JPH05320968A - Method for organic electrolytic fluoration - Google Patents

Abstract

PURPOSE:To improve the yield of a perfluoro compound by using an anode coated with an Ni-based composite film at the time of producing the perfluoro compound using hydrofluoric acid anhydride as an electrolyte by a method for organic electrolytic fluorination. CONSTITUTION:In the case of synthesizing the perfluoro compound such as perfluorooctane sulfonyl fluoride (C8H17SO2F) in a cell into which hydrofluoric acid anhydride is added as the electrolyte by electrolysis, an electrode made of Fe, Ni or the like is used as the cathode, an electrode coated with the composite plated film formed by eutectoid-dispersing polytetrafluoroethylene particle and fluorinated graphite into Ni plated film is used as the anode and sodium fluoride is added as the electroconductive material after previous electrolyzing and furthermore octanesulfonyl fluoride (C8H17SO2F) is added, then electrolysis is executed. Perfluorooctanesulfonyl fluoride is obtained in high yield.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic electrolytic fluorination method for producing a perfluoro compound useful as a surfactant, a water / oil repellant, an inert liquid and the like.

[0002]

2. Description of the Related Art Organic electrolytic fluorination using anhydrous hydrofluoric acid as an electrolytic solution is capable of producing a useful compound which cannot be obtained by other methods, and is expensive. This is an advantageous method because it can be synthesized in one step without using an agent, and it is a usual method to use nickel or its alloy for the anode. However, electrolytic fluorination has a drawback in that the yield of the target substance and the current efficiency are low as compared with general electrode reactions. This is because the carbon-carbon bond of the organic compound to be fluorinated during the anodic fluorination reaction is cleaved, and a small amount of H ₂ O present in the anhydrous hydrofluoric acid, which is the electrolytic solution, is fluorinated at the anode to cause OF. It is considered that ₂ occurs, which further accelerates the cleavage reaction described above and produces many kinds of by-products. In the actual electrolytic fluorination of a compound containing water, an extreme decrease in the yield of the electrolytic reaction is observed as compared with the dehydrated compound.

Further, in the electrolytic fluorination of a compound having a relatively large number of carbon atoms, a large amount of tar is produced and adheres to the surface of the electrode as a film-like substance, so that the cell voltage gradually rises and stable electrolytic operation for a long period of time is difficult. Becomes

In an organic electrolytic fluorination reaction using anhydrous hydrofluoric acid as an electrolytic solution, when a material other than nickel or its alloy is used for the anode, a non-conductivity occurs on the electrode surface or the anode material is eluted. Not suitable for electrolytic fluorination, nickel electrodes are commonly used. However, even if an anode using nickel or its alloy is used, as described above,
The yield of the target product is low and its improvement is required.

[0005]

Means for Solving the Problems In view of the problems of the above-mentioned conventional methods, the present inventors have made earnest studies, and as a result, polytetrafluoroethylene and / or fluorinated graphite particles were co-deposited and dispersed during nickel plating. Surprisingly, the use of an electrode overlaid with a nickel-based composite coating as the anode improves the yield of the perfluoro compound as the target product, and
The present invention has been accomplished by finding a method capable of suppressing the adhesion of tar generated during electrolytic fluorination and easily and efficiently producing a target product.

That is, according to the present invention, an electrode whose surface is coated with a composite plating film in which polytetrafluoroethylene particles and / or graphite fluoride particles are co-dispersed in a nickel plating film is used as an anode. An organic electrolytic fluorination method using anhydrous hydrofluoric acid as an electrolytic solution is provided.

The anode used in the method of the present invention is generally polytetrafluoroethylene (hereinafter often abbreviated as "PTFE") particles in an electrolytic or electroless plating bath for nickel plating. And / or a nickel-based composite plating solution in which fluorinated graphite particles are dispersed is used to plate an electrode base material such as nickel or a nickel alloy, and PTFE particles and / or fluorinated graphite particles are co-deposited in the nickel plating film. It can be obtained by forming the dispersed composite plating film on the surface of the electrode base material. For general methods of forming this type of composite plating film, see Japanese Patent Publication No. 52-006252 and Japanese Patent Publication No. 52-
No. 023983 can be referred to.

