Process of preparing sulfuryl fluoride

Details Process of preparing sulfuryl fluoride Process of preparing sulfuryl fluoride

1999-11-10

2001-05-29

Dunn, Tom (Department: 1754)

Chemistry of inorganic compounds

Halogen or compound thereof

Sulfur containing

Reexamination Certificate

active

06238642

ABSTRACT:

BACKGROUND OF THE INVENTION
The invention relates to a process for the preparation of sulfuryl fluoride.
Sulfuryl fluoride is used, for example, as a fumigant for insecticidal purposes. It is already known that sulfuryl fluoride can be prepared from sulfur dioxide and fluorine in the gas phase, see H. Moissan and P. Lebeau in Ann. Chim. Phys. [7] 26 (1902), pages 145 to 178, in particular pages 159 to 169. However, this type of preparation is very risky, since explosions may occur.
SUMMARY OF THE INVENTION
It was an object of the present invention to devise a process with which sulfuryl fluoride can be prepared in a high yield and with high purity.
This and other objects have been achieved in accordance with the present invention by providing a process for the preparation of sulfuryl fluoride, the process comprising reacting sulfur dioxide and elemental fluorine in the presence of an alkali fluoride and liquid hydrogen fluoride to form sulfuryl fluoride.
DESCRIPTION OF PREFERRED EMBODIMENTS
The process according to the invention provides for sulfur dioxide and elemental fluorine to be reacted together in the presence of an alkali fluoride and hydrogen fluoride. In this case, the hydrogen fluoride is present in the liquid phase. Preferably the alkali fluoride is present in the form of a solution in hydrogen fluoride. For example, the alkali fluoride may be used dissolved in HF. However, it may also be added as a solid to HF, and for example also as a precursor (e.g. as carbonate). It then dissolves during the reaction until it is dissolved in the HF.
As used herein the term “alkali fluoride” refers to LiF, NaF, KF, CsF and RbF, preferably KF. Of course, the alkali fluoride may also be used as an HF adduct.
The fluorine may be used in pure form or as a mixture with inert gas (e.g. N
2
, Ar, etc.).
Advantageously, the operating temperature will lie in the temperature range from −60 to +50° C., preferably −10° C. to +20° C. The pressure is preferably in the range from ambient pressure (about 1 bar absolute) to 10 bar (absolute).
The molar ratio of SO
2
to F
2
is advantageously in the range from 0.9:1 to 1.1:1. The alkali fluoride is preferably present dissolved in the reaction mixture in a quantity of 1 to 20% by weight. The hydrogen fluoride may be used in a stoichiometric excess; it functions as a solvent for the alkali fluoride.
In order to work up the reaction mixture, it is possible, for example, to condense out excess HF from the reaction mixture which is removed in gaseous form. The reaction mixture which has not condensed out is then washed, e.g. with water containing hydrogen peroxide. The remaining pure SO
2
F
2
is then dried, compressed and poured into steel flasks.
The process according to the invention may, for example, be performed as a batch reaction. Alternatively, it is also possible to operate continuously, for example by circulating part of the reaction mixture and isolating resulting sulfuryl fluoride therefrom (as described under “work-up”). Hydrogen fluoride which condenses out is recycled.
The process according to the invention has the advantage that it is very selective—hardly any secondary reactions take place. The reaction takes place rapidly and completely, and at low temperatures.


REFERENCES:
patent: 3320030 (1967-05-01), Bisignani et al.
patent: 3623964 (1971-11-01), Ukihashi et al.
patent: 4003984 (1977-01-01), Jones et al.
patent: 4102987 (1978-07-01), Cook et al.
patent: 1000354 (1954-01-01), None
patent: 2643521 (1977-04-01), None
patent: 1017323 (1966-01-01), None
Moissan, H. and Lebeau, P., Ann. Chim. Phys. [7] 26 (1902), pp. 145-178.
“Handbuch der Anorganischen Chemie, Schwefel, Teil B., Lieferung 3” 1963, 8. Auflage, Verlag Chemie, Weinheim XP002130203, p. 1729-p. 1730.
European Search Report dated Feb. 2, 2000.

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