JPS6017205B2 - Fluoride production method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to electrolytic fluorination of polymeric compounds, and more specifically provides a method for efficiently synthesizing useful fluorine compounds by electrolytic fluorination of solid polymeric compounds under specified conditions. It is something to do.

In general, electrolytic fluorination has the following characteristics: 1) cheap anhydrous hydrofluoric acid is used as a direct fluorination source; 2) high fluorine compounds can be obtained under mild conditions; 3) functional groups are easily preserved; and 4) equipment is required. It has the advantage of being relatively simple.

Therefore, fluorination of a large number of compounds has been attempted by electrolytic methods, and some of them have been industrialized.
However, in the electrolytic fluorination of low-molecular compounds, it is known that the larger the molecular weight, the more difficult it is to obtain a corresponding fluorine compound, and this is especially true for hydrocarbon compounds with a molecular weight of 500 or more. Obtaining fluorine compounds is extremely difficult. That is, with regard to electrolytic fluorination of solid polymer compounds, there have been almost no examples reported so far, including a study of the specific method and the resulting fluoride. As a result of various studies on electrolytic fluorination of solid polymer compounds, the present inventors have discovered that fluorination can be carried out efficiently by installing the polymer compound at the anode or very close to the anode, and that it is a useful fluoride. The present invention was completed based on the discovery that the following can be obtained.

That is, the present invention provides a battery case containing a cathode and an anode, in which a molten mixture of conductive anhydrous hydrofluoric acid or anhydrous hydrofluoric acid and an alkali metal fluoride is used as a melt bath, and the anode or the anode is This is a method for producing fluoride, which is characterized in that a solid polymer compound is placed in the vicinity within 15 sides from 1 to 15, and electricity is supplied to the solid polymer compound. According to the present invention, by electrolytic fluorination of various polymer compounds, not only the interface of the polymer compound in contact with an electrolyte but also the inside can be fluorinated, and polymer chains can be appropriately cut at the same time as fluorination. A fluorine-containing compound having a molecular weight of 500 or more, or even 1000 or more, can be obtained in high yield.

For example, using a polymer compound with a molecular weight of 3000 or more,
A fluorine compound with a low molecular weight of 500 or more can be easily obtained. Furthermore, the produced low molecular weight fluorinated products can also be obtained as compounds into which double bonds, COF, etc. are introduced at the same time, and can be used for various purposes by taking advantage of their reactivity. Of course, in the above case, the fluorination reaction that involves scission of polymer chains is significant, so it is not possible to fluorinate a solid polymer compound and use it as is. There is no problem in using the fluorine compounds obtained at the same time. Therefore, the solid polymer compound used in the present invention has a molecular weight of about 2,000 or more, preferably 4,000 or more, and is insoluble even if it swells in the electrolyte.

Examples include polyethylene, polypropylene, polyvinyl chloride, polystyrene, polyvinylidene fluoride, phenol resin, urea resin, epoxy resin, etc., and these polymer compounds may have various functional groups. When obtaining a low molecular weight fluorine compound by utilizing polymer chain scission in the present invention, it is preferable that the polymer compound used is not crosslinked. Similarly, when a fluorine compound is obtained by cutting a polymer chain, the polymer compound used is advantageously in the form of particles, threads, cloth, or thin films. Generally, by using a polymer compound having the above-mentioned shape, the thickness of which is less than or equal to 2 skins, particularly less than 0.5 years, the interior of the polymer compound can be sufficiently efficiently fluorinated. Note that a polymer compound that is difficult to form a film may be formed into a film using an appropriate binder or support cloth. In the present invention, electrolytic fluorination is carried out by placing a solid polymer compound in the vicinity of columns 0 to 15, preferably columns 0 to 5, from the anode surface. This is extremely important for obtaining fluorine compounds.

