KR20150064748A - Method for purifying fluorinated organic carbonates - Google Patents

Abstract

There is provided a process for the purification of fluoroethylene carbonate resulting from the reaction of fluorinated organic carbonates, especially ethylene carbonate and native fluorine. The process according to the present invention comprises treating said fluorinated organic carbonate with an organosilicon compound having at least one -Si-N-bond, and distilling the resulting mixture in at least one distillation column.

Description

METHOD FOR PURIFYING FLUORINATED ORGANIC CARBONATES FIELD OF THE INVENTION [0001]

Priority is claimed on European Patent Application No. 12187802.9, filed October 9, 2012, the entire content of which is hereby incorporated by reference in its entirety.

The present invention relates to a process for the purification of fluorinated organic carbonates, in particular fluorinated linear carbonates or fluorinated cyclic carbonates, during their production process.

Each of the tri- and tetra-fluorinated carbonates, as well as the fluorinated linear and cyclic carbonates, such as monofluoroethylene carbonate, fluoromethylmethyl carbonate, difluoroethylene carbonate and difluoridated dimethyl carbonate, Solvents or solvent additives.

Generally, fluorinated organic carbonates can be prepared by reaction of a cyclic fluorine with an aliphatic linear or cyclic carbonate that is not substituted by F or has at least one substitutable H atom.

WO 2011/036283 discloses a process for producing tetrafluoroethylene carbonate by reacting nonfluorinated ethylene carbonate in liquid phase or ethylene carbonate having low fluorination degree with elemental fluorine (F ₂ ) Carbonate, trifluoroethylene carbonate and / or tetrafluoroethylene carbonate, or a mixture of two or more thereof.

WO 2009/118369 discloses a process for the production of hydrofluoric acid by depleting HF from the mixture by passing an inert gas through a mixture comprising an organic carbonate, preferably a fluorinated organic carbonate, and hydrogen fluoride, To prepare a mixture. A rare gas, or a mixture of rare gas and nitrogen or carbon dioxide, or a mixture thereof with nitrogen is also suitable as an inert gas for stripping; Air is also suitable, but not desirable. Nitrogen is particularly suitable as a stripping gas.

WO 2009/118368 provides a process for the preparation of HF-lower fluorinated organic carbonates which comprises contacting HF-contaminated fluorinated organic carbonates containing at least one CH-CF group in the molecule with SiO ₂ - Is contacted with an inorganic reactant to form a mixture of a solids and an HF-low-fluorinated organic carbonate, and the resulting HF-low-fluoro-substituted organic carbonate is separated from the solids. It is preferred to use solids with a large surface area, especially amorphous solid silica or silica-containing compounds. Silica gel is highly preferred. Thanks to the large surface of such a gel (e.g., applicable in the form of a shaped body in bead form), a fast HF-elimination reaction is provided.

WO 2011/020830 discloses a process for the preparation of a polymer electrolyte membrane comprising fluoroethylene carbonate, ethylene carbonate, higher fluorinated ethylene carbonate, or carbonate and hydrogen fluoride, and optionally a trace amount of impurities (e.g., trifluoroethylene carbonate) Wherein the reaction mixture is distilled in at least two distillation stages and the HF content in the reaction mixture fed to the first distillation stage is not more than 5% by weight. Preferably, the HF content of the reaction mixture fed to the first distillation column is less than 1% by weight. The purified fluoroethylene carbonate thus obtained is very pure in particular in terms of the HF content, so there is no need to recrystallize it.

It is an object of the present invention to provide a further purification method of the fluorinated organic carbonate to significantly reduce the amount of impurities such as hydrogen fluoride during the manufacturing process. These and other objects, which are obvious from the description and claims, are achieved by the method of the present invention.

Accordingly, the present invention relates to a process for the preparation of fluorinated organic carbonates, comprising treating a fluorinated organic carbonate with an organosilicon compound having at least one -Si-N-bond, and distilling the resulting mixture in at least one distillation column And a method for purifying the same.

In fact, it has been surprisingly found that certain chemical compounds, i.e., organosilicon compounds having one or more -Si-N-bonds function as effective scavengers for impurities such as hydrogen fluoride, water, etc. during the manufacturing process of the fluorinated organic carbonates .

