JP2007008841A - Method for recovering 1,3-dialkyl-2-imidazolidinone - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for efficiently recovering a 1,3-dialkyl-2-imidazolidinone from a solution containing the 1,3-dialkyl-2-imidazolidinone and water in high recovery. <P>SOLUTION: This method for recovering the 1,3-dialkyl-2-imidazolidinone represented by general formula (1) (R is a 1 to 4C alkyl) from a solution containing the compound represented by general formula (1) and water is characterized by dissolving an easily water-soluble inorganic compound in the solution, separating and recovering the organic phase from the water phase, removing the water together with a solvent forming an azeotropic composition with the water in the organic phase, and then distilling and recovering the compound represented by general formula (1). <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for recovering 1,3-dialkyl-2-imidazolidinone with a low distillation heat energy and a high recovery rate.

  1,3-dialkyl-2-imidazolidinone is a highly polar aprotic solvent, and is extremely stable against acids and alkalis as compared with general aprotic polar solvents, and various inorganic substances. Because of its strong solubility in organic compounds, synthetic solvents such as pharmaceuticals, agricultural chemicals, dyes and pigments, decomposition solvents for polychlorinated biphenyls, cleaning agents for electronic parts and molds, polymerization solvents for polymer compounds, etc. As a very useful substance.

  For example, 1,3-dimethyl-2-imidazolidinone (hereinafter abbreviated as DMI) is used in a synthesis reaction using a property having high affinity with water, a purification solvent such as an organic compound, and an extraction solvent. The The DMI used is usually a mixture containing organic compounds such as DMI, water, inorganic salts, inorganic bases, inorganic acids and organic solvents (hereinafter abbreviated as a mixture), and DMI is recovered from this mixture. It may be necessary to reuse it.

  In general, distillation is used to recover DMI contained in such a mixture. However, since it is difficult to separate water and DMI, a high-distillation tower is required to recover DMI with a very low water content, which increases equipment costs. In addition, the distillation kettle has problems such as a decrease in thermal efficiency during distillation because distillation residues such as inorganic salts, inorganic bases, and inorganic acids contained in the mixture are fixed. Furthermore, a method of dehydrating water contained in DMI recovered by distillation with a dehydrating agent such as molecular sieve or silica gel is also used. However, since the used dehydrating agent needs to be regenerated, Equipment is required. Moreover, there is a problem that disposal of used dehydrating agents leads to an increase in industrial waste.

In order to solve these problems, the present inventors have added a solvent that forms an azeotropic composition with water to a mixed aqueous solution of DMI and water, followed by dehydration and then distillation purification (Patent Document 1), DMI and water. And a method of performing distillation purification by adding a solvent that forms an azeotropic composition with water to a mixture of inorganic salts and then dehydrating and removing the inorganic salts by filtration (Patent Document 2), halogenated hydrocarbons from an aqueous calcium chloride solution containing DMI A method of mixing and extracting (Patent Document 3), a method of adding a caustic alkali to a mixture containing DMI and water and separating the mixture into water and an organic phase (Patent Document 4), etc. were filed at the head of the application.
Japanese Patent Laid-Open No. 7-70079 Japanese Patent Laid-Open No. 7-70080 JP-A-3-38571 Japanese Patent Laid-Open No. 11-152272

  However, although the method of Patent Document 1 can obtain DMI with a low water content at a high recovery rate, the amount of azeotropic solvent to be added must be 30 to 300 parts by weight with respect to 100 parts by weight of DMI. In addition, there is a problem in that a large amount of distillation kettle is required for the DMI to be recovered, so that the volumetric efficiency is poor and the amount of heat energy used for distillation is large. Although the method of the above-mentioned Patent Document 2 can avoid the decrease in thermal efficiency because there is no adhesion of inorganic substances to the distillation kettle, the operation becomes complicated by entering the filtration process, and the inorganic substances adhere to the dehydration kettle before filtration and the dehydration process. There are problems such as a decrease in thermal efficiency. Although the method of the above-mentioned patent document 3 can avoid a decrease in thermal efficiency due to inorganic matter fixing to the still, the extraction solvent can be used even if it is used in an amount of 10 to 200 parts by weight relative to 100 parts by weight of an aqueous solution containing DMI. There were problems such as low recovery rate. The method of Patent Document 4 improves the volumetric efficiency of the distillation kettle, reduces the amount of heat energy used for distillation, and avoids sticking of inorganic substances to the kettle, but has a low DMI recovery rate. There was a problem.