That is, by placing the polymer compound to be electrolytically fluorinated in the vicinity of the above-mentioned anode, 1) the current efficiency of fluorination of the polymer compound, 2) the fluorination rate of the resulting fluorine compound, and 3) the cutting of the polymer chain. A significant difference in the proportion of low molecular weight fluoride produced is observed compared to the case where the polymer compound is placed outside the vicinity of the anode described above. Although the reason for this is not clear, the electrolytic fluorination of solid polymer compounds differs significantly depending on the location of the polymer compound in the electrolytic bath, and the supply rate of fluorine from the anode surface and the fluorination agent for the fluorine. It is estimated that the degree of activity as a substance has a very large influence. In the present invention, a specific method for installing a solid polymer compound on the anode or in the vicinity of the anode is a method in which the core polymer compound is melted or dissolved in a solvent and coated on the anode. A method of fixing cloth or membrane-like material using Teflon thread, silk, porous membrane, etc. that is not easily attacked by crab scale bath; A method of wrapping the polymer compound silk, cloth, etc. around the anode as it is: A method is employed in which porous membranes such as Teflon are installed in parallel and the particles of the polymer compound are fixed in the gaps between them. In addition, when forming a coating of a polymer compound that does not have electrical conductivity on the anode surface in a fin melting bath, it is preferable to make the coating sufficiently porous. In the present invention, anhydrous hydrofluoric acid imparted with conductivity or a molten mixture of anhydrous hydrofluoric acid and an alkali metal fluoride is used as the electrolyte. Since pure anhydrous hydrofluoric acid alone does not have electrical conductivity, a conductivity increasing agent is necessary and is usually used at a concentration of 0.1 to 1% by weight. Examples of conductivity increasing agents include alcohols, amines, ammonia, water, etc., which are themselves fluorinated and therefore need to be added sequentially as the fluorination reaction progresses during electrolysis, and alkali metals and alkalis. Some metals, such as fluorides, are simply dissolved in anhydrous hydrofluoric acid. The alkali metals mentioned above are potassium fluoride, cesium fluoride, etc., and the molten mixture with anhydrous hydrofluoric acid is usually KF-HF, KF-2HF, etc. Of course, if it has sufficient electrical conductivity due to impurities mixed in anhydrous hydrofluoric acid or a partial decomposition product of the polymer compound to be electrolytically fluorinated, this will not cause any inconvenience to the fluorination reaction. It is not necessary to specifically add a conductivity enhancer. Next, regarding the electrolytic cell used in the present invention, its shape is not particularly limited, such as cylindrical, rectangular columnar, etc., and its material is metals such as nickel, monel, copper, iron, etc., or materials that can withstand electrolytic ratings such as fluororesin. is used.

The cathode and anode in the electrolytic cell are installed substantially vertically in order to facilitate the escape of gas bubbles generated at the electrodes. The material of the anode is limited in terms of conductivity, corrosion resistance, etc., and nickel, nickel alloy (for example, Monel), carbon, graphite, etc. are used. In general, when anhydrous hydrofluoric acid is used as an electrolytic material, nickel or a nickel alloy is used, and when a molten mixture of anhydrous hydrofluoric acid and an alkali metal fluoride is used, carbon or graphite is used. The shape of the anode includes a plate, a net, a round bar shaped like a sag, a perforated plate, an expanded metal, etc. processed into a flat or wavy shape. On the other hand, the material of the cathode is nickel, nickel alloy, copper, stainless steel, iron, etc., and its shape is the same as that of the anode. Although it is not normally necessary to install a diaphragm between the cathode and anode in an electrolytic cell, if necessary, a partition plate, a perforated plate, or a perforated plate made of a material that can withstand the electrolytic rating may be installed.
A porous membrane may also be installed. Electrolytic conditions such as current density and amount of current in the electrolytic fluorination of the present invention vary depending on the type, property, amount, etc. of the polymer compound used, or the target fluorine compound, and cannot be unconditionally specified.

Generally, electrolysis is carried out at a current density of 0.05 to 1/d, and electrolysis is usually carried out at a constant current, but it is also possible to change the current value periodically or to change the current value gradually as the electrolysis progresses. It is also possible to perform constant potential electrolysis. There are no particular limitations on the temperature, pressure, and electrolyte difference in electrolysis, but in general, when the electrolysis is anhydrous hydrofluoric acid, the temperature is -10 to 15 qC, and the molten mixture of anhydrous hydrofluoric acid and alkali metal fluoride is used. In the case of , it is carried out at a temperature above its melting point. Note that preliminary energization may be performed as appropriate to remove impurities in the electrolytic solution prior to actual energization. In this case, it is convenient to separately provide an electrode for preliminary energization. By electrolytic fluorination of a solid polymer compound in the present invention, a fluorinated compound is usually obtained as a mixture of gas, liquid, and solid.

Therefore, in order to separate and collect a fluorine compound of a desired type and molecular weight, a separation method such as recrystallization, distillation, extraction, etc. may be employed depending on the types of other coexisting compounds. Hereinafter, the present invention will be specifically explained with reference to Examples.
The present invention is not limited in any way by these Examples.

Example 1 An electrolytic cell made of polychlorotrifluoroethylene and having a capacity of about 1000 cc was used.

The anode is a nickel plate with a current-carrying area of 35 mm per side (height 7 mm x medium 5 mm), and the cathode is a nickel plate with the same shape as the two anodes installed in parallel and 4 mm apart from both sides of the anode. be. 7mm thick polyvinyl chloride cloth (Teviron, manufactured by Teijin)
The sample was preliminarily washed with 100 oo of hot water for 2 hours, and then refluxed with methanol for 3 hours to remove soluble materials and used as a sample for electrolytic fluorination.