In the present invention, it is understood that the impurities during the production process of fluorinated organic carbonates include not only hydrogen fluoride and water, but also other by-products and / or second reaction products which may harm the final fluorinated organic carbonate product.

In the present invention, the singular forms are intended to cover plural forms; The plural form is intended to encompass the singular form. Thus, for example, the term "fluorinated organic carbonate" is not limited to a single carbonate compound, but encompasses a composition comprising two or more fluorinated organic carbonates, including isomeric forms.

The organosilicon compounds having one or more -Si-N bonds according to the present invention can react effectively with water, hydrogen halides such as hydrogen fluoride, and / or other impurities, thus rapidly forming a reaction product, Can be removed or separated from the target product in the subsequent steps.

In the present invention, the organosilicon compound having at least one -Si-N-bond specifically includes a compound capable of decomposing target impurities by reacting with at least hydrogen fluoride and / or water by cleavage of Si-N bond I understand it as pointing. The resulting decomposition product may be removed or separated from the target end product in one or more subsequent processes. The organosilicon compound may have at least one Si-N bond in the form of Si-N-Si bond besides a single or plural Si-N bonds per molecule.

In one embodiment according to the present invention, the organosilicon compound having at least one -Si-N-bond is preferably selected from the group consisting of an organosilazane compound, an organodisilazane compound and an organic trisilazane compound. More preferably, the organosilicon compound having at least one -Si-N bond is selected from the group consisting of (N, N-diethylamino) trimethylsilane, N, O-bis (trimethylsilyl) acetamide, N, Trimethylsilyl) -1,4-butanediamine, 1,1,1,3,3,3-hexamethyldisilazane, 1,1,3,3,5,5-hexamethylcyclotrisilazane, and ≪ / RTI > Particular preference is given to 1,1,1,3,3,3-hexamethyldisilazane, and since at least this compound has two -Si-N-linkages, each contains a target impurity such as a hydrogen halide and water As shown in FIG. These compounds may be used alone or in combination with two or more compounds. These compounds are described, for example, in Japanese Patent No. 3,348,344 B2. The expected reaction is:

The amount of organosilicon compound added during the production process of the fluorinated organic carbonate may be determined in relation to the approximate amount of impurities or impurities to be removed. Alternatively, the end point of addition of the organosilicon compound may be determined by physical or chemical methodology, for example by gas chromatography, NIR or MIR. In general, the addition of the organosilicon compound is determined so that the amount thereof is 0.01 to 5% by weight based on the crude product to be treated. Preferably, the amount of organosilicon compound added can be determined by analyzing residual impurities such as HF and / or H ₂ O, the amount being from 0.5 to 2.5 equivalents of the analyzed amount of residual impurities, preferably from 0.8 to 2 Equivalent mole, more preferably 1.0 to 1.5 equivalent mole, and most preferably about 1.2 equivalent mole, although the present invention is not limited thereto.

The organosilicon compound may be added at any one or more stages prior to the separation step to collect the fluorinated organic carbonate as a final product. According to one particular embodiment of the invention, the organosilicon compound can be added to the crude reaction mixture and / or the pre-purification product. The compound may be contacted with the crude reaction mixture or pre-purification product in a batch reactor. Preferably, the compound is added directly to the reactor in which the fluorination reaction of the organic carbonate takes place.

The process of the present invention is particularly suitable for purifying fluorinated organic carbonates produced by reacting an aliphatic linear or branched organic carbonate, in particular a starting compound, with a crude fluorine. The fluorination reaction may be carried out batchwise or continuously, resulting in the crude reaction mixture. These methods are described, for example, in WO 2011/036281, or US Published Patent Application 2006-0036102, which describes a fluorination process carried out continuously. In one alternative, the aliphatic linear or branched organic carbonate used as the starting material may be unsubstituted by the F atom, and after reaction with the elemental fluorine, each reaction product may contain up to perfluorinated at least one F atom Lt; RTI ID = 0.0 > fluorinated < / RTI > organic carbonates. In another alternative, the aliphatic linear or branched organic carbonate used as the starting material is substituted by one or more F atoms and comprises at least one H atom, and after reaction with the native fluorine, And fluorinated organic carbonates that are substituted by two or more F atoms up to perfluorination.

The fluoro substituted organic carbonates which can be purified according to the process of the present invention will now be described.

