2-1,2,3-(CH3)3] - ), 1,2,4-trimethylcyclopentadienyl ([C5H2-1,2,4-(CH3)3] - ), 1,2-dimethylcyclopentadienyl ([C5H3-1,3-(CH3)2] - ), 1,3-dimethylcyclopentadienyl ([C5H3-1,3-(CH3)2] - ), methylcyclopentadienyl ([C5H4-CH3) - Indene (C9H7) - ) or fluorene (C 13 H9 - ).

[0012] In some specific embodiments of the present invention, the term is selected from any one of the following formulas Ti1 to Ti10:

[0013] Ti1 Ti2 Ti3 ,

[0014] Ti4 Ti5 Ti6 ,

[0015] Ti7 Ti8 Ti9 and Ti10 .

[0016] Secondly, the present invention provides a method for preparing the above-mentioned monotitanium complex, comprising the following steps:

[0017] S1: Provides methylene-bridged diarylboronic acid;

[0018] S2: Reaction of methylene-bridged diarylboronic acid with substituted or unsubstituted cyclopentadienyl titanium trichloride yields monocerotitanium complexes;

[0019] Alternatively, methylene-bridged diarylboronic acid can be reacted with substituted or unsubstituted indene-3-titanium chloride to obtain monoceramic titanium complexes;

[0020] Alternatively, methylene-bridged diarylboronic acid can be reacted with substituted or unsubstituted fluorenyl titanium trichloride to obtain monoceramic titanium complexes.

[0021] In this invention, the above-mentioned methylene-bridged diarylboronic acid is obtained by reacting 2,2'-dibromodiphenylmethane with alkyllithium to form a lithium salt, and then reacting the lithium salt with triisopropyl borate.

[0022] In some embodiments of the present invention, 2,2'-dibromodiphenylmethane is preferred. Lithium salts are formed by reacting with excess n-butyllithium at low temperatures. Then it reacts with triisopropyl borate [(CH3)2CHO]3B to give methylene-bridged diarylboronic acid. .

[0023] In this invention, in step S1 above, the molar ratio of 2,2'-dibromodiphenylmethane and alkyllithium is 1:2.0~2.4, preferably 1:2.0~2.2, and the reaction temperature is -78℃~-40℃, preferably -60~-50℃.

[0024] In this invention, in step S2 above, the molar ratio of methylene-bridged diarylboronic acid to substituted or unsubstituted cyclopentadienyl titanium trichloride (or, substituted or unsubstituted fluorenyl titanium trichloride; or, substituted or unsubstituted indene titanium trichloride) is 1.0~1.5:1, preferably 1.0~1.2:1.

[0025] In this invention, in step S2 above, the reaction temperature is 0~50℃, preferably 10~25℃; the reaction time is 8~20 h, preferably 10~14 h.

[0026] The monocerotitanium titanium complex provided by this invention is prepared by direct reaction of methylene-bridged diarylboronic acid and monocerotitanium trichloride compound. This complex uses methylene-bridged diarylboronic acid as an auxiliary ligand. Through the strong electron-withdrawing effect of the boroxy group, the electrophilicity of titanium metal is enhanced, which facilitates the coordination insertion of styrene monomers and thus increases the chain growth rate. Simultaneously, the steric hindrance effect of the methylene-bridged diarylboronic acid auxiliary ligand stabilizes the catalytic active center and inhibits chain transfer reactions. When used as a catalyst for styrene polymerization, it can produce high-molecular-weight, syndiotactic polystyrene with high activity.

[0027] Thirdly, the present invention also provides a monotitanium cyclohexane catalyst, characterized in that it comprises a main catalyst and a co-catalyst;

[0028] The main catalyst is the monocerotitanium complex involved in the above technical solution.

[0029] Preferably, the co-catalyst comprises any one or more of triisobutylaluminum (TIBA) and tri(pentafluorophenyl)boron B(C6F5)3, triphenylcarbontetra(pentafluorophenyl)boron salt ([Ph3C][B(C6F5)4]), and N,N-dimethylphenyltetra(pentafluorophenyl)borate ([HNMe2Ph][B(C6F5)4]), arranged in a certain molar ratio, preferably a combination of triisobutylaluminum (TIBA) and triphenylcarbontetra(pentafluorophenyl)boron salt ([Ph3C][B(C6F5)4]), wherein the molar ratio of Al in triisobutylaluminum (TIBA) to B in [Ph3C][B(C6F5)4] is 60~80:1, such as 60:1, 65:1, 70:1, 75:1 or 80:1, etc.

[0030] In this invention, the molar ratio of the main catalyst to the co-catalyst is 1:(1~1.5), such as 1:1, 1:1.1, 1:1.2, 1:1.3, 1:1.4 or 1:1.5, etc.

