JPS6360027B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for producing aromatic titanocene compounds useful as catalysts for organic reactions such as polymerization and hydrogenation.
The present invention relates to a method for producing aromatic titanocene compounds in high yield.

[Conventional technology and its problems]

As a method for synthesizing aromatic titanocene compounds, a titanocene dihalide is obtained by reacting a halogenated titanium compound with an alkali metal salt of cyclopentadiene or a Grignard reagent at a temperature above room temperature, and after isolating and purifying this, the reaction is carried out at a temperature above room temperature. A method of obtaining aromatic alkali metal compounds by reacting with is already known (for example, L.Summers et al., J.Am.
Chcm.Soc., 77, 3604 pages (1955), MDRausch
et al., J. Organometall Chem., 10, p. 127 (1967
year), etc.).

However, in conventional synthesis methods performed at temperatures above room temperature, both the reaction of titanium halide compounds with alkali metal salts of cyclopentadiene or Grignard reagents, and the reactions of titanocene dihalides with aromatic alkali metal compounds, titanium Side reactions such as reduction of atoms occur, resulting in poor yields. Therefore, in order to obtain aromatic titanocene compounds in good yields, the first reaction product, titanocene dihalide, must be isolated and purified before the next step. It had the disadvantage of not being able to react with aromatic alkali metals. The conventional method of isolating and purifying the titanocene dihalide once not only requires a lot of time for the purification operation but also is uneconomical due to large losses during purification. Therefore, it is strongly desired to carry out the two reactions continuously, but it is currently not possible in practice due to the poor yield of each elementary reaction under the current reaction conditions.

That is, the problem to be solved is that no method has hitherto been found for producing aromatic titanocene compounds with high yield, industrially and economically with good purity.

[Means and actions for solving problems]

In the production of aromatic titanocene compounds, the present invention involves the reaction of a halogenated titanium compound with an alkali metal salt of cyclopentadiene and the reaction of the reaction product with an aromatic alkali metal compound in a polar solvent at a specific molar ratio. This was based on the discovery that the yield of each elementary reaction can be dramatically improved by performing it at low temperatures, and that aromatic titanocene compounds can be synthesized continuously with high yields. It is.

That is, the present invention is based on the general formula (A) TiX ₄ (A) [wherein, X represents a halogen atom]. ] and a halogenated titanium compound represented by the general formula (B) C ₅ H ₅ 'Y (B) [wherein, Y represents Na or Li. ] After reacting the alkali metal salt of cyclopentadiene represented by the following in a polar solvent at a temperature of -50 to 20°C and a molar ratio of (A) and (B) in the range of 1:1.6 to 1:2.5. , this reaction product and general formula (C) [In the formula, Z represents an alkali metal, R ₁ to _{R 3} represent hydrogen or an alkyl hydrocarbon group having 1 to 4 carbon atoms, and one or more of R ₁ to _{R 3} is hydrogen. ] in a polar solvent at a temperature of -50 to 20°C, with a molar ratio of (A) and (C) of 1:
General formula characterized by reaction in the range of 1.6 to 1:2.5 The present invention relates to a method for producing an aromatic titanocene compound represented by:

The manufacturing method of the present invention consists of two consecutive steps.
That is, it consists of a reaction step between a halogenated titanium compound and an alkali metal salt of cyclopentadiene, and a reaction step between the reaction product and an aromatic alkali metal compound.

The reaction of the first step can be shown chemically as follows.

TiX ₄ +2C ₅ H ₅ Y → (C ₅ H ₅ ) ₂ TiX ₂ +2XY [wherein, X represents a halogen atom, and Y represents Na or Li. [This reaction is carried out in a polar solvent under an inert atmosphere,
Do this under stirring. Inert atmosphere means an atmosphere that does not participate in reactions, such as helium, neon, argon, nitrogen, etc.

The alkali metal salt of cyclopentadiene is subjected to the reaction as a solution in a polar solvent. The halogenated titanium compound may be used alone or as a solution in a polar solvent.

"Polar solvent" means a solvent that has a polar group such as oxygen or nitrogen in its molecule and does not cause side reactions such as deactivation in the reaction of the present invention, and specifically includes ethers. , tertiary amines, etc.
Especially dimethyl ether, diethyl ether, 1,
Ethers such as 2-dimethoxyethane, propyl ether, dibutyl ether, and tetrahydrofuran, trimethylamine, triethylamine, N,
Tertiary amines such as N,N',N'-tetramethylethylenediamine are preferably used.

These polar solvents can be used alone or as a mixed solvent, and may include hydrocarbon solvents such as pentane, hexane, octane, and benzene.

