JPS5946886B2 - Synthesis method of sulfur tetrafluoride - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method for synthesizing sulfur tetrafluoride, in particular, using a relatively inexpensive fluorine source without using fluorine gas obtained by electrolyzing hydrofluoric acid using expensive electricity. This invention relates to a method for synthesizing sulfur tetrafluoride with high purity and high yield by regenerating a fluorine source and making it reusable.

Conventionally, methods for synthesizing sulfur tetrafluoride include, for example, a method in which sulfur dichloride and sodium fluoride are reacted in an organic solvent such as acetonyl-IJ (see specification of U, S, P 2992073), dichloride Sulfur, chlorine, and hydrogen fluoride at -50℃
A method in which sulfur tetrafluoride is separated by treating the reaction product with amines (OL8 236367
9), a method of reacting sulfur dichloride with NOF/3HF (see U, S, P4082839), and the like are known.

Among these methods, in the method typified by the above-mentioned specification U, S, P2992073, the sodium fluoride reacted with sulfur dichloride and the by-product common salt are solid, so the reaction must be carried out in the form of a slurry. However, it has disadvantages in terms of reaction operation, such as difficulty in performing the reaction operation and the yield of sulfur tetrafluoride varying greatly depending on the particle size of the sodium fluoride.

In addition, the method typified by 0L82363679 is
It requires a considerably low temperature of -50°C, requires treatment with amines, is complicated in operation, and has the drawbacks of high cost.

In addition, in the method typified by U, S, P 4082839, NOF is corrosive, requires the use of special materials for the equipment, has a low yield of sulfur tetrafluoride, and produces sulfur as a by-product. It has the disadvantage that it precipitates and the operation becomes complicated.

Furthermore, there is a report that sulfur tetrafluoride was obtained in a low yield of 68% by reacting Py(HF)9.2 (Py: pyridine) with sulfur dichloride.

(G, A, 01ahet, al, Inorg,
Chem, 16, 2637 ('77) 5ho
However, according to additional tests conducted by the present inventors, in this method, the yield was not only 68%, but no production of sulfur tetrafluoride was observed.

That is, according to the results of subsequent studies by the present inventors, HE/P 3. When HF/PV was reacted with sulfur dichloride at various molar ratios, it was found that when HF/PV exceeded 5 to 6, the fluorination ability decreased significantly or disappeared completely.

The present inventors have discovered that sulfur tetrafluoride can be easily obtained with high purity and a yield of 90% or more by reacting with sulfur dichloride only when HF/PM = 4 or less, and have already filed a patent application. It was proposed as No. 54-130833 (Japanese Unexamined Patent Publication No. 56-54209).

The basic reaction of this method is as follows.

3SC1□+4Py-HF→SF4+52C12,+4
Among the products obtained using Py-HCl, only SF4 is in a gaseous state, and the others are in a liquid state, so it essentially has the advantage that separation of SF4 is extremely easy.

However, pyridine itself does not participate in the reaction, and as long as this method is used to obtain sulfur tetrafluoride, pyridine can be used as Py-
A large amount of pyridine is produced in the form of HCI, and especially when producing sulfur tetrafluoride on a large scale, a one-pass method consumes a huge amount of pyridine.

The present inventors have conducted various research and examinations with the aim of enabling mass production of sulfur tetrafluoride and effectively recycling pyridine while using the necessary minimum amount of pyridine. 52C1□ produced as a by-product with the production of sulfur
Both Py(HCI) and Py(HCI) are liquid, but if there is a means to substantially completely separate the two, Py(HCI) can easily be used as a raw material for producing sulfur tetrafluoride by reacting with hydrofluoric acid. It has been found that the above object can be achieved only when the reaction between sulfur dichloride and Py(HF) is carried out in the presence of a specific solvent that can be easily converted to Py(HF). Ta.

Thus, the present invention provides sulfur dichloride and Py in the presence of a mixed solvent of methylene chloride and trichlorotrifluoroethane.
(HF) 1 to 4 (PV: pyridine) is reacted with sulfur tetrafluoride.

