JPH0454162A - Method for purifying lactam-containing organic solutions - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] This invention relates to a method for purifying a lactam-containing solution. More specifically, it relates to a method for efficiently separating and purifying active ingredients contained in an organic solution by extracting with water an organic solution containing water-soluble impurities and mainly containing one or more lactam components. .

The method of the present invention is a method for simultaneously producing ε-caprolactam and ω-dodecanelactam by the so-called r-colactamization method, in which r-lactam oil containing these lactams and water as main components is extracted with an organic solvent. By back-extracting the organic solution (extract) with water, ε
- Suitably used when separating caprolactam and ω-dodecanelactam.

[Description of prior art]

As a method for simultaneously producing ε-caprolactam and ω-dodecanelactam, cyclohexanone and cyclododecanone are converted into oximes together as a mixture, and the resulting mixture of cyclohexanone oxime or its salt and cyclododecanone oxime or its salt is treated with sulfuric acid. or Beckmann rearrangement in the presence of fuming sulfuric acid, followed by neutralization with ammonia gas or aqueous ammonia to obtain a lactam mixture, which is extracted with a water-immiscible organic solvent; The lactam oil layer separated from the ammonium sulfate aqueous layer by phase separation is extracted with an organic solvent that is immiscible with water to obtain an extract containing lactam components, and this extract is back-extracted with water to obtain ε- A method (so-called "colactamization method") in which caprolactam is transferred to the aqueous layer while ω-dodecanelactam remains in the organic solvent layer is known as a known technique (for example,
(See Japanese Patent Publication No. 46-7254, Japanese Patent Publication No. 4610168, etc.).

ε-caprolactam and ω by this “colactamization method
- In the simultaneous production method with dodecane lactam, conventionally, the lactam mixture or lactam oil layer is extracted with an organic solvent to obtain an organic solvent solution (extract liquid) containing a lactam component such as ε-caprolactam or ω-dodecane lactam, After separation into water (heavy liquid) containing water-soluble impurities, the extract was directly extracted with water, but in the extraction of the lactam component with the organic solvent, some of the heavy liquid was entrained in the extract. Therefore, during the next water extraction, an emulsion is generated, which tends to cause poor separation between the organic solvent layer and the aqueous layer, requiring an extraction column with a large diameter, and the presence of organic matter in the aqueous layer. This entrains the organic solvent layer to become cloudy, which adversely affects the quality of ε-caprolactam, and the quality of ω-dodecanelactam is also adversely affected by entrainment of water-soluble impurities to the organic solvent layer.

[Problem to be solved by the invention]

An object of the present invention is to extract an emulsion resulting from the heavy liquid in the organic solution when extracting an organic solution containing water containing water-soluble impurities as a heavy liquid and containing one or more lactams with water. To provide an industrially suitable method for purifying a lactam-containing organic solution that prevents the formation of lactam, efficiently transfers and separates the target component from the organic solution side to the aqueous solution side, and obtains the active ingredient with high quality and high yield. There is a particular thing.

[Means to solve the problem]

The inventors aimed to improve the various drawbacks mentioned above in the method of transferring and separating ε-caprolactam from an organic solution mainly containing ε-caprolactam and ω-dodecanelactam to an aqueous layer by water extraction. As a result of extensive research, we found that emulsion formation during water extraction is
During the water extraction, they discovered that "this is due to the water (heavy liquid) containing water-soluble impurities" present in the lactam-containing organic solution, and completed this invention.

That is, this invention extracts a lactam oil containing water-soluble impurities and at least one lactam with a water-immiscible organic solvent, and then cools it.
The present invention relates to a method for purifying a lactam-containing organic solution, which comprises separating and removing a heavy liquid and then back-extracting the resulting organic solution with water to separate target components from the organic solution into an aqueous solution.

[Detailed explanation of each requirement of the present invention]

The method of this invention will be explained in detail below.

In this invention, water containing water-soluble impurities is used as a heavy liquid, and ε-caprolactam and ω-caprolactam are used as active ingredients.
The active ingredient (
When transferring and separating one or more types of lactams) to the aqueous solution side, the water extraction is performed by cooling the organic solution and separating and removing the heavy liquid as an impurity prior to the water extraction. Efficiency and implementation are particularly characteristic.

