JPS582932B2 - Butyraldehyde manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing butyraldehyde by hydroformylating propylene in the presence of a rhodium triphenylphosphine complex catalyst.

In the hydroformylation reaction of olefins, rhodium-based catalysts exhibit high catalytic activity and extremely high selectivity to aldehydes, so research on the hydroformylation reaction of olefins using rhodium-based catalysts has been actively conducted in recent years. .

In particular, catalysts that combine rhodium with amphiphilic ligands such as tertiary phosphine have a high selectivity to more useful linear aldehydes in the hydroformylation reaction of α-olefins. The reaction can be carried out even under pressure lower than that used for conventional methods, and because the catalyst is highly stable, it is possible to separate the reaction products and then circulate the solution containing the tertiary phosphine complex. It has the advantage of being reusable as a catalyst.

As mentioned above, if the reaction pressure can be lowered,
There is an economic advantage that the reactor and the equipment attached thereto are inexpensive.

Furthermore, since the selectivity to linear aldehydes is high, when propylene is used as a raw material, a high proportion of n-butyraldehyde, which is useful as a raw material for n-butanol or 2-ethylhexanol, which is a raw material for a plasticizer, is produced.

On the other hand, when recycling a rhodium-tertiary phosphine complex, a portion of the circulating catalyst liquid is removed due to the accumulation of high-boiling byproducts and the deactivation of the catalyst due to trace amounts of reaction inhibitors contained in the raw materials. It is necessary to continuously extract and replenish the catalyst.

Therefore, the higher the concentration of rhodium and the concentration of tertiary phosphine in the reaction solution, the greater the loss of expensive rhodium and phosphine.

Taking into account the above facts, the present inventors conducted research on a method for hydroformylating propylene at low pressure in the presence of a rhodium triphenylphosphine complex catalyst. The ratio of the normal form and the iso form of butyraldehyde, which is a reaction product (hereinafter referred to as n/i).

) was found to have a maximum value in a specific range of reaction pressure, and the present invention was completed by discovering this unique phenomenon.

The purpose of the present invention is to provide an industrially advantageous method for producing butyraldehyde rich in linear isomers, and the purpose is to process propylene in a solvent in the presence of a rhodium triphenynorephosphine complex catalyst. In a method for producing butyraldehyde by reacting with carbon monoxide and hydrogen, the concentration of triphenylphosphine is 1 to 30 mmole/l.
-Total pressure of solvent, carbon monoxide and hydrogen is 30-100k
This can be easily achieved by carrying out the experiment within the range of g/cm2.

To explain the present invention in detail, the catalyst used in the hydroformylation reaction of the present invention is a rhodium triphenylphosphine complex.

As the phosphine ligand, it is most preferable to use triphenylphosphine, but phosphine in which a lower alkyl group such as a methyl group is further bonded to the phenyl group may also be used.

The form of the catalyst is a complex containing rhodium and phosphine that has been conventionally synthesized by various methods, such as hydroluponyltris (triphenylphosphine).
Complexes such as rhodium may be used, but after dissolving easily available rhodium compounds such as organic acid salts of rhodium such as rhodium acetate or inorganic acid salts of rhodium such as rhodium nitrate and rhodium sulfate in an appropriate solvent. A method of introducing the compound into a hydroformylation reactor and forming a complex in the presence of triphenylphosphine is industrially easy and advantageous.

Hydroformylation reaction of rhodium triphenylphosphine complex The exact form of the active catalyst species is unknown, but it is a complex in which rhodium, phosphine, carbon monoxide, and even hydrogen are coordinated under the reaction conditions. it is conceivable that.

The active complex in this case is not unique, but complexes with different ligands exist in an equilibrium state due to competitive coordination of each ligand, and the equilibrium point changes depending on the concentration of each ligand. It is considered that

Phosphine coordinates with rhodium and shows the effect of increasing the stability of the complex, but in order to obtain a stable catalyst that can be used repeatedly, 5 moles or more of phosphine must be present per 1 g of rhodium atom. is preferable, and the value of n/i tends to increase as the phosphine concentration increases.

Therefore, using phosphine at high concentrations is advantageous from the standpoint of increasing selectivity to n-butyraldehyde.