[0031] In some embodiments of the present invention, the co-catalyst is selected from triphenylcarbontetra(pentafluorophenyl)boron salt ([Ph3C][B(C6F5)4]), and its molar ratio with the monotitanium complex main catalyst is 1.2~1.5:1, such as 1.2:1, 1.3:1, 1.4:1 or 1.5:1, etc.

[0032] Fourthly, the present invention also provides an application of the above-mentioned monocyclic titanium-ceramic catalyst in the catalytic polymerization of styrene to prepare syndiotactic polystyrene. In this application, the above-mentioned monocyclic titanium-ceramic catalyst system is used to catalyze the polymerization of styrene within a certain temperature range for a certain time. After terminating the polymerization, the polymer is separated to prepare syndiotactic polystyrene.

[0033] In some embodiments of the present invention, the polymerization temperature is 30~120°C, such as 30, 40, 50, 60, 70, 80, 90, 110 or 120°C, preferably 70~90°C.

[0034] In some embodiments of the present invention, the polymerization time is 10 to 60 minutes, such as 10, 20 minutes, 30 minutes, 40 minutes, 50 minutes or 60 minutes, preferably 10 to 20 minutes.

[0035] Finally, the present invention also provides a syndiotactic polystyrene, which is prepared by the polymerization reaction of styrene catalyzed by the monotitanium catalyst.

[0036] In this invention, the main catalyst and the co-catalyst in the monocerotitanium catalyst are added separately, premixed, or added in batches.

[0037] In some embodiments of the present invention, the weight-average molecular weight of the syndiotactic polystyrene is 50 × 10⁻⁶. 4 ~100×10 4 g / mol, molecular weight distribution of 2.0~2.5, syndiotacticity ≥98%.

[0038] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0039] (1) The monocyclic titanium complex prepared in this invention uses methylene-bridged diarylboronic acid as an auxiliary ligand. Through the strong electron-withdrawing effect of the borooxy group, the electrophilicity of titanium metal is enhanced, which is beneficial for the coordination insertion of styrene monomers and thus increases the chain growth rate. Simultaneously, through the steric hindrance effect of the methylene-bridged diarylboronic acid auxiliary ligand, the catalytic active center can be stabilized and the chain transfer reaction can be inhibited, thereby enabling the highly active preparation of high molecular weight, syndiotactic polystyrene that can catalyze the syndiotactic polymerization of styrene. Testing shows that the monocyclic titanium complex provided in this invention, as a catalyst, can achieve an activity of up to 2.51 × 10⁻⁶. 8 g·mol -1 Ti·h -1 The ash content of the product is as low as 18 ppm.

[0040] (2) The monotitanium complex prepared in this invention can be used as a catalyst to prepare high molecular weight, narrow-distribution syndiotactic polystyrene. The highest molecular weight of polystyrene can reach 100.7 × 10⁻⁶. 4 g / mol, molecular weight distribution down to 2.0, syndiotacticity ≥99%.

[0041] (3) The monocerotitanium complex prepared by the present invention can be used as a catalyst with a small amount of boron compound as a co-catalyst, avoiding the use of expensive and excessive MAO as a co-catalyst, which can greatly reduce the cost of catalyst. At the same time, it inhibits the chain transfer reaction to alkylaluminum in the polymerization, increases the molecular weight of polymer, and significantly improves the economic benefits of industrial production. Attached Figure Description

[0042] Figure 1 The molecular structure diagram of the metallocene titanium complex Ti2 provided in Example 3;

[0043] Figure 2 The structural diagrams of the classic Cp*TiCl3 catalyst Ti11 and CpTiCl3 catalyst Ti12 in Examples 1-6 are shown for comparison.

[0044] Figure 3 Image of the sPS sample provided in Example 20;

[0045] Figure 4 The sPS carbon spectrum provided in Example 20. Detailed Implementation

[0046] The technical solution 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.

[0047] To further illustrate the present invention, the following embodiments provide a detailed description. The experimental materials used in the following embodiments of the present invention are all commercially available products.

[0048] The structural formulas of the monotitanium complexes in the following examples are as follows. For ease of description, the compounds are numbered as follows:

[0049]

[0050] Formula I;

[0051] In Formula I, the substituent Cp' on titanium is Cp'=cyclopentadienyl (C5H5) - ), pentamethylcyclopentadienyl ([C5(CH3)5] - ), tetramethylcyclopentadienyl ([C5H(CH3)4] - ), 1,2,3-trimethylcyclopentadienyl ([C5H2-1,2,3-(CH3)3] - ), 1,2,4-trimethylcyclopentadienyl ([C5H2-1,2,4-(CH3)3] - ), 1,2-dimethylcyclopentadienyl ([C5H3-1,2-(CH3)2] - ), 1,3-dimethylcyclopentadienyl ([C5H3-1,3-(CH3)2] - ), methylcyclopentadienyl ([C5H4-CH3) - Indene (C9H7) - ), fluorene (C 13 H9 - ).

