JP4610065B2 - Recovery method of organic solvent cleaning liquid - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for efficiently distilling and recovering an organic solvent from a washing solution after washing potassium chloride by-produced with an organic solvent in a specific reaction system.
[0002]
[Prior art]
2,2,2-trifluoroethanol is a raw material for pharmaceutical intermediates, especially anesthetics, while organic carboxylic acid 2,2,2-trifluoroethyl esters, especially vinyl esters, are used in the paint field and optical materials. It is a very important compound. Methods for producing these important fluorine-containing compounds are disclosed in, for example, Japanese Patent Publication Nos. 64-9299 and 64-9300. In this process, in addition to the desired product, an equimolar amount of potassium chloride is by-produced. This potassium chloride contains an organic substance containing fluorine and / or a potassium salt of organic substance, and it is difficult to dispose of it as it is from the viewpoint of environmental protection.
[0003]
The present inventors can efficiently remove fluorine-containing organic substances and / or potassium salts of organic substances by washing the potassium chloride with a specific organic solvent, and the washed potassium chloride is used as a potassium fertilizer. After finding out that it can be used, a patent application was filed (Japanese Patent Application No. 11-308905). However, according to Japanese Patent Application No. 11-308905, a large amount of the specific organic solvent used for cleaning is necessary, and naturally, it is necessary to collect and reuse it when assuming an industrial process.
[0004]
The inventors carefully traced the technique of Japanese Patent Application No. 11-308905, and recovered by distillation the specific organic solvent used for washing the by-product potassium chloride. As a result, when performing distillation recovery, a large amount of a solid substance insoluble and viscous in the can liquid was precipitated. This solid matter clogged the piping for extracting the bottom liquid at the time of discharge, or adhered to the wall surface of the distillation kettle, hindering heat transfer and causing the inability to distill. For this reason, it is necessary to interrupt the operation of the distillation recovery equipment and perform washing with an organic solvent that can dissolve this solid matter, or perform solvent washing, decomposition cleaning, etc. of the distillation tower and piping. As an industrial recovery process, such as a significant decrease and an irregular increase in work volume, it has become a major problem in terms of cost and operation.
[0005]
[Problems to be solved by the invention]
Therefore, the problem to be solved by the present invention is that in the method of distilling and recovering the specific organic solvent used for washing the by-produced potassium chloride, a large amount of a solid substance insoluble and viscous in the can liquid is precipitated. This is to prevent the recovery operation from becoming impossible. By solving this problem, the process for producing 2,2,2-trifluoroethanol and / or organic carboxylic acid 2,2,2-trifluoroethyl ester described in the above-mentioned known literature is the first industrial process. It becomes.
[0006]
[Means for Solving the Invention]
In view of such a situation, the present inventors have intensively studied on the distillation recovery of the organic solvent. As a result, it was surprisingly found that the problem of the precipitation of a large amount of insoluble and viscous solid matter in the can liquid can be prevented only by the presence of the surfactant in the distillation pot liquid. It has come to be completed.
[0007]
That is, the present invention reacts 1,1,1-trifluoro-2-chloroethane with an organic carboxylic acid potassium salt in the presence of an aprotic polar solvent to produce 2,2,2-trifluoroethanol and / or Alternatively, in the process of producing 2,2,2-trifluoroethyl ester of organic carboxylic acid, by-product potassium chloride is washed with an organic solvent, and then the organic solvent is distilled and recovered from the washing liquid. The present invention relates to a method for distilling and recovering an organic solvent characterized in that an activator is present.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
In the present invention, potassium chloride washed with a specific organic solvent is obtained by reacting 1,1,1-trifluoro-2-chloroethane with an organic carboxylic acid potassium salt in the presence of an aprotic polar solvent. , 2-trifluoroethanol and / or 2,2,2-trifluoroethyl ester of organic carboxylic acid is by-product potassium chloride.
[0009]
Here, examples of the aprotic polar solvent include γ-butyrolactone, 1,3-dimethyl-2-imidazolidinone, N-methyl-2-pyrrolidone, sulfolane, dimethyl sulfoxide, dimethylformamide, dimethylacetamide, and the like. Of these, γ-butyrolactone, 1,3-dimethyl-2-imidazolidinone, N-methyl-2-pyrrolidone, and sulfolane are more preferable.