Furthermore, as a preferred embodiment of the present invention, cyclohexanone and cyclododecanone are oximized together as a mixture, and the resulting mixture of cyclohexanone oxime or a salt thereof and cyclododecanone oxime or a salt thereof,
Beckmann rearrangement is carried out in the presence of sulfuric acid or fuming sulfuric acid, followed by neutralization with ammonia gas or aqueous ammonia to obtain a lactam mixture containing mainly ε-caprolactam, ω-dodecanelactam and ammonium sulfate, and the lactam mixture is directly infused with water. After extraction with an organic solvent that is immiscible with or leaving the lactam mixture to stand and phase-separate into a lactam oil layer containing mainly ε-caprolactam and ω-dodecanelactam and an aqueous layer mainly containing ammonium sulfate, The lactam oil layer is extracted with an organic solvent that is immiscible with water to separate the heavy liquid, and ε-caprolactam and ω-
An organic solvent solution containing a lactam component such as dodecane lactam (hereinafter referred to as "organic solution") was obtained, and this organic solution was further extracted with water to transfer ε-caprolactam to the aqueous layer, while ω-dodecane After allowing the lactam to remain in the organic solution layer and separating ε-caprolactam and ω-dodecanelactam, the aqueous layer containing ε-caprolactam and the organic solution layer containing ω-dodecanelactam are each distilled or subjected to other conventional methods. By purifying using
In "colactamization method 1" which simultaneously produces ε-caprolactam and ω-dodecanelactam, the r-lactam mixture or lactam oil layer j (hereinafter referred to as "lactam oil")
Before back-extracting the organic solution obtained by organic solvent extraction with water, the heavy liquid is sufficiently separated from the organic solution by cooling treatment, and in the subsequent water extraction, the aqueous layer is ε-caprolactam, which migrates to
It can be efficiently separated from the ω-dodecane lactam remaining in the organic solution layer.

The aforementioned lactam oil is obtained by the Hetzkmann rearrangement of oximes generated by oximation of cyclohexanone and cyclododecanone, followed by neutralization, and in a subsequent step, the lactam oil is obtained by organic solvent extraction of this lactam oil. When back-extracting an organic solution with water to transfer and separate ε-caprolactam into the aqueous layer, an emulsion may be formed and cause poor separation of ε-caprolactam and ω-dodecanelactam, as described below. However, according to the method of the present invention, as described above, by cooling the organic solution prior to water extraction, the heavy liquid is removed so that emulsion formation no longer occurs. This is because it can be removed to the extent that it does not.

In this invention, water-soluble impurities contained in the lactam oil include ammonium sulfate and water-soluble organic impurities. As an example of water-soluble organic impurities,
Decyl sulfate or decyl sulfate, undecyl sulfate or undecyl sulfate, alkyl sulfate or alkyl sulfate such as dodecyl sulfate or dodecyl sulfate, amino acid salts such as sodium aminocaproate, fatty acid salts, alkyl sulfonates, alkylaryl sulfonic acids Specific examples include anionic surfactants such as salts, and ammonium salts are preferred as the alkyl sulfate.

The presence of these anionic surfactants is due to the presence of raw material cyclohexanone and cyclododecanone, especially linear alkyl alcohols such as n-decyl alcohol, n-undecyl alcohol, and n-dodecyl alcohol contained in cyclododecanone. The lactam mixture mainly contains ε-caprolactam and ω-dodecanelactam from cyclohexanone and cyclododecanone through an oxime formation process, a rearrangement process, and a neutralization process. During the production, these linear or branched alkyl alcohols react with sulfuric acid or fuming sulfuric acid to produce the aforementioned alkyl sulfates (or alkyl sulfates).

In this invention, mainly ε-caprolactam, ω-
a lactam mixture containing dodecane lactam and ammonium sulfate;
Alternatively, mainly ε-caprolactam and ω-caprolactam are separated from the aqueous ammonium sulfate layer by phase separation of this lactam mixture.
The content of ε-caprolactam and ω-dodecane lactam in the organic solution obtained by extracting the lactam oil layer containing dodecane lactam with an organic solvent that is immiscible with water, and then cooling it to separate and remove the heavy liquid. The amount is
The content of both is preferably 10 to 20% by weight.

If the content of ε-caprolactam and ω-dodecanelactam in the organic solution is less than the above-mentioned amount, when the organic solution is extracted with water and the ε-caprolactam in the organic solution is transferred to and separated from the aqueous layer. Therefore, when concentrating and purifying the ε-caprolactam aqueous solution for the purpose of recovering ε-caprolactam from the ε-caprolactam aqueous solution obtained by this water extraction G,
A large amount of energy is required, and the water extraction requires an extraction device with a high number of stages, which is disadvantageous.On the other hand, if the content of ε-caprolactam and ω-dodecanelactam in the organic solution To the extent that it exceeds
During the water extraction, crystals of ω dodecane lactam precipitate, which is not preferable in either case.