Two pieces of this cloth were weighed out with a middle-sized cloth, wrapped around a nickel anode, and fixed using a polytetrafluoroethylene thread. Anhydrous hydrofluoric acid (manufactured by Daikin Corporation), which had been sufficiently pre-electrolyzed in a separate electrolytic tank to remove impurities, was supplied to the electrolytic tank, and approximately 1% by weight of sodium fluoride was added to carry out electrolysis. Ta. The electrolysis temperature was 0° C., and the electrolysis current was 20 hA for 1 hour. After electrolysis, the anhydrous hydrofluoric acid was discharged from the electrolytic cell, and the cloth was taken out, washed thoroughly with warm water, dried, and then weighed and subjected to elemental analysis of fluorine. Furthermore, methanol extraction was performed, and the weight ratio of each was determined from the dry weight of the extract and the extraction residue, and elemental analysis of fluorine was performed on both. (No. 1) Next, divide the polyvinyl chloride cloth with the same dimensions as above into two pieces (each for one day), and fit each piece into a rectangular frame of 7c x 5 skin made of nickel wood with a diameter of 1.5 ribs. It was wrapped and fixed with polytetrafluoroethylene thread. These were placed parallel to each other at 7.5 skin distance from both sides of the anode, and electrolysis was performed under the same conditions as above. (N
o. 2) Furthermore, in the same manner as above, a nickel frame wrapped with polyvinyl chloride cloth was placed at a position 2 feet away from the anode surface, and electrolysis was performed.

(No. 3) No. 2 and 3 are also No. Measurements and analyzes were carried out in the same manner as in 1, and the results are shown in Table 1.

No. 1 and M. Most of the methanol extracted in 2 was also dissolved in chloroform, and the molecular weights measured using a vapor pressure equilibrium molecular weight measuring device (Hitachi Perkin Elmer 115, manufactured by Hitachi, Ltd.) using chloroform as a solvent were 2250 and 2640, respectively. Ta.

- (One was not measured) Example 2 A polystyrene pellet (manufactured by Mitsui Tosho Co., Ltd.) was finely crushed to a diameter of 0.5 willow or less and used as a sample for electrolytic fluorination.

The electrolytic cell used was the same as in Example 1, and the position, shape, etc. of the cathode were also the same as in Example 1. However, a cloth made of polytetrafluoroethylene fiber is used in a bag shape (medium 5.5 x height 7
．． Insert the nickel anode (thickness 3) into this, fill the space inside the bag with 1.5 mm of the above polystyrene particles, and leave the top of the bag open and insert the anode. I installed it. Using the same electrolyte as in Example 1, after applying electricity for 30 hours at an electrolysis temperature of 5°C and an electrolysis current of 1 mA,
Measurements similar to those in Example 1 were performed. The results are shown in Table 2. Electrolysis was carried out in the same manner as above, except that a polytetrafluoroethylene cloth bag containing fine polystyrene particles was placed at a position 1 or 2 degrees from the anode surface. I did it.

However, in this case, the anode on the opposite side of the anode from where the sample was placed was not used. The results are shown in Table 3. Table 3 Example 3 The same electrolytic cell as in Example 1 was used except that the material of the anode was carbon.

Polyethylene microparticles "Flocene" (trade name, manufactured by Tetsutsu Kagaku Co., Ltd.) were used as a sample for electrolytic fluorination. Using a bag made of a porous membrane made of polytetrafluoroethylene similar to that used in Example 2, 1.3 pieces of the above polyethylene fine particles were fixed near the anode in the same manner. The pre-prepared KF-Gold was melted and introduced into an electrolytic cell, and energized at an electrolytic temperature of 9°C and an electrolytic current of 15 hA for 15 hours. Table 4 shows the results measured in the same manner as in Example 1. Table 4: When a bag made of a porous film made of polytetrafluoroethylene containing fine polyethylene particles is installed at a position one point away from the anode surface, the same amount of fine polyethylene particles are deposited as they are on the bottom of the electrolytic cell. Electrolysis was performed in the same manner as above for both cases.

However, in the former case, the anode on the opposite side of the sample installation position was not used. The results are shown in Table 5. Table 5 (No measurements were taken) Example 4 The same electrolytic cell and electrolyte rating as in Example 1 were used.

Fine polyvinyl chloride powder (Sumirit, manufactured by Sumitomo Chemical Co., Ltd.) is dissolved in a mixed solution of tetrahydrofuran and ethyl alcohol, applied to both sides of the nickel plate of the anode, dried, and porous on the side with a thickness of approximately 0.05 mm. Electrolytic fluorination was performed by forming a film of polypinyl chloride. As in Example 1, the electrolysis was carried out under the conditions of 0° C. and 20 mA for 1q hours. The fluorine content of the membrane recovered after electrolysis is 51. plow t
%Met. As a result of methanol extraction, about 65% was extracted, and its fluorine content was 1.5%. It was 2wt%. Example 5 A commercially available strongly acidic cation exchange resin (
Ambalite IR-120) crushed and dried 1
．． Example 2 was carried out under the same conditions and method as in Example 2, except that the electrolytic current was changed to 20 valent A using 52.

Claims (1)

[Scope of Claims] 1. In a battery container containing a cathode and anode, an electrolytic bath is made of conductive anhydrous hydrofluoric acid or a molten mixture of anhydrous hydrofluoric acid and an alkali metal fluoride; A method for producing a fluoride, which comprises placing a solid polymer compound within 15 mm from an anode and energizing it. 2. The method according to claim 1 for producing a fluoride having a lower molecular weight than a polymer compound.