CN101519398B - Preparation of 4-fluoro-1,3-dioxolane-2-one - Google Patents

Abstract

The present invention provides a method for producing 4-fluoro-1,3-dioxolan-2-one with reduced halide content in high yield. The production method of this 4-fluoro-1,3-dioxolane-2-one is characterized in that it comprises: using a fluorinating agent in an organic solvent to react 4-chloro-1,3-dioxolane-2- A step (A) of fluorinating a ketone; a step (B) of rectifying the obtained reaction product liquid containing 4-fluoro-1,3-dioxolan-2-one; and treating with an antacid The process (C).

Description

Process for producing 4-fluoro-1,3-dioxolan-2-one

technical field

The present invention relates to a method for producing 4-fluoro-1,3-dioxolan-2-ones with reduced halide content in high yield.

Background technique

4-Fluoro-1,3-dioxolan-2-one (hereinafter also referred to as "F-EC") is used as a solvent for electrolyte solutions of various batteries, taking advantage of its high dielectric constant.

As a method for producing such F-EC, in addition to the method of directly fluorinating 1,3-dioxolan-2-one with fluorine gas as a starting material, it is also known to use a metal fluoride in approximately the same amount As a fluorinating agent, a method of substituting a chlorine atom at the 4-position of 4-chloro-1,3-dioxolane-2-one (hereinafter also referred to as "Cl-EC") with a fluorine atom (Patent Documents 1 to 3 ).

In Patent Document 1, it is described that Cl-EC and potassium fluoride are mixed and reacted to obtain F-EC in a yield of 70%, but basic conditions such as reaction solvent, reaction temperature, and reaction time are not disclosed. .

In Patent Documents 2 and 3, using 1.2 equivalents of potassium fluoride, Cl-EC and potassium fluoride were reacted in acetonitrile at 80-85°C for 11 hours, and a compound containing the starting material Cl-EC was obtained in a yield of 87.5%. Crude F-EC (if recrystallized, F-EC could be collected at 85% of crude). However, since in this method, Cl-EC is used as the initial raw material and chlorine atoms are replaced by fluorine atoms, unreacted Cl-EC and by-products in the fluorination reaction remain in the crude F-EC after the reaction. Hydrogen chloride (HCl) produced, and chlorine radicals such as chlorine (Cl ₂ ) present as impurities in the starting material Cl-EC. In fact, the chloride ion concentration in the F-EC obtained by rectification after filtering the fluorination reaction product was as high as 189 ppm.

If such F-EC with residual chlorine radicals is used for secondary batteries, etc., the cycle characteristics will be lowered, so it is necessary to control the concentration of chlorine radicals in the purified F-EC to 100ppm or less in terms of chloride ions , preferably less than 50ppm, more preferably less than 20ppm, but because the dielectric constant of F-EC is high, and Cl ^- , HCl, and _Cl in these chloride radicals cannot be sufficiently removed by distillation, these chloride radicals are likely to remain in the solvent in or refined.

In order to remove these chlorine ions, Patent Document 2 employs a method of recrystallizing F-EC from a specific organic solvent, and Patent Document 3 employs a method of contacting a specific low-polarity solvent to precipitate F-EC.

[Patent Document 1] International Publication No. 98/15024 Pamphlet

[Patent Document 2] Japanese Patent Laid-Open No. 2007-8825

[Patent Document 3] Japanese Patent Laid-Open No. 2007-8826

Contents of the invention

The object of the present invention is to provide a method for producing F-EC, which uses Cl-EC as an initial material and fluorinates it with a fluorinating agent, which can maintain high yield and high purity, and reduce the halide content.

The production method of 4-fluoro-1,3-dioxolane-2-one of the present invention is characterized in that it comprises: using a fluorinating agent in an organic solvent to react 4-chloro-1,3-dioxolane- Step (A) of fluorinating 2-ketone; Step (B) of rectifying the obtained reaction product liquid containing 4-fluoro-1,3-dioxolan-2-one; and using an antacid Step (C) of processing.

