JPH06172337A - Method for purifying 2-oxetanone - Google Patents

Abstract

PURPOSE:To remove various impurities and obtain high-purity 2-oxetanone by combining a step for recrystallizing the 2-oxetanone from an organic solvent with a step for subjecting the recrystallized compound to contact treatment with a basic compound. CONSTITUTION:2-Oxetanone containing various impurities is recrystallized at -30 to -100 deg.C with an organic solvent such as dimethyl ether or methanol to remove the impurities such as acetic acid or acrylic acid. The resultant recrystallized compound is then brought into contact with a basic compound such as calcium hydroxide or calcium oxide at 0-30 deg.C for 1min to 1hr. Both the steps are suitably combined to carry out the purification of the 2-oxetanone which is a synthetic intermediate for polyesters and organic chemicals. A high- molecular weight polyester, having film-forming and fiber-forming abilities and excellent in physical properties can stably be produced by using this purified 2-oxetanone.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for purifying 2-oxetanone, which is a synthetic intermediate for polyesters and organic chemicals.

[0002]

2. Description of the Related Art 2-Oxetanone is an important compound as a synthetic intermediate for polyesters and organic chemicals. In particular,
Polyester obtained by polymerizing this is known to be a polymer having a function of being decomposed by microorganisms in the natural environment, and will be an increasingly important polymer material in the future. 2-Oxetanone is generally synthesized from ketene and formaldehyde, and among the crude products after its production, acetone, acetic acid, acetic anhydride, and diketene, which is a dimer of ketene, derived from ketene synthetic raw materials as impurities, It also contains a large number of 2-oxetanone ring-opened products and low polymers. These impurities are
When oxetanone is polymerized, it has the effect of lowering the degree of polymerization and the rate of polymerization, so that not only the polymerization time becomes longer, but also polyesters that are fragile in physical properties are obtained. Therefore, it is indispensable to remove these impurities in order to efficiently synthesize a polyester having a high degree of polymerization with good physical properties in a shorter time.

[0003] Conventionally, many studies have been made on the purification of 2-oxetanone. For example, US-260
2802, a method for decomposing and removing acetic anhydride with alcohol,
U.S. Pat.No.-2759003 describes a method for removing acetic acid and acetic anhydride with sodium hydroxide, British Patent-904341 and German patent-1239287 describes a method for decomposing and removing acetic anhydride with water, German Patent-1954719 and Japanese Patent Publication No. Shows a method for removing acidic substances with metal oxides and non-metal oxides, and German Patent No. 2135190 and Japanese Patent Publication No. 50-13260 show a method for removing acidic substances with hydroxides of alkaline earth metals. There is. It is clear that these purification methods are effective in removing acids and acid anhydrides, but it is impossible to remove all the various impurity components contained in 2-oxetanone. Therefore, as a result, it is currently difficult to stably obtain a high molecular weight polyester having good physical properties.

[0004]

As described above, since it is difficult to stably synthesize a high molecular weight polyester having film-forming and fiber-forming ability by the conventional purification technique for 2-oxetanone, 2-oxetanone is difficult to synthesize. Further, there is a demand for a purification method capable of surely achieving high purity.

[0005]

As a result of intensive studies to solve the above problems, the present inventors have removed various impurities in 2-oxetanone to stably obtain a high molecular weight polyester. The present invention has been completed by finding out a purification method of 2-oxetanone of high purity which can be obtained.

That is, the present invention is a method for purifying 2-oxetanone, which comprises (a) a step of recrystallizing from an organic solvent and (b) a step of contacting with a basic compound.

As the organic solvent used in the recrystallization step of the present invention, acetic acid which is an impurity component in 2-oxetanone, acetic anhydride, diketene, acetone, acrylic acid, and a ring-opened product of 2-oxetanone, 2 An organic compound capable of dissolving at least one kind such as a low polymer of oxetanone, having a melting point lower than that of 2-oxetanone, and having no significant chemical action on 2-oxetanone is used.

Specifically, ethers such as dimethyl ether, diethyl ether and isopropyl ether; cyclic ethers such as tetrahydrofuran and 1,3-dioxane; methanol, ethanol, 1-propanol, 2-
Alcohols such as propanol, 1-butanol, 2-butanol; ketones such as acetone, methyl ethyl ketone, methyl propyl ketone; dichloromethane, chloroform, dibromomethane, 1,2-dimethoxyethane,
Halogen compounds such as methyl iodide; aromatic hydrocarbons such as toluene, m-xylene and chlorobenzene; acetonitrile, ethyl acetate, dimethylformamide, carbon disulfide and the like are preferably used. Among the above organic solvents, a solvent having a boiling point of 100 ° C. or lower is particularly preferably used because it is easily separated from 2-oxetanone.

