JPS5946885B2 - Production method of sulfur tetrafluoride - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing sulfur tetrafluoride, and particularly to a method for producing sulfur tetrafluoride using a pyridine-hydrofluoric acid complex.

Conventionally, various methods have been proposed for producing sulfur tetrafluoride.

One of these methods is to react sodium fluoride and sulfur dichloride in acetonitrile, but this method requires the reaction to be carried out under uniform conditions because the raw material sodium fluoride and the by-product sodium chloride are solids. The operations to carry out the process are difficult, the yield of sulfur tetrafluoride varies greatly depending on the particle size of the sodium fluoride, and furthermore, it is difficult to regenerate sodium fluoride from the by-product sodium chloride. There is a problem.

There is also a method of reacting sulfur tetrachloride and hydrogen fluoride without a catalyst, but it is necessary to carry out the reaction at a low temperature of -30°C or lower.

There is also a method of using NOF as a fluorinating agent for sulfur chlorides, but in this method, handling of corrosive NOF is not easy and the yield of sulfur tetrafluoride is low.

For these reasons, none of the methods can yet be an industrially satisfactory manufacturing method.

The present invention provides an industrially usable method for producing sulfur tetrafluoride, which can maintain a high yield of sulfur tetrafluoride, is easy to operate, and can recycle the reaction medium, Sulfur dichloride and pyridine-hydrofluoric acid complex (Py・(
The gist of the present invention is a method for producing sulfur tetrafluoride, which is characterized by reacting HF)n, n=1 to 4).

Sulfur dichloride is fluorinated with a pyridine-hydrofluoric acid complex and S
For information on how to obtain F4, see Inorg, chem.

There is one report in 16 (10), 2637 (1977).

However, in the method described in the above literature, all < SF
4 is not generated, SOF2 is only slightly generated, and S
It has been found that this cannot be an effective method for producing F4.

Therefore, the inventors of the present invention conducted extensive research into methods for effectively demonstrating the functions of pyridine, and found that by using a pyridine-hydrofluoric acid complex with a low hydrofluoric acid content, S
An interesting fact was discovered that F4 can be obtained in good yield.

That is, in the above-mentioned known literature, P (HF)9.5 and H
It is thought that because a complex with a high F content was used, the raw material 5CI2 could not reach the vicinity of P, so P could not exert an effective catalytic action and no SF4 was produced at all.

In the method of the present invention, for example, the reaction using a P, HF complex is as follows: 3SC12+4P-HF-+SF4+52C1°+4
P, ·HCI Sulfur tetrafluoride (SF4) is produced according to the reaction formula (1), and the by-produced pyridine-hydrochloric acid complex (P -HCI) is treated with excess hydrogen fluoride. , P by expelling HCI as a gas
・(HF)m(rri>5) complex can be formed.

P,.(HF)nn=1-4 can then be regenerated by separating excess hydrogen fluoride from this complex using a suitable method.

The present invention is characterized by the use of a pyridine-hydrofluoric acid complex as a reactant, which can be recycled and reused as described above.
Furthermore, in order to carry out the reaction smoothly, pyridine (abbreviated as P) of the pyridine-hydrofluoric acid complex to be subjected to the fluorination reaction.
It is extremely important that the molar ratio of fluorine and hydrofluoric acid (HF) is from 1:1 to 4.

In other words, in order to effectively express the catalytic action of P,
It is necessary for HF and 5C12 to coordinate to P, and it is thought that the fluorination reaction proceeds only after both have coordinated to P.

Therefore, if excessive HF is added to coma, P becomes HF.
The SCI □ may reach the vicinity of pyridine, which may make it extremely difficult for the reaction to occur, or the reaction may not occur at all.

In this sense, if this ratio is 1:5 or more, the fluorination reaction will hardly proceed and the yield of sulfur tetrafluoride will be extremely low.

Among the above molar ratios considered good in the present invention, further 1:1 to 3
It is more preferable to do so because the yield can be maintained high.

However, even if the above molar ratio is 1:3 to 4, P・(H
F).

The yield of sulfur tetrafluoride can be maintained at a high level by setting the amount of P and the quantitative range of sulfur dichloride (SCI) in moles to P,/SCI□〉3.

Although the above fluorination reaction can be carried out without using a solvent, it is desirable to use a solvent in order to carry out the reaction more smoothly.

Any solvent can be used as long as it is inert to hydrogen fluoride and sulfur dichloride under the reaction conditions, but halogenated hydrocarbons are particularly preferred.

Among halogenated hydrocarbons, solvents such as methylene chloride, chloroform, carbon tetrachloride, fluorotrichloromethane, and trichlorotrifluoroethane (excluding a mixture of methylene chloride and trichlorotrifluoroethane) are particularly desirable.

This is because it is preferable to conduct the reaction in a solvent from the viewpoints of uniform reaction, easy removal of reaction products, and easy control of reaction temperature. .

The fluorination reaction of reaction formula (1) in the above solvent is preferably carried out at a temperature of 0 to 60°C, more preferably 20 to 40°C.

The reason for this is that at temperatures below 0°C, the reaction rate decreases significantly, and at temperatures above 40°C, decomposition of the raw material SCI□ tends to occur.