In this invention, the V-lactam mixture or the lactam oil layer j, that is, the "single heavy liquid contained in the lactam oil" contains, in addition to the above-mentioned "water-soluble impurities such as ammonium sulfate and anionic surfactants," is an aqueous solution containing a small amount of lactam components such as ε-caprolactam and ω-dodecanelactam, most of which are dissolved in the lactam oil, and by extracting the lactam oil with an organic solvent, It is produced by separating it from an organic solvent extract containing lactam components such as ε-caprolactam and ω-dodecanelactam.

Furthermore, the organic solvents used in this invention include:
Aromatic hydrocarbons such as benzene, toluene, xylene, and isopropylbenzene; alicyclic hydrocarbons such as cyclohexane and cyclooctane; and aliphatic carbons having 6 to 8 carbon atoms such as n-hexane, n-hebutane, and n-octane. hydrogen,
Mention may be made of solvents which are liquid at the extraction temperature and are immiscible with water, such as hydrocarbons substituted with nitrogen atoms such as trichloroethylene, carbon tetrachloride, chloroform, among which benzene and toluene are most preferably mentioned. I can do it. Of course, it goes without saying that mixtures of two or more of the above-mentioned solvents can be used.

It goes without saying that the extraction of the lactam oil with an organic solvent is preferably carried out by liquid-liquid extraction for operational reasons;
The extraction operation conditions such as extraction temperature, extraction agent ratio, and extraction time, as well as the extraction method such as the type of extraction device, are not particularly limited as long as they are within the range applicable to ordinary liquid-liquid extraction. Rather, the extraction is carried out so that the contents of ε-caprolactam and ω-dodecanelactam in the organic solution obtained as a result of extraction and subsequent cooling are both within the range of 10 to 20% by weight. All you have to do is decide on the operating conditions and extraction method.

For example, regarding the extraction temperature, it is the temperature at which the lactam oil and organic solvent exist as a liquid in the extraction device, and is therefore above the melting point of the lactam oil, and the extract liquid obtained as a result of extraction as described above. It is desirable that the temperature range be below the boiling point of the heavy liquid 1, preferably about 60 to 80°C.

Further, from an industrial perspective, it is preferable to use a countercurrent type liquid-liquid extraction device, such as a packed column or a perforated plate type column, for the extraction device.

Next, as mentioned above, the above r
Organic solution obtained by organic solvent extraction of lactam oil
A cooling treatment of an organic solution (lactam-containing organic solution) j containing lactam components such as ε-caprolactam and ω-dodecanelactam as active ingredients will be described.

As described above, in the method of the present invention, the lactam-containing organic solution obtained by extracting the lactam oil with an organic solvent is cooled prior to the next water extraction step, and a heavy liquid is extracted from the organic solution. Therefore, in the organic solution supplied to the water extraction process, the heavy liquid in the organic solution is removed to the extent that no emulsion is formed during water extraction. When extracting the lactam oil with an organic solvent, (a) the heavy liquid separated and produced from the lactam oil and the [[] obtained by transferring from the lactam oil to the organic solvent side; After first separating the organic solvent extract containing lactam components such as ε-caprolactam and ω-dodecanelactam, the heavy liquid still accompanying the organic solvent extract can be removed by cooling the organic solvent extract. (Most of it exists in dissolved form in the organic solvent extract)
and (b) the above-mentioned r-lactam-containing organic solution obtained by further separating and removing the Any of the above-mentioned "lactam-containing organic solutions" obtained by separating and removing the heavy liquid from the organic solvent extract is possible. However, in the present invention, it is preferable to subject the r-lactam-containing organic solution 1 of (a) above to water extraction. Of course, when extracting the lactam oil with an organic solvent, the lactam components can be extracted from the lactam oil by using an appropriate extraction device such as a mixer-ceratra and appropriately selecting the extraction operation conditions as described above. It goes without saying that it is also possible to simultaneously perform the extraction of the lactam oil and the separation and removal of the heavy liquid from the lactam oil by cooling.