With respect to the method for recrystallizing 2-oxetanone from an organic solvent, a conventionally known method can be used without particular limitation. However, rapid recrystallization is not preferable because the crystal is formed with impurities contained in the crystal.
On the other hand, very slow crystallization causes a large loss in time. The crystallization rate can be adjusted by the solution concentration and the crystallization temperature. Preferred crystallization conditions are a melting point of 2-oxetanone, a temperature range of -31.2 ° C to -100 ° C, and 20 to 95% by volume of 2-oxetanone.
Is the concentration range. As a means for achieving such a temperature, a known cooling method such as a method using heat of vaporization of a liquefied gas can be used without any limitation. In order to carry out the recrystallization more efficiently, a method such as adding a seed crystal or leaving the seed crystal during repeated recrystallization can be preferably adopted.

Recrystallization can be performed with only a single organic solvent, but it is desirable to use a plurality of organic solvents several times in order to remove various impurities. When using a plurality of organic solvents, it is effective to use an organic solvent having a polarity larger than that of 2-oxetanone and a smaller organic solvent in combination. Here, a dielectric constant, a solubility parameter, or the like is generally used as a physical property value that is a measure of polarity. For example, by recrystallizing from diethyl ether, which has a smaller polarity than 2-oxetanone, impurities having a smaller polarity can be removed. Next, recrystallization is performed from methanol, which has a higher polarity than that of 2-oxetanone, to remove impurities having a high polarity. As the number of times of recrystallization increases, the purity of 2-oxetanone improves, but the recovery rate decreases. Therefore, the range of 1 to 5 times with one organic solvent is suitable.

Although many impurity components are removed by recrystallization, the main components of the impurities, acetic acid and acrylic acid, have high melting points of 16.7 ° C. and 13 ° C., respectively, so their contents are high. When it is large, it may be difficult to separate because it crystallizes at the same time as 2-oxetanone. Therefore, in order to remove these acid components, a step of contact treatment with a basic compound is performed.

In the step of contacting with the basic compound, the method described in the conventionally known method for purifying 2-oxetanone can be used without any limitation.

As a basic compound that can be preferably used,
There are hydroxides and carbonates of alkali and alkaline earth metals, and metal oxides and non-metal oxides. Specifically, hydroxides and carbonates of alkali metals such as sodium hydroxide, sodium carbonate, potassium hydroxide, potassium carbonate, lithium hydroxide; calcium oxide, calcium carbonate, calcium hydroxide, magnesium hydroxide, oxidation Oxides, hydroxides or carbonates of alkaline earth metals such as magnesium, beryllium oxide, barium oxide, strontium oxide; metal oxides such as lead oxide, manganese dioxide, tungsten dioxide and vanadium pentoxide; calcium hydride, Examples thereof include hydrides such as sodium hydride, lithium aluminum hydride, and sodium borohydride.

There are two types of contact treatment with a basic compound: heterogeneous treatment and homogeneous solution treatment. As the heterogeneous treatment, a solid basic compound and 2-oxetanone are mixed and stirred or a column filled with the basic compound is mixed with 2-oxetanone.
A method of flowing down an organic solvent solution of oxetanone or 2-oxetanone is suitably carried out. The shape of the solid basic compound is not particularly limited, but in order to increase the surface area and obtain a contact effect, it may be powdery, porous granular, or attached to a carrier such as pumice or celite. preferable. Separation of 2-oxetanone after the contact treatment with the basic compound is generally carried out by filtration or distillation. In the case of column treatment, it is a more preferable treatment method because a separation operation is unnecessary. .

The uniform solution treatment is carried out by dissolving 2-oxetanone in water or an organic solvent, adding an aqueous solution of a basic compound or an organic solvent solution thereto, and mixing and stirring the mixture. When the treatment is carried out in an aqueous solution, the state of removal of the acidic substance can be confirmed by the change in the pH of the treatment solution. However, when 2-oxetanone is used as an aqueous solution, hydrolysis of 2-oxetanone also partially proceeds, and therefore it is preferable to perform the treatment at low temperature and in a short time. Generally, it is preferable to perform the treatment within the range of 0 ° C. to 30 ° C. and 1 minute to 1 hour because the loss of 2-oxetanone is small.
In the case of homogeneous solution treatment, it is necessary to separate 2-oxetanone from the treatment liquid after the treatment. As a means for separating the 2-oxetanone, a generally known separating means such as a method for extracting and separating the treated 2-oxetanone using a different solvent that is not mixed with the processing solvent, a method for separating by distillation, etc. Alternatively, they are used in combination.

