JP2606875B2 - Method for fluorinating organic compounds - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for continuously fluorinating an organic compound.

(Prior Art) A method of fluorinating an organic compound with fluorine gas is well known. For example, Japanese Patent Application Laid-Open No. 60-202122 describes a method of reacting polyether with fluorine gas. In such a fluorination reaction, a batch system and a continuous system are employed as in a general chemical reaction.
The batch method has a relatively good yield of a perfluoro organic compound obtained by fluorination of an organic compound, but has a disadvantage of low productivity. Therefore, from an industrial point of view, a continuous type is usually adopted to improve productivity. In the case of performing fluorination in a continuous manner, a method of supplying both of them to the reactor in countercurrent is adopted in order to make good contact between the organic compound and the fluorine gas.

(Problems to be Solved by the Invention) However, with the continuous method as described above, it is difficult to completely fluorinate an organic compound as a raw material. That is, incomplete fluorinated compounds having a hydrogen atom bonded in the molecule are mixed in the product. The presence of incomplete fluorinated compounds, even in trace amounts, is disadvantageous because it causes serious problems when used in various applications. On the other hand, if the reaction conditions are strict so that incomplete fluorinated products do not remain, decomposition of the perfluoro organic compound also occurs, and there is a problem that a satisfactory yield cannot be obtained.

Means for Solving the Problems In view of the above problems, the present inventors have reduced the amount of residual hydrogen in a fluorinated product and obtained a high yield of a perfluoro organic compound corresponding to a raw material organic compound. We have been conducting intensive research for the purpose of obtaining it. As a result, they have found that the above objects can be achieved by using amines as an organic compound and supplying hydrogen fluoride to a reactor in addition to fluorine gas as a fluorinating agent, thereby completing the present invention. .

That is, the present invention relates to a method for fluorinating an organic compound by continuously supplying a hydrogen-containing organic compound and a fluorinating agent to a reactor in countercurrent, wherein the organic compound has 4 to 50 carbon atoms. Amines, and as a fluorinating agent, fluorine gas and fluorine gas in a molar ratio of 1 to 35.
% Of hydrogen fluoride in combination with a hydrogen atom of an organic compound.

The amines used in the present invention have 4 to 4 carbon atoms.
50 amines such as linear or cyclic aliphatic primary, secondary or tertiary amines and aromatic amines can be used without any limitation. Further, a hydrogen atom in which a part of a hydrogen atom is substituted by a halogen atom such as a chlorine atom may be used. Among these, those particularly preferred in the present invention include:
Amines having 6 to 25 carbon atoms. Furthermore, when a trialkylamine is used as a raw material, a target perfluoroamine can be obtained in a high yield. Examples of the above amines include tripropylamine, tributylamine, tripentylamine, trihexylamine,
Examples thereof include dipentylbutylamine and dibutylpropylamine.

Partially fluorinated amines in which hydrogen atoms of the above amines are partially substituted with fluorine atoms, for example, the ratio of the number of hydrogen atoms to fluorine atoms (H / F) is 1/1 or less, preferably 1/5 or less,
More preferably, when a partially fluorinated amine such as 1/100 to 1/7 is used as a raw material, the perfluoroamines corresponding to the raw material can be obtained in a high yield, which is preferable in the present invention. It is an aspect. However, the ratio of the hydrogen atom to the fluorine atom is an average value of the whole partially fluorinated amines obtained by assembling the individual partially fluorinated amines having various values.

In the present invention, fluorine gas and hydrogen fluoride are used in combination as a fluorinating agent. Considering the yield of perfluoroamines to be obtained, the ratio of fluorine gas to hydrogen fluoride is 1 to 35% by mole of hydrogen fluoride to fluorine gas.
Preferably, it is used in the range of 3 to 20%. As the hydrogen fluoride, commercially available hydrofluoric anhydride can be used as it is or after further dehydration. In addition, hydrogen fluoride generated by the reaction between the above amines and fluorine gas can be collected and reused.

The ratio of the amines to the fluorinating agent is not particularly limited, but an excess of the fluorinating agent is used in excess of the theoretical amount required to replace all the hydrogen atoms in the amines with fluorine atoms. . Generally, the fluorinating agent is used so that the amount of the fluorine gas is 1 to 6 mol, preferably 1 to 3 mol, per 1 mol of hydrogen atoms contained in the amines.

