Preparation method of organic titanium compound
By using 1,3-difluorobenzene reacts with the compound of formula II under mild alkali and temperature conditions, the defects of using strong alkali and low temperature in the preparation method of the existing organic titanium compound are solved, and an efficient and gentle preparation process is achieved, and industrial production is promoted.
Patent Information
- Application Number
- CN202411804784.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-09
- Publication Date
- 2025-03-28
AI Technical Summary
The existing preparation methods for organic titanium compounds require the use of strong bases such as butyl lithium and low temperature conditions, which lead to adverse industrial production and the lack of mature industrial production processes.
1,3-difluorobenzene is used as starting material and reacted with the compound of formula II under mild alkali and temperature conditions to obtain bis(2,6-difluorophenyl)bis[(1,2,3,4,5-η)-1-methyl-2,4-cyclopentadiene-1-yl]titanium. The process includes reacting the compound of formula II with 1,3-difluorobenzene in the presence of a solvent and a base, adjusting the pH, adding a solvent and performing a post-treatment step to obtain the target compound.
The efficient preparation of organic titanium compounds is achieved under milder alkali and temperature conditions, which improves the reaction yield and reduces the requirements for reaction substrates, and promotes industrial production.
Smart Images
Figure CN119708082A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the field of organic synthesis, and in particular to a method for preparing an organic titanium compound. Background Art
[0002] Organic titanium compounds have a wide range of applications in the fields of materials science and chemistry. For example, U.S. Pat. No. 6,864,019B2 discloses that various organic titanium compounds such as bis(2,6-difluorophenyl)bis[(1,2,3,4,5-η)-1-methyl-2,4-cyclopentadien-1-yl]titanium can be used as photoinitiators.
[0003] U.S. Patent No. 4,910,121A discloses a method for preparing a variety of difluoroarylcyclopentadienyltitanium compounds including bis(2,6-difluorophenyl)bis[(1,2,3,4,5-η)-1-methyl-2,4-cyclopentadien-1-yl]titanium. The method uses butyl lithium as a base and bromofluorobenzene as a raw material, and reacts at -78°C. The reaction yield varies greatly depending on the substrate, ranging from 20% to 92%.
[0004] However, the conditions used in the above method are relatively harsh, requiring the use of a strong base such as butyl lithium, and the reaction also needs to be carried out at a low temperature of -78°C, which is not conducive to industrial production. In addition, bromofluorobenzene lacks a mature industrial production process, which also brings further difficulties to the industrial production of the above organic titanium compounds. Summary of the invention
[0005] The present invention is made to solve the above problems, and aims to provide a method for preparing an organic titanium compound with milder conditions, stronger reaction selectivity and lower requirements on reaction substrates.
[0006] The present invention provides a method for preparing an organic titanium compound, which has the following characteristics:
[0007]
[0008] The steps include:
[0009] In the presence of a solvent and a base, the compound of formula II reacts with 1,3-difluorobenzene to obtain a compound of formula I,
[0010]
[0011] Wherein, the compound of formula II is ||,
[0012] The base is lithium diisopropylamide,
[0013] In Formula I and Formula II, R1 -is a cyclopentadienyl anion or a cyclopentadienyl anion substituted on the ring, R2 - for
[0014] In the preparation method of the organic titanium compound provided by the present invention, it can also have the following characteristics: wherein the substituted cyclopentadienyl anion is a cyclopentadienyl anion substituted by 1-4 C1-C6 alkyl groups on the ring, and each C1-C6 alkyl group is the same or different.
[0015] The method for preparing the organic titanium compound provided by the present invention may also have the following characteristics: wherein the substituted cyclopentadienyl anion is a 1-methylcyclopentadienyl anion.
[0016] The method for preparing the organic titanium compound provided by the present invention may also have the following characteristics: wherein the solvent is any one or more of tetrahydrofuran, 2-methyltetrahydrofuran or tert-butyl methyl ether.
[0017] The method for preparing the organic titanium compound provided by the present invention may also have the following characteristics: wherein the reaction of the compound of formula II with 1,3-difluorobenzene is carried out at -40 to -60°C.
