JPH0720907B2 - Method for producing 2-chloropropionaldehyde - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to vinyl chloride, carbon monoxide and hydrogen according to the following reaction formula (1) CH ₂ = CHCl + CO + H ₂ CH ₃ -CHCl-CHO (1). The present invention relates to a method for producing 2-chloropropionaldehyde using as a raw material.
2-Chloropropionaldehyde can be used as a useful intermediate for chemicals and agricultural medicine.

(Prior Art) A method for producing 2-chloropropionaldehyde using vinyl chloride, carbon monoxide and hydrogen as raw materials is known, and for example,
It is shown in French Patent No. 1,397,779 and HELVETICA CHIMICA ACTA, Vol. 48, No. 5, pages 1151-1157. All of these methods use cobalt carbonyl as a catalyst, and, for example, according to the above-mentioned French Patent No. 1,397,779, the reaction temperature is 110 ° C. and the reaction pressure is 200 atm, and the reaction is performed for 90 minutes,
The reaction results are 57.4% conversion of vinyl chloride and 86.2% selectivity of 2-chloropropionaldehyde.

(Problems to be solved by the invention) However, in the method using these cobalt carbonyls as a catalyst, the catalytic activity per cobalt is extremely low,
This requires a large amount of cobalt carbonyl and a high reaction pressure of 160 to 200 atm, and the reaction temperature of 75 to 125
The method is such that the reaction is carried out at 90 ° C for 90 to 120 minutes. The target product, 2-chloropropionaldehyde, is a thermally unstable substance, and under such reaction temperature and reaction time, a considerable proportion is consumed in the sequential reaction, so that the reaction yield is lowered. The process is poorly reproducible and, in addition, hydrogen chloride is a byproduct of this sequential reaction or other side reaction, which severely corrodes reactor materials and reacts with the cobalt carbonyl catalyst to form cobalt chloride. It has a problem that it also hinders the reuse of.

Further, in any of these methods, a method of separating the reaction solution containing the catalyst from the product 2-chloropropionaldehyde, and a catalyst important in industrially producing 2-chloropropionaldehyde No mention is made of recovery / circulation methods.

The object of the present invention is to solve the problems relating to these catalysts in the prior art, and to efficiently separate the product 2-chloropropionaldehyde from the reaction liquid containing the catalyst and reuse the catalyst, it takes a long time. It is to establish a method for obtaining stable reaction results.

(Means for Solving Problems) The present inventors have conducted detailed research for solving these problems. As a result, when vinyl chloride, carbon monoxide and hydrogen are reacted in the presence of a rhodium compound and a base, the reaction proceeds at a lower temperature and a lower pressure as compared with the conventional method using a cobalt carbonyl catalyst, and Although it has been found that sufficient selectivity to the desired product can be obtained, the method for producing 2-chloropropionaldehyde by an industrially more advantageous method is continuously conducted by continuing the detailed examination of this catalytic reaction. Found and came to the present invention.

That is, in the present invention, when vinyl chloride, carbon monoxide and hydrogen are reacted to produce 2-chloropropionaldehyde, (a) in the presence of a rhodium compound, a base, a water-insoluble or sparingly soluble organic solvent and water. , Vinyl chloride, carbon monoxide and hydrogen to obtain a reaction mixture containing 2-chloropropionaldehyde; (b) separating the reaction mixture into an aqueous layer and an organic layer; 2-chloropropionaldehyde is separated and obtained from the aqueous layer, and the concentration of 2-chloropropionaldehyde in the aqueous layer is reduced to 5% by weight or less; (d) 2-chloropropionaldehyde in the step (c) A step of obtaining regenerated water by subjecting the separated aqueous layer to anion exchange treatment, and (e) returning the regenerated water to the step (a) and reusing it repeatedly with the organic layer. A method for producing 2-chloro propionaldehyde, which comprises a.

In the method of the present invention, it is necessary for the rhodium compound to coexist with a base, a water-insoluble or sparingly-soluble organic solvent, and water.

