JP2002179667A - METHOD FOR MANUFACTURING epsi-CAPROLACTONE - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing high quality ε-caprolactone in high yield without changing reaction condition of the oxidation of cyclohexanone based on a detailed examination of methods separating the ε-caprolactone in the distillation of the obtained crude reaction liquid and collecting the unreacted cyclohexanone. SOLUTION: In this method the crude reaction liquid obtained from oxidation of the cyclohexanone is supplied to a first distillation column, a low boiling point first distillation liquid including unreacted cyclohexanone, or the like, is distilled away from the overhead, a first bottom product of high boiling point including ε-caprolactone, or the like, is collected from the bottom, and then the first distillation liquid is introduced into a second distillation column connected to the overhead of the first distillation column, a low boiling point second distillation liquid and a second bottom product including unreacted cyclohexanone are together obtained, the first bottom product is introduced into a third distillation column connected to the bottom of the first distillation column to obtain a third distillation liquid including ε-caprolactone, and a third bottom product is obtained from the bottom of the column, and the second bottom product is returned to the raw material cyclohexanone.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a method for producing ε-caprolactone with efficient purification. More specifically, the reaction conditions for producing ε-caprolactone by oxidizing cyclohexanone are not strict, and the purification process after the reaction and the recovery process of unreacted cyclohexanone are examined to increase the conversion of cyclohexanone. The present invention relates to a method for producing ε-caprolactone with efficient purification, in which the amount of recycled cyclohexanone is reduced as much as possible.

[0002]

2. Description of the Related Art ε-Caprolactone (hereinafter sometimes referred to as CL-M) has applications such as polyester polyol for polyurethane synthesis and polymer raw materials for other molding materials, and its production method is cyclohexanone (hereinafter referred to as CL-M). ,
A method of oxidizing (sometimes referred to as ANO) is known as a typical method. The oxidation of ANO includes a co-oxidation method performed in the presence of acetaldehyde and an oxidation method using an organic peracid such as peracetic acid as an oxidizing agent. Further, a distillation method is used to separate a target substance from a reaction mixture obtained by oxidation of ANO.

[0003] In the case of producing CL-M by oxidizing the above-mentioned ANO, the obtained reaction crude liquid usually contains the unreacted main raw material ANO in addition to the target substance CL-M, and further uses an oxidizing agent. In this case, the unreacted oxidizing agent (hereinafter, sometimes referred to as AP), a by-product based on the oxidizing agent (hereinafter, sometimes referred to as AC), a solvent of the oxidizing agent (hereinafter, referred to as AE) And CL-M by-products such as adipic acid (hereinafter sometimes referred to as ADA) and a polymer of CL-M (hereinafter sometimes referred to as CL-HB or simply HB). CL-M as a product
In order to remove the unreacted main raw material ANO and to use it for recycling, it is necessary to distill and separate the crude reaction liquid.

In addition, in the oxidation reaction of ANO, the conversion of ANO is improved as much as possible to increase the yield of CL-M and to improve the AN.
Due to the need to improve productivity by reducing the amount of O recovered and recycled, severe reaction conditions such as an increase in the amount of AP charged and an increase in the reaction temperature may be adopted. By-products such as HB increase, and when further heated in the distillation column of the purification system, react with CL-M to form complicated by-products, and eventually reduce the yield of CL-M, and You cannot achieve your goals.

[0005] Therefore, CL-M
And purifying processes for sequentially removing low-boiling substances, which are generally performed for recovering ANO,
In the first distillation column, a distillate mainly composed of AE, AP and AC is distilled, a bottom liquid mainly composed of ANO, CL-M, ADA and HB is taken out, and the bottom liquid is subjected to a second distillation. The distillate is supplied to the distillation column for distillation, ANO to be recycled is obtained from the top of the column, a bottom product mainly composed of CL-M, ADA and HB is obtained, and the bottom product is further supplied to the third distillation column. And product CL
-M as a distillate and ADA and H
When B was discharged as a bottom liquid and used as a waste component, the yield of CL-M was higher than in the case of the above-mentioned method in which the amount of recycled ANO was reduced, but the quality was reduced. In particular, the results of the heat coloring test were poor. As described above, when distillation was carried out without changing the reaction conditions, AN
Although the quality is lower than when O is not recycled or reduced, the yield of CL-M is high, and the CL-M separation method and ANO recovery method in the distillation step are obtained. A detailed review was suggested to be valuable.

