JP6241465B2 - High purity vinylene carbonate - Google Patents

Description

The present invention relates to high-purity vinylene carbonate.
Vinylene carbonate is useful as a solvent and an additive for an electrolytic solution for a lithium secondary battery.

  Several methods have been reported so far for synthesizing vinylene carbonate. For example, a method by dehydrochlorination of chloroethylene carbonate obtained by chlorination of ethylene carbonate (MS Newman and RW Addor, J. Am. Chem. Soc., 75, 1263 (1953), J. Am). Chem. Soc., 77, 3789 (1955)), JP-A-11-180974), a method by dehydrogenation of ethylene carbonate (US Pat. No. 3,457,279) and the like are known.

The vinylene carbonate used as the solvent for the electrolytic solution is required to have a high quality. For example, vinylene carbonate using chloroethylene carbonate as a raw material contains a wide variety of organic chlorine compounds and inorganic chlorine compounds as impurities. doing.
For this reason, several methods have been proposed so far for the purification of crude vinylene carbonate.

  For example, distillation under reduced pressure conditions (MS Newman and RW Addor, J. Am. Chem. Soc., 75, 1263 (1953), J. Am. Chem. Soc., 77, 3789 (1955). )), A method in which vinylene carbonate is partially crystallized by a melt liquid crystal deposition method (UK Patent No. 899205) and a method by zone melting (M. Zief, H. Ruch and CH. Schramm, J. Chem. Education, 40, 351 (1963)) and a method in which a dehydrochlorination reaction of chloroethylene carbonate is carried out in a high boiling point solvent such as dibutyl carbonate and then distilled (Japanese Patent Laid-Open No. 2000-26449), etc. Has been proposed.

Japanese Patent Laid-Open No. 11-180974 U.S. Pat. No. 3,457,279 British Patent No. 899,205 JP 2000-26449 A

M.M. S. Newman and R.M. W. Ador, J .; Am. Chem. Soc. , 75, 1263 (1953) J. et al. Am. Chem. Soc. , 77, 3789 (1955) M.M. Zief, H. et al. Ruch and C.C. H. Schramm, J. et al. Chem. Education, 40, 351 (1963)

However, in the case of the purification method by distillation, an organic chlorine compound having a boiling point close to that of vinylene carbonate is mixed in as an impurity in the product, which is not satisfactory in terms of quality.
Moreover, about the method of performing the dehydrochlorination reaction of a chloroethylene carbonate in a high boiling-point solvent, collection | recovery of an expensive solvent is not easy and is not industrially satisfactory.
On the other hand, with respect to the method by melt liquid crystal deposition, if a high-quality product is to be obtained, the recovery rate must be lowered, which is not economically satisfactory.

The present invention seeks to provide a process by which high quality vinylene carbonate can be produced more economically than conventional processes.

As a result of intensive studies in view of such circumstances, the present inventors have found that the chlorine compound contained as an impurity in the crude vinylene carbonate can be dissolved in a polar solvent and / or an aromatic hydrocarbon solvent, and the amount thereof is small. Even if a non-polar solvent is contained in the solvent, the chlorine compound remains dissolved. Therefore, if the crude vinylene carbonate is purified by crystallization using such a solvent, impurities will adhere to the surface of the product. Or the problem that it precipitates as a solid does not occur, and it has been found that the product quality is improved, and the present invention has been completed.
That is, the gist of the present invention resides in vinylene carbonate having a purity of 99.5% or more and a chlorine compound content of 500 ppm or less as a total chlorine content.

  According to the present invention, it is possible to economically obtain high-quality vinylene carbonate by dissolving crude vinylene carbonate in a solvent containing a polar solvent and / or an aromatic hydrocarbon solvent, and then precipitating vinylene carbonate as a fixed substance. it can.

Hereinafter, the present invention will be described in detail.
The crude vinylene carbonate which is the subject of the present invention is not limited in its production method, but preferably contains a chlorine compound as an impurity. For example, the dehydrochlorination reaction (MS) of chloroethylene carbonate described above is preferable. Newman and RW Addor, J. Am. Chem. Soc., 75, 1263 (1953), J. Am. Chem. Soc., 77, 3789 (1955)) are preferred.

However, the purity of the crude vinylene carbonate as a raw material is preferably purified by simple distillation or the like to 95% or more, more preferably 97% or more.
As the solvent for dissolving the crude vinylene carbonate, a polar solvent and / or an aromatic hydrocarbon solvent, that is, at least one solvent selected from a polar solvent and an aromatic hydrocarbon solvent is used. Such solvents may be used singly or as a mixture of two or more. The “dissolution” in the present invention includes those in which the crude vinylene carbonate and the solvent are in a suspension state like an emulsion.

However, such solvents are preferably those in which the amount of chlorine-containing impurities dissolved is 0.1 g or more, preferably 1 g or more per 100 g of the solvent.
Note that the chlorine compound contained in the crude vinylene carbonate is, for example, chloroethylene carbonate, dichloroethylene carbonate, chloroacetaldehyde, chloroethanol, dimethoxymethyl chloride, reaction when vinylene carbonate is produced by dehydrochlorination of chloroethylene carbonate. Organochlorine compounds such as chlorinated solvents.