[0052] Specifically:

[0053] Monolithic titanium complex Ti1, Cp' is cyclopentadienyl;

[0054] Monolithic titanium complex Ti2, Cp' is pentamethylcyclopentadienyl;

[0055] Monolithic titanium complex Ti3, Cp' is tetramethylcyclopentadienyl;

[0056] Monolithic titanium complex Ti4, Cp' is 1,2,3-trimethylcyclopentadienyl;

[0057] The monolithocene titanium complex Ti5 has Cp' as 1,2,4-trimethylcyclopentadienyl;

[0058] Monolithic titanium complex Ti6, Cp' is 1,2-dimethylcyclopentadienyl;

[0059] Monolithic titanium complex Ti7, Cp' is 1,3-dimethylcyclopentadienyl;

[0060] Monocyclic titanium complex Ti8, Cp' is methylcyclopentadienyl;

[0061] The monolithocene titanium complex Ti9 has an indenyl group as Cp'.

[0062] The monocyclic titanium complex Ti10 has a fluorene group at Cp'.

[0063] I. Synthesis of Monotitanium Complexes

[0064] Example 1

[0065] This embodiment provides the synthesis of methylene-bridged diarylboronic acid A, and the synthesis method is as follows:

[0066] 10.8 g (33 mmol) of 2,2'-dibromodiphenylmethane was added to 140 mL of anhydrous diethyl ether and cooled to -95 °C with liquid nitrogen / acetone under a nitrogen atmosphere. Then, 73 mmol of n-BuLi (1.6 M hexane solution) was added over 5 minutes using a syringe. The reaction mixture was stirred for 30 minutes and then removed from the cooling bath. After stirring at room temperature for 1 hour, the reaction mixture was again cooled to -95 °C with liquid nitrogen / acetone. Triisopropyl borate (10 mL, 43 mmol) was injected into the reaction mixture over 3 minutes using a syringe. The reaction mixture was slowly heated to room temperature overnight and quenched with saturated NH4Cl(aq). The aqueous layer was extracted with Et2O (diethyl ether), and the combined organic layers were washed with brine, dried over anhydrous Na2SO4, and filtered through a silica gel sieve. The silica gel sieve was then washed with Et2O. The filtrate was concentrated under reduced pressure, and n-hexane was added to precipitate the filtrate. After filtration, a white solid methylene-bridged diarylboronic acid A (5.43 g, yield 84%) was obtained.

[0067] 1H NMR (400 MHz, CDCl3) δ (ppm): 7.96 (d, 2H), 7.51(dt, 2H), 7.46 (d,2H), 7.37(dt, 2H), 5.86(s, 1H), 4.39(s, 2H).

[0068] Elemental analysis calculated for C 13 H 11 BO: C, 80.47; H, 5.71; Found: C, 80.39; H, 5.92.

[0069] Example 2

[0070] This embodiment provides a method for synthesizing a monotitanium complex (Ti1).

[0071] 1.94 g / 10 mmol of the ligand methylene-bridged diarylboronic acid was dissolved in 30 mL of toluene. A 30 mL toluene solution of 2.19 g / 10 mmol of Cp-TiCl3 was added dropwise at -78°C. The mixture was then heated to room temperature and reacted under nitrogen protection for 12 hours. After the reaction was complete, the solvent was removed, the mixture was extracted with n-hexane, concentrated, and recrystallized to give a yellow solid powder Ti1 (2.83 g / 7.5 mmol), with a yield of 75%.

[0072] 1 H NMR (400 MHz, CDCl3) δ (ppm): 7.99 (d, 2H), 7.73(d, 2H), 7.48(d,2H), 7.43(dt, 2H), 7.39 (d, 2H) , 7.34(dt, 2H), 6.72(s, 2H), 6.38(d, 1H),4.35(s, 2H).

[0073] Elemental analysis calculated for C 18 H 15 Cl2OTi: C, 57.36; H, 4.01; Found: C, 57.32; H, 4.13.

[0074] Example 3

[0075] This embodiment provides a method for synthesizing a monotitanium complex (Ti2).

[0076] 1.94 g / 10 mmol of the ligand methylene-bridged diarylboronic acid was dissolved in 30 mL of toluene. A 30 mL toluene solution of 2.89 g / 10 mmol of Cp*-TiCl3 was added dropwise at -78°C. The mixture was then heated to room temperature and reacted under nitrogen protection for 12 hours. After the reaction was complete, the solvent was removed, the mixture was extracted with n-hexane, concentrated, and recrystallized to obtain an orange-red solid powder of Ti2 (3.13 g / 7.0 mmol), with a yield of 70%.

[0077] 1 H NMR (400 MHz, CDCl3) δ (ppm): 7.92 (d, 2H), 7.53(dt, 2H), 7.44 (d,2H), 7.35(dt, 2H), 4.35(s, 2H), 2.38(s, 15H).