Specific examples of the halogenated titanium compound used in the present invention include titanium tetrafluoride, titanium tetrachloride, titanium tetrabromide, titanium tetraiodide, and the like. Titanium tetrachloride and titanium tetrabromide are preferable in terms of synthesis yield, and are economical and industrially useful.

Further, specific examples of the alkali metal salt of cyclopentadiene used in the present invention include C ₅ H ₅ Li,
Examples include C ₅ H ₅ Na.

The molar ratio of the halogenated titanium compound and the alkali metal salt of cyclopentadiene during the reaction in the first step is preferably in the range of 1:1.6 to 1:2.5, and more preferably in the range of 1:1.9 to 1:2.2. .

Furthermore, it is important that the reaction be carried out in a temperature range of -50 to 20°C. At temperatures below -50°C, the reaction is slow and the synthesis yield is reduced. At temperatures above 20℃, side reactions such as titanium being reduced by alkali metals occur.
This is not preferred because the yield is extremely low. A more preferable temperature range is -30 to 0°C.

The reaction of the second step can be shown chemically as follows.

This reaction is carried out under the aforementioned inert atmosphere, in a polar solvent, and with stirring. Further, the aromatic alkali metal compound is subjected to the reaction as a solution in the above-mentioned polar solvent.

Specific examples of aromatic alkali metal compounds used in the present invention include phenyllithium, phenyl sodium, p-tolyllithium, 3,4-dimethylphenyllithium, 3,5-dimethylphenyllithium, p-ethylphenyl Examples include lithium, p-butylphenyllithium, and the like.

The amount of aromatic alkali metal compound added in the reaction of the second step is in a molar ratio of 1:1.6 to 1:2.5, more preferably 1:1.9 to the halogenated titanium compound used in the first step. ~1:2.2.

Furthermore, it is important that the reaction be carried out in a temperature range of -50 to 20°C. At temperatures below -50°C, the reaction is slow and the synthesis yield is also reduced. If it exceeds 20°C, side reactions are likely to occur, resulting in an extremely low yield, which is not preferable. A more preferable temperature range is -30 to 0°C.

This manufacturing method is characterized in that the above-described first step and second step are performed continuously. There is no need for a complicated operation of performing the second step after isolating or further purifying the product in the first step. When performing the steps continuously, the polar solvents used in each step may be the same or different. Industrially, it is more preferable to use the same solvent because it is easier to recover and reuse the solvent and it is more economical.

The production method of the present invention is economical because aromatic titanocene compounds can be obtained in high yield, and after the reaction, the target product with high purity can be obtained simply by separating the by-produced inorganic salts and removing the solvent. This eliminates the need for a complicated recovery process, making it extremely useful industrially. Further, if necessary, by performing recrystallization, it is possible to obtain the target product with even higher purity.

〔Effect of the invention〕

As described above, the method of the present invention allows the desired product to be obtained in an extremely high yield by carrying out the reaction at a specific molar ratio in a polar solvent at a low temperature and in a continuous manner, and is therefore easy to operate. It is an economical synthesis method with little loss, and is not only useful industrially but also valuable in the laboratory.

〔Example〕

EXAMPLES The present invention will be specifically explained below with reference to Examples, but the present invention is not limited thereto.

Example 1 After purging a sufficiently dried autoclave with dry helium, 20 g (0.105 mol) of titanium tetrachloride and 100 ml of 1,2-dimethoxyethane were added. Sodium cyclopentadienide (0.21 mol) in 1,2-dimethoxyethane solution (200 ml)
was added over 40 minutes at a temperature of -20°C and under stirring. After continued stirring at −20°C for 30 min, a solution of phenyllithium (0.21 mol) in diethyl ether (200 ml) was added.
was added over 40 minutes at a temperature of -20°C and under stirring. After 1 hour, the temperature was returned to room temperature, solid content was separated in the air, and the liquid was dried in an evaporator to obtain yellow crystals. The yield of diphenylbis(cyclopentadienyl)titanium was determined to be 95% by liquid chromatography. Melting point 145℃
(decomposition), elemental analysis value (theoretical value in brackets): C,
79.6 (79.5); H, 6.2 (6.1); Ti, 14.2 (14.4), ¹
H
−NMRδ value (ppm): 6.19, 6.97. Purity measured by melting point depression method: 96%.

Example 2 Synthesis was carried out in the same manner as in Example 1 except that titanium tetrabromide was used instead of titanium tetrachloride. Yellow crystals were obtained, and the yield of diphenylbis(cyclopentadienyl)titanium was 96% when analyzed by liquid chromatography. Melting point 145℃ (decomposition).
Elemental analysis values: C, 79.4; H, 6.1; Ti, 14.5.