[0010]
The organic carboxylic acid potassium salt is formic acid, acetic acid, propionic acid, butyric acid, acrylic acid, methacrylic acid, crotonic acid, succinic acid, malonic acid, maleic acid, succinic acid, adipic acid, γ-hydroxybutyric acid, 6-hydroxy. Potassium salts such as saturated and unsaturated aliphatic monocarboxylic acids such as hexanoic acid, aliphatic dicarboxylic acids and aliphatic carboxylic acids having a hydroxyl group, and aromatic carboxylic acids such as benzoic acid, phenylacetic acid, salicylic acid and phthalic acids is there. These potassium salts of organic carboxylic acids can be easily synthesized from commercially available organic carboxylic acids and caustic potash, and commercially available products can be used if available.
[0011]
According to the present invention, the above raw material is used for the reaction for producing 2,2,2-trifluoroethanol and / or 2,2,2-trifluoroethyl ester of organic carboxylic acid as a by-product of potassium chloride. Can be implemented. The reaction method and various conditions may be appropriately selected according to the known literature. As a typical example, 2,2,2-trifluoroethanol is synthesized by reacting 1,1,1-trifluoro-2-chloroethane and potassium γ-hydroxybutyrate using γ-butyrolactone as a solvent. Will be described.
[0012]
A pressurized reactor is charged with γ-butyrolactone as a solvent, and raw materials 1,1,1-trifluoro-2-chloroethane and potassium γ-hydroxybutyrate are added. Next, the reaction temperature is 180 to 220 ° C., and the reaction is completed with stirring for 4 to 8 hours. Thereafter, unreacted 1,1,1-trifluoro-2-chloroethane is purged, and then the reaction solution in the pressure vessel is transferred to a distillation column kettle. When this was roughly distilled to extract 2,2,2-trifluoroethanol and water, the remaining kettle contained by-product potassium chloride in the form of a slurry together with γ-butyrolactone and a heavy fraction. Yes.
[0013]
By-product potassium chloride is recovered from this slurry by solid-liquid separation from γ-butyrolactone and a heavy fraction, for example, by operations such as filtration and centrifugal sedimentation. The separated solution is used again for the reaction. On the other hand, the separated by-product potassium chloride still contains a solvent and is further heated under reduced pressure, and this solvent is recovered.
[0014]
The by-product potassium chloride thus obtained is a white or light brown solid and is a particle of several microns to several hundred microns. This by-product potassium chloride usually depends on the type of solvent, reaction conditions, etc., but usually contains almost no water.
[0015]
As an organic solvent for washing the by-product potassium chloride, methanol, ethanol, acetone or the like can be used. These organic solvents are preferably used as a water-containing organic solvent in terms of enhancing the cleaning effect of adhering organic substances by containing water.
[0016]
As a washing method of by-product potassium chloride with a water-containing organic solvent, for example, a by-product potassium chloride and a solvent are charged in a container and washed as a slurry liquid while stirring, or a continuous method, or the washing solution is sprayed directly on the by-product potassium chloride. It is possible to adopt a rinsing method for washing while washing.
[0017]
In these methods, washing with a water-containing organic solvent is carried out. The amount of water contained is 1 to 50% by weight, preferably 5 to 20% by weight, based on the organic solvent. When the water content is less than 1% by weight, the cleaning effect is reduced. On the other hand, when the water content exceeds 50% by weight, the by-product potassium chloride dissolves, and the amount of potassium chloride increases in the organic solvent for cleaning and circulates. This is economically disadvantageous.
[0018]
It is desirable that the water-containing organic solvent used for washing is lower than the boiling point of water because it is recovered by distillation, and methanol, ethanol, acetone, or the like can be used. These solvents can be used as a single solvent or a mixed solvent.
[0019]
The method of distillation recovery is not particularly limited, but may be either batch or continuous. The number of distillation columns, the reflux ratio, and the like can be arbitrarily selected depending on the purity of the solvent to be recovered. The type of the distillation can may be either a natural circulation type or a forced circulation type. The hook liquid may be extracted by a method such as a method using a U-seal or a liquid level gauge.