[0078] Elemental analysis calculated for C 23 H 25 BCl2OTi: C, 61.80; H, 5.64; Found: C, 61.39; H, 5.98.

[0079] Examples 4-5

[0080] Compared with Example 3, Examples 4 and 5 differ only in the feeding ratio of methylene-bridged diarylboronic acid A to Cp*-TiCl3 (see Table 1). The other parameters and steps are the same as in Example 3.

[0081] Table 1. Yield of Monocadorheological Ti2 under different feed rates

[0082]

[0083] The results in Table 1 show that, with other reaction conditions unchanged, a high yield of titanium complex Ti2 can be obtained when the feed ratio of ligand A to Cp*-TiCl3 is in the range of 1.0 to 1.2:1. Among them, the yield of titanium complex Ti2 is the highest when the feed ratio is 1.1:1.

[0084] Examples 6-7

[0085] Compared with Example 3, Examples 6 and 7 differ only in the reaction temperature of methylene-bridged diarylboronic acid A and Cp*-TiCl3 (see Table 2). The other parameters and steps are the same as in Example 3.

[0086] Table 2

[0087]

[0088] The results in Table 2 show that, with other reaction conditions unchanged, the reaction temperature of ligand A with Cp*-TiCl3 can obtain a high yield of titanium complex Ti2 in the range of 0 to 50°C. Among them, the yield of titanium complex Ti2 is the highest when the reaction temperature is 25°C.

[0089] Examples 8-9

[0090] Compared with Example 3, Examples 8 and 9 differ only in the reaction time of methylene-bridged diarylboronic acid A and Cp*-TiCl3 (see Table 3). The other parameters and steps are the same as in Example 3.

[0091] Table 3

[0092]

[0093] The results in Table 3 show that, with other reaction conditions unchanged, the reaction time of ligand A with Cp*-TiCl3 can be within the range of 10 to 14 h to obtain a high yield of titanium complex Ti2. Among them, the yield of titanium complex Ti2 is the highest when the reaction time is 12 h.

[0094] Example 10

[0095] This embodiment provides a method for synthesizing a monotitanium complex (Ti3):

[0096] 1.94 g / 10 mmol of the ligand methylene-bridged diarylboronic acid was dissolved in 30 mL of toluene. A 30 mL toluene solution of 2.75 g / 10 mmol of C5H(CH3)4-TiCl3 was added dropwise at -78°C. The mixture was then heated to room temperature and reacted under nitrogen protection for 12 hours. After the reaction was complete, the solvent was removed by vacuum extraction, the mixture was extracted with n-hexane, concentrated, and recrystallized to give a yellow solid powder of Ti3 3.5 g / 8.1 mmol, with a yield of 81%.

[0097] 1 H NMR (400 MHz, CDCl3) δ (ppm): 7.92 (d, 2H), 7.51(dt, 2H), 7.43 (d,2H), 7.35(dt, 2H), 4.33(s, 2H), 2.39(s, 6H), 2.27(s, 6H).

[0098] Elemental analysis calculated for C 22 H 23 BCl2OTi: C, 61.03; H, 5.35; Found: C, 61.01; H, 5.23.

[0099] Example 11

[0100] This embodiment provides a method for synthesizing a monotitanium complex (Ti4):

[0101] 1.94 g / 10 mmol of the ligand methylene-bridged diarylboronic acid was dissolved in 30 mL of toluene. A 30 mL toluene solution of 2.61 g / 10 mmol of C5H2-1,2,3-(CH3)3-TiCl3 was added dropwise at -78°C. The mixture was then heated to room temperature and reacted under nitrogen protection for 12 hours. After the reaction was complete, the solvent was removed, the mixture was extracted with n-hexane, concentrated, and recrystallized to give a yellow solid powder of Ti4 (3.17 g / 7.6 mmol), with a yield of 76%.

[0102] 1 H NMR (400 MHz, CDCl3) δ (ppm): 7.91 (d, 2H), 7.52(dt, 2H), 7.45 (d,2H), 7.36(dt, 2H), 4.37(s, 2H), 2.36(s, 6H), 2.25(s, 3H).

[0103] Elemental analysis calculated for C 21 H 21 BCl2OTi: C, 60.2; H, 5.05; Found: C, 60.12; H, 5.21.

[0104] Example 12

[0105] This embodiment provides a method for synthesizing a monotitanium complex (Ti5):

[0106] 1.94 g / 10 mmol of the ligand methylene-bridged diarylboronic acid was dissolved in 30 mL of toluene. A 30 mL toluene solution of C5H2-1,2,4-(CH3)3-TiCl3 (2.61 g / 10 mmol) was added dropwise at -78°C. The mixture was then heated to room temperature and reacted under nitrogen protection for 12 hours. After the reaction was complete, the solvent was removed, the mixture was extracted with n-hexane, concentrated, and recrystallized to give a yellow solid powder of Ti4 (3.01 g / 7.2 mmol), with a yield of 72%.

