JP2003238457A - Method for producing fluorinated cyclohexylbenzene - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing fluorinated cyclohexylbenzenes by fluorinating cyclohexylbenzenes at a high conversion rate and high selectivity. <P>SOLUTION: The method for producing the fluorinated cyclohexylbenzenes comprises bringing cyclohexylbenzene which may have a substituent into contact with fluorine gas. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing fluorinated cyclohexylbenzenes. The various fluorinated cyclohexylbenzenes produced by the present invention are useful as additives for various solvents, particularly lithium batteries and lithium ion batteries.

[0002]

2. Description of the Related Art In recent years, energy storage devices such as lithium ion batteries and electric double layer capacitors have been used in mobile phones,
Demand is rapidly increasing due to the rapid spread of digital portable electronic devices such as portable information terminals and laptop computers. Further, from the viewpoint of global environmental problems and energy saving, these energy storage devices have been attracting attention as a power source for electric vehicles and hybrid vehicles.

Since these energy storage devices are electrochemical devices in terms of their operating mechanism, they require an electrolyte as a constituent material. In order to utilize a wide operating potential range, organic electrolysis in which a solute salt is dissolved in an organic solvent is required. Liquid is being used. For example, in a lithium primary battery using lithium metal as a negative electrode, when the positive electrode is manganese dioxide, a mixed solvent of propylene carbonate and 1,2-dimethoxyethane is added to LiClO ₄ or LiCF ₃ SO _4.
An electrolyte solution in which ₃ is dissolved is mainly used, and when the positive electrode is fluorocarbon, an electrolyte solution in which LiBF ₄ is dissolved in γ-butyrolactone is mainly used. Also,
In a lithium ion secondary battery having a lithium-carbon compound as a negative electrode, LiP is used as a mixed solvent of a cyclic carbonic acid ester such as ethylene carbonate or propylene carbonate and a chain carbonic acid ester such as dimethyl carbonate, ethylmethyl carbonate or diethyl carbonate.
An electrolyte solution in which F ₆ is dissolved is used exclusively (Makoto Ue et al., Development and Market of Lithium Ion Battery Materials, CMC, Chapter 6 (1997)).

The electrolyte solution using the non-aqueous solvent as described above can be used at a high voltage because of the high stability of the non-aqueous solvent. The so-called overcharge phenomenon, which results in a voltage of 3, is likely to become a problem. Overcharging can cause not only deformation and heat generation of the battery, but also in extreme cases, such as ignition and explosion, so it is important to improve the safety of the secondary battery during overcharging. is there.

Particularly, as a positive electrode active material of a lithium secondary battery, a lithium transition metal oxide having a layered structure, such as lithium cobalt oxide and lithium nickel oxide, is used because of its large capacity per weight. In overcharged state, these compounds become almost desorbed from lithium ions and become unstable, which may cause a rapid exothermic reaction with the electrolytic solution or deposit lithium metal on the negative electrode. Therefore, safety during overcharge is very important.

[0006] As one of the methods for improving the safety at the time of such overcharge, there is known a method of adding an overcharge inhibitor to the electrolytic solution to cut off the current. The present inventors have found that fluorinated cyclohexylbenzene is effective as an overcharge preventing agent, and when fluorinated cyclohexylbenzene is contained in a non-aqueous electrolyte solution in which a lithium salt is dissolved in a non-aqueous solvent, the fluorinated cyclohexylbenzene is oxidized by itself. It has been found that, by doing so, it has the ability to stop the progress of overcharging, and can keep the performance degradation of the battery under the conditions such as normal charge / discharge and high temperature storage within an allowable range.

[0007]

As mentioned above, fluorinated compounds of cyclohexylbenzene and its derivatives are useful compounds, but a simple method for producing them is not known. An object of the present invention is to provide a simple method for producing fluorinated cyclohexylbenzenes.

[0008]

DISCLOSURE OF THE INVENTION The present inventors have already used the method (J. Org. Chem., 38, 3617) conventionally used for perfluorination of 1,2-dimethoxyethane.
(1973)) was applied to a lactone compound which was considered to be difficult to apply considering its reactivity, and it was found that a fluorinated lactone compound can be obtained with unexpectedly high conversion and high selectivity. For the first time, it succeeded in obtaining a monofluorosulfolane compound that could not be obtained by the conventional production method (Japanese Patent Laid-Open No. 2001-22636).
No. 7 and J. Fluorine Chem. , 10
8, 117 (2001)).

In view of the above circumstances, the present inventors have made extensive studies, and as a result, found that a similar method can be applied to cyclohexylbenzenes, and based on this, the present invention was completed. I arrived. That is, the gist of the present invention resides in a method for producing fluorinated cyclohexylbenzenes, which comprises contacting cyclohexylbenzene which may have a substituent with fluorine gas.

According to the present invention, there is provided a method for producing various fluorinated cyclohexylbenzenes containing a compound which has hitherto been unavailable.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below. In the method of the present invention, cyclohexylbenzene optionally having a substituent (hereinafter referred to as cyclohexylbenzenes) is brought into contact with fluorine gas to produce fluorinated cyclohexylbenzenes.

The raw materials used in the method of the present invention are cyclohexylbenzenes, that is, cyclohexylbenzene and derivatives thereof having a substituent. Examples of the substituent include various substituents which do not inhibit the reaction, for example, a methyl group,
Examples thereof include alkyl groups such as ethyl group and propyl group, and alkoxy groups such as methoxy group and ethoxy group. Specific examples of cyclohexylbenzenes include cyclohexylbenzene, 1-cyclohexyl-4-methylbenzene, 1-cyclohexyl-4-methoxybenzene, (4
-Methylcyclohexyl) benzene and the like can be mentioned, with preference given to cyclohexylbenzene.