The reaction for producing sulfur tetrafluoride in the method of the present invention is as shown in the above formula, with 52C12 and Py(H
CI) are both produced in liquid form, but when a mixed solvent according to the method of the present invention is used, these by-products are substantially separated into 52C12 containing the solvent in the lower layer and Py(HCI) in the upper layer.

In the present invention, it is appropriate that the mixing ratio of the mixed solvent used is 20 to 80% by mole of methylene chloride and 80 to 20% by mole of trichlorotrifluoroethane.

If the amount of methylene chloride used is less than the above range,
The reaction rate is slow, which hinders industrial production, and some solids are produced, which may clog some equipment.
On the other hand, if the amount of methylene chloride used is greater than the above range, it may become substantially difficult to separate the by-produced 52CI2 and Py(HCt), which is not preferable.

Among these ranges, methylene chloride is 30 to 70
When 70 to 30 mol% of trichlorotrifluoroethane is used, the operation can be carried out smoothly, 82C12 is not substantially mixed into the Py(HCI) layer, and the subsequent regeneration operation can be performed easily. This is particularly preferred because it is easy.

Further, in the present invention, it is necessary that the number of n in Py(HF)n serving as a raw material is 1 to 4.

If the number n is lower than 1, the fluorine source is insufficient and p
If a large amount of y must be used, and conversely, the number of n is greater than 4, it will no longer exhibit substantial activity as a fluorinating agent and cannot be used in industrial production methods, so any It's inappropriate.

The usage ratio of sulfur dichloride, which is the other raw material used in the reaction, and Py(HF) 1 to 4 is strictly determined by the number of n in PV(HF) n used, but Py(
HF) In order to achieve a theoretical yield of 90% or more of converting i~4 to sulfur tetrafluoride, Py to 1 sulfur dichloride must be
(HF) It is appropriate that the usage ratio of 1 to 4 is 1 to 10 in terms of Py.

In this case, as the number of n increases, PM(
The proportion of HF) used will shift towards dogs.

Further, as for the ratio of the reaction raw materials and the mixed solvent used, it is appropriate to use the mixed solvent in an amount of about 10 to 200% by volume based on the total amount thereof.

If the usage amount deviates from the above range, 52C12 and P
This is not preferable because separation of y(E(CI)) becomes difficult, solvent vapor easily mixes into the sulfur tetrafluoride, and the volume increases unnecessarily.

Further, it is appropriate that the temperature during the reaction is maintained at 10 to 60°C.

If the reaction temperature is less than the above range, the reaction rate will be insufficient, which will hinder industrial production; on the other hand, if it exceeds the above range, the raw materials will decompose, and some of them will gasify and produce Both are unfavorable because they may be mixed into the sulfur tetrafluoride.

Further, the reaction is usually carried out at normal pressure, but if desired, it can also be carried out under an increased pressure of about 5 atmospheres (gauge pressure).

In fact, as a specific reactor for carrying out the method of the present invention, a complete mixing type reactor having an appropriate stirring device is preferable, and the material thereof is SUS or a particularly chlorine-resistant and corrosion-resistant material such as fluororesin on the inner surface. Preferably, the material is used.

Next, the present invention will be explained by examples.

A complete mixing type reactor made of SUS was used, and the solvents and reaction materials shown in the following table were used, and the results shown in the table were obtained.

Claims (1)

[Claims] 1. Sulfur dichloride and Py(HF) 1 to 4 in the presence of a mixed solvent of methylene chloride and trichlorotrifluoroethane
A method for synthesizing sulfur tetrafluoride, characterized by reacting it with (Py: pyridine). 2 The mixing ratio of methylene chloride and trichlorotrifluoroethane is 20 to 80 mol% for the former, and 80 to 80 mol% for the latter.
A method for synthesizing sulfur tetrafluoride according to claim 1, wherein the content is 20 mol%. 3 The usage ratio of sulfur dichloride and Py(H,p) 1 to 4 is:
The method for synthesizing sulfur tetrafluoride according to claim 1, wherein the molar ratio of the former is 1 to 1 to 10 of the latter in terms of py. 4 The amount of mixed solvent used is the amount of the solvent, sulfur dichloride, Py(
The method for synthesizing sulfur tetrafluoride according to claim 1, wherein the amount is 10 to 200% by volume based on the total amount of HF) 1 to 4 used.