According to one alternative, fluoro substituted aliphatic linear or branched organic carbonates can be purified according to the process of the present invention. In particular, the fluoro substituted organic carbonates of formula (I), (R ¹ O) (R ² O) C (O) can be purified. In the formula (I), R ¹ and R ² may be the same or different. R ¹ and R ² are linear alkyl or branched alkyl, provided that R ¹ and R ² Is substituted by at least one F atom. The term "linear alkyl" preferably refers to a C1 to C5 alkyl group or a C1 to C5 alkyl group substituted by one or more F atoms. The term "branched alkyl" preferably refers to a C3 to C5 alkyl group or a C3 to C5 alkyl group substituted by one or more F atoms. One condition is that R < ¹ > and R < ² > Lt; / RTI > must be replaced by at least one F atom. This condition will not be described again.

Preferably, R ¹ is methyl, fluoromethyl, difluoromethyl, trifluoromethyl, ethyl, fluoroethyl, difluoroethyl, trifluoroethyl, tetrafluoroethyl or pentafluoroethyl, or n -Propyl, isopropyl, n-propyl or i-propyl substituted by from 1 to 7 F atoms. Preferably, R ² is methyl, fluoromethyl, difluoromethyl, trifluoromethyl, ethyl, fluoroethyl, difluoroethyl, trifluoroethyl, tetrafluoroethyl or pentafluoroethyl, n- Propyl, isopropyl, n-propyl substituted by 1 to 7 F atoms or i-propyl.

According to yet another alternative, a fluoro substituted aliphatic cyclic organic carbonate (OR ³ O) C (O) of formula (II) is purified according to the process of the present invention. Preferably, R < ³ > is an aliphatic alkylene group having 2 to 10 C atoms and being substituted by at least one F atom. More preferably, R < ³ > is a C2 to C8 group substituted by at least one F atom. Particularly preferably, R ³ is a C 2 group substituted by 1, 2, 3 or 4 F atoms; A linear or branched C3 group substituted by one or more F atoms; A methylpropylene group substituted by one or more F atoms; A dimethylethylene group substituted by at least one F atom; An ethylethylene group substituted by one or more F atoms; A diethylethylene group substituted by one or more F atoms; Or a methylethylethylene group substituted by one or more F atoms. Preferably, in said alternative embodiments, R ³ is selected from the group consisting of monofluoroethylene, difluoroethylene, trifluoroethylene, tetrafluoroethylene, monofluoromethylethylene, difluoromethylethylene, methylmonofluoro But are not limited to, ethylene, methyldifluoroethylene, monofluoromethylmonofluoroethylene, monofluoromethyldifluoroethylene, difluoromethylmonofluoroethylene, difluoromethyldifluoroethylene, trifluoromethyldifluoroethylene, Lt; / RTI > is ethylene, difluoromethyltrifluoroethylene, or trifluoromethyltrifluoroethylene. In this embodiment, R ³ is preferably monofluoroethylene, difluoroethylene, trifluoroethylene, tetrafluoroethylene and most preferably monofluoroethylene or difluoroethylene. "Difluoroethylene" may be a CF ₂ C-CH ₂ group or a CFH-CFH group in the cis or trans arrangement.

Fluorinated organic carbonates may be provided, for example, as described in JP-A No. 2000-309583, US 2006-0036102, US 7,268,238 or WO 2011036281.

In one particular embodiment of the invention, the fluorinated organic carbonate is selected from the group consisting of monofluoroethylene carbonate, fluoromethylmethyl carbonate, difluoroethylene carbonate, and bis- (fluoromethyl) carbonate. Preferably, the fluorinated organic carbonate is monofluoroethylene carbonate. Alternatively, the fluorinated organic carbonates are selected from the group consisting of ethyl-1-fluoroethyl carbonate, methyl-1-fluoroethyl carbonate, propyl-1-fluoroethyl carbonate, and allyl-1-fluoroethyl carbonate .

The process of the present invention can be applied to purify fluorinated products that have not yet undergone purification treatment. Alternatively, to purify the pre-purified fluorinated product that has been subjected to a pre-purification treatment to provide pre-purified fluorinated carbonate but is considered not to be pure enough to be applied as a solvent or additive for a lithium ion battery The above method can be applied; Or as a solvent or additive for lithium-ion batteries, while it can be applied to purified products that still form some HF upon storage or upon contact with moisture.