As the PTFE to be used, one having a molecular weight of 100,000 or more can be used, but in order to further increase the effect of the present invention by increasing the ratio of the number of fluorine atoms on the PTFE surface in the composite plating film surface, the molecular weight is further increased. PT less than 10,000
It is preferred to use FE oligomers, whereby
This is advantageous because the ratio of the number of fluorine atoms on the PTFE surface in the composite plating film surface can be increased to 40% or more.
Further, the ratio of the number of fluorine atoms can be increased to 60% by further performing contact treatment with fluorine gas before the composite plating. The graphite fluoride can be obtained by direct fluorination of amorphous carbon or graphite (C
F) n or (C ₂ F) n is known (“Solid State I
onics "Vol.1, No.12, PP.87 ~ 110, April 1980, North
-See Holland Publishing Company).

The average particle size of the PTFE particles and the graphite fluoride particles is 0.1 to 150 μm, particularly 0.1 to 15 μm.
However, it is preferable to use as fine particles as possible.

As the plating solution for dispersing the PTFE particles and / or the graphite fluoride particles, a known plating solution used for composite plating can be used. In this case, either an electroplating solution or an electroless plating solution may be used. Generally, an electroplating solution can be used. As the electroplating solution, a Watt bath, a nickel plating solution such as nickel sulfamate, or a nickel alloy plating solution can be used, and those having a known bath composition can be used.

The amount of PTFE particles and / or graphite fluoride particles dispersed in these plating solutions is 1 to 300.
g / l, but especially 10-100 g / l
Is preferred. In this case, these plating solutions have P
A surfactant may be added for the purpose of making the dispersion of TFE particles and graphite fluoride particles in the liquid uniform and increasing the amount of co-deposition on the plating film. As the surfactant, one kind or two or more kinds such as a perfluoroalkyl-based surfactant can be used, and a cationic perfluoroalkylammonium salt is particularly preferable. The amount of these surfactant additives is 0.001 to 10 g / l, especially 0.01 to 10 g / l.
It is good to set it to 1 g / l.

The conditions for performing composite plating using the above plating solution may be the usual conditions for the plating solution, but the PTFE particles / and the fluorinated graphite particles are uniformly and as non-aggregated as possible in the plating solution. Disperse,
In order to increase the eutectoid amount of the particles on the plating film and to uniformly disperse and combine the single particles in the plating film, it is preferable to sufficiently stir, for example, ultrasonic stirring can be used. The eutectoid dispersion amount of the PTFE particles and / or fluorinated graphite in the composite plating film is preferably 2 to 50% by volume, and particularly preferably 10 to 25% by volume.

The starting compounds to be fluorinated in the method of the present invention are saturated and unsaturated organic compounds having hydrogen atoms bonded to carbon atoms. For example, sulfonic acid and its derivatives such as acid chloride, acid fluoride and ester; carboxylic acid and its derivatives such as acid chloride, acid fluoride and ester; and amines such as primary amine, secondary amine and tertiary amine; Examples thereof include ethers; phenols; alcohols; ketones; aldehydes; aliphatic and aromatic compounds such as sulfur-containing compounds such as thioethers. Further, an organic compound in which a part of hydrogen atoms of the above-mentioned organic compound is replaced with a fluorine atom or a chlorine atom can also be used as a raw material compound.

The conditions for demonstrating the electrolytic fluorination method of the present invention are not particularly limited and can be appropriately selected from the range of known electrolytic fluorination conditions. Usually, temperature -15 to
20 ° C, current density 0.2-6A / dm ² , tank voltage 4-8V
It is done in the range of. The organic compound as a raw material and anhydrous hydrofluoric acid may be supplied by either a batch method or a continuous method.

Next, the electrolytic cell is not particularly limited, and a known one can be used. Iron, stainless steel, nickel and nickel alloys can be used as the material of the electrolytic cell, and iron and nickel can be generally used as the cathode.

Hydrogen and low-molecular-weight compounds having a low boiling point generated by decomposition of hydrogen and organic compounds generated at the cathode in the electrolytic fluorination reaction are usually discharged through a reflux condenser provided in the upper part of the electrolytic cell.

When the boiling point is high, the perfluorinated organic compound fluorinated by the electrolytic fluorination method of the present invention is separated into layers from the electrolytic solution and settles, so that it can be recovered from the lower part of the electrolytic cell. When the target substance has a low boiling point and becomes a gas, it can be taken out from the upper portion of the electrolytic cell, cooled, and recovered.