  Therefore, the present invention provides a method for efficiently recovering 1,3-dialkyl-2-imidazolidinone from a solution containing 1,3-dialkyl-2-imidazolidinone and water with high recovery rate. With the goal.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have dissolved water and a readily soluble inorganic compound in a solution containing the compound represented by the general formula (1) and water, and the After separating into an organic phase containing the compound represented by the formula (1) and removing water contained in the obtained organic phase using a solvent that forms an azeotropic composition with water, the general formula (1) By adopting a method for recovering the compounds represented by distillation, it is possible to reduce the thermal energy required for distillation, to avoid a decrease in thermal efficiency due to sticking of inorganic substances to the distillation kettle, to be recovered at a high recovery rate, and to share with water. It has been found that the above-mentioned problems can be solved, such as reducing the amount of solvent used to form the boiling composition.

  Furthermore, even if the amount of the extraction solvent is reduced by using an extraction solvent when separating the aqueous phase and the organic phase containing the compound represented by the general formula (1) from the mixture, it is represented by the general formula (1). As a result, it was found that the recovery rate of the obtained compound to the organic phase was improved, and the present invention was completed.

  That is, the present invention relates to the general formula (1)

(Wherein R represents an alkyl group having 1 to 4 carbon atoms)
In recovering the compound represented by general formula (1) from the solution represented by formula (1) and water, an inorganic compound that is readily soluble in water is dissolved in the solution, and the organic phase separated from the aqueous phase is recovered. Then, after removing water in the organic phase together with a solvent that forms an azeotropic composition with water, the compound represented by the general formula (1) is recovered by distillation. It relates to the collection method.

  According to the present invention, it is possible to provide a method for recovering a compound represented by the general formula (1) efficiently and at a high recovery rate from a solution containing the compound represented by the general formula (1) and water. it can.

  R in General formula (1) shows a C1-C4 alkyl group.

  Examples of the compound represented by the general formula (1) include 1,3-dimethyl-2-imidazolidinone, 1,3-diethyl-2-imidazolidinone, 1,3-dipropyl-2-imidazolidinone. 1,3-dibutyl-2-imidazolidinone and the like.

  The solution containing the compound represented by the general formula (1) and water is not particularly limited. For example, a solution composed of the compound represented by the general formula (1), water and inorganic salts, and an inorganic base in the solution, Examples include inorganic acids and solutions in which organic compounds other than the compound represented by the general formula (1) such as organic solvents such as water-soluble alcohols are dissolved. As such a solution, for example, a solution comprising DMI, water and methanol (see Japanese Patent Application Laid-Open No. 62-25167), a solution containing DMI, water, potassium hydroxide and unreacted α-aminoanthraquinone ( (See JP-A-60-1169).

  Water and a readily soluble inorganic compound are dissolved in a solution containing the compound represented by the general formula (1) and water, and an organic phase containing the compound represented by the general formula (1) is separated from the aqueous phase. To do.

  Although there is no restriction | limiting in particular in the inorganic compound easily soluble in water, As an inorganic compound easily soluble in water, an inorganic salt, an inorganic base, or an inorganic acid is mentioned, for example.

  Examples of the inorganic salt include sodium chloride, sodium bromide, sodium sulfate, potassium chloride, potassium bromide, potassium sulfate, magnesium chloride and magnesium sulfate. Examples of inorganic bases include sodium hydroxide, potassium hydroxide, magnesium hydroxide, lithium hydroxide, calcium hydroxide, sodium carbonate, potassium carbonate, sodium bicarbonate, and potassium bicarbonate.