Thus, in another embodiment of the present invention, the fluorinated organic carbonates treated with the organosilicon compounds are selected from the group consisting of ternary fluorides obtained from reactions involving one or more steps of reacting the raw fluorine with an organic carbonate having a low degree of substitution by fluorine Or a pre-purification product obtained from a reaction comprising at least one step of reacting the raw fluorine with an organic carbonate having a low degree of substitution by fluorine and at least one step of removing hydrogen fluoride. Preferably, the fluorinated organic carbonate to be treated is a crude reaction mixture obtained from a reaction comprising at least one step of reacting the raw fluorine with an organic carbonate having a low degree of substitution by fluorine and at least one step of removing hydrogen fluoride. In particular, the addition of the organosilicon compound may be carried out by adding to the reactor where the reaction takes place, comprising at least one step of reacting the elemental fluorine with the organic carbonate.

It is preferred to post-treat the HF from the pre-purification reaction mixture containing the fluorinated organic carbonate obtained in the fluorination step with the crude fluorine, and in the treatment with the organosilicon compound being subsequently or simultaneously. One skilled in the art would expect that in the fluorination step, one mole of HF is produced for one mole of consumed F ₂ . Several processes are suitable for post-treatment purification to remove HF. These preferred methods include one or more stripping steps using one or more gases, one or more distillation steps, or both. The HF removal method from the raw product is described in WO 2009/118369. An inert gas such as N ₂ is passed through the crude product to remove entrained HF. One alternative is the distillation process, as described for example in WO 2011/020830, which removes HF, for example, by the combined distillation process. The two methods can be combined with each other or combined with an adsorption treatment to remove HF, for example by contacting with silica.

As the post-purification treatment step, it is particularly preferable to combine the stripping method and the distillation method.

Alternatively, the organosilicon compound may be added after the above-mentioned pre-purification step to remove most of the existing HF, preferably before the final separation step such as distillation.

In another embodiment of the present invention, the purification process is carried out in several steps including the following steps to provide a purified carbonate:

a) reacting fluorine with an organic carbonate having a low fluorination degree to obtain a crude reaction mixture containing a fluorinated organic carbonate containing hydrogen fluoride;

b) one or more steps of treating the crude reaction mixture comprising the fluorinated organic carbonate with an organosilicon compound having at least one -Si-N- linkage to remove hydrogen fluoride;

c) one or more steps of further removing hydrogen fluoride contained in the pre-purification fluorinated organic carbonate to lower the content of hydrogen fluoride; And

d) one or more steps of distilling the purified fluorinated organic carbonate as described above to recover the purified fluorinated organic carbonate.

After the treatment according to the invention, the content of hydrogen fluoride in the reaction product is preferably not more than 5% by weight, more preferably not more than 2% by weight, based on the weight of the reaction mixture. Particularly preferably, the content is 1% by weight or less. Even more preferably, the content is 0.5% by weight or less. Even more preferably, the content is 0.1 wt.% Or less.

Further details of the post-treatment-purification of the fluorinated organic carbonate will be described below.

In the simplest manner, the stripping step can be carried out by blowing an inert gas into the reaction mixture in a vessel containing the reaction mixture. This can be done batchwise or continuously.

The stripping step is preferably carried out so that sufficient contact is made between the reaction mixture and the gas. For example, the reaction mixture may be sprayed into the stream of inert gas, or the stripping gas and the liquid to be treated may be contacted in the bubble tray. One highly desirable method is to perform in a stripping column. De geotap in is the inner member or packing having a large specific surface area per unit m ³ to provide a large contact surface between gas and liquid mounting. Suitable packings are, for example, lashing. The stripping tower is a cylindrical tube normally located in the vertical direction. Inert gas is introduced into the bottom of the stripping tower below the packing; The reaction mixture is fed to the top. An inert gas, including hydrogen fluoride, is discharged from the tower through separate lines at the top.

The removal efficiency of hydrogen fluoride from HF-containing carbonates is higher at high temperatures. If the contact is carried out in a container, it can be supplied in a known manner, for example by heating the walls of the container. Optionally, the inert gas and / or the liquid to be treated can be heated.

If the reaction is carried out in a stripping column with an inner member or packing, it is desirable to heat the inert gas, the liquid to be treated, or both to improve the efficiency of the stripping process.