The base described here generally means a Lewis base containing a periodic VB group element such as nitrogen, phosphorus or arsenic.
In the absence of these bases, rhodium compounds do not catalyze the reaction at all. Among these bases, preferred as the base used in the method of the present invention are those represented by the general formula P (R ¹ R ² R ³ ) (wherein P represents a phosphorus atom,
R ¹ , R ² and R ³ each represent the same or different alkyl, aryl, cycloalkyl, alkoxy, aryloxy or cycloalkoxy group) or an amine having a pKa in the range of 3 to 11 Is preferred. In particular, the base has the general formula P (R ¹ R ² R ³ )
(Wherein P represents a phosphorus atom, and R ¹ , R ² and R ³ represent the same or different alkyl, aryl, cycloalkyl, alkoxy, aryloxy or cycloalkoxy groups, respectively) and pKa Is preferably a combination with amines in the range of 3 to 11. As amines having a pKa in the range of 3 to 11 described here,
In general, compounds containing amino groups, such as aliphatic amines, aromatic amines, diamines, triamines,
Amino alcohols, amino acids, amides, urea compounds, guanidines, amidines, or a substituent such as an alkyl group, an aryl group, a carboxyl group, a hydroxyl group or a halogen, which is contained in the nitrogen atom or carbon atom of these compounds Among the nitrogen-containing compounds, pKa is 3 to 11
The compound in the range of is mentioned. In addition, among other heterocyclic compounds containing one or more nitrogen atoms, pKa is 3 to 11
Compounds in the range of are also preferable. Above all, pKa is 3 ~ 11
More preferably, it is at least one or more of a pyridine compound, a quinoline compound, an imidazole compound, and a morpholine compound in the range.

These bases are specifically exemplified as follows.

That is, the general formula P (R ¹ R ² R ³ ) (wherein P represents a phosphorus atom, and R ¹ , R ² and R ³ are the same or different alkyl, aryl, cycloalkyl, alkoxy, aryloxy or Examples of the base represented by (which represents a cycloalkoxy group) include trimethylphosphine, triethylphosphine, tripropylphosphine, tributylphosphine, trioctylphosphine, triphenylphosphine, tricyclohexylphosphine, tribenzylphosphine, and the like, and trimethylphosphite. , Triethylphosphite, tripropylphosphite, tributylphosphite, trioctylphosphite, triphenylphosphite, tricyclohexylphosphite, tribenzylphosphite, and other phosphites. . In addition to the compounds represented by the above general formula P (R ¹ R ² R ³ ) as special phosphines, they are bonded to diphosphines such as bisdiphenylphosphinomethane and bisdiphenylphosphinoethane and crosslinked polystyrene. Phosphines and the like are also preferably used.

Further, the pyridine compound, quinoline compound, imidazole compound or morpholine compound having a pKa in the range of 3 to 11 is exemplified as follows.

That is, the pyridine compound has the general formula (In the formula, R ¹ , R ² , R ³ , R ⁴ and R ⁵ are each hydrogen,
Pyridine having a pKa in the range of 3 to 11 among compounds represented by alkyl group, aryl group, cycloalkyl group, halogen, hydroxyl group, alkoxy group, aryloxy group, cycloalkoxy group, carboxyl group or acetyl group) There are compounds, examples of which are pyridine, picoline, ethylpyridine, 2,4-lutidine, α
-Colidine, phenylpyridine, cyclohexylpyridine, benzylpyridine, 3-pyridinol, methoxypyridine, phenoxypyridine, aminopyridine and the like. In addition, polynuclear pyridines such as 2,2′-bispyridine are also mentioned as examples of the pyridine compound.

In addition to quinoline, examples of quinoline compounds include
There are 2-methylquinoline, 4-methylquinoline, dimethylquinoline, 2-ethylquinoline, phenylquinoline, methoxyquinoline and the like, and various isoquinoline compounds can also be used.

On the other hand, the imidazole compound has the general formula (In the formula, R ¹ , R ² , R ³ and R ⁴ each represent hydrogen, an alkyl group, an aryl group or a cycloalkyl group, and
R ³ and R ⁴ may form a condensed imidazole which forms a ring containing carbons at positions 4 and 5 of the imidazole ring), and a compound having pKa in the range of 3 to 11 There are, as examples of these, imidazole, N-methylimidazole, N-ethylimidazole, 2-methylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-undecylimidazole, N-benzyl-
2-methylimidazole, 2,4,5-triphenylimidazole, benzimidazole, 2-methylbenzimidazole, 2-phenylbenzimidazole and the like can be mentioned.