  Examples of inorganic acids include sulfuric acid, hydrochloric acid, and phosphoric acid. These inorganic compounds that are readily soluble in water can be used alone or in combination of two or more. These water-soluble inorganic compounds can be recovered and reused as necessary.

  The inorganic compound readily soluble in water is used in the form of a solid, a suspension or an aqueous solution.

  The amount of the inorganic compound that is readily soluble in water varies depending on the type of the compound represented by the general formula (1) to be used and the type of other compounds contained in the solution containing water, or the mixing ratio thereof. Although not possible, using a part of the solution containing the compound represented by the general formula (1) and water in advance, an amount such that the compound represented by the general formula (1) remaining in the aqueous phase becomes a desired amount Can be determined by a method such as Usually, the usage-amount of the inorganic compound easily soluble in water is 5-300 weight part with respect to 100 weight part of water in the solution containing the compound represented by General formula (1) and water. It is preferable that the inorganic compound to be used is within this range in terms of the recovery rate of the compound represented by the general formula (1) and the efficiency of removing water in the organic phase.

  The temperature at which an inorganic compound readily soluble in water is dissolved in a solution containing the compound represented by the general formula (1) and water is particularly within the temperature range in which the inorganic compound readily soluble in water is dissolved in the solution. It is not limited. Usually, the temperature is selected as room temperature.

  The pressure at which an inorganic compound that is readily soluble in water is dissolved in a solution containing the compound represented by the general formula (1) and water is not particularly limited. Usually, the pressure is under atmospheric pressure.

  The temperature at which the aqueous phase and the organic phase containing the compound represented by the general formula (1) are separated is such that the aqueous phase and the organic phase containing the compound represented by the general formula (1) are separated, and the general formula If it is below the boiling point of the compound represented by (1), it will not restrict | limit at all. Usually, the temperature is room temperature.

  The pressure at the time of separating from the aqueous phase and the organic phase containing the compound represented by the general formula (1) is not limited at all. Usually, the pressure is under atmospheric pressure.

  Separation of the aqueous phase and the organic phase containing the compound represented by the general formula (1) may be either a batch type or a continuous type, and the type of apparatus is not particularly limited. For example, a batch type treatment method using a stirring tank type or a continuous type using a tube type may be used.

  Water contained in the organic phase containing the compound represented by the general formula (1) separated from the aqueous phase is removed using a solvent that forms an azeotropic composition with water.

  The solvent that forms an azeotropic composition with water is not particularly limited as long as it can be separated from the compound represented by the general formula (1) by distillation. Among them, it is preferable from an economical viewpoint that an azeotropic mass fraction of water is 0.05 or more and an industrially general-purpose solvent is selected and used. Examples of such solvents include hydrocarbons, halogenated hydrocarbons, acid esters, alcohols, ethers, ketones and amines.

  Examples of the hydrocarbons include aromatic hydrocarbons such as benzene, toluene and xylene, and aliphatic hydrocarbons such as hexane and cyclohexane.

  Examples of the halogenated hydrocarbons include aliphatic halogenated hydrocarbons such as methyl chloride and methylene dichloride, and aromatic halogenated hydrocarbons such as chlorobenzene.

  Examples of the acid esters include methyl acetate, ethyl acetate, butyl acetate, and methyl methacrylate.

  Examples of alcohols include hexanol, cyclohexanol, and isopropyl alcohol.

  Examples of ethers include anisole, dibutyl ether, dipropyl ether and the like.

  Examples of ketones include cyclohexanone, methyl isobutyl ketone, and methyl ethyl ketone.

  Examples of amines include hexylamine, 2-ethylhexylamine, and trimethylamine.

  These solvents that form an azeotropic composition with water can be used alone or in combination of two or more. These solvents that form an azeotropic composition with water can be recovered and reused.

  The amount of the solvent that forms an azeotropic composition with water used for removing water contained in the organic phase is usually 5 to 30 parts by weight with respect to 100 parts by weight of the compound represented by the general formula (1). If it is enough.

  The number of stages of the distillation column used when removing water in the organic phase using a solvent that forms an azeotropic composition with water is usually 2 to 5 stages, preferably 2 to 3 stages. The distillation effect does not change even if the number of distillation towers is 5 or more.