(A) a step of recrystallizing from an organic solvent,
Basically, the order of (b) the step of contacting with the basic compound is not particularly limited. However, 2-oxetanone is hydrolyzed by water to give 3-
May produce hydroxypropionic acid. This 3
-Hydroxypropionic acid, like acetic acid and acrylic acid, has an inhibitory effect on polymerization, and therefore it must be removed. Removal of 3-hydroxypropionic acid
It can be carried out relatively easily not only by contact treatment with a basic compound but also by distillation or solvent extraction operation. Although 2-oxetanone is generally subjected to a distillation treatment after purification and immediately before it is used for polymerization, as long as this distillation is performed, the step (a) and the step (b) may be performed before or after. There is no problem at all. However, in the (b) contact treatment step with a basic compound, when performing a heterogeneous treatment using a solid basic compound such as a metal or non-metal hydride or oxide, not only an acidic substance, Even water can be removed. In this case, it is also possible to carry out the step (a) prior to the step (b), and after the step (b) is finished, it is subjected to polymerization without distillation. Therefore, it is preferable to carry out the step (a) prior to the step (b),
It is also an advantageous method.

The degree of purification of 2-oxetanone by the purification method of the present invention can be confirmed by liquid chromatography or gas chromatography under ordinary analytical conditions. 2-Oxetanone causes polymerization, conversion to acrylic acid, and the like by heat, and therefore analysis is preferably performed by liquid chromatography at low temperature.

[0018]

INDUSTRIAL APPLICABILITY The purification method of the present invention is a method which can surely highly purify 2-oxetanone containing various impurities.

The method for purifying 2-oxetanone of the present invention is as follows:
(A) a step of recrystallizing from an organic solvent, and (b) a step of contacting with a basic compound, and the recrystallization step of (a) has been disclosed as a method for purifying 2-oxetanone. It is a new method that has not been done. The step of contacting with the basic compound (b) is a method that has been disclosed conventionally. Both the steps (a) and (b) may be performed independently.
It has some effect on the purification of 2-oxetanone. However, it is difficult to reliably, stably and highly purify 2-oxetanone containing various impurities. However,
By combining the steps (a) and (b),
A remarkable refining effect appears.

By using 2-oxetanone purified by the purification method of the present invention, a high molecular weight polyester having film forming ability and fiber forming ability and excellent physical properties can be stably obtained.

[0021]

The present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

Example 1 (1) Recrystallization of 2-oxetanone In a 300 ml flask, commercially available crude 2-oxetanone 4 was used.
0 ml and 20 ml of diethyl ether were added and the mixture was cooled in a dry ice / ethanol bath (-72 ° C) to crystallize 2-oxetanone. After crystallization, the diethyl ether phase containing the impurity component was separated and removed by decantation. To the crystals, add 20 ml of fresh diethyl ether,
It was dissolved at room temperature. Before the crystals of 2-oxetanone are completely dissolved, cool in a dry ice / ethanol bath,
Recrystallization was performed using the undissolved crystal as a seed crystal. The same recrystallization operation was repeated twice more with diethyl ether. Next, the same recrystallization operation was performed twice using methanol.

(2) Contact Treatment of 2-Oxetanone with Basic Compound After Recrystallization After removing the methanol phase, the crystal was heated to room temperature and melted. 500 ml of water was added to the melted 2-oxetanone to dissolve it. While cooling this aqueous solution in an ice bath,
Neutralize using a specified aqueous sodium hydroxide solution,
When the pH reached 9, 200 ml of chloroform was added to extract 2-oxetanone. Further, the same extraction operation is performed twice, and the extraction liquids are combined (total volume 600 ml),
Dried over magnesium sulfate. After filtration, the solvent was evaporated from the filtrate under reduced pressure and then distilled. 2-Oxetanone was obtained as a distillate fraction of about 30 ° C./3 mmHg.
The total recovery was 75%.

The purity of 2-oxetanone was evaluated using liquid chromatography.

Liquid Chromatography Conditions Column: ODS Column 30 cm × 1 + 15 cm
x1 temperature; 20 ° C. mobile phase; acetonitrile: water = 8: 2 flow rate; 1 ml / min detection; UV detector (206 nm) Most impurities other than acetic acid were removed by recrystallization treatment. Subsequent sodium hydroxide treatment significantly reduced acetic acid.

The purities obtained by liquid chromatography are shown in Table 1.