In the production method of the present invention, it is preferable to include a step (D) of removing the organic solvent after the fluorination step (A) and before the rectification step (B).

Antacids are preferably alkaline earth metal oxides, alkaline earth metal bicarbonates, alkaline earth metal phosphates, alkaline earth metal carboxylates, alkali metal bicarbonates, alkali metal phosphates, alkali metal carboxylates , silicon oxide, aluminum oxide, silicon-aluminum composite oxide, or two or more of them.

The anti-acid agent is preferably an acid-resistant porous substance, more preferably silicon oxide, aluminum oxide, silicon-aluminum composite oxide, or two or more of them.

The fluorinating agent is preferably a compound represented by the formula MF (wherein, M is an alkali metal atom or a quaternary ammonium cation).

Furthermore, from the viewpoint of suppressing the decomposition of carbonates, it is preferable to adjust the pH to 6 to 7 and perform the rectification step (B) under such conditions.

In the present invention, the so-called "halogen" refers to hydrogen chloride (HCl) and chlorine (Cl ₂ ) produced by-products in the fluorination reaction, and chloride ions (Cl ^- ) present as impurities in the initial raw material Cl-EC Chlorine such as; fluorine ion (F ^- ) or fluorine (F ₂ ) or hydrogen fluoride (HF) from fluorinating agent; fluoride ion (F ^- ) from by-product impurity in the reaction, etc. Wherein, unreacted Cl-EC and F-EC as the target product are not included in the halide.

Invention effect

By adopting the production method of the present invention, F-EC with reduced halide content can be produced while maintaining high purity.

Detailed ways

The production method of F-EC of the present invention includes the following fluorination step (A), rectification step (B) and antacid treatment step (C).

The fluorination step (A) is a step of fluorinating 4-chloro-1,3-dioxolan-2-one with a fluorinating agent in an organic solvent.

The rectification step (B) is a step of rectifying the obtained reaction product liquid containing 4-fluoro-1,3-dioxolan-2-one.

The antacid treatment step (C) is a step of treating with an antacid. The antacid treatment step is performed at least once during the step (A), before the step (A), after the step (A), during the step (B), before the step (B), and after the step (B).

Each step will be described below.

Fluorination process (A)

The fluorination of Cl-EC is carried out by fluorinating Cl-EC with a fluorinating agent in an organic solvent.

The reaction formula of the fluorination step (A) in the present invention is as follows.

Wherein, both the initial substance Cl-EC and the target substance F-EC are liquids.

As the fluorinating agent, in addition to hydrofluoric acid and fluorine gas, a compound represented by the formula MF (where M is an alkali metal atom or a quaternary ammonium cation) is preferable because it is easy to obtain and the efficiency of the fluorination reaction is high.

Examples of the compound represented by MF include alkali metal fluorides such as KF, NaF, CsF, and LiF, compounds of quaternary ammonium cations and fluorine anions, and the like. Among them, alkali metal fluorides are preferable because of their ease of handling and high reactivity, and KF is particularly preferable because of their high reactivity.

The fluorination step (A) is performed in an organic solvent. Since the presence of water lowers the reactivity, it is preferably carried out in a substantially anhydrous state.

As the organic solvent, an aprotic organic solvent is preferable, and a polar organic solvent is more preferable from the viewpoint of increasing the reaction rate. Specifically, acetonitrile (AN), tetrahydrofuran (THF), N-methylpyrrolidone (NMP), dichloromethane, chloroform, nitromethane, N,N-dimethylformamide, N,N-dimethyl Acetamide, 1,3-dimethyl-2-imidazolinone, glyme solvents, acetone, toluene, ethyl acetate and the like. Among them, acetonitrile is preferable from the viewpoint of high dielectric constant and low viscosity, and N-methylpyrrolidone is preferable from the viewpoint of high dielectric constant and appropriate boiling point.

From the viewpoint of a good conversion (yield), the amount of the fluorinating agent used relative to Cl-EC is preferably 1 equivalent or more, preferably 1.5 equivalents, of the fluorinating agent relative to 1 equivalent of chlorine atoms in Cl-EC. or more, particularly preferably 2 equivalents or more. The upper limit is not particularly limited, but is 3 equivalents from the viewpoint of ease of post-processing.

