|Systematic IUPAC name|
|Other names |
3D model (JSmol)
|Molar mass||33.073 g mol−1|
|Appearance||Yellow gas |
|195.63 J K−1 mol−1|
Std enthalpy of
|139.33 kJ mol−1|
| Hydrogen sulfide |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Sulfanyl (HS•), 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 H2S is detoxified. Sulfanyl is one of the top three sulfur-containing gasses in gas giants such as Jupiter and is very likely to be found in brown dwarfs and cool stars. It was originally discovered by Margaret N. Lewis and John U. White at the University of California 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 with the formula RS., where R = alkyl or aryl.
Absorption lines of sulfanyl in space were first detected in the infrared by Yamamura (2000) in a star R And. In the sun •SH was detected at several ultraviolet wavelengths: 326.0459, 327.5468, 328.9749, 330.0892 and 330.1112 nm. 
Sulfanyl has been detected in interstellar gas,  and it is possibly present in comets. 
Various theoretical studies have examined HS• in atmospheres. In Earth's atmosphere HS• reacts with NO2 to make two products HSNO2 and HSONO. HSONO decomposes to HSO and NO. HS• also reacts with O2 and N2O.  HS• can also react with Cl2 producing HSCl and a Cl• atom.  HS• destroys ozone producing HSO• and oxygen.  HS• is formed in the Earth's atmosphere by the reaction of HO•, the hydroxyl radical, on carbon disulfide, carbon oxysulfide and hydrogen sulfide with side products of carbon dioxide and water. Photodissociation of hydrogen sulfide also produces the radical in air. 
In a planetary atmosphere that contains H2S, HS• will be formed if the temperature and pressure are high enough. The ratio of H2S and HS• is given by:
For a hydrogen dominated atmosphere in a gas giant or star: H2S has the same level as HS• at
At higher temperatures HS• breaks up into sulfur vapour and H2. The line of equal S and HS concentration follows the line
The lines of equal concentration cross at 1509 K and 1.51 Pa, with HS• being left out of the mix at lower temperatures and pressures. •SH is expected to be the second or third most common sulfur containing gas in gas giants or brown dwarfs. 
Thermal decomposition of mercaptans, such as ethyl mercaptan yields HS•. 
The radical can be formed by the action of ultraviolet radiation on hydrogen sulfide, which splits off a hydrogen atom. A wavelength of 190 nm gives maximum absorption. 
In humans superoxide dismutase [Cu-Zn] converts the hydrosulfide ion (HS−) to HS•. This happens as the Cu2+ ion in the enzyme is converted to Cu+. 
Sulfide dehydrogenase as found in sulfur bacteria catalyses the oxidation of HS− to HS•, by removing a single electron. 
When sulfur minerals are leached with ferric ions HS• is formed in this way:
with the H2S•+ radical then passing a proton to water to make the HS• radical. M is a metal such as zinc or copper.  This has potential for bioleaching in metallic ore extraction.
The hydrosulfide ion HS− can be oxidized to HS• with cerium (IV) sulfate. 
Being a radical, HS• is quite reactive. In water HS can react with O2 producing SO2− and H+. SO2− reacts further with O2 to make SO2 and superoxide O2−. In water HS• has an equilibrium with S− • and H+. The hydroxyl radical •OH combines with H2S to form HS• and water.  Other reactions investigated by Tiee (1981) are HS• + ethylene, HS• + O2 → HO• + SO, and reactions with itself HS• + HS• → H2S2 or H2 and S.  The disulfide can further react with HS• to make the disulfide radical HS–S• and H2S. 
The ionization energy of HS is 10.4219 eV.  The reduction potential to go to HS− is 0.92 eV.  HS• in water can ionize to S•− and H+. The S•− can catalyze a cis-trans conversion in lipids. 
The interatomic distance between sulfur and hydrogen in the radical is 0.134 nm. 
HS• reacts with carboxylic acids to make carbonyl sulfide (COS) and probably is the main source of this substance in the atmosphere of Earth. 