  As a method of removing water in the organic phase using a solvent that forms an azeotropic composition with water, a known method, for example, adding the solvent that forms an azeotropic composition with water to the separated and recovered organic phase. First, water is distilled out of the system together with the solvent, and the distilled liquid is cooled and condensed to separate water and the solvent to remove the water. The separated solvent enters the system from the top of the distillation column. A method of returning and recycling is used.

  After removing water in the organic phase using a solvent that forms an azeotrope with water, the solvent that forms an azeotrope with water is removed by distillation, followed by distillation represented by the general formula (1). Compounds can be recovered.

  In separating an aqueous phase and an organic phase containing a compound represented by the general formula (1) by dissolving an inorganic compound easily soluble in water in a solution containing the compound represented by the general formula (1) and water The compound represented by the general formula (1) can also be recovered in the extraction solvent.

  The extraction solvent is any solvent that can extract the compound represented by the general formula (1) from the aqueous phase, a solvent immiscible with water, or a solvent that can be separated from the compound represented by the general formula (1) by distillation. Not limited. Among them, it is preferable from the economical viewpoint to select and use industrially general-purpose solvents. Examples of such extraction solvents include hydrocarbons, halogenated hydrocarbons, acid esters, alcohols, ketones and amines.

  Hydrocarbons include aromatic hydrocarbon compounds such as benzene, toluene, xylene, mesitylene, ethylbenzene, isopropylbenzene, and amylbenzene. Halogenated hydrocarbons include acid esters such as methyl chloride, methylene dichloride, chloroform, and chlorobenzene. As the alcohols, ethyl acetate, butyl acetate, propyl formate, butyl formate, diethyl carbonate, methyl propionate, methyl butyrate, etc., and alcohols are distilled and separated from the compound represented by the general formula (1) recovered with 5 or more carbon atoms. Hexanols, heptanols, octanols, amyl alcohols, benzyl alcohols and the like having a possible boiling point difference, ethers such as anisole having a boiling point difference capable of being separated by distillation from the compound represented by the general formula (1) recovered with 2 or more carbon atoms , Diisopro Examples of ketones such as ruether, dibutyl ether, and ethyl isoamyl ether include methyl isobutyl ketone and diethyl ketone having a boiling point difference that can be separated by distillation from the compound represented by the general formula (1) in which the alkyl group has 2 or more carbon atoms in the alkyl group. , Ethylbutylketone, dipropylketone, and the like as amines such as diisobutylamine, triethylamine, hexylamine having a boiling point difference that can be separated from the compound represented by the general formula (1) recovered with 4 or more carbon atoms, 2- Examples include ethylhexylamine.

  The use of the above-mentioned solvent capable of forming an azeotropic composition with water is preferable because it can be used for removing water in the organic phase containing the compound represented by the general formula (1).

  By using the extraction solvent, the recovery rate of the compound represented by the general formula (1) when separated from the aqueous phase can be improved.

  The amount of the extraction solvent used is usually 5 to 10 parts by weight with respect to 100 parts by weight of the aqueous solution containing the compound represented by the general formula (1) and water.

  The temperature at which the compound represented by the general formula (1) is recovered in the extraction solvent is not particularly limited as long as the extraction solvent can exhibit the ability to extract the compound represented by the general formula (1). The temperature is usually room temperature.

  There is no restriction | limiting in particular in the pressure at the time of collect | recovering the compound represented by General formula (1) in an extraction solvent. The pressure is usually under atmospheric pressure.

  When a solvent that forms an azeotropic composition with water is used as an extraction solvent used for recovering the organic phase containing the compound represented by the general formula (1) that is separated from water, the water azeotropes with the water used for extraction. If the amount of the solvent that forms the composition is sufficient to remove the water in the organic phase containing the composition, it is not necessary to add a new solvent that forms an azeotropic composition with water.

Examples of the present invention will be shown below, but the present invention is not limited thereto.
The analysis of DMI was based on gas chromatography (hereinafter abbreviated as “GC”).