From the viewpoint of easy handling, the reaction temperature is preferably 30°C or higher, more preferably 50°C or higher. The upper limit is the boiling point of the organic solvent used.

In addition, as a catalyst, a compound of a quaternary ammonium cation and a halide anion represented by the formula (1) can be used.

R ₄ N ⁺ X ^- (1)

In the formula, R is an alkyl group, phenyl group, benzyl group or cycloalkyl group with 1 to 7 carbon atoms; X is a halogen atom. When this catalyst is used, F-EC can be obtained in a high yield in a short time.

As the catalyst, a compound in which R is an alkyl group having 1 to 7 carbon atoms in the formula (1) is preferable from the viewpoint of ease of handling.

In addition, the halogen atom constituting the catalyst is preferably a fluorine atom from the viewpoint of high initial reactivity.

Specific examples of the compound (1) of a quaternary ammonium cation and a halide anion as a catalyst include, for example, tetramethylammonium fluoride, tetraethylammonium fluoride, tetrapropylammonium fluoride, tetrabutylammonium fluoride, etc. .

From the viewpoint of high reactivity, the catalyst is preferably used in an amount of 0.01 to 0.5 equivalents to the fluorinating agent.

The reaction between the starting material Cl-EC and the fluorinating agent is carried out in an equimolar ratio, but from the viewpoint of reactivity, it is preferable to use 1 to 2 moles of the fluorinating agent, more preferably 1 to 1.5 moles, relative to 1 mole of Cl-EC. .

A wide range can be used for the concentration of the starting material Cl-EC in the organic solvent, but it is preferably 5% by mass or more, more preferably 20% by mass or more, from the viewpoint of ease of reaction control. The upper limit is preferably 60% by mass, more preferably 50% by mass.

When the catalyst (compound 1) is used, the reaction is faster than the reaction of the conventional production method, and the reaction is completed in less than 1/2 of the conventional reaction time under the same yield. The yield is also 80-85%, which is equal to or higher than the existing method.

Distillation process (B)

The rectification step is a step of treating the F-EC reaction product liquid obtained in the fluorination step (A) using a rectification column to obtain F-EC with high purity. F-EC was obtained as a fraction at 74°C (1 mmHg). In addition, the boiling point of Cl-EC is 100°C (1mmHg), and it can be separated by rectification.

In addition, the following organic solvent removal step (D) or solid content removal step (E) may be inserted before subjecting to the rectification step (B).

Moreover, since the F-EC reaction product liquid obtained by the fluorination step (A) is sometimes acidic (for example, pH 1 to 2), in this case, from suppressing F-EC or a small amount of remaining Cl-EC and ethylene carbonate From the viewpoint of decomposing the ester (EC), it is preferable to adjust the pH to 6 to 7, and to perform the rectification step (B) under this condition.

The pH can be adjusted by adding antacids to the F-EC reaction product liquid obtained in the fluorination step (A), and removing acids (HF, HCl, etc.) by adsorption (with the following antacid treatment step (C) In addition, it is also possible to use a method of evaporating the acid by heating to a temperature that does not decompose such as F-EC (for example, 50 to 130°C), a method of evaporating the acid under reduced pressure, adding a pH adjuster or a basic compound (such as Sodium bicarbonate, potassium bicarbonate, sodium carbonate, potassium carbonate, calcium carbonate, cesium carbonate, sodium hydroxide, potassium hydroxide, etc.) are adjusted by one method or in combination of two or more methods.

Antacid treatment process (C)

This step is a step of removing halides present in the reaction system with an antacid.

Through antacid treatment, halides can be removed efficiently, and the remaining halides in the final product (refined F-EC) can be reduced to less than 10 ppm, further reduced to less than 1 ppm, and further reduced to less than 0.1 ppm.

As antacids, compounds having properties of adsorbing and reacting with halides are effective.