[0006]

Accordingly, an object of the present invention is to conduct a detailed study on a method for separating CL-M and a method for recovering ANO in a distillation step without changing the above reaction conditions, and to obtain a high yield and a high yield. It is an object of the present invention to provide a manufacturing method for obtaining CL-M having a high quality.

[0007]

Means for Solving the Problems The inventors of the present invention have made intensive studies to solve the above-mentioned problems, and as a result, supplied the crude reaction liquid to the first distillation column, and simultaneously conducted ANO and CL-M as bottoms. The method of taking out, separating ANO in the second distillation column, and taking a series of steps to sequentially obtain CL-M in the subsequent third distillation column cannot solve the problem of the present invention. Feeding into the column, separating ANO and CL-M as distillate and bottoms, respectively, separating and feeding each to the second and third distillation towers and purifying them to obtain good results To complete the present invention.

The gist of the present invention is as follows. In the first invention, a reaction crude liquid (A) obtained by oxidizing cyclohexanone with an organic peracid is supplied to a first distillation column, and a low-boiling first distillate containing unreacted cyclohexanone is supplied from the top of the column. A ₁ ) is distilled off, and a high-boiling first bottoms (A ₂ ) containing ε-caprolactone is obtained from the bottom of the column, and the first distillate (A ₁ ) is discharged from the first distillation column. It is led to the second distillation column following the top,
A distillate (A ₁₁ ) is obtained, a _second bottoms liquid (A ₁₂ ) containing unreacted cyclohexanone is obtained, and the first bottoms (A ₂ ) is discharged to the first distillation column at the bottom of the first distillation column. 3 Distillation tower, ε
- with obtaining a third distillate containing caprolactone (A _21), from the bottom of the column to obtain a third cans exudates (A _22), the second bottom exudates (A ₁₂₎ is returned to the raw material cyclohexanone ε- The present invention relates to a method for producing caprolactone. The second invention relates to the method for producing ε-caprolactone according to the first invention, wherein the organic peracid is peracetic acid. In the third invention, the reaction crude liquid (A) contains as a main component an organic peracid, an acid based on the organic peracid, a solvent for the organic peracid, a polymer of cyclohexanone, ε-caprolactone, adipic acid and ε-caprolactone. The present invention relates to the method for producing ε-caprolactone according to the first or second invention. According to a fourth aspect of the present invention, the first distillate (A ₁ ) comprises an organic peracid, an acid based on an organic peracid, a solvent for the organic peracid and cyclohexanone as main components.
The present invention also relates to a method for producing ε-caprolactone. According to a fifth aspect of the present invention, the first bottoms (A ₂ ) comprises the ε-caprolactone, adipic acid, and a polymer of ε-caprolactone as the main components, wherein The present invention relates to a method for producing caprolactone.
A sixth invention is described in any one of the first to fourth inventions, wherein the second distillate (A ₁₁ ) contains an organic peracid, an acid based on the organic peracid, and a solvent of the organic peracid as main components. And a method for producing ε-caprolactone. The seventh invention provides the ε-caprolactone according to any one of the first to fourth inventions, wherein the second bottoms (A ₁₂ ) contains an acid based on an organic peracid and unreacted cyclohexanone as main components. It relates to a manufacturing method. In the eighth invention, the main component of the third distillate (A ₂₁ ) is ε.
The present invention relates to the method for producing ε-caprolactone according to any one of the above first to third and fifth aspects, which is caprolactone. A ninth invention is directed to the ε-caprolactone according to any one of the first to third and fifth inventions, wherein the third bottoms (A ₂₂ ) contains a polymer of adipic acid and ε-caprolactone as a main component. And a method for producing the same.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The contents of the present invention will be described below in detail.
In the method for producing ε-caprolactone according to the present invention, an organic peracid is used, and an organic peracid having a -CO-OOH group such as peracetic acid, perpropionic acid, and perisobutyric acid is used. , Acetic acid and the like.

When these organic peracids are used, cyclohexanone is oxidized to ε-caprolactone, which itself is converted to an organic acid having a lower boiling point than ε-caprolactone, such as acetic acid, propionic acid, and isobutyric acid. When the co-oxidation method is used, ε-caprolactone and acetic acid are obtained by air oxidation using cyclohexanone and acetaldehyde as raw materials.

