Method for manufacturing sulfur tetrafluoride

Abstract

An object of this invention is to provide a simple method for producing sulfur tetrafluoride. The object is achieved by a method for producing sulfur tetrafluoride, comprising step A of reacting a fluorinated halogen compound with sulfur chloride, the fluorinated halogen compound being represented by formula: XF.sub.n, wherein X is chlorine, bromine, or iodine; and n is a natural number of 1 to 5.

Claims

1. A composition comprising sulfur tetrafluoride and ICl, wherein the composition comprises 1.2 equivalents or less of the ICl with respect to the sulfur tetrafluoride in terms of molar ratio, and the composition does not comprise a halide salt.

Description

EXAMPLES

(1) Examples are given below to illustrate the present invention in more detail, but the present invention is not limited to these Examples.

(2) The IF.sub.5-pyridine-HF complex used in the Examples is a known substance described in S. Hara, M. Monoi, R. Umemura, C. Fuse, Tetrahedron, 2012, 68, 10145-10150.

Example 1

Synthesis of SF.SUB.4 .(1)

(3) A 300-mL flask was charged with 3.4 mL (11 g) of IF.sub.5, and 2.0 mL (3.4 g) of S.sub.2Cl.sub.2 was added dropwise with stirring at room temperature. A vigorous reaction occurred to generate gas. The gas was collected with a syringe and introduced into a gas cell, and its infrared spectrum was measured. The results showed absorption at 746.9 cm.sup.−1 and 820 cm.sup.−1, which are peaks of SF.sub.4. This indicated that SF.sub.4 was formed.

(4) Generation of gas was not observed 1 hour after the completion of the dropwise addition. It was thus presumed that the reaction had already been completed.

(5) No solid products were visually observed.

Example 2

Synthesis of SF.SUB.4 .(2)

(6) An autoclave was charged with 3.47 g (25.7 mmol) of S.sub.2Cl.sub.2 at room temperature. After cooling, the pressure in the reactor was reduced, and 10.5 g (47.2 mmol) of IF.sub.5 was placed in the reactor.

(7) After the mixture was stirred for 3.5 hours, cooling was stopped, and the temperature thereof was slowly brought back to room temperature. As a result, the pressure was increased to 0.6 MPa.

(8) A cylinder was connected to the autoclave. The generated gas was liquefied and recovered in the cylinder by cooling the cylinder, thereby obtaining 4.57 g of SF.sub.4 (yield: 82%).

(9) In the autoclave, 9.4 g of liquid remained. This liquid was collected, and .sup.19F-NMR measurement showed peaks of IF.sub.5.

(10) No solid products were visually observed.

(11) When titration of a part (0.3959 g) of the liquid with 0.1 N sodium thiosulfate was performed until the color disappeared, 34 mL of 0.1 N sodium thiosulfate was required. This neutralized solution was diluted 400-fold with pure water, and the weight ratio of iodine, chlorine, and fluorine in the diluted solution was determined by using ion chromatography and a fluoride ion electrode. The weight ratio was the following: iodine: 73%; chlorine: 22.3%; and fluorine: 1.7%. This result showed that in addition to SF.sub.4, ICl was produced as a main by-product.

Example 3

Recovery of Iodine

(12) 10 mL of 30% hydrogen peroxide solution was added to 30 mL of the aqueous solution containing iodine ions obtained in Example 2 to precipitate iodine. By filtration, 0.24 g of the precipitated iodine was recovered.

(13) The recovery was 95%.

Example 4

Synthesis of SF.SUB.4 .(3)

(14) An autoclave (volume: 200 mL) was charged with 3.85 g (12 mmol) of an IF.sub.5-pyridine-HF complex. After addition of 2.5 mL of dichloromethane and cooling, 0.48 mL (6 mmol) of S.sub.2Cl.sub.2 was added dropwise. No generation of heat or gas was observed.

(15) The autoclave was sealed and then gradually heated to 70° C. in an oil bath. After 20 minutes, the pressure was increased to 0.3 MPa, which indicates formation of gas.

(16) After stirring for 3 hours, the temperature thereof was cooled to room temperature, and a cylinder was connected to the autoclave.

(17) The generated gas was liquefied and recovered in the cylinder by cooling the cylinder, thereby obtaining 0.9 g of SF.sub.4 (yield: 69%).