Examples of compounds having the ability to adsorb halides include metal compounds, inorganic porous substances, and the like. As metal compounds, oxides, hydroxides, carboxylates, carbonates, bicarbonates, silicates, phosphates, phosphites, borates, etc. of alkali metals or alkaline earth metals are preferably used, Periodic Table VIB Oxides of group metals (such as Cr, Mo, W, etc.), basic carboxylates, basic carbonates, basic sulfates, tribasic sulfates, basic phosphites, etc. Specific examples of such metal compounds include magnesium oxide, calcium oxide, magnesium hydroxide, calcium hydroxide, barium hydroxide, lithium carbonate, sodium carbonate, potassium carbonate, lithium bicarbonate, sodium bicarbonate, and potassium bicarbonate. , magnesium carbonate, calcium carbonate, barium carbonate, calcium silicate, potassium acetate, calcium acetate, calcium stearate, zinc stearate, calcium phosphite, iron oxide, tin oxide, lead red, lead white, dibasic o Lead phthalate (dibasic lead phthalate), dibasic lead carbonate, aluminum hydroxide, etc. In addition, as the inorganic porous substance, for example, silicon oxides such as silica, aluminum oxides such as alumina, natural zeolites, synthetic zeolites, molecular sieves (3A, 4A, 5A, 13X, etc.), silicon oxides such as various hydrotalcites, etc., can be used. In addition to aluminum composite oxides and the like, various commercially available porous antacids and the like can be used. Examples of commercially available porous antacids include an inorganic porous body formed from an amorphous silica-alumina gel (Secado, trade name, manufactured by Shinagawa Chemical Industry Co., Ltd.), a hydrated porous body containing aluminum and iron ( Mizusawa Chemical Co., Ltd. product Alpha Matt, brand name) and the like.

These antacids may be used alone or in combination of two or more.

In the present invention, in particular, oxides of alkaline earth metals, bicarbonates of alkaline earth metals, phosphates of alkaline earth metals, carboxylates of alkaline earth metals, bicarbonates of alkali metals, An antacid with low nucleophilicity such as alkali metal phosphate, alkali metal carboxylate, silicon oxide, aluminum oxide, silicon-aluminum composite oxide, or two or more of them.

In addition to trisodium phosphate, sodium acetate, potassium acetate, and potassium bicarbonate, particularly preferred antacids are also preferably acid-resistant porous substances, more preferably silicon oxides, aluminum oxides, silicon-aluminum composite oxides, or two of them. more than one porous substance.

The antacid treatment process (C) is carried out in the following stages (1) to (6), specifically before the process (A), during the process (A), after the process (A), before the process (B), and in the process ( B) and at least one stage after the step (B) is carried out.

(1) Before the fluorination step (A):

That is, Cl-EC as a starting material is treated with an antacid. Due to the presence of chloride radicals (Cl ⁻ , HCl, Cl _{2 ,} etc.) generated during the synthesis in the starting material Cl-EC, these halide radicals are removed.

(2) In the fluorination process (A):

In the fluorination process (A), in addition to chlorine radicals in the initial raw materials, fluorine (F ₂ ), hydrogen fluoride (HF), and fluoride ions (F ^- ) from fluorinating agents (fluorine gas, hydrofluoric acid, MF, etc.) In addition to these halides, fluoride ions (F ^- ) etc., which are impurities derived from by-products of the fluorination reaction, exist, so these halides are removed.

(3) After the fluorination step (A):

In the reaction product obtained in the fluorination step (A), the same halides as in (2) above exist, so these halides are removed.

(4) Before the rectifying process (B):

Before the rectification step (B), the reaction product obtained by the fluorination step (A) is sometimes subjected to removal of the organic solvent (distillation), or removal of the antacid agent when at least one antacid treatment has been performed ( filter) processing.

Before the rectification step (B), the concentration varies slightly depending on whether the organic solvent removal step (D) and the solid content removal step (E) described later are performed, but since the same halogen radicals as in the above (3) exist, So remove those halides. Also, as described above, it is difficult to remove chlorine radicals (Cl ⁻ , HCl, Cl _{2 ,} etc.) and fluoride radicals (F ⁻ , HF, F _{2 ,} etc.) in distillation (rectification).