The reaction crude liquid (A) obtained by oxidizing cyclohexanone with an organic peracid contains ε-caprolactone, unreacted cyclohexanone, unreacted organic peracid, and a solvent of an organic peracid (eg, ethyl acetate, acetic acid, etc.). ), Acids based on organic peracids, caprolactone oligomers, caprolactone polymers, oxycaproic acid, adipic acid and other by-product impurities of unknown structure. As described above, since the reaction crude liquid is a multi-component reaction mixture which is unstable with time with heat, when ANO or CL-M is purified by distillation, CL-M
The polymerization is usually performed under reduced pressure in order to reduce the polymerization loss.
For example, in the first distillation column to which the reaction crude liquid (A) is supplied, the bottom temperature is 100 to 200 ° C., the top pressure is 100 mmHg or less, the bottom liquid of the first distillation column is supplied, and CL-
The third distillation column for obtaining M has a bottom temperature of 100 to 200.
C., at a top pressure of 50 mmHg or less. The second distillation column to which the distillate from the first distillation column is supplied has a bottom temperature of 120 to 200 ° C. and a top pressure of 50 m in consideration of deterioration of ANO.
It is desirable to carry out at mHg or less.

The distillation conditions in the first distillation column are such that the main components of the distillate are AE, AP, AC having a low boiling point and unreacted A.
It is composed of NO, and the main component of the bottom liquid is CL-
M, ADA, and HB are selected. More specifically, the bottom temperature is 100 to 200 ° C., and the top pressure is 100
A condition of not more than mmHg is preferable. As described above, almost all of the unreacted ANO is distilled out as a distillate, and even if it is mixed in the bottoms, it is not a problematic amount.

The distillate from the first distillation column is supplied to the second distillation column, and the distillate whose main components are AE, AP and AC,
The bottoms are separated into bottoms whose main components are ANO and AC, and this bottoms is recycled to the raw material cyclohexanone and reused.

The bottom product from the first distillation column is supplied to a third distillation column installed in parallel with the second distillation column. The bottom liquid from the bottom of the tower is mainly composed of ADA and HB, and cannot be recycled in the production process according to the present invention, and is once subject to disposal.

Next, the manufacturing method will be described with reference to the drawings (block flowchart). FIG. 1 shows a flow according to the present invention in which a first distillation column is divided into a second distillation column and a third distillation column, and the reaction crude liquid (A) obtained when ε-caprolactone is produced by oxidation of cyclohexanone.
Include CL-M, ANO, AE, AP, AC, AD
A and HB are contained and supplied to the first distillation column, where they are separated by distillation into a first distillate (A ₁ ) and a first bottoms (A ₂ ).

The first distillate (A ₁ ) contains AN as a main component.
O, AE, AP and AC are contained and supplied to the second distillation column. In the first bottoms (A ₂ ), the target product C as a main component
In addition to LM, ADA and HB are included and supplied to the third distillation column.

The first distillate (A ₁ ) supplied to the second distillation column
Is distilled and separated into a second distillate (A ₁₁ ) mainly composed of AE, AP and AC, and a second distillate (A ₁₂ ) mainly composed of ANO and AC. The raw material ANO is recycled as it is and reused.

The first bottoms (A) supplied to the third distillation column_Two)
Is distilled and separated, and the third distillate (A _{twenty one}) Is the CL-M
Not from the top to avoid undesired polymerization of
It is extracted from the middle stage. Distillation from the top of the tower
Although not shown, the first steam
It is charged in a retaining tower and recycled. On the other hand, the third can
(A_{twenty two}) Is mainly composed of ADA and HB.
Since certain components cannot be obtained, they are usually discarded.

FIG. 2 is a block diagram showing a conventional method in which the first to third distillation columns are connected in series. The reaction crude liquid (B) obtained when ε-caprolactone is produced by oxidation of cyclohexanone is shown in FIG. , C
LM, ANO, AE, AP, AC, ADA, HB
And the reaction crude liquid (A) according to the present invention shown in FIG.
Is the same as The reaction crude liquid (B) is supplied to the first distillation column, and the first distillate (B ₁ ) whose main components are AE, AP and AC, and the main components are ANO, CL-M, and ADA by distillation.
And a first bottom liquid (B ₂ ) which is HB.

