JP5313579B2 - Process for producing novel fluorinated 1,2-oxathiolane 2,2-dioxide - Google Patents

Description

  The present invention relates to 1,2-oxathiolane 2,2-dioxide, which is expected to be used in electrolyte solvents and additives for lithium ion secondary batteries, functional material intermediates, pharmaceutical intermediates, organic solvents, and the like. It relates to a manufacturing method.

  The electrolyte solution of a lithium ion secondary battery is generally composed of an electrolyte and an organic solvent. Examples of the organic solvent include cyclic carbonates represented by ethylene carbonate and propylene carbonate, chains represented by dimethyl carbonate and diethyl carbonate. In many cases, it is composed of a carbonate ester, γ-butyrolactone, or a mixture thereof. However, these organic solvents have problems in the use temperature range, viscosity, electrochemical stability, and the like. Therefore, as a means for solving such a problem, studies have been made to introduce fluorine into the above-mentioned organic compounds and attempt to improve those problems. As cyclic carbonates, 4-fluoro-1,3- Dioxolan-2-one, 4-chloro-5-fluoro-1,3-dioxolan-2-one (Patent Documents 1 and 2), 4-fluoro-5-methyl-1,3-dioxolan-2-one, 4 -Fluoro-4-methyl-1,3-dioxolan-2-one, 4,5-difluoro-4-methyl-1,3-dioxolan-2-one, 4-chloro-5-fluoro-5-methyl-1 , 3-dioxolan-2-one (Patent Document 3), 4- (fluoromethyl) -1,3-dioxolan-2-one, 4- (difluoromethyl) -1,3-dioxolan-2-one, 4- (Difluoromethyl) -5- (trifluoromethyl) -1,3-dioxolan-2-one, 4- (fluoromethyl) -4-methyl-1,3-dioxolan-2-one, 4- (fluoromethyl) ) -5,5-dimethyl-1,3-dioxolan-2-one, 4- (1-fluoroethyl))-1,3-dioxolan-2-one, 4- (1-fluoropropyl) -1,3 -Dioxolan-2-one, 4- (1-fluorobutyl) -1,3-dioxolan-2-one (Patent Document 4), 4- (Trifluoromethyl) -1,3-dioxolan-2-one (Patent) Documents 5 to 8), 4-fluoro-1,3-dioxan-2-one (Patent Document 9), as chain carbonic acid ester, fluoromethyl-methyl carbonate (Patent Document 10), bis (fluoromethyl) carbonate (Patent Documents 10 and 11), 1-fluoroethyl-ethyl carbonate (Patent Document 11), γ-fluoro-γ-butyrolactone (Patent Document 12) and the like have been reported so far. However, there are no reports yet on a compound in which fluorine is introduced into sultone, which is a cyclic sulfonic acid ester, and its synthesis method.

  On the other hand, as a method for introducing a fluorine atom into a compound, a method using a halogen exchange reaction, a direct fluorination reaction using a fluorine gas, an electrolytic fluorination reaction, or the like as described above is known.

  In the first halogen exchange reaction, for example, when obtaining 4-fluoro-1,3-dioxolan-2-one, a method of fluorinating a corresponding chlorinated product with potassium fluoride has been reported (Patent Document 2). However, generally a high reaction temperature and a long reaction time are often required.

  In the case of the direct fluorination reaction using the second fluorine gas, it is generally difficult to obtain a partially fluorinated compound with good selectivity, and certain cyclic carbonates such as 4- Fluoro-1,3-dioxolan-2-one (Patent Documents 13 and 14), trans-4,5-difluoro-1,3-dioxolan-2-one (Patent Document 15), Or it is only reported to have been obtained by reaction with 1,3-dioxan-2-one). On the other hand, when γ-butyrolactone is fluorinated with fluorine gas, the selectivity of the target product is very low, and several types of monofluorinated products are obtained in addition to γ-fluoro-γ-butyrolactone. There is a problem that it is very difficult (Non-Patent Document 1, Patent Document 16). Further, when dimethyl carbonate is fluorinated with fluorine gas, bis (fluoromethyl) carbonate, fluoromethyl-difluoromethyl carbonate, etc. are by-produced in addition to fluoromethyl-methyl carbonate, so that purification is difficult. (Patent Document 17).