Furthermore, examples of the morpholine compound include N-methylmorpholine, N-ethylmorpholine, and the like, in addition to morpholine.

Examples of the rhodium compound used in the method of the present invention include rhodium oxide, mineral acid salt, organic acid salt, and rhodium complex compound. Among these various rhodium compounds, a halogen-free rhodium compound is particularly preferable. Examples of these include rhodium oxide, rhodium nitrate, rhodium sulfate, rhodium acetate, triacetylacetonato rhodium, dicarbonylacetylacetonato rhodium, dodecacarbonyl tetrarhodium, hexadecacarbonyl hexarhodium and the like. Further, a halogen-containing rhodium compound such as rhodium chloride, rhodium bromide, rhodium iodide or dichlorotetracarbonyl dirhodium is used, and an alkaline compound in an amount equal to or more than these halogen atoms in the reaction system, for example, sodium hydroxide, water. Addition of potassium oxide, potassium carbonate, trimethylamine, triethylamine or the like can also be used as a means for producing a halogen-free rhodium compound in the reaction system. Further, as the above-mentioned base and rhodium compound preferably used in the method of the present invention, those in which a complex compound is formed by a rhodium compound and at least a part of these bases are further preferably used.
Examples of these include, for example, hydridocarbonyltristriphenylphosphine rhodium [RhH (CO) (PP
h _{3) 3],} nitro silt list Li triphenylphosphine rhodium _{[Rh (NO) (PPh 3} ) 3], η- cyclopentadienyl bis triphenylphosphine rhodium [Rh (C ₅ H ₅₎
(PPh ₃ ) ₂ ] and the like. Among these various rhodium compounds, a rhodium compound having low solubility in water is particularly preferably used in the method of the present invention.
The rhodium complex compounds described above, such as hydridocarbonyltristriphenylphosphine rhodium, are mentioned as examples of particularly preferable rhodium compounds also in this respect.

In the method of the present invention, the rhodium compound is 0.0001 to 10 as a rhodium atom with respect to 1 liter of the liquid phase in the reaction system.
It is used in an amount corresponding to 00 milligram atoms, preferably in the range 0.001 to 100 milligram atoms. The base used in the method of the present invention is used in an amount of 0.1 to 50 mol, preferably 0.5 to 100 mol, per 1 gram atom of rhodium.

In addition, the water-insoluble or sparingly-soluble organic solvent used in the method of the present invention means an organic solvent having low solubility in water, and usually, the amount dissolved in water is 5% by volume or less at the use temperature. However, from the industrial point of view, those having a solubility in water of 0.5% by volume or less are preferable. Further, as these solvents, those which dissolve the rhodium compound, are less likely to be deteriorated under the reaction conditions, and are inactive in the reaction system are particularly preferably used. Hydrocarbons are particularly preferable as such a solvent. More specifically, hexane, heptane, octane,
Saturated hydrocarbons such as nonane and decane, aromatic hydrocarbons such as benzene, toluene and xylene are preferably used, and ligroin, kerosene, gas oil, diesel oil and the like industrially obtained as a mixture of hydrocarbons are also used. Included in these examples. In addition to these, ethers such as dipropyl ether and dibutyl ether, kents such as diisobutyl ketone and holone, and esters such as butyl butyrate and butyl benzoate are also exemplified as preferable solvents.

Further, in the present invention, a solvent having a smaller specific gravity than water is used as a solvent, and the reaction has a stirrer and a stationary separation tank in the lower part, and the lower stationary separation while continuously supplying water from the upper part. It is particularly preferable to carry out the reaction using a reactor of a system in which the 2-chloropropionaldehyde is continuously withdrawn from the tank. Any of the above-mentioned solvents, that is, hydrocarbons, ethers, ketones or esters has a specific gravity smaller than that of water, and can be preferably used in this case as well.