[0018] The method for preparing the organic titanium compound provided by the present invention may also have the following characteristics: wherein, after the reaction of the compound of formula II with 1,3-difluorobenzene, a post-treatment step is further included:
[0019] Add acid to the reaction solution obtained by reacting the compound of formula II with 1,3-difluorobenzene, adjust the pH value to 5-7, add ethyl acetate and stir, filter, take the filtrate, separate the liquids, take the organic phase, concentrate, and wash with n-heptane to obtain the target compound.
[0020] The method for preparing the organic titanium compound provided by the present invention may also have the following feature: wherein the reaction is carried out under the protection of an inert gas.
[0021] The method for preparing the organic titanium compound provided by the present invention may also have the following characteristics: wherein the molar ratio of the compound of formula II to 1,3-difluorobenzene is 1:(1-5). Preferably, the molar ratio of the compound of formula II to 1,3-difluorobenzene is 1:(3-4).
[0022] The method for preparing the organic titanium compound provided by the present invention may also have the following characteristics: wherein the molar ratio of the compound of formula II to the base is 1:(1-5). Preferably, the molar ratio of the compound of formula II to the base is 1:(3-4).
[0023] The method for preparing the organic titanium compound provided by the present invention may also have the following characteristics: wherein the mass ratio of the compound of formula II to the solvent is 1:(5-10).
[0024] Functions and Effects of the Invention
[0025] According to the preparation method of the organic titanium compound involved in the present invention, since 1,3-difluorobenzene is selected as the starting material, the present invention can not only complete the reaction under a milder base and a milder temperature, but also improve the reaction yield to a certain extent. DETAILED DESCRIPTION
[0026] In order to make the technical means, creative features, objectives and effects achieved by the present invention easier to understand, the present invention is described in detail below in conjunction with embodiments.
[0027] Unless otherwise specified, all raw materials in the following examples are commercially available products.
[0028] <Example 1>
[0029] Preparation method of bis(2,6-difluorophenyl)bis[(1,2,3,4,5-η)-1-methyl-2,4-cyclopentadien-1-yl]titanium
[0030] This embodiment provides a method for preparing bis(2,6-difluorophenyl)bis[(1,2,3,4,5-η)-1-methyl-2,4-cyclopentadien-1-yl]titanium, comprising the following steps:
[0031] Under nitrogen protection, 297 g of 1,3-difluorobenzene (2.6 mol, 3.0 eq) and 2100 g of tetrahydrofuran were added to the reaction vessel, the temperature was lowered to -50 ° C, 1300 mL of 2 mol / L tetrahydrofuran solution of lithium diisopropylamide (2.6 mol, 3.0 eq) was added, and the mixture was stirred at -50 ° C for 1 h, followed by the addition of 240 g of dichlorobis[(1,2,3,4,5-H)-1-methyl-2,4-cyclopentadien-1-yl]-titanium (cas number: 1282-40-2, 0.866 mol, 1.0 eq), and the reaction was stirred at -50 ° C for 3 h to obtain a reaction solution.
[0032] To the above reaction solution, add 12 wt % aqueous hydrochloric acid solution to adjust the pH value to 6, add 1500 g of ethyl acetate, stir at 20 ° C for 1 h, filter, separate the liquids, take the organic phase, concentrate, wash with n-heptane, centrifuge, take the solid, and dry to obtain 325 g of the target compound with a yield of 88.4% and a purity of 99.1%.
[0033] <Example 2>
[0034] Preparation method of bis(2,6-difluorophenyl)bis[(1,2,3,4,5-η)-1-methyl-2,4-cyclopentadien-1-yl]titanium
[0035] This embodiment provides a method for preparing bis(2,6-difluorophenyl)bis[(1,2,3,4,5-η)-1-methyl-2,4-cyclopentadien-1-yl]titanium, comprising the following steps:
[0036] Under nitrogen protection, 16.4 g of 1,3-difluorobenzene (144.4 mmol, 4.0 eq) and 87.5 g of tetrahydrofuran were added to the reaction vessel, cooled to -50 ° C, 72.2 mL of 2 mol / L tetrahydrofuran solution of lithium diisopropylamide (144.4 mmol, 4.0 eq) was added, and stirring was continued at -50 ° C for 1 h, followed by adding 10 g of dichlorobis[(1,2,3,4,5-H)-1-methyl-2,4-cyclopentadien-1-yl]-titanium (cas number: 1282-40-2, 36.1 mmol, 1.0 eq), and stirring was continued at -50 ° C for 3 h to obtain a reaction solution.