  In this case, specific examples of such a nonpolar solvent include propane, butane, isobutane, pentane, 2-methylbutane, neopentane, cyclopentane, hexane, 2-methylpentane, 3-methylpentane, heptane, 2-methylhexane, Examples include 3-methylhexane, cyclohexane, octane, isooctane, nonane, isononane, decane, and the like.

  Specific examples of polar solvents used in the present invention include, for example, methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, isobutanol, t-butanol, 1-pentanol, and 2-pentanol. 3-pentanol, amyl alcohol, isoamyl alcohol, 1-hexanol, 2-hexanol, 3-hexanol, 2-methyl-2-pentanol, 2-methyl-3-pentanol, 3-methyl-3-pentanol 1-heptanol, 2-heptanol, 3-heptanol, 4-heptanol, 2-methyl-2-hexanol, 3-methyl-3-hexanol, 4-methyl-4-hexanol, 2-methyl-4-hexanol, 4 -Methyl-2-hexanol, 2-ethylhexanol, benzyl Lucol, phenol, resorcinol, 1-phenylethanol, 2-phenylethanol, 1-phenyl-2-butanol, 3-phenyl-1-butanol, 1,2-propanediol, 1,3-propanediol, 1,2- Alcohols such as butanediol, 1,3-butanediol, 1,4-butanediol, ethylene glycol, glycerol; ethanolamine, propanolamine, methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, methylethylamine, methyl Butylamine, propylamine, dipropylamine, tripropylamine, diisopropylamine, triisopropylamine, t-butylamine, 1,2-ethylenediamine, N, N, N ′, N′-tetra Amines such as til-1,2-ethylenediamine, di (n-butyl) amine, tributylamine, aniline, N-methylaniline, N, N-dimethylaniline, toluidine, N, N-dimethyltoluidine; acetaldehyde, butyraldehyde Aldehydes such as butanone, acetone, methyl propyl ketone, diethyl ketone; methyl formate, ethyl formate, propyl formate, butyl formate, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, propion Carboxylic acid esters such as methyl acid, γ-butyrolactone and butyl propionate; dimethyl ether, diethyl ether, methyl ethyl ether, dibutyl ether, diisopropyl ether, dioxane, trioxane, tetrahydrofuran , Ethers such as methyl-t-butyl ether and dimethoxyethane; heteroaromatic compounds such as furan, pyrrole, pyridine and thiophene; carboxamides such as formamide, dimethylformamide, diethylformamide, dimethylacetamide, diethylacetamide and N-methylpyrrolidone Nitriles such as acetonitrile, propionitrile, butyronitrile; haloaromatic compounds such as chlorobenzene, 1,2-dichlorobenzene, 1,3-dichlorobenzene, promobenzene; ethyl bromide, ethyl chloride, ethyl fluoride, Halogenated alkyl compounds such as butyl bromide, butyl chloride, methyl chloride, chloroform, dichloroethane, dichloromethane; nitromethane, nitroethane, 1-nitropropane, 2-nitropropane, 1-nitro Tan, 2-nitrobutane, nitrobenzene, 2-nitrotoluene, nitro compounds such as 3-nitrotoluene and the like.

Among these, ethers, ketones, esters, and alcohols are preferable.
Specific examples of the aromatic hydrocarbon solvent include benzene, toluene, xylene, ethylbenzene, mesitylene, isopropylbenzene, and the like. Among these, benzene, toluene and xylene are preferable, and toluene is particularly preferable.
The amount of the solvent used is not particularly limited, but is usually 0.5 to 20 times by weight, preferably 0.7 to 5 times by weight, more preferably 0.8 to 3 weights with respect to the crude vinylene carbonate. Is double.

  For crystallization, a solution of about 5 to 70% by weight of vinylene carbonate may be allowed to stand to precipitate crystals, but it is preferable to precipitate crystals by bringing the solution into a supercooled state. In this case, for example, the solution is first cooled to 0 to 20 ° C. (temperature A), stirred at temperature A for about 1 to 2 hours, and further to a temperature B lower than temperature A by 5 to 15 ° C., for example 0.1 A technique is preferred in which the temperature is lowered at a rate of 10 ° C./hour and the mixture is stirred at this temperature B for about 1 to 2 hours for crystallization.

  When crystallization is performed in a supercooled state, a local temperature distribution is created by adding a cooled solvent to the solution, or by introducing a solid at a low temperature such as dry ice, etc. It is also preferable to add a solvent having low solubility of vinylene carbonate such as an aliphatic hydrocarbon, create a local concentration distribution by adding liquid or solid vinylene carbonate, or add seed crystals.

As a method for further precipitation or growth of crystals, for example, cooling, a method of adding a solvent having a low solubility of vinylene carbonate such as an aliphatic hydrocarbon, a method of adding a cooled solvent, a method of adding liquid vinylene carbonate Etc. or a combination thereof can be used.
The recovery rate of vinylene carbonate depends on the solubility in the solvent used, and can be arbitrarily set depending on the temperature and the amount of the solvent. Usually, the recovery rate of vinylene carbonate is set to 60% or more, preferably 80% or more. Is done.