In the method of the present invention, it is not necessary to consider the solubility of 2-chloropropionaldehyde in these water-insoluble or sparingly soluble organic solvents. This is because the solubility of 2-chloropropionaldehyde in water supplied to the reaction system together with these organic solvents is extremely high.

The stirrer used in the reaction apparatus preferably used in the method of the present invention may be of any type as long as it has a function of efficiently mixing and stirring the reaction solvent, water and carbon monoxide and hydrogen. be able to.
The stationary separation tank only needs to have a function of separating the reaction solvent and water, and has a diameter such that the speed of the descending water is a speed that does not entrain the solvent into small droplets by stirring. Is preferred.

In the method of the present invention, the amount of water to be present during the reaction is not particularly limited, but when the amount is extremely small, the effect is small, and even when the amount is extremely large, the reaction result does not increase to some extent. Usually, the amount of water is preferably 0.01 or more and 1000 or less by weight ratio with respect to vinyl chloride supplied to the reactor as a raw material. Particularly, the range of 0.1 to 100 is more preferably used.

When the base used in the present invention is water-soluble,
It is also preferable to supply at least a part of the base in a form of being dissolved in water to be supplied to the reaction system. For example,
It is preferable to supply imidazole as a base to the reactor in the form of an imidazole aqueous solution.

As described above, in the method of the present invention, the reaction product, 2-chloropropionaldehyde, is taken out from the reaction system in the form of being mostly dissolved in the aqueous layer. 2-from the water layer
It is easy to separate chloropropionaldehyde, and ordinary distillation operation or extraction operation can be used. In the case of distillation, considering the thermal stability of 2-chloropropionaldehyde, the distillation temperature is preferably as low as possible, usually 40 to 90 ° C. What is important in this separation of 2-chloropropionaldehyde is residual 2-
It is to reduce the concentration of chloropropionaldehyde to 5% by weight or less. This is because a small amount of rhodium component is dissolved in the water layer, and the loss of rhodium to the outside of the reaction system cannot be ignored unless the water layer is repeatedly used. This is because it is important to keep the concentration of -chloropropionaldehyde in the reaction system as low as possible when the bed is recycled to the reactor in order not to reduce the catalytic activity. Therefore, the lower the concentration of 2-chloropropionaldehyde in the aqueous layer is, the more preferable it is, and it is more preferable to lower it to 1% by weight or less if possible.

The water layer thus obtained is returned to the reactor and reused repeatedly, but various by-products and impurities in the raw materials are accumulated during long-term use. Among these, there are substances that inhibit the catalytic activity, but it has been found that anions such as chloride ion and sulfide ion significantly inhibit the catalytic activity among them. The present inventors have conducted a study on a method for removing substances that inhibit these catalytic activities, and as a result, it is possible to almost completely remove these substances having an activity inhibiting effect out of the system by subjecting the aqueous layer to anion exchange treatment. Found out. As the anion exchange treatment method, a commonly used anion exchange method can be adopted, and examples thereof include a method of passing the aqueous layer through a column packed with an anion exchange resin. As the anion exchange resin, either a strongly basic anion exchange resin or a weakly basic anion exchange resin can be used, but the selection is made in consideration of the removal efficiency of these anions and the regeneration cost. Can be decided In addition, a method using an ion-exchange membrane, a method using an ion-exchange solution, etc. are also given as examples of the anion-exchange treatment.

The residual concentration of anions in the regenerated water obtained by these anion exchange treatments is preferably low, but some residual amount is acceptable, and it is usually 50 milliequivalent or less per 1 liter of the regenerated water as total anions. If so, the effect on the reaction is small.

In carrying out the method of the present invention, other components in the reaction system, such as additives for improving the stability of the rhodium catalyst, additives for improving the activity and selectivity of the catalyst, such as carboxylic acid Even if they coexist, there is no particular problem. When these additives are soluble in the water layer, be careful not to remove these effective components out of the system by appropriately selecting the anion exchanger used in the anion exchange treatment of the water layer. It is necessary to.