[0020]
As a method for adding the surfactant, in the case of a batch, there is a method in which an appropriate amount of water and a surfactant are added together with the cleaning liquid, followed by distillation. In the case of continuous, the kettle liquid is continuously extracted, but the surfactant is added so that the concentration in the kettle becomes constant. The surfactant may be added by any method of adding to the kettle or the distillation column supply liquid.
[0021]
In the present invention, any of anionic, cationic, amphoteric, and nonionic surfactants can be used as the surfactant present in the distillation kettle. For example, as an anionic surfactant, fatty acid soap, N-acyl amino acid salt, alkyl ether carboxylate, acyl peptide, alkyl sulfonate, alkyl benzene sulfonate, alkyl naphthalene sulfonate, sulfo succinate, α-olefin sulfonate, alkyl sulfate, alkyl ether sulfate, alkyl allyl ether sulfate, alkyl amide sulfate, alkyl phosphate, alkyl ether phosphate, alkyl allyl ether phosphate, fluoroalkyl carboxylate, fluoroalkyl Sulfonates and the like can be used. As the cationic system, aliphatic amine salts, aliphatic quaternary ammonium salts, benzethonium chloride, benzalkonium salts, pyridinium salts and the like can be used. As the amphoteric system, carboxybetaine system, aminocarboxylate, imidazolinium betaine, and the like can be used. As the nonionic system, polyoxyethylene secondary alcohol ether, polyoxyalkylphenyl ether, polyoxyethylene sterol ether, glyceric acid ester, polyethylene glycol fatty acid ester, fatty acid alkanolamide, polyoxyethylene fatty acid amide and the like can be used. Among these, preferred surfactants include anionic surfactants such as fatty acid soaps, alkyl sulfonates, alkyl benzene sulfonates, and alkyl ether carboxylates.
[0022]
Also, soaps, detergents and the like that are produced by mixing these surfactants can be used.
[0023]
The concentration of the surfactant to be added is not particularly limited, but is preferably 0.01% to 10% by weight, more preferably 0.1% to 1% by weight with respect to the amount of water. is there. If the addition amount of the surfactant is less than 0.01% by weight, it is impossible to prevent the sticky solid matter insoluble in the can liquid from being precipitated. If the addition amount exceeds 10% by weight, the addition amount becomes large and industrial. The process is not economical and not preferable.
[0024]
The effect of the surfactant is not clear, but it can provide fluidity without solidifying or fixing the high-boiling organic compound contained in the by-product potassium chloride dissolved in the cleaning liquid in the distillation kettle. A small amount of surfactant can be used to fluidize and maintain high-boiling organic substances that are sticky and strongly adherent. This is thought to be because there is no adhesion in the distillation kettle or reaggregation of solids. . This high boiling point organic substance is considered to have been generated by decomposition, polymerization, etc. of organic carboxylic acids during the reaction. These high boiling point organic substances are easily dissolved in an organic solvent, but are difficult to dissolve in water. Therefore, when the concentration of the water in the kettle increases, the high boiling point organic substance precipitates as a highly concentrated sticky solid. Moreover, when temperature becomes low, a viscosity will become still higher and it will become easy to solidify. Further, since the specific gravity is larger than that of water, it is easy to deposit on the bottom of the pot or the discharge line of the pot liquid. Therefore, in the distillation kettle without the presence of a surfactant, only the liquid is discharged and the solid matter is not discharged but stays in the kettle, or becomes stuck in the kettle, adheres to the kettle, jacket, coil, etc. It is thought that it is impossible to cook the still because the heat transfer from
[0025]
With reference to FIG. 1, an embodiment of the organic solvent distillation recovery method of the present invention will be described.