[0037] To the above reaction solution, add 12 wt % aqueous hydrochloric acid solution to adjust the pH value to 6, add 60 g of ethyl acetate, stir at 20 ° C for 1 h, filter, separate the liquids, take the organic phase, concentrate, wash with n-heptane, centrifuge, take the solid, and dry to obtain 13.3 g of the target compound with a yield of 86.7% and a purity of 99.0%.
[0038] <Example 3>
[0039] Preparation method of bis(2,6-difluorophenyl)bis[(1,2,3,4,5-η)-1-methyl-2,4-cyclopentadien-1-yl]titanium
[0040] This embodiment provides a method for preparing bis(2,6-difluorophenyl)bis[(1,2,3,4,5-η)-1-methyl-2,4-cyclopentadien-1-yl]titanium, comprising the following steps:
[0041] Under nitrogen protection, 10.3 g of 1,3-difluorobenzene (90.2 mmol, 2.5 eq) and 87.5 g of tetrahydrofuran were added to the reaction vessel, cooled to -50 ° C, 45.1 mL of 2 mol / L tetrahydrofuran solution of lithium diisopropylamide (90.2 mmol, 2.5 eq) was added, and the mixture was stirred at -50 ° C for 1 h, followed by the addition of 10 g of dichlorobis[(1,2,3,4,5-H)-1-methyl-2,4-cyclopentadien-1-yl]-titanium (cas number: 1282-40-2, 36.1 mmol, 1.0 eq), and the reaction was stirred at -50 ° C for 3 h to obtain a reaction solution.
[0042] To the above reaction solution, add 12 wt % aqueous hydrochloric acid solution to adjust the pH value to 6, add 60 g of ethyl acetate, stir at 20 ° C for 1 h, filter, separate the liquids, take the organic phase, concentrate, wash with n-heptane, centrifuge, take the solid, and dry to obtain 12.5 g of the target compound with a yield of 81.7% and a purity of 99.1%.
[0043] <Comparative Example 1>
[0044] Preparation method of bis(2,6-difluorophenyl)bis[(1,2,3,4,5-η)-1-methyl-2,4-cyclopentadien-1-yl]titanium
[0045] This comparative example provides a method for preparing bis(2,6-difluorophenyl)bis[(1,2,3,4,5-η)-1-methyl-2,4-cyclopentadien-1-yl]titanium, comprising the following steps:
[0046] Under nitrogen protection, 20.9 g of 2-bromo-1,3-difluorobenzene (108.3 mmol, 3.0 eq) and 87.5 g of tetrahydrofuran were added to the reaction vessel, cooled to -50 ° C, 54.2 mL of 2 mol / L tetrahydrofuran solution of lithium diisopropylamide (108.3 mmol, 3.0 eq) was added, and stirring was continued at -50 ° C for 1 h, followed by adding 10 g of dichlorobis[(1,2,3,4,5-H)-1-methyl-2,4-cyclopentadien-1-yl]-titanium (cas number: 1282-40-2, 36.1 mmol, 1.0 eq), and stirring was continued at -50 ° C for 3 h to obtain a reaction solution. The reaction solution was tested using HPLC, and the content of the target product in the reaction solution was only 35.4%. Another 45.2% of the product was suspected to be monochloro(2,6-difluorophenyl)bis[(1,2,3,4,5-η)-1-methyl-2,4-cyclopentadien-1-yl]titanium, but it was not further verified.
[0047] <Comparative Example 2>
[0048] Preparation method of bis(2,6-difluorophenyl)bis[(1,2,3,4,5-η)-1-methyl-2,4-cyclopentadien-1-yl]titanium
[0049] This comparative example provides a method for preparing bis(2,6-difluorophenyl)bis[(1,2,3,4,5-η)-1-methyl-2,4-cyclopentadien-1-yl]titanium, comprising the following steps:
[0050] Under nitrogen protection, 20.9 g of 2-bromo-1,3-difluorobenzene (108.3 mmol, 3.0 eq) and 87.5 g of tetrahydrofuran were added to the reaction container, the temperature was lowered to -78 ° C, 68 mL of 1.6 mol / L n-butyl lithium n-hexane solution (108.3 mmol, 3.0 eq) was added, and the reaction was continued to be stirred at -78 ° C for 1 h, followed by the addition of 10 g of dichlorobis[(1,2,3,4,5-H)-1-methyl-2,4-cyclopentadien-1-yl]-titanium (cas number: 1282-40-2, 36.1 mmol, 1.0 eq), and the reaction was continued to be stirred at -78 ° C for 3 h to obtain a reaction solution.