In this invention, the extent to which water (heavy liquid) containing water-soluble impurities such as anionic surfactant substances is removed by cooling treatment in the lactam-containing organic solution is determined by the amount of water-soluble impurities in the lactam oil. content, the content of the heavy liquid in the lactam-containing organic solution, which is determined by the extraction conditions and extraction method when extracting the lactam oil with an organic solvent, and the extraction operation conditions in the next water extraction step. Although it is difficult to generalize, in this invention, water-soluble impurities such as anionic surfactants that are entrained in the lactam-containing organic solution supplied to the water extraction step. It is sufficient that the water (heavy liquid) j containing the water (heavy liquid) does not form an emulsion during the water extraction.

For boat fishing, the lactam-containing organic solution supplied to the water extraction step contains a heavy liquid in an amount such that the content of anionic surfactant in the lactam-containing organic solution is 10 ppm by weight or less. It is preferable that the heavy liquid in the lactam-containing organic solution is finally subjected to a cooling treatment to be separated and removed.

Therefore, in the present invention, the temperature at which the lactam-containing organic solution is cooled before water extraction cannot be generalized, and the content of the lactam component and heavy liquid in the lactam-containing organic solution and the following It should be determined by taking into account the extraction operating conditions adopted in the water extraction process, but -
For boat fishing, it is preferable to cool the lactam oil to a temperature that is approximately 5 to 40°C lower than the extraction temperature of the lactam oil with an organic solvent.

Furthermore, the method for cooling the lactam-containing organic solution is not particularly limited. For example, a method of cooling with a refrigerant such as cooling water can be applied.

In addition, in this invention, on the downstream side of the cooler,
Further, a stationary separation tank such as a decanter that is usually used industrially is provided, and the heavy liquid separated by cooling the lactam-containing organic solution is completely separated and removed from the lactam-containing organic solution. It is desirable to supply the organic solution to a water extraction device, and since ε-caprolactam and ω-dodecanelactam, especially ε-caprolactam, are effectively contained in the separated heavy liquid, commercial production is possible. From this point of view, it goes without saying that it is desirable to recover the lactam component by, for example, returning the separated heavy liquid to the above-mentioned "lactam oil extraction process using an organic solvent."

As described above, when the lactam oil is extracted with a organic solvent, the extract liquid, that is, the heavy liquid that accompanies the lactam-containing organic solution, is cooled by cooling the lactam-containing organic solution prior to the next water extraction step. However, the method for removing the heavy liquid in the lactam-containing organic solution is not limited to this V cooling treatment method. For example, the method for removing the heavy liquid in the lactam-containing organic solution is Of course, a treatment method of heating and concentrating the liquid under reduced pressure is also possible. However, considering ease of operation,
The r-cooling-j treatment method, which is the method of this invention, is preferable.

The lactam-containing organic solution from which the heavy liquid containing water-soluble impurities such as anionic surface-active substances has been removed is then subjected to water extraction. Extraction operation conditions such as extraction time, standing time for liquid separation after extraction, type of extraction device, extraction method, etc. are not particularly limited, and may be any method applied in normal liquid-liquid extraction. For example, as in the extraction of lactam oil with an organic solvent, it is preferable to use an industrially used countercurrent liquid-liquid extraction device such as a packed column or perforated plate column. .

[Examples] Next, the method of the present invention will be specifically explained with reference to Examples and Comparative Examples. However, the present invention is not limited to the following Examples unless it exceeds the spirit thereof. .

Example 1 850 g of an organic substance (hereinafter referred to as "lactam oil") mainly containing 47% by weight of ε-caprolactam, 36% by weight of ω-dodecanelactam, and 13% by weight of water was placed in a glass container (capacity 51) equipped with a stirrer. Preparation, then 215
Add 0g of toluene, stir and mix at a temperature of 68°C,
2903 g of toluene extract containing 3% by weight of ε-caprolactam and 11% by weight of ω-dodecanelactam;
．． 0 wt% ε-caprolactam and 0.3 wt% ω-
97 g of separated heavy liquid containing dodecane lactam was obtained.

When 320 g of this toluene extract was placed in a glass container with a volume of 11ffi and cooled to a temperature of 60°C in a water bath, 2 g of a heavy liquid containing 38% by weight of ε-caprolactam and 1.6% by weight of ω-dodecanelactam was obtained. Obtained.

Therefore, this heavy liquid was separated using a separating funnel, and 318 g of the remaining toluene extract was transferred to a glass container with a capacity of 2N equipped with a stirrer, and 456 g of water was added and mixed by stirring.
When caprolactam was back-extracted into the aqueous layer, no emulsion was formed and the liquid was easily separated by standing for a short time.
278 g of an organic phase (toluene phase) containing 12% by weight of ω-dodecanelactam and 496 g of an aqueous phase containing 7.1% by weight of ε-caprolactam were obtained.