However, as mentioned earlier, the use of phosphine at higher concentrations is less likely to result in loss of phosphine, since it is necessary to continuously withdraw a portion of the circulating catalyst liquid to prevent the accumulation of deactivated catalyst and high-boiling by-products. This is uneconomical as it leads to an increase in

Moreover, it is difficult to treat a waste catalyst liquid containing a large amount of phosphine, and it is also very difficult to recover phosphine from a waste catalyst liquid in which various high-boiling byproducts coexist.

Therefore, increasing the selectivity to n-butyraldehyde at the lowest possible phosphine concentration is most preferred in the industrial implementation of the hydroformylation reaction.

According to the hydroformylation reaction of the present invention, the above conditions can be satisfied because the reaction pressure and the value of n/i exhibit a unique relationship in the presence of a low concentration of phosphine.

That is, in a range where the phosphine concentration is 30 mmole/l-solvent or less, the total pressure of carbon monoxide and hydrogen (hereinafter referred to as water gas partial pressure).

) when the hydroformylation reaction is carried out at 30 to 100 kg/cm2, the value of n/i shows the maximum value,
If the water gas partial pressure is lower than 30k9/crA or higher than 100kg/cni, n/
The value of i becomes .

In the range of phosphine concentration from 30 to 50 mmole/l-solvent, the value of n/i is such that the water gas partial pressure is approximately 100 kg
/cni or less, it is almost constant regardless of pressure.

When the phosphine concentration exceeds 50 mmole/l of solvent, a tendency is shown that is consistent with the conventional general knowledge that the lower the water gas partial pressure, the larger the value of n/i.

The phenomenon described above is clear from FIG.

Figure 1 shows the water gas content at various triphenylphosphine concentrations in a propylene hydroformylation reaction using toluene as a solvent at a rhodium concentration of 10 mg, #-1-luene (rhodium metal equivalent), and a reaction temperature of 120°C. It is a diagram illustrating the relationship between pressure and the value of n/i.

Curve 1 is triphenylphosphine concentration 100 mmole
/l-toluene, curve 2 is at a heliphenylphosphine concentration of 30 mmole/l-toluene, curve 3 is at a triphenylphosphine concentration of 10 mmole/l-toluene, and curve 4 is at a triphenylphosphine concentration of 1 mmole/l-toluene.
This is a diagram illustrating the results of each reaction using l-toluene.

Therefore, in the method of the present invention, the phosphine concentration is set to 30
mmole/l-solvent or less, and 1 mmole/l to obtain a stability of the complex that allows recycling of the catalyst.
In the range above l-solvent, the water gas partial pressure is 30-100k
The hydroformylation reaction is carried out in the range of g/1.

Regarding the rhodium concentration, the higher the rhodium concentration, the higher the reaction rate, but it is not a factor that changes the value of n/i.

Therefore, the rhodium concentration is determined in consideration of the improvement in the reaction rate and the accompanying increase in catalyst cost by increasing the rhodium concentration.

Usually, the rhodium concentration is 0.1 to 5 in terms of rhodium metal.
00 mg/l-solvent, preferably 1-100 mg/l-
Adopted in a range of solvents.

As with general chemical reactions, the higher the reaction temperature, the higher the reaction rate, but the n/i value decreases and the yield of n-butyraldehyde deteriorates. Preferably, the reaction is carried out.

The solvent used in the hydroformylation reaction of the present invention is a solvent with a higher boiling point than the butyraldehyde so that the catalyst dissolved in the solvent can be recycled and reused after the produced butyraldehyde is separated by distillation. It is desirable to do so.

Specifically, aromatic hydrocarbons such as toluene and xylene, saturated aliphatic hydrocarbons such as decane, or alcohols such as butanol are used.

Also, if desired, the reaction product, butyraldehyde, can be used as a solvent.

The molar ratio of hydrogen to carbon monoxide in the water gas used is not a critical factor in the method of the present invention, but usually the water gas ranges from 1/3 to 7 moles of hydrogen per mole of carbon monoxide. used.