It is therefore advantageous to heat the inert gas, in particular nitrogen, before introducing it into the reaction mixture. The heating temperature is preferably 60 DEG C or higher, more preferably 75 DEG C or higher. The heating temperature is more preferably 100 DEG C or higher. The temperature may be, for example, 120 ° C or higher. Preferably, the heating temperature is 150 DEG C or less. Depending on the heat resistance and abrasion resistance of the containers, towers, pipes and accessories used, the temperature may exceed 150 ° C.

It is preferable to heat the reaction mixture before the continuous stripping process is performed. If a vessel is used to carry out the batch process, the reaction mixture may be heated prior to and / or during the stripping process. Preferably, the reaction mixture is heated to a temperature of at least 60 占 폚. Preferably the reaction mixture is heated to a temperature below 120 ° C.

It is advantageous to carry out the stripping step at atmospheric pressure. If desired, a little vacuum pressure can be applied. For example, the pressure can be reduced to 0.5 bar or even 0.2 bar. The temperature should not be so high that the inert gas flow can escape from the organic compound.

In the batch process, stripping is performed until the maximum amount of hydrogen fluoride present is at the desired level.

In a continuous process in the stripping tower, the height of the column is chosen to reach the desired residual hydrogen fluoride concentration for a given concentration of hydrogen fluoride, inert gas and flow rate of the reaction mixture.

The post-treatment-purification may be carried out by various distillation operations as described in WO 2011/020830. In this process, the pre-purification reaction mixture is distilled into at least two distillation stages, and the reaction mixture is fed to the first distillation stage. Excess hydrogen fluoride can be removed, for example, by treatment with an organosilicon compound according to the invention and / or by stripping prior to the distillation steps.

The expression "at least two distillation stages" indicates that the mixture is passed through a distillation column at least twice. According to one embodiment, the separation subject mixture is passed through a distillation tower at least twice. This embodiment can be performed with a batch distillation process.

According to another embodiment, the at least two distillation stages are carried out in two or more distillation columns. This embodiment is particularly suitable for performing a continuous distillation process.

In the first distillation stage, a mixture of low boiling materials (e.g., carbon fluoride and hydrogen fluoride) is withdrawn from the top; High boiling point components are discharged at the bottom and fed to the second distillation stage. Often, the pressure at the top of the column in the first distillation stage is less than 100 mbar (abs.). Preferably, the pressure at the top of the column in the first distillation step is less than 75 mbar (abs.). Preferably, the pressure is above 10 mbar (abs.). It is particularly preferred if the pressure at the top of the column in the first distillation step is in the range of 10 to 50 mbar (abs.).

The mixture of low boiling materials discharged from the top of the column in the first distillation stage can be separated from each other if desired. For example, the mixture may be washed with water to remove hydrogen fluoride, or, more preferably, the mixture may be stripped with an inert gas to remove the hydrogen fluoride. The remaining fluorocarbonate is separable by distillation. Alternatively, the mixture from the top of the column of the first distillation stage can be separated into various compounds by simply distilling it without any further treatment such as washing or stripping. Carbonates with a high degree of fluorination are important byproducts because they can be applied as additives for lithium ion battery solvents. If desired, these carbonates can be disposed of or burned. All recovered hydrogen fluoride is also an important product in itself.

In the second column, the bottom product of the first column is distilled. Preferably, the pressure at the top of the column in the second distillation step is less than 50 mbar (abs). More preferably, the pressure at the top of the second tower is 30 mbar (abs.) Or less. Preferably, the pressure at the top of the tower in the second distillation step is above 5 mbar (abs.). At the top of the column in the second distillation step, a high purity fluorocarbonate, such as monofluoroethylene carbonate, is obtained. The content of hydrogen fluoride in the purified organic carbonate is not more than 30 ppm by weight, preferably not more than 20 ppm by weight. Even a lower fluorination content, for example less than 10 ppm, may be achieved.

Wherever the disclosure of all patents, patent applications, and publications incorporated herein by reference is inconsistent with the present disclosure, the present disclosure shall prevail.

