Hydrogen disulfide is the inorganic compound with the formula H₂S₂. This

hydrogen chalcogenide Hydrogen chalcogenides (also chalcogen hydrides or hydrogen chalcides) are binary compounds of hydrogen with chalcogen atoms (elements of group 16: oxygen, sulfur, selenium, tellurium, and polonium). Water, the first chemical compound in this serie ...

is a pale yellow volatile liquid with a camphor-like odor. It decomposes readily to hydrogen sulfide (H₂S) and elemental sulfur.R. Steudel "Inorganic Polysulfanes H₂S_''n'' with ''n'' > 1" in Elemental Sulfur and Sulfur-Rich Compounds II (Topics in Current Chemistry) 2003, Volume 231, pp 99–125.

Structure

The structure of hydrogen disulfide is similar to that of

hydrogen peroxide Hydrogen peroxide is a chemical compound with the formula . In its pure form, it is a very pale blue liquid that is slightly more viscous than water. It is used as an oxidizer, bleaching agent, and antiseptic, usually as a dilute solution (3%� ...

, with C₂

point group symmetry In group theory, the symmetry group of a geometric object is the group of all transformations under which the object is invariant, endowed with the group operation of composition. Such a transformation is an invertible mapping of the ambient ...

. Both molecules are distinctly nonplanar. The dihedral angle is 90.6°, compared with 111.5° in H₂O₂. The H−S−S bond angle is 92°, close to 90° for unhybridized divalent sulfur.

Synthesis and reactions

Hydrogen disulfide can be synthesised by dissolving alkali metal or

alkaline earth metal The alkaline earth metals are six chemical elements in group 2 of the periodic table. They are beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), and radium (Ra).. The elements have very similar properties: they are all ...

polysulfide Polysulfides are a class of chemical compounds containing chains of sulfur atoms. There are two main classes of polysulfides: inorganic and organic. Among the inorganic polysulfides, there are ones which contain anions, which have the general formu ...

s in water. When the solution is mixed with concentrated

hydrochloric acid Hydrochloric acid, also known as muriatic acid, is an aqueous solution of hydrogen chloride. It is a colorless solution with a distinctive pungent smell. It is classified as a strong acid Acid strength is the tendency of an acid, symbol ...

at −15 °C, a yellow oil consisting a mixture of

polysulfane A polysulfane is a chemical compound of formula , where ''n'' > 1 (although disulfane () is sometimes excluded). Polysulfanes consist of unbranched chains of sulfur atoms terminated with hydrogen atoms. Compounds containing 2 – 8 concatenated ...

s (H₂S_n) will pool below the aqueous layer. Fractional distillation of this oil gives hydrogen disulfide separate from any other polysulfides (mostly trisulfide).Georg Brauer: ''Handbook of Preparative Inorganic Chemistry'' Volume I, page 391, Wiley, 1963. Hydrogen disulfide readily decomposes under ambient conditions to hydrogen sulfide and sulfur. In

organosulfur chemistry Organosulfur compounds are organic compounds that contain sulfur. They are often associated with foul odors, but many of the sweetest compounds known are organosulfur derivatives, e.g., saccharin. Nature abounds with organosulfur compounds—sulfur ...

, hydrogen disulfide adds to

alkene In organic chemistry, an alkene is a hydrocarbon containing a carbon–carbon double bond. Alkene is often used as synonym of olefin, that is, any hydrocarbon containing one or more double bonds.H. Stephen Stoker (2015): General, Organic, an ...

s to give

disulfide In biochemistry, a disulfide (or disulphide in British English) refers to a functional group with the structure . The linkage is also called an SS-bond or sometimes a disulfide bridge and is usually derived by the coupling of two thiol groups. In ...

s and

thiol In organic chemistry, a thiol (; ), or thiol derivative, is any organosulfur compound of the form , where R represents an alkyl or other organic substituent. The functional group itself is referred to as either a thiol group or a sulfhydryl gro ...

Quantum tunneling and its suppression in deuterium disulfide

The

deuterated Isotopic labeling (or isotopic labelling) is a technique used to track the passage of an isotope (an atom with a detectable variation in neutron count) through a reaction, metabolic pathway, or cell. The reactant is 'labeled' by replacing specific ...

form of hydrogen disulfide DSSD, has a similar geometry to HSSH, but its tunneling time is slower, making it a convenient test case for the

quantum Zeno effect The quantum Zeno effect (also known as the Turing paradox) is a feature of quantum-mechanical systems allowing a particle's time evolution to be slowed down by measuring it frequently enough with respect to some chosen measurement setting. Somet ...

, in which frequent observation of a quantum system suppresses its normal evolution. Trost and Hornberger have calculated that while an isolated DSSD molecule would spontaneously oscillate between left and right chiral forms with a period of 5.6 milliseconds, the presence of a small amount of inert helium gas should stabilize the chiral states, the collisions of the helium atoms in effect "observing" the molecule's momentary chirality and so suppressing spontaneous evolution to the other chiral state.

Health effects

Hydrogen disulfide has been described as "having a severe and irritating odour" that is similar to camphor or , causing "tears and a smarting sensation in the nostrils". If it is present in high concentrations, it can cause dizziness, disorientation and ultimately unconsciousness.

References

{{Hydrides by group Hydrogen compounds Disulfides