[0026]
The still 1 is filled with water or a distillation feed solution. Steam 9 is supplied to the jacket of the still 1 and the distillation operation is started. All the liquid condensed in the condenser 3 is refluxed to the distillation column 2 from the reflux line 7 and is kept in a state of equilibrium distillation. Next, supply of the distillation feed liquid 5 to the distillation column 2 is started. The recovered liquid is recovered in the distillate receiver 4 through the distilling line 6. The water content of the recovered liquid can be adjusted by changing the ratio of the flow rate of the reflux line 7 and the liquid amount of the distillation line 6 (reflux ratio). In the distillation pot 1, water and high-boiling organic substances are concentrated, but discharged from the pot liquid discharge line 8. In order to reduce the fluctuation of the liquid level in the distillation kettle, the discharge method is a method of extracting with a U seal line or a method of extracting while monitoring the liquid level with a liquid level gauge. The surfactant is charged directly or continuously or intermittently into the still 1 taking into account the concentration in the still.
[0027]
According to the present invention, the organic solvent used for the washing can be recovered by distillation without causing clogging when the kettle liquid is extracted and without causing the cooking kettle to be uncooked. It became.
[0028]
【The invention's effect】
In the presence of an aprotic polar solvent, 1,1,1-trifluoro-2-chloroethane and an organic carboxylic acid potassium salt are reacted to form 2,2,2-trifluoroethanol and / or an organic carboxylic acid 2 In the method of producing 2,2,2-trifluoroethyl ester, the by-product potassium chloride is washed with an organic solvent, and then the washing liquid is recovered. There was a big problem as an industrial process.
[0029]
According to the present invention, these operational problems can be solved, and as a result, the operability is greatly improved, and the frequency of performing periodic and irregular disassembly and cleaning operations to solve the problems is extremely low. As a result, the cost and work amount for solvent recovery were greatly reduced.
[0030]
【Example】
EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited to these Examples.
[0031]
Reference example 1
To a 2000 L autoclave equipped with a magnetic stirrer, 1100 kg of γ-butyrolactone, 35 kg of water, 220 kg of potassium γ-hydroxybutyrate, 240 kg of 1,1,1-trifluoro-2-chloroethane were added, and after sealing, heated to 200 ° C., 6 Time reaction was performed. After the reaction, 1,1,1-trifluoro-2-chloroethane, 2,2,2-trifluoroethanol, and γ-butyrolactone accompanying water were extracted by simple distillation. The residue was cooled to room temperature, and by-produced potassium chloride was filtered off. This solid was dried at 110 ° C. for 4 hours under 2 kPa to obtain 155 kg of raw salt.
[0032]
This raw salt did not contain moisture and 7.9% of organic matter remained, and this was used as raw salt. The organic matter was measured by igniting raw salt in air at 600 ° C. for 1 hour, and using the weight loss as an organic component.
[0033]
Example 1
1000 kg of the raw salt obtained in Reference Example 1 was stirred with 1000 kg of 10% aqueous methanol and allowed to stand, and about 700 kg of the supernatant was obtained. Fill the distillation kettle with water, and feed this liquid into the atmospheric pressure continuous distillation equipment shown in Fig. 1 (column diameter 60mm, column length (packed bed) 1000mm, packing: pole ring, reboiler: 20L container). Recovery distillation was performed at a rate of 2 L / min and a reflux ratio of 2. During the distillation, “Cherina” manufactured by Kao Corporation (containing linear alkylbenzene sulfonic acid and the like, concentration 23%) was added to the distillation kettle at 2 g / min. During distillation for 5 hours, there was no clogging of piping, changes in operation, etc.
[0034]
Comparative Example 1
In Example 1, recovery distillation was performed without adding Karina Co., Ltd. CHERINA. After about 1 hour, the liquid level of the distillation pot increased, and the discharge of the pot liquid disappeared. When the distillation was stopped and the piping was disassembled, it was confirmed that brown solids blocked the piping in the piping. After removing this solid matter, the recovered distillation was resumed. However, after about 30 minutes, the liquid level of the distillation kettle increased, the liquid in the kettle was not discharged, the discharge line was clogged, and the distillation was interrupted. .
[0035]
Example 2
The same recovery distillation was performed except that the addition rate of Karina manufactured by Kao Corporation was 0.2 g / min in Example 1. During distillation for 5 hours, there was no change in piping, that is, operation.