As detailed above, if the hydroformylation reaction of propylene is carried out according to the method of the present invention, butyraldehyde with a high proportion of n-butyraldehyde can be obtained while minimizing the loss of rhodium and phosphine.
It is industrially very advantageous.

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

General experimental method in Examples and Comparative Examples Internal volume 20
50ml of toluene in a 0ml electromagnetic stirring autoclave
After charging a predetermined amount of triphenylphosphine and rhodium acetate, and purging the autoclave with argon gas, 250 mmole of propylene was charged by distillation.

The autoclave was heated to a predetermined temperature, and a mixed gas of carbon monoxide and hydrogen (H2/CO=1.17 (molar ratio)) was injected under pressure to start the reaction.

During the reaction, the autoclave and a gas pressure accumulator were connected via a constant pressure device so that the pressure was kept constant, and the gas consumed by the reaction was replenished.

The reaction was considered complete when no gas absorption was observed, and after cooling the autoclave, the gas and liquid phases were analyzed for residual propylene and butyraldehyde by gas chromatography.

As a result, the propylene reaction rates were all 99% or higher, and the selectivity to butyraldehyde was 98φ or higher in all cases.

Moreover, in Examples and Comparative Examples, the pressure is expressed as total pressure.

The water gas partial pressure varies depending on the reaction temperature, propylene concentration, and propylene reaction rate, so it cannot be expressed unambiguously, but the total pressure and water gas partial pressure under the conditions of the examples and comparative examples described below are The relationship is shown in Table-1.

Examples 1 to 7 Experiments were conducted according to the experimental method described above, with the rhodium concentration being 10 mg/l-toluene in terms of rhodium metal.

Table 2 shows the reaction conditions and the n/i value of the produced butyraldehyde.

Even if the reactions of Examples 1 to 7 were carried out in a continuous flow reaction, Table-2
The same results as in Table 2 were obtained even when the reaction was carried out using a catalyst-containing toluene solution in which butyraldehyde was distilled off from the reaction product solution.

Comparative Examples 1 to 10 The rhodium concentration was 10 mg/l-toluene in terms of rhodium metal, and the triphenylphosphine concentration was 1 to 30 m
The total pressure is 30 kg/c within the range of mole/l-toluene.
Experiments were conducted according to the experimental method above at m2G or less and at 100 kg/cm2G or more.

The reaction conditions and experimental results are shown in Table 3.

Comparative Examples 11 to 14 The rhodium concentration was 10 mg/l-toluene in terms of rhodium metal, and the triphenylphosphine concentration was 50 mmol.
Experiments were carried out according to the experimental method above at e/l-toluene.

The reaction conditions and experimental results are shown in Table 4.

Comparative Examples 15-18 Rhodium concentration is 100 mg/l- in terms of rhodium metal.
The experiment was conducted using toluene at a reaction temperature of 90° C. according to the experimental method described above.

The results and reaction conditions are shown in Table-5.

Comparative Examples 19-20 The same experiment as in Example was conducted except that triphenylphosphite was used instead of triphenylphosphine as a ligand.

The reaction conditions and results are shown in Table-6.

Comparative Examples 21 to 23 Hexene was used instead of propylene as the raw material olefin.
An experiment was conducted in the same manner as in the example except that 1 was used at a concentration of 2.5 mole/l of the reaction solution and benzene was used instead of toluene as the solvent.

The reaction conditions and experimental results are shown in Table-7.

[Brief explanation of the drawings] Figure 1 shows a reaction temperature of 120°C and a rhodium concentration of 10mg/
The results of the hydroformylation reaction of propylene in l-toluene (rhodium metal equivalent) are plotted with n/i as the vertical axis.
The graph is drawn with water gas partial pressure on the horizontal axis and triphenylphosphine concentration as a parameter.

Claims (1)

[Claims] 1 In a method for producing butyraldehyde by reacting propylene with carbon monoxide and hydrogen in a solvent in the presence of a rhodium triphenylphosphine complex catalyst, the concentration of triphenylphosphine is 1 to 30 mmol/l-
The total pressure of solvent, carbon monoxide and hydrogen is 30 to 100 kg.
1. A method for producing butyraldehyde rich in linear isomers, the method being carried out in the range of /cm2.