(3) Polymerization Recrystallization-purified by sodium hydroxide treatment 2-
Take 2 g of oxetanone in a test tube for polymerization, and then use 5 μl of a tetramethylammonium acetate / acetonitrile solution as an initiator (2-oxetanone: initiator = 30,0).
(00: 1 molar ratio) was added and polymerization was carried out at 40 ° C. Two
After 0 hours, chloroform was added to the polymerization system to dissolve the produced polyester. Using a chloroform solution of the polymerization reaction product, the number average molecular weight and the weight average molecular weight of the produced polyester portion were determined by size exclusion chromatography. Most of the remaining chloroform solution was poured into a large excess of methanol to precipitate / precipitate the polyester. After the precipitated polyester was dried, it was weighed to determine the polymerization rate.

The results of the number average molecular weight, the weight average molecular weight and the polymerization rate are also shown in Table 1.

Comparative Example 1 Commercially available crude 2-oxetanone was not recrystallized but Example 1
In the same manner as in (2) in (2) above, contact treatment with a basic compound was performed for purification. Then, the purified product was polymerized in the same manner as in (3) of Example 1. The results are also shown in Table 1. Comparative Example 2 2-oxetanone obtained by only recrystallizing (1) in Example 1 was polymerized in the same manner as in (3) of Example 1, and the results are also shown in Table 1.

[0030]

[Table 1]

Examples 2-4, Comparative Example 3 (1) Recrystallization of 2-oxetanone In a 300 ml flask, commercially available crude 2-oxetanone 4 was used.
0 ml and 20 ml of each solvent shown in Table 2 were added, and the mixture was cooled in a dry ice / ethanol bath (-72 ° C) to recrystallize 2-oxetanone. After crystallization, the solvent phase containing the impurity component was separated and removed by decantation. The same recrystallization operation was performed by using a single solvent or a plurality of solvents as many times as shown in Table 2.

(2) Contact Treatment with Basic Compound of 2-Oxetanone after Recrystallization The crystal after decantation was heated to room temperature and melted, and then 500 ml of water was added and dissolved. This aqueous solution was neutralized with an aqueous 6N sodium hydroxide solution while cooling with an ice bath, and when the pH reached 9, 200 ml of chloroform was added to extract 2-oxetanone. Further, the same extraction operation was performed twice, and the extracts were combined (total amount: 600 ml) and dried over magnesium sulfate. After filtration, the solvent was evaporated from the filtrate under reduced pressure and then distilled. 2-Oxetanone was obtained as a fraction in the range of 30 ° C / 3mmHg to 52 ° C / 13mmHg.
Total recoveries ranged from 60 to 90%.

The purity of 2-oxetanone was evaluated by liquid chromatography in the same manner as in (2) of Example 1. The purities obtained by liquid chromatography are also shown in Table 2.

(3) Polymerization 2 purified by the above recrystallization-basic compound contact treatment
-Oxetanone was polymerized in the same manner as (3) of Example 1. The results of the number average molecular weight, the weight average molecular weight, and the polymerization rate of the produced polyester are shown in Table 3.

Comparative Example 3 2-oxetanone obtained by recrystallizing (1) in Example 4 was polymerized in the same manner as in (3) of Example 1, and the results are also shown in Table 3.

[0036]

[Table 2]

[0037]

[Table 3]

Examples 5 to 7 (1) Recrystallization of 2-oxetanone In the same manner as in (1) of Example 1, recrystallization of 2-oxetanone was performed.

(2) Treatment of 2-oxetanone with a basic compound after recrystallization After removing the methanol phase, the crystals were heated to room temperature and melted. To the melted 2-oxetanone, 100 ml of diethyl ether was added and dissolved. Magnesium sulfate was added to this solution, and the mixture was stirred at room temperature for 2 hours and dried. The solid basic compound shown in Table 4 was added to a diethyl ether solution of 2-oxetanone from which magnesium sulfate was separated by filtration, and the mixture was stirred at room temperature for 3 hours. Then, the basic compound was separated by filtration, and diethyl ether was evaporated under reduced pressure, and then 2-oxetanone was obtained by distillation.

The purity of 2-oxetanone was evaluated by liquid chromatography in the same manner as in Example 1 and shown in Table 4.
Also described in.

(3) Polymerization 2 purified by the above recrystallization-basic compound contact treatment
-Oxetanone was polymerized in the same manner as (3) of Example 1. The number average molecular weight, the weight average molecular weight, and the polymerization rate of the produced polyester are shown in Table 5.

Comparative Examples 4 to 6 2-oxetanone obtained by subjecting (2) in Examples 5 to 7 to the contact treatment with the basic compound is the same as in Example 1 (3).
Polymerization was carried out in the same manner as in, and the results are also shown in Table 5.
The purity is shown in Table 4.

[0043]

[Table 4]

[0044]

[Table 5]

Claims (1)

[Claims] 1. A process of (a) recrystallizing from an organic solvent,
And (b) a step of contact-treating with a basic compound, the method for purifying 2-oxetanone.