[0107] 1H NMR (400 MHz, CDCl3) δ (ppm): 7.93 (d, 2H), 7.56(dt, 2H), 7.41 (d,2H), 7.32(dt, 2H), 4.37(s, 2H), 2.37(s, 6H), 2.24(s, 3H).

[0108] Elemental analysis calculated for C 21 H 21 BCl2OTi: C, 60.2; H, 5.05; Found: C, 60.63; H, 5.32.

[0109] Example 13

[0110] This embodiment provides a method for synthesizing a monotitanium complex (Ti6), which is as follows:

[0111] 1.94 g / 10 mmol of the ligand methylene-bridged diarylboronic acid was dissolved in 30 mL of toluene. A 30 mL toluene solution of C5H3-1,2-(CH3)2-TiCl3 (2.47 g / 10 mmol) was added dropwise at -78°C. The mixture was then heated to room temperature and reacted under nitrogen protection for 12 hours. After the reaction was complete, the solvent was removed, the mixture was extracted with n-hexane, concentrated, and recrystallized to give a yellow solid powder of Ti6 (3.31 g / 8.2 mmol), with a yield of 82%.

[0112] 1 H NMR (400 MHz, CDCl3) δ (ppm): 7.91 (d, 2H), 7.52(dt, 2H), 7.43 (d,2H), 7.36(dt, 2H), 4.37(s, 2H), 2.32(s, 6H).

[0113] Elemental analysis calculated for C 20 H 19 BCl2OTi: C, 59.32; H, 4.73; Found: C, 59.83; H, 4.62.

[0114] Example 14

[0115] This embodiment provides a method for synthesizing a monotitanium complex (Ti7):

[0116] 1.94 g / 10 mmol of the ligand methylene-bridged diarylboronic acid was dissolved in 30 mL of toluene. A 30 mL toluene solution of 2.47 g / 10 mmol of C5H(CH3)4-TiCl3 was added dropwise at -78 °C. The mixture was then heated to room temperature and reacted under nitrogen protection for 12 hours. After the reaction was complete, the solvent was removed by vacuum extraction, the solution was extracted with n-hexane, concentrated, and recrystallized to give a yellow solid powder of Ti6 3.11 g / 7.7 mmol, with a yield of 77%.

[0117] 1 H NMR (400 MHz, CDCl3) δ (ppm): 7.85 (d, 2H), 7.57(dt, 2H), 7.46 (d,2H), 7.32(dt, 2H), 4.35(s, 2H), 2.42(s, 6H).

[0118] Elemental analysis calculated for C 20 H 19 BCl2OTi: C, 59.32; H, 4.73; Found: C, 59.12; H, 4.61.

[0119] Example 15

[0120] This embodiment provides a method for synthesizing a monotitanium complex (Ti8), which is as follows:

[0121] 1.94 g / 10 mmol of the ligand methylene-bridged diarylboronic acid was dissolved in 30 mL of toluene. A 30 mL toluene solution of 2.33 g / 10 mmol of C5H(CH3)4-TiCl3 was added dropwise at -78 °C. The mixture was then heated to room temperature and reacted under nitrogen protection for 12 hours. After the reaction was complete, the solvent was removed by vacuum extraction, the mixture was extracted with n-hexane, concentrated, and recrystallized to obtain a yellow solid powder of Ti8 (2.45 g / 6.8 mmol), with a yield of 68%.

[0122] 1 H NMR (400 MHz, CDCl3) δ (ppm): 7.81 (d, 2H), 7.53(dt, 2H), 7.45 (d,2H), 7.38(dt, 2H), 4.36(s, 2H), 2.46(s, 3H).

[0123] Elemental analysis calculated for C 19 H 17BCl2OTi: C, 58.38; H, 4.38; Found: C, 58.89; H, 4.18.

[0124] Example 16

[0125] This embodiment provides a method for synthesizing a monotitanium complex (Ti9), which is as follows:

[0126] 1.94 g / 10 mmol of the ligand methylene-bridged diarylboronic acid was dissolved in 30 mL of toluene. A 30 mL toluene solution of 2.70 g / 10 mmol of Ind-TiCl3 was added dropwise at -78°C. The mixture was then heated to room temperature and reacted under nitrogen protection for 12 hours. After the reaction was complete, the solvent was removed by vacuum extraction, the solution was extracted with n-hexane, concentrated, and recrystallized to give a yellow solid powder of Ti1 (3.34 g / 7.8 mmol), with a yield of 78%.

[0127] 1 H NMR (400 MHz, CDCl3) δ (ppm): 7.96 (d, 2H), 7.42(dt, 2H), 7.35 (d,2H), 7.31(dt, 2H), 6.69(s, 5H), 4.33(s, 2H).

[0128] Elemental analysis calculated for C 18 H 15 BCl2OTi: C, 57.36; H, 4.01; Found: C, 57; H, 4.43.

