JPS6126913B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing rhodium complexes.

Rhodium complexes can be used as catalysts for various organic reactions, and in particular, have been used industrially as catalysts for hydroformylation reactions in recent years. In the hydroformylation reaction, rhodium is usually supplied to the reaction system as a solution of rhodium acetate in water or alcohol, and a method is adopted in which a reaction-active catalyst species is formed within the reaction system. However, since rhodium acetate is not soluble in the aromatic solvents commonly used as solvents for hydroformylation reactions, it often precipitates as solid rhodium acetate immediately after being introduced into the reaction system, and is soluble in the reaction solvent. A soluble rhodium complex may not be formed and may not be used effectively.

As a result of intensive studies in view of the above circumstances, the present inventors found that the formula [1] Rh(OCOCH ₃ )L ₃ [1] can be easily obtained by adding tertiary phosphine to a rhodium acetate solution and reacting them. The present invention was achieved by discovering that a rhodium complex soluble in an aromatic solvent represented by the formula (wherein L represents tertiary phosphine) is produced.

As a method for preparing the rhodium complex represented by formula [1], rhodium acetate () ([Rh
( _OCOCH3 ) ₂ ] ₂ ) with tetrafluoroboric acid and triphenylphosphine to obtain tris(triphenylphosphine)rhodium()tetrafluoroborate (Rh( _PPh3 ) ⁺ _3BF ^- ₄ ), This was heated with an excess amount of lithium acetate to produce acetatotris(triphenylphosphine)rhodium (Rh).
A method for obtaining (OCOCH ₃ )(PPh ₃ ) ₃ ) is known (JP-A-47-3320, J.Chem.Soc.(A)3224
(1971)).

On the other hand, in the method for producing a rhodium complex according to the present invention, the above formula [ The rhodium complex shown in 1] is obtained, and it is economical because it does not require auxiliary agents such as tetrafluoroboric acid or lithium acetate, and is also excellent in terms of operability.

The present invention will be explained in detail below.

Rhodium acetate used in the method of the invention
Rhodium acetate () is usually available as an aqueous solution, an acetic acid aqueous solution, or an acetic acid solution, and it can be used as is by dispersing it in the solvent mentioned below, or solid rhodium acetate () can be dissolved in the solvent mentioned later. It may also be used.

Examples of tertiary phosphine include trialkylphosphines such as triisopropylphosphine and tri-n-butylphosphine, tricycloalkylphosphines such as tricyclohexylphosphine, triphenylphosphine, tritolylphosphine, tri( Examples include triarylphosphines such as p-chlorophenyl)phosphine and trialkylphosphines such as tribenzylphosphine. Among them, triarylphosphines such as triphenylphosphine are preferably used. The amount of these tertiary phosphine to be used is arbitrarily selected, but usually 3 moles or more per 1 gram atom of rhodium,
Preferably, about 3 to 20 moles are used.

In the method of the present invention, one or a mixture of two or more solvents that can dissolve both rhodium acetate and tertiary phosphine is used. Specific examples of such solvents include alcohols such as methanol, ethanol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, sec-butyl alcohol, and cyclohexanol, formaldehyde, acetaldehyde,
Aldehydes such as propionaldehyde, ethers such as diethyl ether, dioxane, and tetrahydrofuran, acetone, ethyl methyl ketone,
Ketones such as diethyl ketone, amides such as acetamide, propionamide, N,N-dimethylformamide, N,N-dimethylacetamide, nitriles such as acetonitrile, propiononitrile, benzonitrile, ethyl acetate, methyl propionate, etc. esters, sulfoxides such as dimethyl sulfoxide, carboxylic acids such as acetic acid, pyridines such as pyridine and methylpyridine,
Examples include hydrocarbons such as benzene, triene, and decane. Among these, preferred solvents include methanol, ethanol, acetone, and N,N-dimethylformamide. The amount of these solvents to be used is not particularly limited as long as it is at least the amount that can dissolve rhodium acetate (2) and tertiary phosphine.

In order to produce the rhodium complex represented by the above formula [1] by the method of the present invention, rhodium acetate () and tertiary phosphine are dissolved in the above solvent,
Stirring may be carried out at 150°C, preferably 20 to 100°C, for 30 minutes to 4 hours, and in some cases, as the reaction progresses, an orange rhodium complex represented by the above formula [1] is precipitated. The rhodium complex produced can be isolated by crystallization using a conventional method.

The rhodium complex produced by the method of the present invention can be used in various homogeneous complex catalytic reactions, but in such cases, the reaction product solution can be used as it is or with a suitable solvent without isolating the rhodium complex. In addition, after dissolving the precipitated rhodium complex, it can be used as a catalyst solution.

However, in homogeneous complex catalytic reactions using such rhodium complexes, contamination of water and accumulation of acetic acid may be avoided in some cases, and
Since the solvent used during the production of the rhodium complex may be mixed into the product produced by the catalytic reaction, it is necessary to add a solvent with a higher boiling point than the solvent used during the production of the rhodium complex to the reaction product liquid obtained by the method of the present invention. It is preferable to add water, acetic acid, or the solvent used in producing the rhodium complex by distilling it off.