The conditions of GC analysis are as follows.
Column: Thermon 1000 + KOH (10 + 3%), 3 mm × 2 m
Carrier gas: Nitrogen gas Column temperature: 200 ° C

  95% sodium hydroxide at room temperature to 236.6 g of an aqueous solution containing 159.7 g (67.5% by weight) of DMI, 71.6 g (30.3% by weight) of water and 5.3 g (2.2% by weight) of sodium hydroxide After adding 175.3 g of an aqueous solution and stirring, the mixture was allowed to stand for 30 minutes. The stationary mass was separated into an organic phase and an aqueous phase with a separatory funnel to obtain 173.6 g of an organic phase containing 157.4 g (90.7 wt%) of DMI and 16.2 g (9.3 wt%) of water. To this organic phase, 15.7 g of toluene (10 parts by weight with respect to 100 parts by weight of DMI) was charged into a distillation kettle, water and toluene were azeotroped in a two-stage distillation column, and the distilled liquid was separated by a reflux tube to give toluene. The phase was returned to the distillation kettle, and water was extracted out of the system for dehydration. When the top temperature of the distillation tower reaches the boiling point of toluene, the dehydration process is completed, and after toluene is distilled off at a reduced pressure of 13.33 kPa, the reduced pressure is changed to 4.0 kPa and purified by distillation. 151.4 g of 100 ppm DMI (recovery = 94.8%) was obtained. When the first cut of distillation and the residue in the kettle are recovered in the next batch, the recovery rate is improved to 99%.

  To 236.6 g of an aqueous solution having the same composition as in Example 1, 18.9 g of sodium chloride and 15.9 g of methylene chloride (10 parts by weight with respect to 100 parts by weight of DMI) were added and stirred, and then allowed to stand for 30 minutes. The organic phase and the aqueous phase were separated with a separatory funnel to obtain 177.4 g of an organic phase containing 159.0 g (89.6 wt%) of DMI and 2.5 g (1.4 wt%) of water. This organic phase is charged into a distillation kettle, water and methylene chloride are azeotroped in a two-stage distillation column, the distilled liquid is separated by a reflux tube, the methylene chloride phase is returned to the distillation kettle, and water is withdrawn from the system. The dehydration process was performed. When the top temperature of the distillation tower reaches the boiling point of methylene chloride, the dehydration process is completed, and after the methylene chloride is distilled off at a reduced pressure of 26.7 kPa, the distillation is purified by changing the reduced pressure to 4.0 kPa. 151.1 g (recovery rate = 94.6%) of DMI having a water content of 90 ppm was obtained. When the first cut of distillation and the residue in the kettle are recovered in the next batch, the recovery rate is improved to 99%.

  182.6 g of 98% sulfuric acid and 24.0 g of xylene (15 parts by weight with respect to 100 parts by weight of DMI) were added to 236.6 g of an aqueous solution having the same composition as in Example 1, and the mixture was stirred and allowed to stand for 30 minutes.

  The organic phase and the aqueous phase were separated with a separatory funnel to obtain 186.5 g of an organic phase containing 158.3 g (84.9% by weight) of DMI and 4.3 g (2.3% by weight) of water. This organic phase is charged into a distillation kettle, water and xylene are azeotroped in a five-stage distillation column, the distilled liquid is separated by a reflux tube, the xylene phase is returned to the distillation kettle, and water is taken out of the system and dehydrated. Processing was performed. When the top temperature of the distillation tower reaches the boiling point of xylene, the dehydration process is completed, and after the xylene is distilled off at a reduced pressure of 26.7 kPa, distillation is purified by changing the reduced pressure to 4.0 kPa. 150.2 g of 90 ppm DMI (recovery rate = 93.9%) was obtained. When the first cut of distillation and the residue in the kettle are recovered in the next batch, the recovery rate is improved to 99%.