The molar ratio of fluorine gas (F ₂ ) to cyclohexylbenzenes is usually 0.1 to 100.
Although it is a degree, it is more preferably 0.5 to 10.
Fluorine gas which is brought into contact with cyclohexylbenzene to react with it is a compound having extremely high reactivity, and therefore, in order to prevent runaway of the reaction, it is preferable to use fluorine gas diluted with an inert gas. Examples of the inert gas used for diluting the fluorine gas include nitrogen, helium,
Examples thereof include hydrogen fluoride and perfluoroalkanes having 4 or less carbon atoms. The concentration of fluorine in the diluted fluorine gas is usually 1 to 50% by volume, preferably 5 to 30% by volume. If the concentration is too low, productivity will be poor, and if it is too high, reaction control will be difficult.

The reaction between cyclohexylbenzenes and fluorine gas is usually carried out by introducing diluted fluorine gas into liquid phase cyclohexylbenzenes. At this time, a solvent inert to fluorine gas may be present. Examples of the above-mentioned solvent inert to the fluorine gas are perfluoroalkanes such as acetonitrile, perfluorocyclobutane, perfluorohexane, perfluorooctane, and perfluorodecane, and Lubrication Magazine, Vol. 32, No. 2, page 107. Such perfluoropolyether oil (for example, "Demnum" manufactured by Daikin Industries, Ltd., "Fomblin" manufactured by Oushimont, "Crytox" manufactured by DuPont, etc.), chlorotrifluoroethylene oligomer oil (eg, manufactured by Daikin Industries, Ltd. " Chlorofluoroalkane such as "Daifloyl"). The ratio of cyclohexylbenzenes to the inert solvent is
Usually 10 to 99% by weight, preferably 50 to 95% by weight
Is. If this ratio is too low, the pot efficiency will decrease, and if it is too high, the effect of dilution will be diminished.

The reaction temperature is usually in the range of -80 to 100 ° C, preferably -30 to 80 ° C. The reaction pressure is usually atmospheric pressure, but in some cases it may be carried out under reduced pressure or increased pressure. The reaction time varies depending on the type of cyclohexylbenzenes, the type of solvent, the reaction temperature, etc., but is usually 1 to 500 hours, preferably 5 to 100 hours.

During this reaction, a fluoride salt such as sodium fluoride may be added to the reaction system in order to absorb hydrogen fluoride produced by the reaction. It is also possible to vaporize cyclohexylbenzenes and react them with fluorine gas in the vapor phase. Also in this case, it is necessary to dilute with an inert gas in order to prevent runaway of the reaction. The reaction temperature of the gas phase reaction is usually 30 to 250 ° C, preferably 50 to 150 ° C.

The reaction system may be a batch system, a semi-batch system, or a flow system, and a microreactor whose heat transfer can be easily controlled can also be used. By the above reaction, fluorinated cyclohexylbenzenes mainly having hydrogen atoms on the benzene ring substituted with fluorine atoms are obtained. The fluorinated cyclohexylbenzenes to be obtained may be various substitution products having different degrees of fluorination, from mono-substitution products, di-substitution products to perfluoro substitution products, but by adjusting the reaction conditions, conventional production methods can be used. The unknown compound can be obtained in high yield and high selectivity.

[0018]

EXAMPLES Hereinafter, specific embodiments of the present invention will be described in detail with reference to Examples.
It is not limited by these examples. Example 1 Volume 30 provided with gas inlet and gas outlet for liquid phase
A 0 ml Teflon (R) container was charged with 100 g of cyclohexylbenzene, and 30 vol of nitrogen gas was added to this.
Fluorine gas diluted to 100% was introduced at a rate of 0.045 mol / hr, the reaction temperature was kept at 10 ° C., the reaction pressure was kept at atmospheric pressure, and the reaction was performed for about 24 hours. After the reaction was completed, the liquid phase was analyzed.

As a result of GC / MS analysis and NMR analysis, 1
-Cyclohexyl-2-fluorobenzene 30%, 1
-Cyclohexyl-3-fluorobenzene 5%, 1-
13% of cyclohexyl-4-fluorobenzene was produced, and in addition to this, trace amounts of five kinds of compounds considered to be cyclohexyldifluorobenzene in which hydrogen atoms on the benzene ring were substituted with fluorine atoms were confirmed. A compound having no cyclohexylbenzene skeleton was not found.

Example 2 Example 1 except that (4-methylcyclohexyl) benzene was used as a raw material instead of cyclohexylbenzene.
The reaction was performed under the same conditions as above. GC / MS analysis and NM
As a result of R analysis, 1- (4-methylcyclohexyl) -2
-Fluorobenzene 30%, 1- (4-methylcyclohexyl) -3-fluorobenzene 5%, 1- (4-
Methylcyclohexyl) -4-fluorobenzene is 13
% Was generated.

[0021]

According to the present invention, cyclohexylbenzenes can be fluorinated with high conversion and high selectivity to obtain fluorinated cyclohexylbenzenes.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Makoto Ue             3-3-1 Chuo 8-chome, Ami Town, Inashiki District, Ibaraki Prefecture             Within Mitsubishi Chemical Corporation F-term (reference) 4H006 AA02 AC30 BB61 BE53 EA33

Claims (3)

[Claims] 1. A method for producing fluorinated cyclohexylbenzenes, which comprises contacting cyclohexylbenzene which may have a substituent with fluorine gas. 2. The method for producing fluorinated cyclohexylbenzenes according to claim 1, wherein the fluorine gas is diluted with nitrogen, helium, hydrogen fluoride or a perfluoroalkane having 4 or less carbon atoms. 3. The method for producing fluorinated cyclohexylbenzenes according to claim 1, wherein the main product is monofluorinated cyclohexylbenzenes.