Disulfur decafluoride is a
chemical compound
A chemical compound is a chemical substance composed of many identical molecules (or molecular entities) containing atoms from more than one chemical element held together by chemical bonds. A molecule consisting of atoms of only one element ...
with the formula . It was discovered in 1934 by
Denbigh and Whytlaw-Gray. Each
sulfur atom of the molecule is
octahedral
In geometry, an octahedron (plural: octahedra, octahedrons) is a polyhedron with eight faces. The term is most commonly used to refer to the regular octahedron, a Platonic solid composed of eight equilateral triangles, four of which meet a ...
, and surrounded by five
fluorine atoms and one sulfur atom. The two sulfur atoms are connected by a single bond. In the molecule, the oxidation state of each sulfur atoms is +5, but their
valency is 6 (they are
hexavalent). is highly
toxic
Toxicity is the degree to which a chemical substance or a particular mixture of substances can damage an organism. Toxicity can refer to the effect on a whole organism, such as an animal, bacterium, or plant, as well as the effect on a subs ...
, with toxicity four times that of
phosgene.
It is a colorless liquid with a burnt match smell similar to
sulfur dioxide.
Production
Disulfur decafluoride is produced by
photolysis of :
:
Disulfur decafluoride arises by the decomposition of
sulfur hexafluoride. It is produced by the electrical decomposition of
sulfur hexafluoride ()—an essentially inert
insulator used in high voltage systems such as
transmission lines
In electrical engineering, a transmission line is a specialized cable or other structure designed to conduct electromagnetic waves in a contained manner. The term applies when the conductors are long enough that the wave nature of the transmis ...
,
substations and
switchgear
In an electric power system, a switchgear is composed of electrical disconnect switches, fuses or circuit breakers used to control, protect and isolate electrical equipment. Switchgear is used both to de-energize equipment to allow work to be ...
. is also made during the production of .
Properties
The S-S bond dissociation energy is 305 ± 21 kJ/mol, about 80 kJ/mol stronger than the S-S bond in
diphenyldisulfide.
At temperatures above 150 °C, decomposes slowly (
disproportionation
In chemistry, disproportionation, sometimes called dismutation, is a redox reaction in which one compound of intermediate oxidation state converts to two compounds, one of higher and one of lower oxidation states. More generally, the term can ...
) into and :
:S
2F
10 →
SF6 +
SF4
reacts with
to give
. It reacts with to form in the presence of ultraviolet radiation.
: + → 2
In the presence of excess
chlorine
Chlorine is a chemical element with the symbol Cl and atomic number 17. The second-lightest of the halogens, it appears between fluorine and bromine in the periodic table and its properties are mostly intermediate between them. Chlorine i ...
gas, reacts to form
sulfur chloride pentafluoride ():
: + → 2
The analogous reaction with
bromine
Bromine is a chemical element with the symbol Br and atomic number 35. It is the third-lightest element in group 17 of the periodic table ( halogens) and is a volatile red-brown liquid at room temperature that evaporates readily to form a simi ...
is reversible and yields . The reversibility of this reaction can be used to synthesize from .
Ammonia
Ammonia is an inorganic compound of nitrogen and hydrogen with the formula . A stable binary hydride, and the simplest pnictogen hydride, ammonia is a colourless gas with a distinct pungent smell. Biologically, it is a common nitrogenous wa ...
is oxidised by into
.
Toxicity
was considered a potential
chemical warfare pulmonary agent
A pulmonary agent, or choking agent, is a chemical weapon agent designed to impede a victim's ability to breathe. They operate by causing a build-up of fluids in the lungs, which then leads to suffocation. Exposure to the eyes and skin tends to ...
in
World War II
World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposing ...
because it does not produce
lacrimation
Tears are a clear liquid secreted by the lacrimal glands (tear gland) found in the eyes of all land mammals. Tears are made up of water, electrolytes, proteins, lipids, and mucins that form layers on the surface of eyes. The different types of ...
or skin irritation, thus providing little warning of exposure.
Disulfur decafluoride is a colorless gas or liquid with a
SO2-like odor. It is about four times as poisonous as phosgene. Its toxicity is thought to be caused by its
disproportionation
In chemistry, disproportionation, sometimes called dismutation, is a redox reaction in which one compound of intermediate oxidation state converts to two compounds, one of higher and one of lower oxidation states. More generally, the term can ...
in the lungs into , which is inert, and , which reacts with moisture to form
sulfurous acid and
hydrofluoric acid.
See also
*
Phosgene
*
Perfluoroisobutene
Perfluoroisobutene (PFIB) is the perfluorocarbon counterpart of the hydrocarbon isobutene and has the formula (CF3)2C=CF2. An alkene, it is a colorless gas that is notable as a highly toxic perfluoroalkene. Few simple alkenes are as toxic.
Safet ...
*
Bis(trifluoromethyl) disulfide
References
*
External links
*
{{Chemical agents
Pulmonary agents
Sulfur fluorides
Hypervalent molecules