[0129] Example 17

[0130] This embodiment provides a method for synthesizing substituted cyclopentadiene titanium trichloride (fluorenyl titanium trichloride), and the synthesis method is as follows:

[0131] 1.66 g / 10 mmol of fluorene was dissolved in 30 mL of tetrahydrofuran. 4 mL / 10 mmol of n-butyllithium was added dropwise at -78°C, and the mixture was allowed to rise to room temperature under nitrogen protection for 12 hours. The system was then cooled to -78°C, and 1.89 g / 10 mmol of titanium tetrachloride was added dropwise. The mixture was allowed to rise to room temperature and reacted overnight. After the reaction was complete, the solvent was removed by vacuum, the mixture was extracted with n-hexane, concentrated, and recrystallized to give 3.29 g / 8.5 mmol of fluorene-titanium trichloride as a yellow solid powder, with a yield of 85%.

[0132] 1H NMR (400 MHz, CDCl3) δ (ppm): 7.72(d, 4H), 7.45(d, 4H), 7.35 (d,2H), 6.69(s, 2H), 6.42(d, 1H).

[0133] Elemental analysis calculated for C 13 H9Cl3Ti: C, 48.88; H, 2.84; Found: C, 49.32; H, 2.78.

[0134] Example 18

[0135] This embodiment provides a method for synthesizing a monotitanium complex (Ti10), which is as follows:

[0136] 1.94 g / 10 mmol of the ligand methylene-bridged diarylboronic acid was dissolved in 30 mL of toluene. A 30 mL toluene solution of 3.19 g / 10 mmol of Flu-TiCl3 was added dropwise at -78°C. The mixture was then heated to room temperature and reacted under nitrogen protection for 12 hours. After the reaction was complete, the solvent was removed, the mixture was extracted with n-hexane, concentrated, and recrystallized to give a yellow solid powder Ti1 (3.29 g / 6.9 mmol), with a yield of 69%.

[0137] 1 H NMR (400 MHz, CDCl3) δ (ppm): 7.98 (d, 2H), 7.72(d, 4H), 7.45(d,4H), 7.42(dt, 2H), 7.35 (d, 2H) , 7.31(dt, 2H), 6.69(s, 2H), 6.42(d, 1H),4.33(s, 2H).

[0138] Elemental analysis calculated for C 26 H 19 BCl2OTi: C, 65.47; H, 4.01; Found: C, 65.39; H, 3.98.

[0139] II. Catalytic Polymerization of Styrene

[0140] The polymerization reaction was carried out in a two-necked flask equipped with a stirrer. Before polymerization, the flask was evacuated and vacuum dried under an infrared lamp for at least 2 hours. After the flask cooled to room temperature, the reaction system was placed on an oil bath heater. Once the reaction system reached the set polymerization temperature, freshly distilled styrene, a certain amount of TIBA, and a boron compound co-catalyst solution in a specific molar ratio were injected sequentially using a syringe. The mixture was stirred thoroughly for 2 minutes, and then a certain amount of titanium catalyst solution was injected using a syringe. After the polymerization reaction reached the set time, stirring was stopped, and an alkyd solution was added to terminate the reaction. The mixture was stirred for at least two hours, washed with ethanol, filtered to obtain the polymerization product, and then dried in a vacuum drying oven at 50°C until constant weight.

[0141] In the following examples, the polymerization activity was calculated using the final mass of the styrene polymer, the amount of titanium catalyst, and the polymerization time (activity = mass of styrene polymer / (molar amount of catalyst × time)). The molecular weight and molecular weight distribution of the prepared styrene polymer were determined by high-temperature gel permeation chromatography (HT-GPC) using 1,2,4-trichlorobenzene as solvent and mobile phase, concentration 1.5 g / L, flow rate 1 mL / min. The syndiotacticity of the polymer was determined by high-temperature carbon spectroscopy, and the polymer ash content was determined according to the national standard GB / T 9345-2008 "Determination of Ash Content in Plastics".

[0142] Examples 19-28

[0143] Based on the above polymerization method, styrene polymerization was carried out using different monocyclic titanium complexes as catalysts. The polymerization conditions were as follows: 2 µmol of monocyclic titanium complex, triisobutylaluminum (TIBA) cocatalyst, Al / Ti molar ratio = 100:1; triphenylcarbontetra(pentafluorophenyl)boron salt ([Ph3C][B(C6F5)4]), B / Ti molar ratio = 1.5:1, temperature 80℃, 100 mL of styrene, and polymerization time 10 minutes.

[0144] The specific reaction results are shown in Table 4 below:

[0145] Table 4

[0146]

[0147] As shown in Table 4, titanium complexes with methylene-bridged diarylboronic acid can catalyze the copolymerization of styrene with high activity. In comparison, Ti2 complexes with pentamethyl groups exhibit higher polymerization activity and produce polymers with higher molecular weights.