[0018]

EXAMPLES The present invention will be specifically described below with reference to the following examples, but the present invention is not limited to these examples.

Example 1 The anode was a watt bath in which a low molecular weight PTFE [trade name: Cefraral Lube (manufactured by Central Glass Co., Ltd.)] was dispersed on a nickel plate (width 5 cm, height 12.5 cm, thickness 0.1 cm). It was produced by co-fold plating. This surface has a low molecular weight P
20% of TFE was present, and the contact angle with water was 140 degrees, which showed water repellency. In an iron electrolytic cell (capacity 800 ml), these 5 electrodes as an anode and an iron plate cathode (width 5 cm, height 1)
Six sheets (2.5 cm, thickness 0.1 cm) were alternately arranged at 3 mm intervals. After 623 ml of anhydrous hydrofluoric acid was introduced into the electrolytic cell and preliminary electrolysis was performed at a cell voltage of 5.5 V, 0.6 g of sodium fluoride was added as a conductive agent. Then, 30.6 g of octane sulfonyl fluoride (C ₈ H ₁₇ SO ₂ F) was added, and the current density was about 1 A / dm ² for 52.6 hours.
Energized up to 60 AH. The electrolytic cell was cooled from the outside to maintain the temperature of the electrolytic solution at 10 ° C. The cell voltage was stable at 5.4 to 5.6V. 56.0 g of octane sulfonyl fluoride was used in all electrolysis. The product was taken out from the bottom of the electrolytic cell, the amount thereof was measured, and the composition was quantified by gas chromatography. As a result, 58.1 g of perfluorooctanesulfonyl fluoride (C ₈ F ₁₇ SO ₂ F) was synthesized. The yield was 40.5%.

Comparative Example 1 In the same electrolytic cell as in Example 1, 5 nickel plate anodes and 6 iron plate cathodes were alternately arranged at 3 mm intervals. After 614 ml of anhydrous hydrofluoric acid was introduced into the electrolytic cell and preliminary electrolysis was performed at a cell voltage of 5.5 V, 0.6 g of sodium fluoride was added as a conductive agent. After that, 30.4 g of octanesulfonyl fluoride was added, and electricity was supplied to about 258 AH of electricity at a current density of about 1 A / dm ² for 53.6 hours. The electrolytic cell was cooled from the outside to maintain the temperature of the electrolytic solution at 10 ° C. The cell voltage was 5.5 V in the initial stage of electrolysis, but the conductivity decreased in about 40 hours and reached 6.5 V at the end of electrolysis. 55.4 g of octane sulfonyl fluoride was used in the whole electrolysis. The product was taken out from the bottom of the electrolytic cell, the amount thereof was measured, and the composition was quantified by gas chromatography, whereby 22.3 g of perfluorooctanesulfonyl fluoride could be synthesized. The yield was 15.7%.

Example 2 Using the same electrolytic cell and anode as in Example 1, 614 ml of anhydrous hydrofluoric acid was introduced and preliminary electrolysis was carried out at a cell voltage of 5.5 V. Then, tripentylamine ((C ₅ H ₁₁ ) ₃ N)
Was added for ² hours at a current density of about 1 A / dm ² for 250 hours to supply electricity of 1250 AH. The electrolytic cell was cooled from the outside to maintain the temperature of the electrolytic solution at 10 ° C. During the electrolysis, tripentylamine and anhydrous hydrofluoric acid were intermittently added. 139 g of tripentylamine was used during all energization. The cell voltage did not rise until the end of electrolysis and was stable at 5.5 to 5.7V. The product was intermittently taken out from the bottom of the electrolytic cell, washed with water, the amount thereof was measured, and the composition was quantified by gas chromatography. As a result, 210 g of perfluorotripentylamine ((C ₅ F ₁₁ ) ₃ N) was synthesized. The yield was 42.8%.

After the completion of electrolysis, the electrode was taken out and observed. As a result, there was no tar-like deposit on the anode and it showed water repellency.