The method of the present invention is usually carried out at a reaction temperature of 20 to 150 ° C. and a reaction pressure of 1 to 200 kg / cm ² gauge, preferably 20 to 120 kg / cm ^2.
It is done in the gauge range. The reaction temperature is preferably as low as possible from the viewpoint of the thermal stability of the produced 2-chloropropionaldehyde, and for this reason, 20 to 100 ° C. is a particularly preferable temperature range. The mixing molar ratio of the raw material carbon monoxide and hydrogen is usually in the range of 10 to 0.1, and preferably in the range of 4 to 0.2. Carbon monoxide and hydrogen may be any mixed gas containing both components in the above composition ratio, and water gas, a gas such as methane, a gas inert to the reaction such as nitrogen, or carbon dioxide was contained. Things are used. The other raw material, vinyl chloride, is used in the form of gas, liquid, or solution dissolved in the solvent used for the reaction. The temperature of the anion exchange treatment is not particularly limited, but is preferably low in terms of the stability of the dissolved rhodium compound and the thermal stability of the anion exchanger used, at room temperature. To 60 ° C.

The method of the present invention can be carried out by any of a batch method, a semi-batch method and a continuous method, but the continuous method is more preferable.
In the case of the continuous method, for example, a rhodium compound and a water-insoluble or sparingly-soluble organic solvent and, in some cases, a base are charged into a pressure-resistant reactor, and water or an aqueous solution of a base in some cases is stirred with stirring. Of the reaction product, 2-vinylpropionaldehyde, which is a reaction product, from the upper part of the reactor and the raw materials vinyl chloride, carbon monoxide and hydrogen continuously supplied from the lower part of the reactor, and from the lower part of the stationary separation tank installed below. The reaction is carried out by continuously taking out the aqueous layer containing.

The aqueous layer is then subjected to a distillation apparatus operated under reduced pressure to separate substantially all of the reaction product 2-chloropropionaldehyde, followed by anion exchange apparatus to remove anions in the aqueous layer. After removing almost all the amount, it is recycled to the reactor for reuse.

(Action and Effect of the Invention) By the method of the present invention, it is possible to produce 2-chloropropionaldehyde with vinyl chloride, carbon monoxide and hydrogen as raw materials at a lower temperature and under a lower pressure and with higher activity than the conventional method. it can.

In particular, according to the method of the present invention, it becomes possible to continue the reaction while repeatedly using the catalyst for a long time while maintaining the higher catalytic activity than the conventional one.

(Examples) Hereinafter, the method of the present invention will be described more specifically with reference to Examples.

Pressure resistance 10 with a 10-stage impeller and hot water jacket
0Kg / cm ² Gauge Reactor 1 (made of SUS 316L, inner diameter 25mm, height 350mm, actual volume about 170cm ³ , inner diameter 25mm, height 150
mm static separator 2 is attached), 1 mmol of hydridocarbonyltristriphenylphosphine rhodium, 5 mmol of triphenylphosphine and 50 ml of toluene as a reaction solvent are charged, and the reaction temperature is 50 ° C. and the reaction pressure is 50 ° C.
Under conditions of 75 Kg / cm ² gauge, vinyl chloride 17.5 g / hour and a molar ratio from the introduction pipes 11 and 12 provided at the bottom of the reactor.
About 4 l / h of a mixed gas of carbon monoxide and hydrogen of 1: 2 were continuously supplied. At the same time, 15 g of an imidazole solution in which 15 g of imidazole was dissolved per liter was supplied from the imidazole solution storage tank 6 at a rate of 150 g / hour from the pipe 19 and the liquid introduction pipe 20 provided at the upper part of the reactor. A liquid take-out pipe 13 is installed below the stationary separation tank 2 provided in the lower part of the reactor, and the reaction product is taken from the liquid take-out pipe 13 so as to keep the liquid level in the reactor constant. A water layer consisting of an imidazole aqueous solution containing chloropropionaldehyde is continuously taken out of the reactor, while the pressure inside the reactor 1 is kept constant from a gas extraction pipe 18 provided at the upper part of the reactor. Thus, the gas containing unreacted vinyl chloride and unreacted carbon monoxide and hydrogen was continuously extracted. In the water layer, in addition to imidazole and 2-chloropropionaldehyde, a small amount of chloride ions (probably existing as imidazole hydrochloride), propionic acid, and rhodium at a concentration of 1.8 ppm are present. Was confirmed. Then, the water layer is a pressure of 50 mm mercury column, the temperature of the can
In a glass batch distillation device 3 operated at 60 ℃
Most of 2-chloropropionaldehyde is separated to give 2-
It was recovered from the bottom discharge pipe 15 as an aqueous solution having a chloropropionaldehyde content of 1.5% by weight. From the distillate outlet 14 of the batch-type distillation apparatus 3, 7.2 g of 2-chloropropionaldehyde (containing 10.2% by weight of water) was obtained per hour.