[0148] Examples 29-30

[0149] Based on the polymerization method described above, different co-catalysts (i.e., activator B in Table 5) were combined with TIBA to activate the monotitanium cadmium complex Ti2 to catalyze the polymerization of styrene. The polymerization conditions were: 2 µmol of monotitanium cadmium complex Ti2, Al / Ti molar ratio = 100:1, B / Ti molar ratio = 1.5:1, temperature 80℃, 100 mL of styrene, and polymerization time 10 minutes.

[0150] The specific reaction results are shown in Table 5 below:

[0151] Table 5

[0152]

[0153] The results in Table 5 show that the co-catalyst composed of triisobutylaluminum (TiBA) and triphenylcarbontetra(pentafluorophenyl)boron salt ([Ph3C][B(C6F5)4]) and the monotitanium complex Ti2 have better catalytic performance and higher activity in styrene polymerization.

[0154] Examples 31-32

[0155] Examples 31-32 provide results of styrene bulk polymerization catalyzed by the monotitanium-based titanium complex Ti2 at different B / Ti ratios. Polymerization conditions: 2 µmol of monotitanium-based titanium complex Ti2, Al / Ti molar ratio = 100:1, cocatalyst triisobutylaluminum (TIBA), triphenylcarbontetra(pentafluorophenyl)boron salt ([Ph3C][B(C6F5)4]), temperature 80°C, 100 mL of styrene, and polymerization time 10 minutes.

[0156] The specific reaction conditions and polymerization results are shown in Table 6.

[0157] Table 6

[0158]

[0159] As can be seen from the data in Table 6, when the molar ratio of the co-catalyst triphenylcarbontetra(pentafluorophenyl)boron salt ([Ph3C][B(C6F5)4]) to the main catalyst Ti2 is 1~1.5:1, it can catalyze the syndiotactic polymerization of styrene with high activity. Among them, the molar ratio of the co-catalyst triphenylcarbontetra(pentafluorophenyl)boron salt ([Ph3C][B(C6F5)4]) to the main catalyst Ti2 is 1.5:1, which has the highest catalytic activity.

[0160] Examples 33-36

[0161] Examples 33-36 provide results of styrene polymerization catalyzed by the monotitanium-based titanium complex Ti2 at different temperatures. Polymerization conditions: 2 µmol of monotitanium-based titanium complex Ti2, cocatalyst triisobutylaluminum (TIBA), Al / Ti molar ratio = 100:1, triphenylcarbontetra(pentafluorophenyl)boron salt ([Ph3C][B(C6F5)4]), B / Ti molar ratio = 1.5:1, 100 mL of styrene, and polymerization time of 10 minutes.

[0162] The specific reaction conditions and polymerization results are shown in Table 7.

[0163] Table 7

[0164]

[0165] The results in Table 7 show that the monotitanium-ceramic complex Ti2 can catalyze the polymerization of styrene with high activity at 30–120 °C. The polymerization process is better when carried out in the range of 70–90 °C, and the catalytic activity for styrene polymerization is the highest at 80 °C.

[0166] Examples 37-39

[0167] Examples 37-39 provide results of styrene polymerization catalyzed by the monotitanium-based titanium complex Ti2 at different time points. Polymerization conditions: 2 µmol of monotitanium-based titanium complex Ti2, cocatalyst triisobutylaluminum (TIBA), Al / Ti molar ratio = 100:1, triphenylcarbontetra(pentafluorophenyl)boron salt ([Ph3C][B(C6F5)4]), B / Ti molar ratio = 1.5:1, temperature 80°C, and 100 mL of styrene.

[0168] The specific reaction conditions and polymerization results are shown in Table 8.

[0169] Table 8

[0170]

[0171] Table 8 shows that the monotitanium cyclopentadiene complex Ti2 can catalyze the polymerization of styrene with high activity within 10 to 60 min, with better polymerization results within 10 to 20 min, exhibiting high catalytic activity and high polymer molecular weight.

[0172] Comparative Examples 1-6

[0173] To more clearly demonstrate the monoceramic titanium complexes of the present invention and their effect on catalyzing styrene polymerization, comparative examples 1-6 provide classic monoceramic titanium complexes Ti11 and Ti12 (see attached examples). Figure 2The performance of the titanium complex Ti11 and Ti12 in catalyzing the polymerization of styrene was described. The titanium complexes Ti11 and Ti12 were prepared according to reports in the literature (Macromolecules 1998, 31, 7588-7597), with a reported yield of 60%. The monocyclic titanium cyclopentadienyl catalyst disclosed in this invention exhibits significantly higher activity than the classic Cp*TiCl3 (Cp* = pentamethylcyclopentadienyl ...