HS—S• is called disufanyl with lengthening chains as trisulfanyl, tetrasulfanyl and pentasulfanyl HSSSSS•. S−* is termed sulfanidyl. HS+ is known as sulfanylium, and the common hydrosulfide ion HS− is also known as sulfanido for a ligand or sulfanide as an anion. Further down the periodic table, HSe• is known as selanyl, and HTe• is termed tellanyl.
Sulfuric acid or sulphuric acid, known in antiquity as oil of vitriol, is a mineral acid composed of the elements sulfur, oxygen and hydrogen, with the molecular formula H2SO4. It is a colorless, odorless and viscous liquid that is miscible with water.
Sulfur dioxide or sulphur dioxide is the chemical compound with the formula SO
2. It is a toxic gas responsible for the odor of burnt matches. It is released naturally by volcanic activity and is produced as a by-product of copper extraction and the burning of sulfur-bearing fossil fuels.
In organic chemistry, a thiol, or thiol derivative, is any organosulfur compound of the form R−SH, where R represents an alkyl or other organic substituent. The −SH functional group itself is referred to as either a thiol group or a sulfhydryl group, or a sulfanyl group. Thiols are the sulfur analogue of alcohols, and the word is a blend of "thio-" with "alcohol".
Methyl is an organic compound with the chemical formula CH•
3. It is a metastable colourless gas, which is mainly produced in situ as a precursor to other hydrocarbons in the petroleum cracking industry. It can act as either a strong oxidant or a strong reductant, and is quite corrosive to metals.
Hydrogen sulfide is a chemical compound with the formula H
2S. It is a colorless chalcogen-hydride gas, and is poisonous, corrosive, and flammable, with trace amounts in ambient atmosphere having a characteristic foul odor of rotten eggs. The underground mine gas term for foul-smelling hydrogen sulfide-rich gas mixtures is stinkdamp. Swedish chemist Carl Wilhelm Scheele is credited with having discovered the chemical composition of purified hydrogen sulfide in 1777. The British English spelling of this compound is hydrogen sulphide, a spelling no longer recommended by the Royal Society of Chemistry or the International Union of Pure and Applied Chemistry.
In organic chemistry, an organic sulfide or thioether is an organosulfur functional group with the connectivity R−S−R' as shown on right. Like many other sulfur-containing compounds, volatile sulfides have foul odors. A sulfide is similar to an ether except that it contains a sulfur atom in place of the oxygen. The grouping of oxygen and sulfur in the periodic table suggests that the chemical properties of ethers and sulfides are somewhat similar, though the extent to which this is true in practice varies depending on the application.
Methanethiol is an organosulfur compound with the chemical formula CH
3SH. It is a colorless gas with a distinctive putrid smell. It is a natural substance found in the blood, brain and feces of animals, as well as in plant tissues. It also occurs naturally in certain foods, such as some nuts and cheese. It is one of the chemical compounds responsible for bad breath and the smell of flatus. Methanethiol is the simplest thiol and is sometimes abbreviated as MeSH. It is very flammable.
Sulfide (British English also sulphide) is an inorganic anion of sulfur with the chemical formula S2− or a compound containing one or more S2− ions. Solutions of sulfide salts are corrosive. Sulfide also refers to chemical compounds large families of inorganic and organic compounds, e.g. lead sulfide and dimethyl sulfide. Hydrogen sulfide (H2S) and bisulfide (SH−) are the conjugate acids of sulfide.
Bisulfide is an inorganic anion with the chemical formula HS−. It contributes no color to bisulfide salts, and its salts may have a distinctive putrid smell. It is a strong base. Bisulfide solutions are corrosive and attack the skin.
Carbonyl sulfide is the chemical compound with the linear formula OCS. It is a colorless flammable gas with an unpleasant odor. It is a linear molecule consisting of a carbonyl group double bonded to a sulfur atom. Carbonyl sulfide can be considered to be intermediate between carbon dioxide and carbon disulfide, both of which are valence isoelectronic with it.