[Comparative Example 1]
236.6 g of an aqueous solution having the same composition as in Example 1 was charged into a distillation kettle, and purified by distillation at a reduced pressure of 4.0 kPa using a 10-stage distillation column. After cutting water as the first fraction and further cutting 7.9 g of DMI containing 2.4 wt% water as the middle fraction, 128.9 g of DMI with a water content of 400 ppm was obtained (recovery rate = 80.7%). It was. Even if the initial distillation cut and residual loss in the distillation are recovered in the next batch, the recovery rate is improved only to 85.5%. In addition, after the water was cut as the first distillation, inorganic salts were stuck to the wall of the still.

[Comparative Example 2]
236.6 g of an aqueous solution having the same composition as in Example 1 and 63.9 g of toluene (40 parts by weight with respect to 100 parts by weight of DMI) were placed in a flask, and water and toluene were azeotroped in a two-stage distillation column to distill off. Was separated by a reflux tube, the toluene phase was returned to the distillation kettle, water was taken out of the system, and dehydration was performed. When the top temperature of the distillation column reached the boiling point of toluene, the dehydration process was completed, and after cooling, filtration was performed to remove the precipitated inorganic substances, but most of them adhered to the flask. DMI adhering to the inorganic salt separated by filtration was washed with 31.0 g of toluene (19 parts by weight with respect to DMI) to obtain an organic phase. The obtained organic phase was charged into a distillation kettle, and toluene was distilled off at a reduced pressure of 13.33 kPa. Then, distillation was purified by changing the reduced pressure to 4.0 kPa, and 150.1 g of DMI having a water content of 100 ppm (recovery rate = 94.0%). When the first cut of distillation and the residue in the kettle are recovered in the next batch, the recovery rate is improved to 99%.

[Comparative Example 3]
236.6 g of an aqueous solution having the same composition as in Example 1 and 71.0 g of methylene chloride (30 parts by weight with respect to 100 parts by weight of the aqueous solution) were placed in a flask, stirred vigorously for 10 minutes at room temperature, and then allowed to stand for 30 minutes for liquid separation. And separated into an organic phase and an aqueous phase. The obtained organic phase was charged into a distillation kettle, and methylene chloride was distilled off at a reduced pressure of 26.7 KPa in a two-stage distillation column. 121.4 g (recovery rate = 76.0%) was obtained. Even if the first-distilled cut of distillation and the residue in the kettle are recovered in the next batch, the recovery rate is improved only to 80%.

[Comparative Example 4]
111.3 g of 85% potassium hydroxide was added to 236.6 g of an aqueous solution having the same composition as in Example 1, and the mixture was stirred and allowed to stand for 30 minutes. The stationary mass was separated into an organic phase and an aqueous phase with a separatory funnel to obtain 189.2 g of an organic phase containing 157.1 g (83.0 wt%) of DMI and 32.1 g (17.0 wt%) of water. . The obtained organic phase was charged into a distillation kettle and purified by distillation at a reduced pressure of 4.0 kPa using a 5-stage distillation column. After cutting water as the first distillation, 142.1 g (recovery rate = 89.0%) of DMI having a water content of 500 ppm was obtained.

  The recovery method of the present invention is useful for recovering the compound represented by the general formula (1) efficiently and at a high recovery rate from the mixture containing the compound represented by the general formula (1) and water. . Moreover, the recovery method of the present invention can reduce the cost of distillation equipment and the energy required for distillation, and can reduce the amount of solvent used to form an azeotropic composition with water to be used.

Claims (3)

General formula (1)

(Wherein R represents an alkyl group having 1 to 4 carbon atoms)
In recovering the compound represented by general formula (1) from the solution represented by formula (1) and water, an inorganic compound that is readily soluble in water is dissolved in the solution, and the organic phase separated from the aqueous phase is recovered. 1,3-dialkyl-2-imidazolidinone, wherein the water in the organic phase is removed together with a solvent that forms an azeotropic composition with water, and then the compound represented by the general formula (1) is recovered by distillation. Recovery method. The recovery method according to claim 1, wherein the water-soluble inorganic compound is an inorganic salt, an inorganic base, or an inorganic acid. The recovery according to claim 1, wherein an extraction solvent is used for recovering an organic phase separated from an aqueous phase by dissolving an inorganic compound readily soluble in water in a solution containing the compound represented by the general formula (1) and water. Method.