The third electrolytic fluorination method is considered to be one of effective means for introducing fluorine into an organic compound and is used.
Representative examples of the electrolytic fluorination method include: (1) a method in which anhydrous hydrogen fluoride is used as an electrolytic solution, nickel is used as an anode, and an organic compound is electrolyzed (generally called Simmons method). (2) Tertiary amine hydrofluoride or quaternary ammonium hydrofluoride as the electrolyte, and platinum as the anode to fluorinate organic compounds How to do is known.

  However, in the former method (1), a perfluoro compound is mainly obtained, and it is generally difficult to obtain a monofluorinated product, and there is no report that a monofluoro compound is obtained using this method. In addition, relatively expensive nickel must be used for the anode with anhydrous hydrogen fluoride as the electrolyte, and there is a problem that electrolysis conditions and equipment are limited. Furthermore, when the electrolysis temperature is as high as room temperature or higher, and when the electrolysis temperature is generally 0 ° C. or higher, there is a problem that side reactions including decomposition of cation and polymerization tend to proceed. The method of the latter (2) is characterized in that partial fluorination is possible, and cyclic carbonates and lactones (Non-patent Document 2), chain carbonates (Patent Document 18), and cyclic ethers (Patent Document 19). Non-patent document 2) has been reported for monofluorination. However, in these methods, a very expensive platinum electrode is used, and during electrolysis, platinum is eluted as the electrolysis proceeds, so that the running cost of equipment and the like is great.

On the other hand, in recent years, there is a report example in which an aromatic compound is electrolytically fluorinated (Patent Document 20) using a “diamond electrode” obtained by depositing a boron-doped diamond thin film on a silicon substrate or the like. However, although the diamond electrode is excellent in terms of corrosion resistance and durability, there is a problem that versatility is not high because the basic research has not yet been completed and an inexpensive manufacturing technique has not been established.
Patent Document 1 JP 62-290072
Patent Document 2 WO 98/15024
Patent Document 3 Japanese Patent Laid-Open No. 62-290071
Patent Document 4 Japanese Patent Laid-Open No. 9-251861
Patent Document 5 JP 7-165750 A
Patent Document 6 JP 7-291959 A
Patent Document 7 JP-A-8-287950
Patent Document 8 JP-A-10-199567
Patent Document 9 JP2002-175948
Patent Document 10 JP 10-144346 A
Patent Document 11 JP 2004-14134
Patent Document 12 JP-A-11-54150
Patent Document 13 JP2000-309583
Patent Document 14 US2006-0167279A1
Patent Document 15 JP 2000-344763
Patent Document 16 JP 2001-226367 A
Patent Document 17 JP2004-10491
Patent Document 18 JP2006-1843
Patent Document 19 JP 2003-73873 A
Patent Document 20 JP 2000-204492 A
Non-Patent Document 1 J. Fluorine Chem., 108, p107, (2001).
Non-Patent Document 2 Tetrahedron Lett., 43, p1502, (2002).

  An object of the present invention is to provide 5-fluoro-1,2-oxathiolane, which is expected to be used as an electrolyte solution solvent and additive for lithium ion secondary batteries, functional material intermediates, pharmaceutical intermediates, organic solvents, and the like. Therefore, it is to provide 2-dioxide and its production method.

As a result of intensive studies, the present inventors have completed the present invention. That is, the present invention provides the following.
[1] 5-Fluoro-1,2-oxathiolane 2,2-dioxide represented by [Chemical Formula 1] below.

[2] The process for producing 5-fluoro-1,2-oxathiolane 2,2-dioxide according to [1], wherein the compound of the following [Chemical Formula 2] is electrolytically fluorinated.