On the other hand, the water layer is a strongly basic anion exchange resin (trade name, Levatit M500) 1000 regenerated into a hydroxyl group type through the pipe 15.
After passing through a glass column 4 filled with ml, chlorine ions and propionic acid were removed, and the recovered water was recovered as recycled water in a recycled water storage tank 5 through a liquid outlet 16. It was confirmed that the concentrations of residual chlorine ions and propionic acid in the regenerated water were all 5 milliequivalents or less per liter, and the rhodium concentration did not change within the analytical error range. The reclaimed water was returned to the reactor again via the pipe 17 and the liquid introducing pipe 20 for reuse.

In this way, continuous operation was carried out for 72 hours. The distillate from the vacuum distillation unit contains an average of 10.4% water.
With 2-chloropropionaldehyde, the amount produced per hour became almost constant within about ± 10% from about 5 hours after the start of the operation, and remained almost constant until 72 hours thereafter. From the 68th hour to the 72nd hour after the start of the reaction, an average of 7.4 g of 10.4% by weight water content per hour was calculated.
2-Chloropropionaldehyde was obtained.

[Brief description of drawings]

FIG. 1 is a process chart for explaining an embodiment of the present invention. In the figure, 1 is a reactor, 2 is a stationary separation tank, 3 is a batch distillation device,
4 is a column packed with an ion exchange resin, 5 is a reclaimed water storage tank, and 6 is an imidazole aqueous solution storage tank.

Claims (6)

[Claims] 1. A reaction mixture containing (a) a rhodium compound, a base, vinyl chloride, carbon monoxide and hydrogen in the presence of water and a water-insoluble or sparingly-soluble organic solvent and water to form a reaction mixture containing 2-chloropropionaldehyde. And (b) separating the reaction mixture into an aqueous layer and an organic layer, and (c) separating and obtaining 2-chloropropionaldehyde from the aqueous layer to obtain 2-chloropropionaldehyde in the aqueous layer. Reducing the concentration of the compound to 5% by weight or less; (d) a step of anion-exchange treatment of the aqueous layer from which 2-chloropropionaldehyde has been separated in the step (c) to obtain reclaimed water; A process for producing 2-chloropropionaldehyde, which comprises the step of returning regenerated water to the step (a) and repeatedly reusing it together with the organic layer. 2. A solvent having a smaller specific gravity than water is used as a solvent, and a reaction is provided with a stirrer and a stationary separation tank in the lower part, and water is continuously supplied from the upper part from the lower stationary separation tank. The method according to claim 1, which is carried out by using a reaction device of a continuous withdrawal system. 3. A base is represented by the general formula P (R ¹ R ² R ³ ) (where P
Represents a phosphorus atom, and R ¹ , R ² and R ³ represent the same or different alkyl, aryl, cycloalkyl, alkoxy, aryloxy or cycloalkoxy groups.)
The method according to claim 1 or 2, which is a base represented by: 4. The method according to claim 1 or 2, wherein the base is an amine having a pKa in the range of 3-11. 5. The base has the general formula P (R ¹ R ² R ³ ) (where P
Represents a phosphorus atom, and R ¹ , R ² and R ³ represent the same or different alkyl, aryl, cycloalkyl, alkoxy, aryloxy or cycloalkoxy groups.)
The method according to claim 1 or 2, which is a combination of at least one or more of the base represented by and the amine having a pKa in the range of 3 to 11. 6. An amine having a pKa in the range of 3 to 11 has a pKa of
Is at least one or more of a pyridine compound, a quinoline compound, an imidazole compound or a morpholine compound in the range of 3 to 11;
Method described in section.