Example 3 Synthesis was carried out in the same manner as in Example 1 except that p-tolyllithium was used instead of phenyllithium.
Yellow crystals were obtained, and the yield of di-p-tolylbis(cyclopentadienyl)titanium analyzed by liquid chromatography was 96%. melting point
150℃ (decomposition).

Elemental analysis value (theoretical value in the box: C, 80.1
(80.0); H, 6.7 (6.7); Ti, 13.2 (13.3). ¹ H−
NMRδ value (ppm): 2.19, 6.17, 6.79.

Example 4 Using tetrahydrofuran instead of 1,2-dimethoxyethane, the reaction between titanium tetrachloride and sodium cyclopentadienide was carried out at -30°C, and the second reaction with phenyllithium was carried out at -10°C. The synthesis was carried out in the same manner as in Example 1 except for the following. Yellow crystals were obtained, and the yield of diphenylbis(cyclopentadienyl)titanium was 94% when analyzed by liquid chromatography. Melting point 145℃ (decomposition). Elemental analysis values: C, 80.1; H, 6.2; Ti, 13.7.

Example 5 Synthesis was carried out in the same manner as in Example 4 except that p-tolyllithium was used instead of phenyllithium.
Yellow crystals were obtained, and the yield of di-p-tolylbis(cyclopentadienyl)titanium analyzed by liquid chromatography was 96%. melting point
150℃ (decomposition). Elemental analysis value: C, 80.6; H,
6.9; 12.5.

Comparative Example 1 The reaction was carried out in the same manner as in Example 1, except that the reaction between titanium tetrachloride and sodium cyclopentadienide and the second reaction with phenyllithium were carried out at 35°C. After the reaction was completed, the reaction solution was filtered and the solution was dried in an evaporator to obtain a reddish brown tar. The yield of diphenylbis(cyclopentadienyl)titanium analyzed by liquid chromatography was 23%.

Comparative Example 2 The reaction was carried out in the same manner as in Example 1, except that the reaction between titanium tetrachloride and sodium cyclopentadienide and the second reaction with phenyllithium were carried out at -65°C. After the reaction was completed, the reaction solution was filtered and the solution was dried in an evaporator to obtain a dark red tar-like substance. The yield of diphenylbiscyclopentadienyl titanium analyzed by liquid chromatography was 28%.

Comparative example 3 Addition amount of sodium cyclopentadienide
The reaction was carried out in the same manner as in Example 1 except that the amount was changed to 0.126 mol (titanium tetrachloride/sodium cyclopentadienide molar ratio = 1/1.2). After the reaction was completed, the reaction solution was filtered and the solution was dried in an evaporator to obtain a reddish brown tar. The yield of diphenylbis(cyclopentadienyl)titanium analyzed by liquid chromatography was 34%.

Comparative Example 4 The reaction was carried out in the same manner as in Example 1 except that the amount of phenyllithium added was 0.315 mol (titanium tetrachloride/phenyllithium molar ratio = 1/3). After the reaction was completed, the reaction solution was filtered and the solution was dried in an evaporator to obtain a reddish brown tar.

The yield of diphenylbis(cyclopentadienyl)titanium analyzed by liquid chromatography was 38%.

Claims (1)

[Claims] 1 General formula (A) TiX ₄ (A) [In the formula, X represents a halogen atom. ] A halogenated titanium compound represented by the general formula (B) C ₅ H ₅ Y (B) [wherein, Y represents Na or Li. ] in a polar solvent at a temperature of -50 to 20°C, with a molar ratio of (A) and (B) of 1:
After reacting in the range of 1.6 to 1:2.5, this reaction product and general formula (C) [In the formula, Z represents an alkali metal, R ₁ to _{R 3} represent hydrogen or an alkyl hydrocarbon group having 1 to 4 carbon atoms,
One or more of R ₁ to _{R 3} is hydrogen. ] in a polar solvent at a temperature of -50 to 20°C, with a molar ratio of (A) and (C) of 1:
General formula characterized by reaction in the range of 1.6 to 1:2.5 A method for producing an aromatic titanocene compound represented by 2. The manufacturing method according to claim 1, wherein (A) is titanium tetrachloride or titanium tetrabromide, and Z in (C) is lithium. 3. The manufacturing method according to claim 1 or 2, wherein the reaction temperature between (A) and (B) is -30 to 0°C, and the reaction temperature with (C) is -30 to 0°C.