[0051] 80 mL of saturated aqueous ammonium chloride solution and 80 mL of dichloromethane were added to the reaction solution for extraction. The organic phase was concentrated, washed with n-heptane, centrifuged, and the solid was taken and dried to obtain 10.9 g of the target compound with a yield of 69.8% and a purity of 98.8%.
[0052] Functions and Effects of the Embodiments
[0053] According to the preparation method of the organic titanium compound involved in the above embodiment, since the bromine atom in 2-bromo-1,3-difluorobenzene has better leaving performance than the other two hydrogen atoms on the benzene ring, and the leaving performance of the three aromatic hydrogen atoms in 1,3-difluorobenzene is similar and worse than that of the bromine atom in 2-bromo-1,3-difluorobenzene, in theory, 2-bromo-1,3-difluorobenzene is more likely to form 2,6-difluorobenzene anion under the action of base, and further react with dichlorobis[(1,2,3,4,5-H)-1-methyl-2,4-cyclopentadien-1-yl]-titanium. However, the applicant unexpectedly found that when 1,3-difluorobenzene is selected as the starting material and a relatively weaker base is used, the target product can be obtained in a better yield under milder reaction conditions than 2-bromo-1,3-difluorobenzene commonly used in the prior art.
[0054] The above-mentioned embodiments are preferred examples of the present invention and are not intended to limit the protection scope of the present invention.
Claims
1. A method for preparing an organic titanium compound, characterized in that: For preparing the compound shown in formula I, The steps include: In the presence of a solvent and a base, the compound of formula II reacts with 1,3-difluorobenzene to obtain a compound of formula I, Wherein, the compound of formula II is The base is lithium diisopropylamide, In Formula I and Formula II, R 1- is a cyclopentadienyl anion or a cyclopentadienyl anion substituted on the ring, R 2- for 2. The method for preparing an organic titanium compound according to claim 1, characterized in that: in, The substituted cyclopentadienyl anion is a cyclopentadienyl anion substituted by 1 to 4 C1-C6 alkyl groups on the ring, and each C1-C6 alkyl group is the same or different.
3. The method for preparing an organic titanium compound according to claim 2, characterized in that: in, The substituted cyclopentadienyl anion is a 1-methylcyclopentadienyl anion.
4. The method for preparing an organic titanium compound according to claim 1, characterized in that: in, The solvent is any one or more of tetrahydrofuran, 2-methyltetrahydrofuran or tert-butyl methyl ether.
5. The method for preparing an organic titanium compound according to claim 1, characterized in that: in, The reaction of the compound of formula II with 1,3-difluorobenzene is carried out at -40 to -60°C.
6. The method for preparing an organic titanium compound according to claim 1, characterized in that: After the reaction of the compound of formula II with 1,3-difluorobenzene, a post-treatment step is also included: Add acid to the reaction solution obtained by reacting the compound of formula II with 1,3-difluorobenzene, adjust the pH value to 5-7, add ethyl acetate and stir, filter, take the filtrate, separate the liquids, take the organic phase, concentrate, and wash with n-heptane to obtain the target compound.
7. The method for preparing an organic titanium compound according to claim 1, characterized in that: in, The reaction was carried out under the protection of inert gas.
8. The method for preparing an organic titanium compound according to claim 1, characterized in that: in, The molar ratio of the compound of formula II to the 1,3-difluorobenzene is 1:(1-5).
9. The method for preparing an organic titanium compound according to claim 1, characterized in that: in, The molar ratio of the compound of formula II to the base is 1:(1-5).
10. The method for preparing an organic titanium compound according to claim 1, characterized in that: in, The mass ratio of the compound of formula II to the solvent is 1:(5-10).
Citation Information
Patent Citations
Photopolymerizable composition containing metallocenes
US4910121A
Recording material formulations for holographic media
US6864019B2