The reaction is usually carried out at atmospheric pressure, but if necessary, it may be carried out under increased pressure.

Note that in consideration of the separation of produced SF4, it is desirable to carry out the reaction under a pressure of up to 10 Kp/ffl.

The quantitative relationship between the amount of pyridine and sulfur dichloride when the reaction is carried out under the above solvent and reaction temperature conditions will be described.

Figure 1 shows the molar ratio of hydrofluoric acid and pyridine in the pyridine-hydrofluoric acid complex (HF/pyridine and the amount of sulfur tetrafluoride produced) using the molar ratio between the amount of pyridine and the amount of sulfur dichloride in the pyridine complex as a parameter. It shows the relationship.

It can be seen that in the range of P.(HF)n of the present invention, n=1 to 4, the yield of sulfur tetrafluoride increases as the molar ratio Py/5C12 of pyridine and sulfur dichloride increases.

From Figure 1, in the range of n=1 to 2, Py/5C12=1
Even with 5, the yield of sulfur tetrafluoride is over 80%, but n =
In the range of 3 to 4, P, /SCI□〉3, preferably P
, /SCIN4 is desirable.

Next, the pyridine-hydrochloric acid complex P・(HF)n (n = 1
The circulation method of ~4) will be explained.

To the pyridine-hydrochloric acid complex produced by reaction formula (1),
HCI is produced by the following formula % formula % (
2) It becomes a pyridine-hydrofluoric acid complex.

The above reaction (2) is considered to be a substitution reaction between HCI and HF, but the present inventors have found that the reaction rate of this reaction varies greatly depending on the molar ratio m of hydrofluoric acid HF and pyridine/hydrochloric acid complex.

That is, in order to carry out reaction (2) at a reaction rate of 100%, it is necessary that m≧6.

For example, if m=4, the reaction rate is about 60%,
About 40% of the initially present Py-HCI remains unreacted.

From the above, it follows that Jtm≧6 for the pyridine-hydrofluoric acid complex P.(HF) obtained in reaction (2).

Therefore, in order to use this in the fluorination reaction (1) of sulfur dichloride, HF is removed to produce P.(HF)n.

(n=1 to 4).

This HF removal reaction occurs, for example, by distillation under reduced pressure, according to the following formula (%) (3), and the desired pyridine-hydrofluoric acid complex is obtained.

Note that simple vacuum distillation can be achieved up to n=3, but when n=1
To obtain the pyridine-hydrofluoric acid complex of ~3, it is necessary to distill under reduced pressure in the presence of sodium fluoride.

The P,.(HF)1-4 obtained here can be recycled and used in reaction (1), and HF can be used in reaction (2).

Next, the present invention will be further explained by examples.

Example 1 0.2 mol of sulfur dichloride 5CI2 is placed in a container containing 120 ml of methylene chloride solvent, and the temperature of the solvent is kept at 30°C. Pyridine/hydrofluoric acid of HF/Py (molar ratio) -3 is added to this solvent. 0.92 mol of complex P.(HF)3 was introduced, and the reaction was carried out for 3 hours.

The amount of sulfur tetrafluoride obtained was 0.18 mol, and the yield was 90%.

Next, the by-produced pyridine/hydrochloric acid complex P-HCI was treated with 8 times equivalent amount of hydrofluoric acid at room temperature to remove the hydrochloric acid of P, .HCI, and the pyridine/hydrofluoric acid complex P, .(HF
) 8 was obtained.

Next, P,.(HF)8 was distilled under reduced pressure to yield 100%.
P,.(HF)3 was recovered.

Examples 2 to 12 and Comparative Examples 13 to 15 The same operations as in Example 1 were performed under the conditions shown in Table 1, and the results are also shown in Table 1.

(Example 1 will also be described.

)

[Brief explanation of the drawing]

Figure 1 is a graph showing the change in the yield of sulfur tetrafluoride depending on n in the pyridine-hydrofluoric acid complex P. be. The reaction conditions were a temperature of 30°C, a time of 3 hours, and a case where methylene chloride was used as a solvent.

Claims (1)

[Claims] 1. Sulfur dichloride and pyridine/hydrofluoric acid complex (Py/(H
F) A method for producing sulfur tetrafluoride, which comprises reacting n, n=1 to 4). 2. The method for producing sulfur tetrafluoride according to claim 1, which uses an organic compound that is inert to hydrofluoric acid and sulfur dichloride under the reaction conditions as a solvent. 3. The method for producing sulfur tetrafluoride according to claim 2, wherein the organic compound is a halogenated hydrocarbon that is inert under the reaction conditions. 4. Claim 3 in which the halogenated hydrocarbon is methylene chloride, chloroform, carbon tetrachloride, fluorotrichloromethane, trichlorotrifluoroethane, or a mixture thereof (excluding a mixture of methylene chloride and trichlorotrifluoroethane) 6. The method for producing sulfur tetrafluoride according to any one of claims 1 to 4, wherein the reaction is carried out at 0 to 60°C. 6 Is the reaction at normal pressure ~10Ky/cr? A method for producing sulfur tetrafluoride according to any one of claims 1 to 5, which is carried out in t.