The amines and the fluorinating agent are fed continuously and countercurrently into the reactor. As a result, the amines, which are the raw materials, are more fluorinated and the fluorination reaction is more difficult to proceed, so that the amines come into contact with the fluorine gas in a zone having a higher fluorine gas content closer to the supply side of the fluorinating agent. Efficiency is increased. The reactor used in the present invention is preferably a long cylindrical body in order to maintain a long contact time between the amines and the fluorinating agent. Then, it is preferable that the amine is supplied from one end of the long cylindrical body and the fluorinating agent is supplied from the other end. The fluorine gas and the hydrogen fluoride as the fluorinating agent may be supplied to the reactor after being mixed in advance, or may be separately supplied to the reactor. The fluorinating agent is
It can be supplied as it is, and nitrogen, helium,
It can be used after being diluted with an inert gas such as neon or carbon dioxide to about 5% by volume. When the above-mentioned H / F ratio is 1/5 or less, and further when a partially fluorinated amine such as 1/100 to 1/7 is used as a raw material, 20% by volume or more, preferably 50% by volume or more Good results are obtained when a high concentration of the fluorinating agent is used.

On the other hand, the amines can be supplied as they are, but in order to perform the fluorination reaction mildly, it is preferable to dilute and supply the perfluoroamines, particularly the perfluoroamines corresponding to the raw material amines. . The mixing amount of the amines and the perfluoroamines is not particularly limited, but it is preferable to use the perfluoroamines in an amount of 30 to 600 parts by weight, more preferably 60 to 400 parts by weight, based on 100 parts by weight of the amines. .

The method of the present invention is effective when the amines and the fluorinating agent are reacted in a continuous manner. When the amines and the fluorinating agent are continuously reacted, the following 3
There are two cases.

When both amines and fluorinating agent are continuously supplied to the reactor When one of amines and fluorinating agent is continuously supplied to the reactor and the other is intermittently supplied Amines When both the fluorinating agent and the fluorinating agent are intermittently supplied to the reactor, in the present invention, nickel, nickel alloy, other metal particles, Raschig ring, etc. are used in order to increase the efficiency of contact between the amines and the fluorinating agent. It is preferable to use wire or wire mesh as the filler.

The reaction is usually carried out under normal pressure to a pressure of 3 atm, but may be further pressurized. The reaction temperature is preferably selected from the range of 30 to 180 ° C, more preferably 70 to 150 ° C, in consideration of the speed of the fluorination reaction and the yield of the target perfluoro compound. The residence time of the amines as raw materials in the reactor is not particularly limited, but is usually selected from the range of 1 to 80 hours. As a material of the reactor, nickel, a nickel alloy or the like is usually used. In the fluorination reaction, a known catalyst such as brass, cobalt, copper, gold, and silver may be used in the form of a net or particles. In addition, wavelength 200
The fluorination reaction can be promoted by irradiating light of up to 600 nm.

After the fluorination reaction, nitrogen purging, neutralization reaction, distillation and the like are performed as necessary to remove hydrogen fluoride contained in the product and increase the purity of the target perfluoroamine.

The perfluoroamines corresponding to the raw materials intended in the present invention include those in which the hydrogen atoms of the raw material non-fluorinated amines or partially fluorinated amines are simply completely replaced by fluorine atoms. Of course, it also includes compounds in which an amino group has been eliminated or converted into another functional group by fluorination, and further, when amines containing a carbon-carbon multiple bond are used as a raw material, the multiple bond is saturated. Amines to which a fluorine atom has been added until the above. When the carbon number of the raw material is 6 or more, in some cases, the structure may change from chain to cyclic at the same carbon number simultaneously with fluorination,
The perfluoroamines obtained thereby are also the perfluoroamines referred to in the present invention.

(Effects) According to the method of the present invention, the amount of incomplete fluorinated compounds having a hydrogen atom bonded in the molecule can be extremely reduced, and the desired perfluoroamines can be produced in high yield. Obtainable. This effect is particularly remarkable when partially fluorinated amines are used as the starting amines. Therefore, the fluorinated product obtained by the method of the present invention can be used as it is in applications in which incomplete fluorinated compounds containing hydrogen atoms are not mixed.

The reason why the above-mentioned effects of the present invention can be obtained is not known in detail, but the present inventors speculate that hydrogen fluoride promotes fluorination by fluorine gas.

Example 1 The electrolytic fluorination of tripentylamine in anhydrous hydrofluoric acid is performed, and the fluorination proceeds and separates from the reaction solution and precipitates, and the fluorination containing perfluorotripentylamine which accumulates at the bottom of the electrolytic cell is generated. The material was extracted from the lower part of the electrolytic cell and used as a raw material for the fluorination reaction of the present invention. Its composition (% by weight) was as follows. Perfluorotripentylamine 32.2%, other perfluoro compounds
18.8%, partially fluorinated 49% (H / F (ratio of number) = 0.07
Five). The analysis was performed by gas chromatography (GC-8A manufactured by Shimadzu Corporation). The column used was a capillary column FS-WCOT having a length of 25 m and a diameter of 0.25 mm coated with silicone OV-215 manufactured by Gas Chromo Corporation. The column temperature was 65 ° C.) and gas chromatography-mass spectrometry was used. The value of H / F of the partially fluorinated compound is determined for each of the partially fluorinated compound peaks in the gas chromatogram, while determining the area ratio and determining the composition formula of the compound,
From this, it was determined by calculating the ratio (H / F) of the number of hydrogen atoms and fluorine atoms contained in the whole partially fluorinated product.