(5) In the rectifying process (B):

In the rectification step (B), since there are halides derived from the decomposition of impurities, these halides are removed.

(6) After the rectifying process (B):

After the rectification step (B), there are halides other than the halides evaporated or distilled off by the heating or decompression of the rectification, so these halides are removed.

The present invention is characterized in that antacid treatment is performed in at least one of the stages (1) to (6). If the antacid treatment is performed only after the rectification step (B), impurities may be mixed, so it is preferable to perform the antacid treatment at the stages (1) to (5) as much as possible.

The antacid treatment includes, for example, the following methods: (I) adding an antacid to the starting material, the reaction product, the residue after removal of the organic solvent, and the fraction after rectification, and mixing them well; (II) using A method in which the initial raw material, the reaction product liquid, the residue after removal of the organic solvent, and the fraction after rectification are passed through a column filled with an antacid; /or the method of filling antacid in rectification column etc. The treatment temperature in these cases is usually about room temperature to 130°C, preferably about room temperature to 100°C. Also, for example, when amorphous silica-alumina gel is used as an antacid agent, the temperature is preferably about 40 to 100°C. If the treatment temperature is too high, it may cause the decomposition of the initial substance Cl-EC or the target substance F-EC. The processing time is usually about 3 to 5 hours. The method of (III) is particularly preferable from the viewpoint of easiness of scale-up.

The amount of antacids used varies depending on the type of Cl-EC or F-EC to be treated, the type of antacids used, the remaining amount of halides, the content of polyfluorinated compounds, etc., and cannot be generalized. Normally, it is preferably about 1 to 50 parts by mass relative to 100 parts by mass of Cl-EC or F-EC, and more preferably about 1 to 10 parts by mass in view of cost.

From the viewpoint of improving the reaction rate in the fluorination step, the antacid treatment step (C) is preferably treated before the fluorination step (A), that is, the starting material (Cl-EC) is treated in advance.

In addition, it is preferable to perform the antacid treatment step (C) after the fluorination step (A) and before the rectification step (B), since it is advantageous in minimizing halogen radicals.

In addition, it is preferable to perform the antacid treatment step (C) in the rectification step (B) (that is, at the same time) because it is easy to scale up.

Organic solvent removal process (D)

From the viewpoint of suppressing the decomposition of F-EC, the distillation temperature is 100° C. or lower, preferably under reduced pressure.

Solid component removal process (E)

The antacid can be removed by a solid component removal method such as filtration immediately after the antacid treatment step (C) or in a subsequent step.

The F-EC obtained in this way has high purity (99% or more, further 99.5% or more), and the content of impurities such as halides is reduced to less than 1 ppm. As a result, coloring does not occur over a long period of time, and the solvent used as the electrolytic solution is a solvent that eliminates hindering factors.

In addition, when the degree of removal of impurities such as halides does not reach the target (coloring, etc.), the antacid treatment step (C) and the rectification step (B) may be repeated.

Example

The following examples are given to illustrate the production method of the present invention, but the present invention is not limited to these examples.

The analytical methods used in the following examples are as follows.

(1) NMR

Device: AC-300 manufactured by BRUKER

Determination conditions:

¹⁹ F-NMR: 282MHz (benzotrifluoride=-62.3ppm)

¹ H-NMR: 300MHz (benzotrifluoride=7.51ppm)

(2) Gas Chromatography (GC)

Device: Shimadzu Corporation GC-17A

Column: DB624 (manufactured by J&W scientific)

Measuring conditions: 100°C → hold for 5 minutes → increase temperature at 10°C/min → 230°C

Example 1 (antacid treatment before step (A))

Antacid treatment process (C)

To 500g (4.08mol, pH1～2) Cl-EC (manufactured by Aldrich), add 100g of amorphous silica-alumina gel (secado KW, neutral silica gel, trade name, manufactured by Shinagawa Chemical Industry Co., Ltd.), Stir at room temperature for 2 hours.