[0036]
Example 3
The same recovery distillation was performed except that the surfactant added in Example 1 was 35% sodium laurate aqueous solution. During distillation for 5 hours, there was no change in piping, that is, operation.
[0037]
Example 4
1000 g of the raw salt obtained in Reference Example 1 was stirred with 1000 g of 10% aqueous methanol and filtered to obtain a filtrate. To a glass 1500 ml three-necked flask, add 100 g of water and 1 g of 35% sodium laurate aqueous solution to the filtrate, and fill a 4 mm long 4 mm glass radich ring into a distillation tower with an inner diameter of 30 mm and a height of 200 mm. The methanol was distilled at a reflux ratio of 1. When about 90% of methanol was extracted, distillation was stopped and the three-necked flask was returned to room temperature. At this time, the pot liquid was a slurry in which a brown solid was dispersed, and was not attached to the wall of the three-necked flask, and could be extracted in a slurry state by tilting the flask.
[0038]
Comparative Example 2
In Example 4, the same distillation was performed without adding 35% sodium laurate aqueous solution. At this time, the liquid in the kettle is separated into a liquid and a brown viscous product, and the flask is tilted to try to extract the liquid from the kettle, but the solid matter is attached to the flask. I was able to extract only the extent.
[0039]
Example 5
A distillation operation similar to the method of Example 4 was performed except that the amount of 35% sodium laurate aqueous solution added was changed from 1 g to 0.1 g. As a result, at this time, the pot liquid was a slurry in which a brown solid was dispersed, and was not attached to the wall, and could be easily drawn out in a slurry state by tilting the flask.
[0040]
Example 6
The same distillation operation as in Example 4 was performed except that 35% sodium laurate aqueous solution was changed to “Mama Lemon” manufactured by Lion Corporation (containing sodium linear alkylbenzenesulfonate, etc., concentration 27%). As a result, at this time, the pot liquid was a slurry in which a brown solid was dispersed, and was not attached to the wall, and could be easily drawn out in a slurry state by tilting the flask.
[0041]
Example 7
The same distillation operation as in Example 4 was performed except that 35% sodium laurate aqueous solution was changed to powdered soap. As a result, at this time, the pot liquid was a slurry in which a brown solid was dispersed, and was not attached to the wall, and could be easily drawn out in a slurry state by tilting the flask.
[0042]
Example 8
The same distillation operation as in Example 4 was performed except that 10% aqueous methanol was changed to 10% aqueous ethanol. As a result, at this time, the pot liquid was a slurry in which a brown solid was dispersed, and was not attached to the wall, and could be easily drawn out in a slurry state by tilting the flask.
[0043]
Example 9
The same distillation operation as in Example 4 was performed except that 10% aqueous methanol was changed to 10% aqueous acetone. As a result, at this time, the pot liquid was a slurry in which a brown solid was dispersed, and was not attached to the wall, and could be easily drawn out in a slurry state by tilting the flask.
[Brief description of the drawings]
FIG. 1 is a flowchart showing one embodiment of a distillation apparatus for carrying out the method of the present invention.
[Brief description of symbols]
DESCRIPTION OF SYMBOLS 1 Distilling pot 2 Distilling tower 3 Condenser 4 Distillate receiver 5 Distillate feed liquid 6 Distillation line 7 Reflux line 8 Kettle liquid discharge line 9 Steam

Claims (4)

In the presence of an aprotic polar solvent, 1,1,1-trifluoro-2-chloroethane is reacted with an organic carboxylic acid potassium salt to give 2,2,2-trifluoroethanol and / or an organic carboxylic acid 2, In the method of producing 2,2-trifluoroethyl ester, by-product potassium chloride is washed with an organic solvent, and then the organic solvent is distilled and recovered from the washing liquid, a surfactant is present in the distillation pot liquid. A method for recovering an organic solvent by distillation. The method for distilling and recovering an organic solvent according to claim 1, wherein the surfactant is an anionic surfactant. 3. The organic solvent distillation recovery method according to claim 1, wherein the organic solvent is a hydrous organic solvent. The organic solvent distillation recovery method according to any one of claims 1 to 3, wherein the organic solvent is at least one selected from methanol, ethanol, and acetone.

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