While preferred embodiments of the present invention have been shown and described, it will be apparent to those skilled in the art that various changes and modifications can be made therein without departing from the spirit or teaching of the invention. The implementations and embodiments described herein are illustrative only and not intended to be limiting. Many modifications and variations of the systems and methods are possible within the scope of the present invention. Accordingly, the scope of protection is not limited to the embodiments described herein, but is limited only by the following claims, the scope of which encompasses all equivalents of the subject matter of the claims.

Examples

Example  1-1 Monofluoroethylene Carbonate ("F1EC")  Preparation of crude reaction mixture containing

The preparation of FIEC is carried out by reacting ethylene carbonate ("EC") with F ₂ / N ₂ in the reactor. At the same time, 1,1,1,3,3,3-hexamethyldisilazane compound is added to the reactor to lower the content of free HF. The crude reaction mixture also includes HF and additional fluorinated ethylene carbonate, such as difluoroethylene carbonate ("F2EC") as well as EC and F1EC.

Example  1-2 Purification of the reaction mixture

The reaction mixture from Example 1-1, in which the content of HF was lowered by treatment with a 1,1,1,3,3,3-hexamethyldisilazane compound, was removed by contact with nitrogen gas in a stripping column to remove HF Lower the content.

Example  1-3 distillation

After the purification step, the resulting reaction mixture is distilled to provide the final product F1EC. As the amount of free HF in the final product is significantly reduced, it provides a highly refined F1EC.

Claims (11)

Treating the fluorinated organic carbonate with an organosilicon compound having at least one -Si-N-linkage, and distilling the resulting mixture in at least one distillation column. The method according to claim 1, wherein the organosilicon compound having at least one -Si-N-bond is selected from the group consisting of an organosilazane compound, an organodisilazane compound, and an organic trisilazane compound. 3. The method of claim 1 or 2, wherein the organosilicon compound having at least one -Si-N bond is selected from the group consisting of (N, N-diethylamino) trimethylsilane, N, O-bis (trimethylsilyl) , N'-bis (trimethylsilyl) -1,4-butanediamine, 1,1,1,3,3,3-hexamethyldisilazane, 1,1,3,3,5,5-hexamethylcyclo ≪ / RTI > trisilazane, and any combination thereof. 4. The method according to any one of claims 1 to 3, wherein the organosilicon compound having at least one -Si-N-bond is 1,1,1,3,3,3-hexamethyldisilazane. 5. A process according to any one of claims 1 to 4, wherein the fluorinated organic carbonate is a crude reaction obtained from a reaction comprising at least one step of reacting the raw fluorine with an organic carbonate having a low degree of substitution by fluorine Or a pre-purification product obtained from a reaction comprising at least one step of reacting a crude fluorine with an organic carbonate having a low degree of substitution by fluorine and at least one step of removing hydrogen fluoride. 6. The process of claim 5, wherein the fluorinated organic carbonate is selected from the group consisting of one or more steps of reacting the crude fluorine with an organic carbonate having a low degree of substitution and a crude fluorinated organic carbonate obtained from a reaction comprising one or more steps of removing hydrogen fluoride Way. The method of claim 5 or 6, wherein the step of removing hydrogen fluoride is carried out by stripping using one or more gases, distillation, or both. 8. The process according to any one of claims 1 to 7, wherein the fluorinated organic carbonate is selected from the group consisting of monofluoroethylene carbonate, fluoromethylmethyl carbonate, difluoroethylene carbonate and bis- (fluoromethyl) carbonate. Lt; / RTI > 9. The process according to any one of claims 1 to 8, wherein the amount of organosilicon compound used for the treatment is from 0.01 to 5% by weight, based on the fluorinated organic carbonate to be treated. 10. The method according to any one of claims 1 to 9,
a) reacting fluorine with an organic carbonate having a low fluorination degree to obtain a crude reaction mixture containing a fluorinated organic carbonate containing hydrogen fluoride;
b) one or more steps of treating the crude reaction mixture comprising the fluorinated organic carbonate with an organosilicon compound having at least one -Si-N- linkage to remove hydrogen fluoride;
c) one or more steps of further removing hydrogen fluoride contained in the pre-purification fluorinated organic carbonate to lower the content of hydrogen fluoride; And
d) one or more steps of distilling the purified fluorinated organic carbonate as described above to recover the purified fluorinated organic carbonate
≪ / RTI > 11. The method of claim 10, wherein steps (a) and (b) are performed simultaneously in the same reactor.