[0174] In this invention, the polymerization conditions for Comparative Examples 1-5 and Examples 20, 33-36 were as follows: 2 µmol of monotitanium cyclopentadiene complex Ti2 / Ti11 / Ti12, 100 mL of triisobutylaluminum (TIBA) cocatalyst (Al / Ti molar ratio = 100:1), 100 mL of triphenylcarbontetra(pentafluorophenyl)boron salt ([Ph3C][B(C6F5)4]) (B / Ti molar ratio = 1.5:1), 100 mL of styrene, and 10 minutes of polymerization time.

[0175] Comparative Example 6 a Polymerization conditions: 2 µmol of monotitanium thiocyanate complex Ti12, MAO cocatalyst, Al / Ti molar ratio = 500:1, 100 mL of styrene, polymerization time 10 min.

[0176] The comparison results between Comparative Examples 1-6 and Examples 20, 33-36 are shown in Table 9 below:

[0177] Table 9

[0178]

[0179] Comparisons of Comparative Examples 1-6 with those of Examples 20 and 33-36 show that the monotitanium cyclopentadiene complexes provided by the present invention, due to the electronic and steric effects provided by the methylene-bridged diarylboronic acid, can catalyze the polymerization of styrene with high activity, exhibiting very high catalytic activity (2.51 × 10⁻⁶) at 80°C. 8 g·mol -1 Ti·h -1 The resulting polystyrene product has a high molecular weight (50~100×10). 4 The ash content is extremely low (18 ppm), superior to classic Cp*TiCl3 and CpTiCl3. Therefore, the monotitanium-based complexes provided by this invention can be used to prepare syndiotactic polystyrene with excellent performance.

[0180] The results of Comparative Examples 5 and 6 show that when a small amount of boron co-catalyst is used, the classic CpTiCl3 catalytic activity is particularly low, and an excessive amount of MAO catalyst is required to improve the catalytic activity. However, the monolithocene titanium complex and its catalyst provided by the present invention only require a small amount of boron co-catalyst to catalyze styrene polymerization with high activity, without the need for a large amount of expensive MAO as a co-catalyst, showing good economic benefits.

[0181] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A mono-cyclopentadienyl titanium complex, characterized in that, It has the structure of Formula I: Formula I; Wherein, Cp' is selected from substituted or unsubstituted cyclopentadienyl, substituted or unsubstituted indenyl, or substituted or unsubstituted fluorenyl.

2. The mono-metallocene titanium complex of claim 1, wherein, The substituted or unsubstituted cyclopentadienyl, substituted or unsubstituted indenyl, or substituted or unsubstituted fluorenyl groups are selected from C1 to C6 alkyl groups.

3. The mono-metallocene titanium complex of claim 1 or 2, wherein, Cp' is selected from cyclopentadienyl, pentamethylcyclopentadienyl, tetramethylcyclopentadienyl, 1,2,3-trimethylcyclopentadienyl, 1,2,4-trimethylcyclopentadienyl, 1,2-dimethylcyclopentadienyl, 1,3-dimethylcyclopentadienyl, methylcyclopentadienyl, indenyl, or fluorenyl.

4. A process for the preparation of a mono-metallocene titanium complex as claimed in any one of claims 1 to 3, characterized in that, Includes the following steps: S1: Provides methylene-bridged diarylboronic acid; S2: Reaction of methylene-bridged diarylboronic acid with substituted or unsubstituted cyclopentadienyl titanium trichloride yields monocerotitanium complexes; Alternatively, methylene-bridged diarylboronic acid can be reacted with substituted or unsubstituted indene-3-titanium chloride to obtain monoceramic titanium complexes; Alternatively, methylene-bridged diarylboronic acid can be reacted with substituted or unsubstituted fluorenyl titanium trichloride to obtain monoceramic titanium complexes.

5. A mono-metallocene titanium catalyst characterized in that, Including the main catalyst and the co-catalyst; The main catalyst is the monocyclic titanium complex according to any one of claims 1 to 3 or the monocyclic titanium complex prepared by the preparation method according to claim 4.

6. The mono-metallocene titanium catalyst of claim 5, wherein, The cocatalyst comprises any one or more of triisobutylaluminum, tris(pentafluorophenyl)boron, triphenylcarbontetra(pentafluorophenyl)boron, or N,N-dimethylphenyltetra(pentafluorophenyl)borate.

7. The mono-metallocene titanium catalyst according to claim 5 or 6, characterized in that, The molar ratio of the main catalyst to the co-catalyst is 1:(1~1.5).

8. The application of the monocerotitanium catalyst according to any one of claims 5 to 7 in the catalytic polymerization of styrene to prepare syndiotactic polystyrene.

9. Use according to claim 8, characterized in that, The main catalyst and co-catalyst in the monolithocene titanium catalyst are added separately, premixed, or added in batches.

10. Use according to claim 8 or 9, characterized in that, The polymerization temperature is 30~120℃; The polymerization time is 10~60 min; The polystyrene has a weight-average molecular weight of 500,000 to 1,000,000, an anachronism of ≥98%, and a molecular weight distribution of 2.0 to 2.5.

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