For example, in the hydroformylation reaction of propylene using a rhodium catalyst, solvents with a higher boiling point than the reaction product butyraldehyde, such as aromatic hydrocarbons such as toluene and xylene, aliphatic saturated hydrocarbons such as decane, and alcohols such as butanol, are used. is used as a reaction solvent, rhodium concentration (rhodium alone equivalent value) 1 to 200 mg/l - solvent, tertiary phosphine concentration 5 to 1000 mol/Rh - gram atom,
Reaction temperature 50~200℃, oxo gas partial pressure 30~100Kg/
cm ² , and the reaction conditions are H ₂ /CO (molar ratio) of oxo gas 0.1 to 10. Therefore, when the rhodium complex produced by the method of the present invention is used in the hydroformylation reaction of propylene, a low boiling point solvent such as methanol, ethanol, acetone, etc. is used during the production of the rhodium complex, and the resulting rhodium It is preferable to add the above-mentioned solvent for hydroformylation reaction to the complex-containing liquid, distill off water, acetic acid, or a low boiling point solvent, and then supply the liquid to the hydroformylation reaction system.

Next, the present invention will be explained in more detail with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist thereof.

Example 1 Triphenylphosphine was added to a 100 ml glass flask equipped with a reflux condenser under an inert gas atmosphere.
2.5 g and 35 ml of methanol were charged and heated in an 80°C oil bath with stirring to dissolve them. This solution has a rhodium concentration of 0.118g/ml (rhodium equivalent value)
About 1 ml of rhodium acetate () aqueous solution in methanol 10
When the solution was dispersed in 1 ml and heated under reflux, it was initially a dark brown homogeneous solution, but after about 1 hour, an orange precipitate began to separate out. After refluxing for 3 hours, the precipitate was separated while hot, washed several times with a small amount of methanol, and dried in vacuum to give 0.3 g.
An orange solid was obtained. The elemental analysis values of the obtained solid (C: 70.22, H: 5.12, P: 9.79) are
Calculated value of RhP ₃ C ₅₆ H ₄₃ O ₂ (C: 70.9, H: 5.1,
P: 9.5), and absorption at 1600 cm ^-1 (Nudiol) due to Rh-(OCOCH ₃ ) was observed in the infrared absorption spectrum, and the obtained orange solid was Rh(OCOCH ₃ ) [P(C ₅ H ₅ ) ₃ ] ₃ was confirmed.

Example 2 Using the same equipment as used in Example 1, the same rhodium acetate as used in Example 1 was used.
When 5 ml of aqueous solution (1), 12 g of triphenylphosphine and 50 ml of N,N-dimethylformamide were charged and stirred at 90°C, an orange precipitate began to precipitate in about 30 minutes. After reacting for 4 hours, it was cooled, and the precipitated orange solid was separated, washed several times with a small amount of acetone, and then vacuum dried to give 2.72 g.
An orange solid was obtained. The obtained orange solid was subjected to elemental analysis and infrared absorption spectroscopy.
It was confirmed that Rh( _OCOCH3 )[P _{( C5H5} ) ₃ ] ₃ .

Reference example 1 Rh obtained by the same method as Example 1
When 45 ml of toluene was added at 80° C. to a methanol solution containing a precipitate of (OCOCH ₃ )[P(C ₆ H ₅ ) ₃ ] ₃ , the precipitate was rapidly dissolved. This was distilled under normal pressure in an oil bath at 90°C to distill out 68 ml of a mixed liquid consisting of methanol, water, acetic acid and toluene. Add toluene to the distillation residue to make 100ml, and the rhodium concentration is 1.06g/l.
A deep red toluene solution of (calculated as rhodium alone) was obtained. This was diluted 10 times with toluene to prepare a catalyst solution.

In a stainless steel autoclave with an internal volume of 200 ml and a vertical stirring type, 5 ml of the above catalyst solution, 0.5 m mole of triphenylphosphine (the amount including triphenylphosphine contained in the catalyst solution), and toluene.
After charging 45ml and replacing the inside of the autoclave with 30Kg/cm ² G nitrogen gas three times, it was distilled using the distillation method.
250m mole of propylene was press-fitted. The autoclave was heated to 120° C., and oxo gas of H ₂ /CO=1 was introduced from the pressure accumulator through the constant pressure regulator into the 50 Kg/cm ² autoclave to start the reaction. Calculate the half-life due to the hydroformylation reaction from the absorption curve of oxo gas pressure in the pressure accumulator, and calculate the rate constant k〓
(Unit: mole/l.hr) was found to be 5.15. Further, the reaction solution was uniform throughout the hydroformylation reaction, and no rhodium compound precipitation was observed.

In order to compare the catalytic activity, a rhodium acetate aqueous solution (rhodium concentration 0.109 obtained by diluting rhodium concentration 118 g/l with methanol) was used as the catalyst liquid.
When a reaction similar to the above-mentioned hydroformylation reaction was carried out using 5 ml of catalyst solution of g/l, k〓 was
It was 5.11 mole/l・hr.

Claims (1)

[Scope of Claims] 1 Rh(OCOCH ₃ )L ₃ (wherein L represents tertiary phosphine), characterized in that rhodium acetate () and tertiary phosphine are subjected to a liquid phase reaction in the presence of a solvent. A method for producing a rhodium complex represented by: 2. The method according to claim 1, wherein the tertiary phosphine is triphenylphosphine. 3. The method according to claim 1 or 2, wherein the solvent is an aliphatic or alicyclic alcohol having 1 to 6 carbon atoms. 4. The method according to claim 1 or 2, wherein the solvent is N,N-dimethylformamide.