Comparative Example 1 When the toluene extract was back-extracted with water in the same manner as in Example 1 except that the toluene extract was not cooled before being extracted with water, an emulsion was formed and after the stirring was stopped. Even after standing for 30 minutes, phase separation between the organic phase and the aqueous phase could not be achieved.

Example 2 1349 g of lactam oil mainly containing 43% by weight of ε-caprolactam, 43% by weight of ω-dodecanelactam, and 10% by weight of water was placed in a glass container equipped with a stirrer (capacity: 10%).
1), then add 4745g of toluene,
Stir and mix at a temperature of 70°C, 9.5% by weight of ε-caprolactam and 9.6% by weight! % of ω-dodecane lactam and 121 g of separated heavy liquid were obtained.

5974 g of this toluene extract was placed in a glass container with a capacity of 10 A and cooled to a temperature of 40"C in a water bath. 15% by weight of ε-caprolactam and 0.7% by weight of ω
- 48 g of heavy liquid containing dodecane lactam was separated, 9.4
5925 g of a toluene extract containing ε-caprolactam in a weight % and ω-dodecane lactam in a weight % of 9.7 weight % was obtained.

Therefore, the toluene extract 5925 obtained after cooling
When ε-caprolactam was transferred to a glass container with a capacity of 10 f and equipped with a stirrer, 3000 g of water was added, and the ε-caprolactam was back-extracted into the aqueous layer. Good liquid separation between the organic phase and the aqueous phase was easily obtained.

Comparative Example 2 A toluene extract was back-extracted with water in the same manner as in Example 2, except that heavy liquid separation from the toluene extract by cooling was not performed before the toluene extract was extracted with water. As a result, an emulsion was generated, and it took 15 minutes for phase separation between the organic phase and the aqueous phase, and the aqueous phase contained a cloudy emulsion.

[Explanation of effects]

The method of the present invention includes an oximation step, a Beckmann rearrangement step, and a Beckmann rearrangement step from cyclohexanone and cyclododecanone, as described above, in r-colactamization method 1 for simultaneously producing ε-caprolactam and ω-dodecanelactam.
Furthermore, the lactam mixture obtained through the neutralization step is extracted with an organic solvent that is immiscible with water, and then the obtained lactam-containing organic solution is extracted with water, and the lactam-containing organic/8
f! ! .

Either ε-caprolactam and ω-dodecanelactam were separated and purified by transferring and separating the ε-caprolactam in the aqueous layer, or the lactam-containing organic solution contained water-soluble substances such as anionic surfactants. Due to the presence of heavy liquid containing impurities, poor separation of the organic solvent layer and aqueous layer due to emulsion formation is likely to occur during the water extraction process, requiring an extraction column with a large diameter, and When organic matter is entrained in the organic solvent layer, it becomes cloudy, which adversely affects the quality of ε-caprolactam, and conversely, when water-soluble impurities are entrained in the organic solvent layer, it adversely affects the quality of ω-dodecanelactam. In contrast, heavy liquid separation by cooling the lactam-containing organic solution before water extraction prevents emulsion formation during the water extraction process, thereby reducing (a) large amounts of impurities; (b) It is possible to prevent the organic layer containing water-soluble impurities from mixing with the aqueous layer and obtain high-quality ε-caprolactam. Dodecane lactam can be obtained, and (C) a decrease in extraction efficiency in the water extraction step can be prevented, and ε-caprolactam and ω-dodecane lactam can be recovered in high yield. ) When water extraction is carried out by continuous countercurrent extraction, the process can be performed using a column with a small diameter. Therefore, it is possible to apply an extraction column with a high number of theoretical plates, and it is hoped that the extraction efficiency will be improved from the viewpoint of the equipment. This has the effect of providing a method for purifying a lactam-containing organic solution that can eliminate the complexity of extraction operations associated with increased equipment size.

Patent applicant: Ube Industries Co., Ltd.

Claims (2)

[Claims] (1) Lactam oil containing water-soluble impurities and at least one lactam is extracted with an organic solvent that is immiscible with water, and then cooled to separate and remove the heavy liquid, and the resulting organic A method for purifying a lactam-containing organic solution, which is characterized by separating a target component from an organic solution into an aqueous solution by back-extracting the solution with water. (2) The method for purifying a lactam-containing organic solution according to claim (1), wherein the lactam consists of ε-caprolactam and ω-dodecanelactam, and the target component is ε-caprolactam.