The first bottom liquid (B ₂ ) is supplied to the second distillation column, and the second distillate (B ₂₁ ) containing ANO as a main component and CL
Is separated into a second bottom liquid (B ₂₂ ) containing M, ADA and HB as main components, and the second second liquid (B ₂₁ )
Is recycled into raw materials.

The second distillate (B ₂₂ ) is supplied to the third distillation column, and the third distillate (B ₂₂₁ ) containing CL-M as a main component.
And a third bottoms containing ADA and HB as main components (B ₂₂₂ )
The former is provided for the purpose of manufacture, but the latter is usually discarded because it does not have a constant chemical composition.

[0022]

The present invention will be described below in detail with reference to examples.
However, the present invention is not limited to these. What
In the examples, all “%” represent “% by weight”. (Example 1) (1) Reference example for obtaining a crude reaction liquid subjected to the following distillation operation: Cyclohexano
170 g of a 30% solution of peracetic acid in ethyl acetate
5 g / h (51.4 g / h as pure peracetic acid, cyclohexane
1.1 mole times the amount of xanone) and a reaction temperature of 5
A continuous reaction was performed at 0 ° C. The obtained crude reaction solution was analyzed.
At the time, ε-caprolactone (CL-M) 28.78%;
Unreacted cyclohexanone (ANO) 0.52%; unreacted
1.31% of peracetic acid (AP); by-product adipic acid (ADA)
0.59%; caprolactone polymer (HB) 0.30
Acetic acid (AC) 21.16%; ethyl acetate (AE) 4
7.34%; water 0%. (2) Production of CL-M from reaction crude liquid according to the above reference example
Example A reaction crude liquid (A) was supplied to a first distillation column shown in FIG.
Under distillation conditions of a bottom temperature of 200 ° C and a top pressure of 100 mmHg
It was subjected to a low-boiling distillation treatment. Unreacted in the first distillation column
Low boiling containing ANO, unreacted peracetic acid, ethyl acetate and acetic acid
The thing is the first distillate (A₁) And supplied to the second distillation tower.
At a bottom temperature of 200 ° C and a top pressure of 100 mmHg.
Unreacted peracetic acid, ethyl acetate, and acetic acid are removed from the second
Fluid (A ₁₁) And unreacted ANO and acetic acid
Part is the second bottoms liquid (A₁₂) Taken out and anti
It is added to the ANO of the reaction system as a raw material and recycled.
Was used for In the first distillation column, the product ε-
Prolactone, by-product adipic acid and caprolactone polymerization
The high boiler containing waste is the first bottoms (A_Two)
It is supplied to the third distillation column and has a bottom temperature of 120 to 200 ° C.
Under the distillation conditions of 50 mmHg at the top pressure,
From the top and the middle stage of the preparation stage
Kuton is the third distillate (A_{twenty one}) As a by-product
Dipinic acid and caprolactone polymer are discharged from the bottom of the column
Liquid (A_{twenty two}) Was discharged as. (3) Details of Operating Conditions of Distillation Column Specifications related to the first distillation column (removing low-boiling distillation column) in this example
, Reflux, distillation and bottom quantitative operation conditions, second distillation column
Reflux, distilling, bottoming (ANO recovery)
Operating conditions and yield (partial disposal), first distillation column
Reflux and distilling (removal) of the third distillation tower (product tower) connected to
Low-boiling recycling), can removal and product extraction (side cut)
Table 1 shows the quantitative operation conditions.