The precipitated solid is separated by a method such as filtration or centrifugation. If necessary, the solid surface is further washed with a suitable solvent. This solid is usually heated above its melting point to obtain vinylene carbonate as a liquid. This vinylene carbonate can be used as a product as it is, but if necessary, the residual solvent can be removed by topping or the like.
High purity vinylene carbonate can be obtained by such a method.

However, the high-purity vinylene carbonate referred to in the present invention means a purity of 99.5% or more, preferably 99.7% or more, more preferably 99.9% or more, and the chlorine compound content is 500 ppm or less as the total chlorine content. , Preferably 200 ppm or less, more preferably 50 ppm or less.
This method can also obtain a vinylene carbonate having a sufficient quality. However, when a higher quality vinylene carbonate is required, the method of the present invention can be used repeatedly.

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples as long as the gist of the present invention is not exceeded.
The analysis was performed by gas chromatography. For the purity, when the solvent remained, a value obtained by cutting the solvent was used.
Purity = (Vinylene carbonate area) / (Total area−Residual solvent peak area)
Examples 1-10
A 500 ml four-necked flask equipped with a stirring function was charged with vinylene carbonate (VC) and a solvent, and cooled at a rate of 2 ° C. per hour while stirring. Solids precipitated when cooled to a certain temperature (temperature A). After stirring at that temperature for 1 hour, the mixture was cooled to a predetermined temperature (temperature B) at a rate of 2 ° C. per hour and further stirred for 1 hour. The solid was separated by filtration, washed twice with hexane at 5 ° C., and then melted by heating to recover the liquid. The results are shown in Table 1 below.

Examples 11 and 12
A 50 ml three-necked flask equipped with a stirring function was charged with 10 g of vinylene carbonate (purity 99.24%, total chlorine 6270 ppm) and 10 g of solvent, and cooled with stirring to precipitate a solid. After stirring at 5 ° C for 1 hour, stirring was stopped and the mixture was allowed to stand at -5 ° C for 12 hours. The solid was separated by filtration, washed twice with hexane at 5 ° C., and then melted by heating to recover the liquid. The results are shown in Table 2 below.

Example 13
A 250 L reactor equipped with a stirring function was charged with 40.0 kg of vinylene carbonate (purity 98.69%, total chlorine 3160 ppm), 40.0 kg of toluene, and 40.0 kg of hexane, and cooled while stirring. After adding 40 g of seed crystals at 14.7 ° C. and stirring for 30 minutes, the mixture was stirred at 14.3 to 5 ° C. for 6 hours, and further cooled to 4.0 ° C. over 4 hours. The solid was filtered off and washed twice with 40 kg of hexane at 5 ° C. to obtain VC as a solid. Recovery rate 93.2%, purity 99.94%, total chlorine 11ppm.

Example 14
A 250 L reactor equipped with a scraping blade was charged with 50.0 kg of vinylene carbonate (purity 98.69%, total chlorine 3160 ppm), 50.0 kg of toluene, and 50.0 kg of hexane, and cooled with stirring. After adding 50 g of seed crystals at 14.7 ° C. and stirring for 30 minutes, the mixture was cooled to 4.0 ° C. over 2.5 hours. The solid was filtered off and washed twice with 50 kg of hexane at 5 ° C. to obtain VC as a solid. Recovery rate 93.3%, purity 99.94%, total chlorine 15ppm.

Comparative Example 1
100 g of vinylene carbonate (purity 99.24%, total chlorine 6270 ppm) was subjected to precision distillation twice using a four-stage distillation column at a reflux ratio of 5 to 10. Yield 69%, purity 99.80%, total chlorine content 530 ppm.

Claims (6)

Purity is 99.9% or more, and the content of chlorine compound is 15 ppm or less as a total chlorine content, and does not precipitate when dissolved in a nonpolar solvent. An industrial purification method for vinylene carbonate,
A method for purifying vinylene carbonate in which crude vinylene carbonate is dissolved in a mixed solvent of an aromatic hydrocarbon solvent and a nonpolar solvent, and then cooled to precipitate vinylene carbonate as a solid. Nonpolar solvents are propane, butane, isobutane, pentane, 2-methylbutane, neopentane, cyclopentane, hexane, 2-methylpentane, 3-methylpentane, heptane, 2-methylhexane, 3-methylhexane, cyclohexane, octane, The method for purifying vinylene carbonate according to claim 1, which is at least one selected from the group consisting of isooctane, nonane, isononane and decane. The method for purifying vinylene carbonate according to claim 1, wherein the mixed solvent is a mixed solvent of toluene and hexane. The method for purifying vinylene carbonate according to any one of claims 1 to 3, wherein the weight ratio of the aromatic hydrocarbon solvent to the nonpolar solvent is 90:10 to 50:50. The method for purifying vinylene carbonate according to any one of claims 1 to 4, wherein the amount of the mixed solvent used is 0.5 to 20 times the weight of the crude vinylene carbonate. The method for purifying vinylene carbonate according to any one of claims 1 to 5, wherein the crude vinylene carbonate after cooling is crystallized in a supercooled state.