Ammonium hydrosulfide is the chemical compound with the formula [NH4]SH.
The sulfur cycle is a biogeochemical cycle in which the sulfur moves between rocks, waterways and living systems. It is important in geology as it affects many minerals and in life because sulfur is an essential element (CHNOPS), being a constituent of many proteins and cofactors, and sulfur compounds can be used as oxidants or reductants in microbial respiration. The global sulfur cycle involves the transformations of sulfur species through different oxidation states, which play an important role in both geological and biological processes. Steps of the sulfur cycle are:
The hydrogen cycle consists of hydrogen exchanges between biotic (living) and abiotic (non-living) sources and sinks of hydrogen-containing compounds.
Sodium sulfide is a chemical compound with the formula Na2S, or more commonly its hydrate Na2S·9H2O. Both the anhydrous and the hydrated salts in pure crystalline form are colorless solids, although technical grades of sodium sulfide are generally yellow to brick red owing to the presence of polysulfides and commonly supplied as a crystalline mass, in flake form, or as a fused solid. They are water-soluble, giving strongly alkaline solutions. When exposed to moist air, Na2S and its hydrates emit hydrogen sulfide, an extremely toxic, flammable and corrosive gas which smells like rotten eggs.
Sodium hydrosulfide is the chemical compound with the formula NaHS. This compound is the product of the half-neutralization of hydrogen sulfide with sodium hydroxide (NaOH). NaSH and sodium sulfide are used industrially, often for similar purposes. Solid NaSH is colorless. The solid has an odor of H2S owing to hydrolysis by atmospheric moisture. In contrast with sodium sulfide, which is insoluble in organic solvents, NaSH, being a 1:1 electrolyte, is more soluble.
Potassium hydrosulfide is the inorganic compound with the formula KSH. This colourless salt consists of the cation K+ and the bisulfide anion [SH]−. It is the product of the half-neutralization of hydrogen sulfide with potassium hydroxide. The compound is used in the synthesis of some organosulfur compounds. Aqueous solutions of potassium sulfide consist of a mixture of potassium hydrosulfide and potassium hydroxide.
Polythionic acid is an oxoacid which has a straight chain of sulfur atoms and has the chemical formula Sn(SO3H)2 (n > 2). Trithionic acid (H2S3O6), tetrathionic acid (H2S4O6) are simple examples. They are the conjugate acids of polythionates. The compounds of n < 80 are expected to exist, and those of n < 20 have already been synthesized. Dithionic acid (H2S2O6) does not belong to the polythionic acids due to strongly different properties.
Hydrogen thioperoxide, also called oxadisulfane or sulfur hydride hydroxide, is the chemical with the structure H–S–O–H. It can be considered as the simple sulfur-substituted analog of the common hydrogen peroxide (H–O–O–H) chemical, and as the simplest hydrogen chalcogenide containing more than one type of chalcogen. The chemical has been described as the "missing link" between hydrogen peroxide and hydrogen disulfide (H–S–S–H), though it is substantially less stable than either of the other two. It is the inorganic parent structure of the sulfenic acid class of organic compounds (R–S–O–H) and also the oxadisulfide linkage (R1–S–O–R2), where "R" is any organic structure. Sulfur is present in oxidation state 0.
Hydrogen chalcogenides are binary compounds of hydrogen with chalcogen atoms. Water, the first chemical compound in this series, contains one oxygen atom and two hydrogen atoms, and is the most common compound on the Earth's surface.
Sulfoxylic acid (H2SO2) (also known as hyposulfurous acid or sulfur dihydroxide) is an unstable oxoacid of sulfur in an intermediate oxidation state between hydrogen sulfide and dithionous acid. It consists of two hydroxy groups attached to a sulfur atom. Sulfoxylic acid contains sulfur in an oxidation state of +2. Sulfur monoxide (SO) can be considered as a theoretical anhydride for sulfoxylic acid, but it is not actually known to react with water.