Solid component removal process (E)

After the stirring was completed, the amorphous silica-alumina gel was removed by filtration to prepare antacid-treated Cl-EC (pH 6-7).

Fluorination process (A)

A reflux tube was attached to the upper part of a 3L glass three-necked flask equipped with a stirring device, 355 g (6.12 mol) of spray-dried potassium fluoride was added, and the water was removed by flame drying while stirring under vacuum. Then, 1.3 L of acetonitrile and 500 g (4.08 mol) of antacid-treated Cl-EC were added and stirred using a syringe. The reaction was carried out at a reaction temperature of 85°C, and the progress was analyzed by gas chromatography (GC). After reacting for 6 hours, it was confirmed that the peak of the raw material disappeared, and the reaction ended. After the reaction, salts (potassium fluoride, potassium chloride, etc.) in the reaction product were filtered to obtain a reaction product solution (pH 2-3).

Organic solvent removal process (D)

Acetonitrile was distilled off from the obtained reaction product liquid using an evaporator. At this time, a small amount of acid by-product in the fluorination reaction is also volatilized.

Distillation process (B)

The residue (pH3-4) was subjected to rectification using a thorn-shaped separation (vigreux, rigreu-one) tube to obtain colorless and transparent F-EC as a 74° C. (1 mmHg) fraction with a yield of 63% and a GC purity of 99.8%.

¹⁹ F-NMR and ¹ H-NMR analysis were carried out to identify the obtained F-EC.

¹⁹ F-NMR (deuterated acetone): -122.6～-122.3ppm (1F)

¹ H-NMR (deuterated acetone): 4.54～4.91ppm (2H), 6.42～6.68ppm (1H)

Next, the following tests were performed on the obtained purified F-EC. The results are shown in Table 1.

(with or without coloring)

It was stored at room temperature for one day, and the presence or absence of coloring was visually judged.

◯: No coloring was observed.

×: Coloring was observed.

(anion analysis)

As a device, the concentration of anions (Cl ^- , F ^- , I ^- , NO ₂ , NO ₃ , PO ₄ , SO ₄ ) was measured using an ion chromatograph HIC-20ASUPER (detection limit: 1 ppm) manufactured by Shimadzu Corporation. .

(Metal ion analysis)

As a device, the concentration of metal ions (Al, Fe, Ca, K, Mg, Na, Ni, Zn) was measured using an emission spectrometer SPS3000ICP (detection limit: 10 ppm) manufactured by Seiko Instrument Co., Ltd.

(pH measurement)

The pH (basic or acidic) of F-EC after rectification was studied by the color development of litmus paper. Further, other pHs were measured using a pH electrode for a low-conductivity water-nonaqueous solvent (manufactured by Horiba, Ltd. 6377-10D).

Example 2 (antacid treatment after step (A))

Fluorination process (A)

A reflux tube was attached to the upper part of a 3L glass three-necked flask equipped with a stirring device, 355 g (6.12 mol) of spray-dried potassium fluoride was added, and the water was removed by flame drying while stirring under vacuum. Then, 1.3 L of acetonitrile and 500 g (4.08 mol) of untreated Cl-EC were added and stirred using a syringe. The reaction was carried out at a reaction temperature of 85°C, and the progress was analyzed by gas chromatography (GC). After reacting for 6 hours, it was confirmed that the peak of the raw material disappeared, and the reaction ended. After the reaction, the salt in the reaction product was filtered to obtain a reaction product liquid (pH 1-2).

Antacid treatment process (C)

100 g of silica gel (Silica gel 60 manufactured by Merck, trade name, particle size 0.063 to 0.200 mm) was added to the obtained filtrate, and stirred at room temperature for 2 hours.

Solid component removal process (E)

Then, antacid (silica gel) etc. are filtered.

Organic solvent removal process (D)

Acetonitrile was distilled off from the obtained filtrate (pH 6-7) using an evaporator.