[3] The production method according to [2], wherein the compound of [Chemical Formula 2] is electrolytic fluorinated at −40 to 0 ° C.
[4] The production method according to [2], wherein the compound of [Chemical Formula 2] is electrolytically fluorinated at -40 to 0 ° C. using KF-nHF (n is 8 to 20) as an electrolytic solution.
[5] Electrochemical fluorination of a compound of [Chemical Formula 2] at -40 to 0 ° C using KF-nHF (n is 8 to 20) as an electrolyte and a carbon electrode as an anode [2] The manufacturing method as described in.
[6] It is characterized by electrolytic fluorination of a compound of [Chemical Formula 2] at -40 to 0 ° C. using KF-nHF (n is 8 to 20) as an electrolytic solution and a glassy carbon electrode as an anode [2] ] The manufacturing method of description.

  According to the present invention, novel 5-fluoro-1,2-oxathiolane 2,2-dioxide can be efficiently obtained. Further, by performing electrolysis within the range of -40 ° C to 0 ° C, side reactions including cation decomposition and polymerization can be suppressed. Furthermore, elution of the anode can be suppressed by using the carbon electrode.

  In the method for producing 5-fluoro-1,2-oxathiolane 2,2-dioxide of the present invention, an example of a suitable electrolyte is an alkali metal fluoride represented by the following general formula: MF · nHF (M: alkali metal). As the alkali metal, potassium and cesium are preferable, and potassium is particularly preferable. The range of n is preferably 8-20.

The equivalent amount of the alkali metal fluoride salt is 1 to 100 equivalents, particularly preferably 2 to 30 equivalents, based on 1,2-oxathiolane 2,2-dioxide as a reaction substrate.
As the electrode, a material including carbon in the anode is used, and glassy carbon is particularly preferable. The surface of glassy carbon is different from the normal carbon structure (graphite sheet or diamond structure) in that the carbon layer surface is long and connected in a ribbon shape. This unit is intricately entangled and isotropic as a whole. It has become. In addition, the structurally weak layer structure has few ends and has a strong structure.

  On the other hand, the cathode is not particularly limited as long as it is a material that generates hydrogen by electrolysis, and specifically, various metals such as platinum, nickel, and iron, and alloys including these metals ( (Including nickel steel, steel and the like), and materials containing carbon similar to the anode can be used. That is, an electrode including platinum, nickel, or iron (platinum electrode, nickel electrode, iron electrode, or alloy electrode including these metals) and a carbon material electrode can be used.

The electrolysis temperature is preferably -40 to 0 ° C. If it exceeds 0 ° C., side reactions including cation decomposition and polymerization will proceed. If the temperature is lower than -40 ° C, the substrate is precipitated out of the system as crystals.
Current density, 0.001~1 A / cm ^2, can be carried out in particularly from 0.005~1 A / cm ^2, when the current density is small (less than 0.001A / cm ^2), the area of the electrode or use electrodes In this case, the efficiency of electrolytic fluorination may be reduced because the number of the above increases and the apparatus becomes complicated and at the same time stirring becomes difficult. On the other hand, when the current density is large (exceeding 1 A / cm ² ), an undesirable side reaction proceeds and the selectivity of the target product may be reduced. More preferably, the current density is within a range of 0.01 to 0.5 A / cm ² .

  The energization amount can be in the range of 0.1 to 10 F / mol. However, when the energization amount is small (less than 0.1 F / mol), there is a problem that the raw material conversion rate is low and the yield of the target product is low. On the other hand, when the energization amount is large (exceeding 10 F / mol), there is a problem that further electrolytic fluorination of the target product occurs, polyfluorinated compounds are by-produced, and the selectivity and yield of the target product decrease. Arise. Therefore, the energization amount is preferably in the range of 1.0 to 4.0 F / mol.

