Sulfanyl (
•), also known as the mercapto radical, hydrosulfide radical, or hydridosulfur, is a simple
radical molecule consisting of one hydrogen and one sulfur atom. The radical appears in metabolism in organisms as H
2S is detoxified. Sulfanyl is one of the top three sulfur-containing gasses in
gas giant
A gas giant is a giant planet composed mainly of hydrogen and helium. Gas giants are also called failed stars because they contain the same basic elements as a star. Jupiter and Saturn are the gas giants of the Solar System. The term "gas giant" ...
s such as
Jupiter
Jupiter is the fifth planet from the Sun and the largest in the Solar System. It is a gas giant with a mass more than two and a half times that of all the other planets in the Solar System combined, but slightly less than one-thousandth t ...
and is very likely to be found in
brown dwarf
Brown dwarfs (also called failed stars) are substellar objects that are not massive enough to sustain nuclear fusion of ordinary hydrogen ( 1H) into helium in their cores, unlike a main-sequence star. Instead, they have a mass between the most ...
s and cool stars. It was originally discovered by Margaret N. Lewis and John U. White at the
University of California
The University of California (UC) is a public land-grant research university system in the U.S. state of California. The system is composed of the campuses at Berkeley, Davis, Irvine, Los Angeles, Merced, Riverside, San Diego, San Franci ...
in 1939.
They observed molecular absorption bands around 325 nm belonging to the system designated by
2Σ+ ← 2Πi. They generated the radical by means of a radio frequency discharge in
hydrogen sulfide. HS
• is formed during the degradation of hydrogen sulfide in the atmosphere of the Earth. This may be a deliberate action to destroy odours or a natural phenomenon.
The organic analogue of sulfanyl is
thiyl radical In chemistry, a thiyl radical has the formula RS, sometimes written RS• to emphasize that they are free radicals. R is typically an alkyl or aryl substituent. Because S–H bonds are about 20% weaker than C–H bonds, thiyl radicals are relativ ...
with the formula RS
., where R =
alkyl
In organic chemistry, an alkyl group is an alkane missing one hydrogen.
The term ''alkyl'' is intentionally unspecific to include many possible substitutions.
An acyclic alkyl has the general formula of . A cycloalkyl is derived from a cycloa ...
or
aryl
In organic chemistry, an aryl is any functional group or substituent derived from an aromaticity, aromatic ring, usually an aromatic hydrocarbon, such as phenyl and naphthyl. "Aryl" is used for the sake of abbreviation or generalization, and "Ar ...
.
Natural occurrence
Absorption lines of sulfanyl in space were first detected in the
infrared
Infrared (IR), sometimes called infrared light, is electromagnetic radiation (EMR) with wavelengths longer than those of visible light. It is therefore invisible to the human eye. IR is generally understood to encompass wavelengths from around ...
by Yamamura (2000) in a star
R And. In the sun
•SH was detected at several
ultraviolet
Ultraviolet (UV) is a form of electromagnetic radiation with wavelength from 10 nm (with a corresponding frequency around 30 PHz) to 400 nm (750 THz), shorter than that of visible light, but longer than X-rays. UV radiation ...
wavelength
In physics, the wavelength is the spatial period of a periodic wave—the distance over which the wave's shape repeats.
It is the distance between consecutive corresponding points of the same phase on the wave, such as two adjacent crests, t ...
s: 326.0459, 327.5468, 328.9749, 330.0892 and 330.1112 nm.
Sulfanyl has been detected in
interstellar gas
In astronomy, the interstellar medium is the matter and radiation that exist in the space between the star systems in a galaxy. This matter includes gas in ionic, atomic, and molecular form, as well as dust and cosmic rays. It fills interstella ...
, and it is possibly present in comets.
Various theoretical studies have examined HS
• in atmospheres. In Earth's atmosphere
HS
• reacts with NO
2 to make two products HSNO
2 and HSONO. HSONO decomposes to HSO and NO.
HS
• also reacts with O
2 and N
2O.
HS
• can also react with Cl
2 producing HSCl and a Cl
• atom. HS
• destroys
ozone
Ozone (), or trioxygen, is an inorganic molecule with the chemical formula . It is a pale blue gas with a distinctively pungent smell. It is an allotrope of oxygen that is much less stable than the diatomic allotrope , breaking down in the lo ...
producing HSO
• and oxygen.
HS
• is formed in the Earth's atmosphere by the reaction of HO
•, the
hydroxyl radical
The hydroxyl radical is the diatomic molecule . The hydroxyl radical is very stable as a dilute gas, but it decays very rapidly in the condensed phase. It is pervasive in some situations. Most notably the hydroxyl radicals are produced from the ...
, on
carbon disulfide
Carbon disulfide (also spelled as carbon disulphide) is a neurotoxic, colorless, volatile liquid with the formula and structure . The compound is used frequently as a building block in organic chemistry as well as an industrial and chemical n ...
,
carbon oxysulfide and
hydrogen sulfide with side products of
carbon dioxide
Carbon dioxide ( chemical formula ) is a chemical compound made up of molecules that each have one carbon atom covalently double bonded to two oxygen atoms. It is found in the gas state at room temperature. In the air, carbon dioxide is trans ...
and water. Photodissociation of hydrogen sulfide also produces the radical in air.
In a planetary atmosphere that contains H
2S, HS
• will be formed if the temperature and pressure are high enough.
The ratio of H
2S and HS
• is given by:
:log(''X''/''X'') = −3.37 + 8785/''T'' + 0.5 log ''P
T'' + 0.5 log ''X''
H2
For a hydrogen dominated atmosphere in a gas giant or star: H
2S has the same level as HS
• at
:
.
At higher temperatures HS
• breaks up into sulfur vapour and H
2. The line of equal S and HS concentration follows the line
:
s.
on hydrogen sulfide, which splits off a hydrogen atom. A
. This happens as the Cu
.
, by removing a single electron.
When sulfur minerals are leached with ferric ions HS
radical. M is a metal such as zinc or copper.
.
is quite reactive. In water HS can react with O
. SO
. In water HS
. The hydroxyl radical
and water.
and S. The disulfide can further react with HS
S.
The ionization energy of HS is 10.4219 eV. The reduction potential to go to HS
is 0.92 eV.
. The S
s.
The interatomic distance between sulfur and hydrogen in the radical is 0.134 nm.
(COS) and probably is the main source of this substance in the atmosphere of Earth.