Distillation process (B)

The residue (pH 6-7) was subjected to rectification using a thorn separation tube to obtain colorless and transparent F-EC as a 74°C (1 mmHg) fraction with a yield of 60% and a GC purity of 99.5%.

The purified F-EC was carried out in the same manner as in Example 1, and the presence or absence of coloration, anion analysis, metal ion analysis, and pH measurement were performed. The results are shown in Table 1.

Example 3 (antacid treatment after step (A))

In addition to using amorphous silica-alumina gel (secado KW manufactured by Shinagawa Kasei Co., Ltd., neutral silica gel, trade name) instead of the silica gel used in the antacid treatment step (C) of Example 2, In the same manner as in Example 2, colorless and transparent F-EC was obtained as a fraction at 74°C (1 mmHg), with a yield of 65% and a GC purity of 99.6%.

The purified F-EC was carried out in the same manner as in Example 1, and the presence or absence of coloration, anion analysis, metal ion analysis, and pH measurement were performed. The results are shown in Table 1.

Example 4 (antacid treatment before step (A))

Using alumina (merck company alumina 90, trade name, particle size 0.063 ~ 0.200mm) instead of the silica gel used in the antacid treatment process of Example 1, in the same manner as in Example 1, to obtain The 74°C (1mmHg) fraction of colorless and transparent F-EC has a yield of 68% and a GC purity of 99.8%.

The purified F-EC was carried out in the same manner as in Example 1, and the presence or absence of coloration, anion analysis, metal ion analysis, and pH measurement were performed. The results are shown in Table 1.

Example 5 (antacid treatment in step (B))

Fluorination process (A)

A reflux tube was attached to the upper part of a 3L glass three-necked flask equipped with a stirring device, 355 g (6.12 mol) of spray-dried potassium fluoride was added, and the water was removed by flame drying while stirring under vacuum. Then, 1.3 L of acetonitrile and 500 g (4.08 mol) of untreated Cl-EC were added and stirred using a syringe. The reaction was carried out at a reaction temperature of 85°C, and the progress was analyzed using gas chromatography (GC). After reacting for 6 hours, it was confirmed that the peak of the raw material disappeared, and the reaction ended. After the reaction, salts (potassium fluoride, potassium chloride, etc.) in the reaction product were filtered to obtain a reaction product solution (pH 1-2).

Organic solvent removal process (D)

Acetonitrile was distilled off from the obtained reaction product liquid using an evaporator. At this time, the acid in the filtrate is also volatilized.

Distillation process (B) + antacid treatment process (C)

Using a distillation column filled with amorphous silica-alumina gel (secado KW manufactured by Shinagawa Chemical Industry Co., Ltd., neutral silica gel, trade name), the residue (pH 3 to 4) was subjected to rectification to obtain 74 ℃ (1mmHg) fraction of colorless and transparent F-EC.

The purified F-EC was carried out in the same manner as in Example 1, and the presence or absence of coloration, anion analysis, metal ion analysis, and pH measurement were performed. The results are shown in Table 1.

Example 6 (antacid treatment after step (B))

Fluorination process (A)

A reflux tube was attached to the upper part of a 3L glass three-necked flask equipped with a stirring device, 355 g (6.12 mol) of spray-dried potassium fluoride was added, and the water was removed by flame drying while stirring under vacuum. Then, 1.3 L of acetonitrile and 500 g (4.08 mol) of untreated Cl-EC were added and stirred using a syringe. The reaction was carried out at a reaction temperature of 85°C, and the progress was analyzed by gas chromatography (GC). After reacting for 6 hours, it was confirmed that the peak of the raw material disappeared, and the reaction ended. After the reaction, salts (potassium fluoride, potassium chloride, etc.) in the reaction product were filtered to obtain a reaction product solution (pH 1-2).

Organic solvent removal process (D)

Acetonitrile was distilled off from the obtained reaction product liquid using an evaporator. At this time, the acid in the filtrate is also volatilized.

Distillation process (B)

The residue (pH 3 to 4) was subjected to rectification using a thorn separation tube to obtain colorless and transparent F-EC as a 74°C (1 mmHg) fraction.