The electrolysis method can be performed by constant current electrolysis, constant potential electrolysis, or a combination of both.
After completion of the reaction, when the organic compound and the electrolytic solution are not mixed (two-phase system), the upper organic compound phase of the electrolytic solution is separated from the electrolytic solution by decantation. Next, a crude product is obtained by combining the volatile organic compound obtained by heating the electrolyte under reduced pressure and the organic compound phase. On the other hand, when the organic substance and the electrolyte are mixed (homogeneous), the electrolyte is directly distilled to obtain a volatile organic substance, or the electrolyte mixture is washed with water, and an organic solvent (diethyl ether, dichloromethane, chloroform) is obtained. , Ethyl acetate, etc.) and then the solvent is distilled off to obtain a crude product. The crude product obtained through these steps is purified by distillation, recrystallization, silica gel column chromatography, etc. to obtain high-purity 5-fluoro-1,2-oxathiolane 2,2-dioxide. Can do.

(Example)
1,2-oxathiolane 2,2-dioxide (7.5 mol, 910 g), potassium fluoride / 20 hydrogen fluoride (KF / 20HF, 1.9 mol, 900 g) on a 3000 mL SUS container (inside Teflon (registered trademark) coating) , 1,2-oxathiolane 2,2-dioxide HF equivalent number 5), in a constant temperature bath at -40 to -30 ° C, using glassy carbon as anode and nickel electrode as cathode, current density 72mA / cm Constant current electrolysis was performed at ² (current 5A). After conducting an electrolytic fluorination reaction by supplying 2.0 F / mol over 82 hours, the reaction vessel was depressurized with a vacuum pump, and the low boiling point was collected with a liquid nitrogen trap. The remaining liquid was dissolved in dichloromethane, the inorganic salt was filtered, and concentrated with an evaporator to obtain 867 g of a crude product. As a result of gas chromatography analysis, the raw material conversion was 89% and the product selectivity was 72%.

  Recrystallization from dichloromethane / hexane gave 610 g (isolation yield 58%) of 5-fluoro-1,2-oxathiolane 2,2-dioxide (99% or more). Also, no change in the weight of the anode was observed at the end of electrolysis.

(Product analysis results)
¹ H-NMR (300 MHz, solvent: CDCl ₃ , standard substance: tetramethylsilane)
6.20ppm (ddd, J = 0.3, 3.9, 58.8 Hz, 1H), 3.45-3.39ppm (m, 2H), 3.00-2.73ppm (m, 2H)
¹⁹ F-NMR (282 MHz, solvent: CDCl ₃ , standard substance: CF ₃ Cl)
-118.304ppm (ddd, J = 13.3, 30.7, 56.8 Hz, 1F)
¹³ C-NMR (75 MHz, solvent: CDCl ₃ , standard substance: CDCl ₃ )
107.46ppm (d, J = 237.3 Hz, 1C), 41.97ppm (s, 1C), 30.94ppm (d, J = 24.6Hz, 1C)
Boiling point: 70 ° C (0.1kPa), melting point: 62 ° C
(Comparative example)
In a container made of 100mL tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer (PFA), 1,2-oxathiolane 2,2-dioxide (56 mmol, 6.8 g), potassium fluoride · hydrogen difluoride (KF · 2HF, 28 mmol, 28g, 1,2-oxathiolane 2,2-dioxide HF equivalent number 10), in a constant temperature bath at 70 ° C, using a porous carbon electrode as the anode and a nickel electrode as the cathode, current density 200mA / Constant current electrolysis was performed at cm ² (current 0.5 A). When a current of 2.0 F / mol was applied for 6 hours to conduct an electrolytic fluorination reaction, a polymer-like viscous substance was attached to the anode. The desired 5-fluoro-1,2-oxathiolane 2,2-dioxide was not found.

Claims (4)

A method for producing 5-fluoro-1,2-oxathiolane 2,2-dioxide shown in the following [Chemical Formula 1],

The above-mentioned [Chemical Formula 2] compound is produced by electrolytic fluorination at −40 to 0 ° C. using KF · nHF (n is 8 to 20) as an electrolytic solution and using a glassy carbon electrode as an anode. Method.

Current density during electrolysis is 0.001-1 A / cm ² The manufacturing method according to claim 1, wherein The manufacturing method of Claim 1 or 2 whose energization amount is 0.1-10F / mol. The manufacturing method in any one of Claims 1-3 whose electrolyte solution is KF * 20HF.