Using the above fluorinated product as a raw material, fluorination of the fluorinated product with a fluorine gas was carried out using a nickel reactor having an inner diameter of 1 cm and a length of 300 cm filled with nickel shavings having a reflux condenser above. The raw material was supplied from the top of the reactor at a rate of 8 g / hour, and fluorine gas was supplied from the lower part of the reactor at a rate of 6 ml / min at room temperature. At the same time, 10% hydrogen fluoride was added to the fluorine gas supply line immediately before the reactor in a molar ratio to the fluorine gas. Nitrogen gas was supplied to the center of the reactor at a rate of 24 ml / min. Heating was carried out from outside to keep the temperature of the reactor at 140 ° C. The residence time of the reaction solution in the reactor was about 30 hours. After the reaction reached a steady state, the reaction product was collected for 35 hours. In addition,
During this period, the amount of the raw materials supplied to the reactor was 280 g (90.1 g of perfluorotripentylamine, 52.7 g of a perfluoro compound at its end, 137.2 g of partially fluorinated product). The amount of the reaction product was 260.7 g (93% recovery), and did not contain incomplete fluorinated products. After washing with water, precision distillation was performed to obtain 214.5 g of perfluorotripentylamine.

Perfluorotripentylamine increase rate by fluorine gas treatment Is 138%.

Comparative Example 1 Using the electrolytically fluorinated product shown in Example 1, the reaction product after the fluorination of the product with the fluorine gas and the reaction reached a steady state was collected into the fluorine gas of hydrogen fluoride. Was carried out in the same manner as in Example 1 except that the supply of was stopped.

In this case, the collected amount of the reaction product was 236.5 g (recovery rate of 84.5 g).
%), Followed by precision distillation after washing with water to obtain 146.8 g of perfluorotripentylamine. The increase rate of tripentylamine by the fluorine gas treatment is 63%.

Example 2 Except that the amount of hydrogen fluoride added to fluorine gas was changed variously, fluorination of the electrolytic fluorination product of tripentylamine was performed in exactly the same manner as in Example 1, and the reaction product was collected. (35 hours).

Table 1 shows the relationship between the amount of hydrogen fluoride added and the amount of perfluorotripentylamine obtained by post-treatment (washing, distillation) of the collected reaction product.

Comparative Example 2 Using the electrolytic fluorinated product shown in Example 1, the fluorination with fluorine gas and the reaction product after the reaction reached a steady state were performed by supplying hydrogen fluoride to the fluorine gas. Except that the molar ratio was changed to 60%, the procedure was exactly the same as in Example 1.

In this case, the collected amount of the reaction product was 198.8 g (recovery rate of 71.0 g).
%), Followed by precision distillation after washing with water to obtain 154.9 g of perfluorotripentylamine. The increase rate of tripentylamine by fluorine gas is 72%.

Comparative Example 3 The fluorination product containing perfluorotetrahydropyran was obtained by electrolytic fluorination of tetrahydropyran in hydrofluoric anhydride. The composition (% by weight) was as follows. 38% of perfluorotetrahydropyran, 23% of other perfluoro compounds, 39% of partially fluorinated compounds,
(H / F (ratio of numbers) = 0.13).

Using the above mixture as a raw material, fluorination with fluorine gas was performed using the same apparatus as in Example 1. Raw materials were supplied at a rate of 10 g / hour from the top of the reactor, and fluorine gas was supplied at a rate of 10 ml / min at room temperature from the lower part of the reactor. The experiment was performed three times, and the fluorine gas supply line was placed at a position just before the reactor in a molar ratio of 1.2% to 8% with respect to the fluorine gas.
%, 33% hydrogen fluoride. Nitrogen gas was supplied to the center of the reactor at a rate of 30 ml / min. Heating was performed from the outside so that the temperature of the reactor was 140 ° C. The residence time of the reaction solution in the reactor was about 25 hours. After the reaction reached a steady state, the reaction product was collected for 30 hours. During this time, the amount of the raw material mixture supplied to the reactor was 300 g.
(114 g of perfluorotetrahydropyran, 69 g of other perfluoro compounds, 117 g of partially fluorinated product).

Table 2 shows the relationship between the amount of hydrogen fluoride added and the amount of perfluorotetrahydropyran obtained and the rate of increase. In each case, no incomplete fluorinated product was contained.

Claims (1)

(57) [Claims] 1. A method for fluorinating an organic compound by continuously supplying a hydrogen-containing organic compound and a fluorinating agent to a reactor in countercurrent, wherein the organic compound has 4 carbon atoms.
Substitution with hydrogen atoms of an organic compound, characterized by using up to 50 amines and using a combination of fluorine gas and hydrogen gas at a molar ratio of 1 to 35% with respect to fluorine gas as a fluorinating agent. Fluorination method by reaction.