Antacid treatment process (C)

100 g of amorphous silica-alumina gel (secado KW manufactured by Shinagawa Kasei Co., Ltd., neutral silica gel, trade name) was added to the obtained F-EC fraction, and stirred at room temperature for 2 hours.

Solid component removal process (E)

The amorphous silica-alumina gel was removed from the resulting antacid-treated F-EC by filtration to obtain purified F-EC with a yield of 61% and a GC purity of 99.6%.

The purified F-EC was carried out in the same manner as in Example 1, and the presence or absence of coloration, anion analysis, metal ion analysis, and pH measurement were performed. The results are shown in Table 1.

Comparative example 1

Except that the antacid treatment step of Example 1 was not carried out, the same operation as Example 1 was carried out to obtain light yellow F-EC as a 74°C (1mmHg) fraction with a yield of 62% and a GC purity of 99.5%.

The purified F-EC was carried out in the same manner as in Example 1, and the presence or absence of coloration, anion analysis, metal ion analysis, and pH measurement were performed. The results are shown in Table 1.

From the results in Table 1, it can be known that by antacid treatment, coloring does not occur, halogen radicals (chlorine and fluoride ions, etc.) are reduced, and the content of metal ions is also small.

Examples 7-12

Purified F-EC was manufactured in the same manner except that N-methylpyrrolidone was used instead of acetonitrile which was the organic solvent in each of Examples 1 to 6.

The obtained purified F-EC was subjected to coloration, anion analysis, metal ion analysis, and pH measurement in the same manner as in Example 1. The results are shown in Table 2.

From the results in Table 2, it can be seen that when N-methylpyrrolidone is used as the organic solvent, coloring does not occur, the halogen radicals (chlorine and fluorine ions, etc.) are reduced, and the content of metal ions is also small. Examples 13-18

In each of the fluorination steps (A) of Examples 1 to 6, 10 mol% of tetrabutylammonium fluoride (TBAF) was added as a catalyst relative to 355 g (6.12 mol) of potassium fluoride, and the same Operate and manufacture refined F-EC.

The obtained purified F-EC was subjected to coloration, anion analysis, metal ion analysis, and pH measurement in the same manner as in Example 1. The results are shown in Table 3.

From the results in Table 3, it can be seen that when TBAF is used as a catalyst for fluorination, coloring does not occur, halides (chlorine and fluorine ions, etc.) are reduced, and the content of metal ions is also small.

Claims (9)

1. A method for producing 4-fluoro-1,3-dioxolan-2-one, characterized in that it comprises: A step (A) of fluorinating 4-chloro-1,3-dioxolane-2-one with a fluorinating agent in an organic solvent; Step (B) of rectifying the obtained reaction product liquid containing 4-fluoro-1,3-dioxolan-2-one; and the step (C) of treating with an antacid, Wherein, the antacid is silicon oxide, aluminum oxide, silicon-aluminum composite oxide, or two or more porous substances thereof. 2. The manufacturing method according to claim 1, characterized in that: The antacid treatment step (C) is performed before the fluorination step (A). 3. The manufacturing method according to claim 1, characterized in that: An antacid treatment step (C) is performed after the fluorination step (A) and before the rectification step (B). 4. The manufacturing method according to claim 1, characterized in that: An antacid treatment step (C) is performed in the rectification step (B). 5. The manufacturing method according to claim 1, characterized in that: An antacid treatment step (C) is performed after the rectification step (B). 6. The manufacturing method according to claim 1, characterized in that: After the fluorination step (A) and before the rectification step (B), a step (D) of removing the organic solvent is included. 7. The manufacturing method according to any one of claims 1 to 6, characterized in that: The antacid is an acid-resistant porous substance. 8. The manufacturing method according to any one of claims 1 to 6, characterized in that: The fluorinating agent is a compound represented by the formula MF, wherein M is an alkali metal atom or a quaternary ammonium cation. 9. The manufacturing method according to any one of claims 1 to 6, characterized in that: The pH is adjusted to 6-7, and the rectification step (B) is carried out under this condition.