Comparative Example 2 In the same electrolytic cell as in Example 1, using a nickel plate as the anode, 600 ml of anhydrous hydrofluoric acid was introduced, and the cell voltage was 5.5V.
After performing a pre-electrolysis in
When electrolysis was carried out at a current density of about 1 A / dm ² and a cell voltage of 5.5 V, 40 hours after energization, the cell voltage increased due to a decrease in conductivity, so the current density was lowered and electrolysis was continued. After about 90 hours, the current density was 0.25 A / dm ² and the cell voltage was 8.
Since it reached 5V, electrolysis was terminated. The amount of electricity supplied is 3
It was 72 AH. During the electrolysis, tripentylamine and anhydrous hydrofluoric acid were intermittently added. 40.5 g of tripentylamine was used during all energization. The product was intermittently taken out from the bottom of the electrolytic cell, washed with water, the amount thereof was measured, and the composition was quantified by gas chromatography. As a result, 29.1 g of perfluorotripentylamine was synthesized. The yield was 19.8%. After completion of electrolysis, the electrode was taken out and observed, and the anode was covered with a tar-like compound.

Example 3 The anode was a nickel plate similar to that used in Example 1 and graphite fluoride [trade name: Cefbon (manufactured by Central Glass Co., Ltd.)].
It was manufactured by performing eutectoid plating in a Watts bath in which was dispersed. Graphite fluoride was present on the surface in an amount of 3% and exhibited a water repellency with a contact angle with water of 130 degrees. In the same electrolytic cell as in Example 1, 5 m of this electrode and 6 m of iron flat plate cathode were used as anodes for 3 m.
It was arranged alternately at m intervals. After 614 ml of anhydrous hydrofluoric acid was introduced into the electrolytic cell and preliminary electrolysis was performed at a cell voltage of 5.5 V, 0.6 g of sodium fluoride was added as a conductive agent.
After that, 30.0 g of octane sulfonyl fluoride was added, and electricity was supplied to the electric quantity of 258 AH at a current density of about 1 A / dm ² for 53.9 hours. 55.5 g of octane sulfonyl fluoride was used in all electrolysis. The electrolytic cell was cooled from the outside to maintain the temperature of the electrolytic solution at 10 ° C. The cell voltage is 5.
It was stable at 3 to 5.9V. The product was taken out from the bottom of the electrolytic cell, and its amount was measured by the same method as in Example 1 to find that perfluorooctanesulfonyl fluoride was 4%.
7.6 g could be synthesized. The yield was 33.5%.

Example 4 Using the same electrolytic cell and anode as in Example 3, 614 ml of anhydrous hydrofluoric acid was introduced, preliminary electrolysis was performed at a cell voltage of 5.5 V, and then 23.0 g of tripentylamine was added. , With a current density of about 1 A / dm ² for 252 hours, with an electric charge of 1210
Power was supplied to AH. During the electrolysis, tripentylamine and anhydrous hydrofluoric acid were intermittently added. 135 g of tripentylamine was used during the whole electrolysis. The electrolytic cell was cooled from the outside to maintain the temperature of the electrolytic solution at 10 ° C. The cell voltage is 5.
It was stable at 3 to 5.9V. The product was intermittently taken out from the bottom of the electrolytic cell, and the amount thereof was measured by the same method as in Example 2 to find that perfluorotripentylamine was 16%.
8.8 g could be synthesized. The yield was 34.6%.

[0026]

EFFECTS OF THE INVENTION By using as an anode an electrode coated with a nickel-based composite coating of low surface energy in which PTFE particles and / or graphite fluoride particles are co-eutectically dispersed in nickel plating, it is possible to achieve a performance by electrolytic fluorination. The yield of the fluoro compound production can be improved, and the electrolytic fluorination operation can be performed for a long time.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroaki Sakaguchi 5253 Oki Ube, Ube City, Yamaguchi Prefecture Ube Laboratory, Central Rural Glass Co., Ltd. Ube Laboratory Co., Ltd. (72) Inventor Yasushi Kida 5253 Oki Obe, Ube City, Yamaguchi Prefecture Central Rural Glass Co., Ltd. Ube Laboratory

Claims (1)

[Claims] 1. Polytetrafluoroethylene particles and / or
Alternatively, an organic electrolytic fluorination method using anhydrous hydrofluoric acid as an electrolytic solution, wherein an electrode whose surface is coated with a composite plating film in which graphite fluoride particles are co-dispersed in a nickel plating film is used as an anode.