Comparative Example (1) Reference Example for Obtaining a Reaction Crude Liquid to be Distilled Below A reaction crude liquid (B) was obtained in the same manner as in the above example. (2) Comparative example of production of CL-M from the above crude reaction liquid (B) The crude reaction liquid (B) was fed to the first distillation column shown in FIG. 2 and distilled at a bottom temperature of 200 ° C. and a top pressure of 100 mmHg. The mixture was subjected to a low-boiling distillation under the conditions. In the first distillation column, low-boiling substances containing unreacted peracetic acid, ethyl acetate and acetic acid are distilled off as a first distillate (B ₁ ), and unreacted ANO, product CL-M,
ADA and HB were taken out as the first bottoms (B ₂ ) and supplied to the second distillation column. In the second distillation column, unreacted ANO is distilled as a second distillate (B ₂₁ ) under distillation conditions of a bottom temperature of 200 ° C. and a top pressure of 50 mmHg, and is added to the ANO of the reaction system as a reaction raw material. On the other hand, a high-boiling product containing the product CL-M, by-product adipic acid and a polymer of caprolactone is taken out as a second bottoms (B ₂₂ ), supplied to a third distillation column, and supplied to a third distillation column. Temperature 120
The product ε-caprolactone is taken out from the middle stage between the top and the charging stage as a third distillate (B ₂₂₁ ), not at the top, but under the distillation conditions at a top pressure of 50 mmHg within the range of ~ 200 ° C, The by-product adipic acid and caprolactone polymer were discharged from the bottom of the column as a third bottoms (B ₂₂₂ ). (3) Details of operating conditions of distillation column In this comparative example, quantitative operation conditions of charging, refluxing, distilling, and bottoming of the first distillation column (de-boiling distillation column), and the second distillation column (ANO recovery column) ), Quantitative operation conditions of reflux, distilling (ANO recovery) and bottoming (partial disposal), charging, refluxing, distilling (removal) of a third distillation column (product column) connected to the second distillation column. Table 2 shows the quantitative operation conditions for low-boiling recycling, can removal and product withdrawal (side cut).

[0024]

[Table 1]

[0025]

[Table 2]

[0026]

According to the distillation process of the present invention, the deterioration of the hue of the product ε-caprolactone, which was observed in the conventional process, was not observed, and a great effect was obtained. The reason why this deterioration has not been observed is not yet clear, but conventionally, the first, second and third distillation operations are performed in series, and ANO and CL-M coexist until the second distillation column. On the other hand, in the method of the present invention, the first distillation operation is first performed, and the unreacted ANO component and the product CL-M are previously separated in the stage of the first distillation column, and then the respective purified distillations are performed. Is assumed.

[Brief description of the drawings]

FIG. 1 is a block flowchart of a process for producing ε-caprolactone according to the present invention.

FIG. 2 is a block flowchart of a process for producing ε-caprolactone according to a comparative example.

Claims (9)

[Claims] 1. A reaction crude liquid (A) obtained by oxidizing cyclohexanone with an organic peracid is supplied to a first distillation column, and a low-boiling first distillate (A) containing unreacted cyclohexanone is supplied from the top of the column.
₁ ) was distilled off, and a high-boiling first bottoms (A ₂ ) containing ε-caprolactone was obtained from the bottom of the column.
₁ ) is led to a second distillation column following the top of the first distillation column to obtain a second distillate (A ₁₁ ) having a low boiling point and a second bottoms (A ₁₂ ) containing unreacted cyclohexanone. , And the first bottoms (A ₂ ) are led to a third distillation column following the bottom of the first distillation column to obtain a third distillate (A ₂₁ ) containing ε-caprolactone, Wherein the third bottoms (A ₂₂ ) are obtained from the reaction mixture and the second bottoms (A ₁₂ ) are returned to the raw material cyclohexanone. 2. The method for producing ε-caprolactone according to claim 1, wherein the organic peracid is peracetic acid. 3. The reaction crude liquid (A) contains an organic peracid, an acid based on an organic peracid, a solvent of the organic peracid, cyclohexanone, ε-caprolactone, adipic acid and a polymer of ε-caprolactone as main components. Item 3. The method for producing ε-caprolactone according to Item 1 or 2. 4. The method according to claim 1, wherein the first distillate (A ₁ ) contains an organic peracid, an acid based on the organic peracid, a solvent for the organic peracid and cyclohexanone as main components. A method for producing caprolactone. 5. The method for producing ε-caprolactone according to claim 1, wherein the first bottoms (A ₂ ) contains a polymer of ε-caprolactone, adipic acid and ε-caprolactone as a main component. . 6. The ε-caprolactone according to claim 1, wherein the second distillate (A ₁₁ ) contains an organic peracid, an acid based on the organic peracid and a solvent of the organic peracid as main components. Manufacturing method. 7. The process for producing ε-caprolactone according to claim 1, wherein the second bottoms (A ₁₂ ) contains an acid based on an organic peracid and unreacted cyclohexanone as main components. 8. The method for producing ε-caprolactone according to claim 1, wherein the main component of the third distillate (A ₂₁ ) is ε-caprolactone. 9. The third bottoms liquid (A ₂₂ ) contains adipic acid and ε
2. A polymer containing a polymer of caprolactone as a main component.
The method for producing ε-caprolactone according to any one of items 1 to 3, and 5 above.