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 Sulfur, S; Hydrogen, H | |
| Names | |
|---|---|
| IUPAC name Dihydrogen disulfide | |
| Systematic IUPAC name Disulfane | |
Other names
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| Identifiers | |
3D model (JSmol) | |
| ChEBI | |
| ChemSpider |
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| Properties | |
| H2S2 | |
| Molar mass | 66.14 g·mol−1 |
| Appearance | Pale yellow liquid |
| Density | 1.334 g/cm3 |
| Melting point | −89.6 °C (−129.3 °F; 183.6 K) |
| Boiling point | 70.7 °C (159.3 °F; 343.8 K) |
| Hazards | |
| Flash point | flammable |
| Related compounds | |
Related compounds | |
Except where otherwise noted, data are given for materials in theirstandard state (at 25 °C [77 °F], 100 kPa). | |
Hydrogen disulfide is theinorganic compound with the formulaH2S2. Thishydrogen chalcogenide is a pale yellow volatile liquid with a camphor-like odor. It decomposes readily tohydrogen sulfide (H2S) and elementalsulfur.[1]
The connection of atoms in the hydrogen disulfide molecule isH−S−S−H. The structure of hydrogen disulfide is similar to that ofhydrogen peroxide, with C2point group symmetry. Both molecules are distinctly nonplanar. Thedihedral angle between theHa−S−S andS−S−Hb planes is 90.6°, compared with 111.5° inH2O2. TheH−S−S bond angle is 92°, close to 90° for unhybridized divalent sulfur.[1]
Hydrogen disulfide can be synthesised bycrackingpolysulfanes (H2Sn) according to this idealized equation:
The main impurity is trisulfane (H2S3).[1] The precursor polysulfane is produced by the reaction ofhydrochloric acid with aqueoussodium polysulfide. The polysulfane precipitates as an oil.[1][2]
Upon contact with water oralcohols, hydrogen disulfide readily decomposes under ambient conditions tohydrogen sulfide and sulfur.
It is more acidic thanhydrogen sulfide, but the pKa has not been reported.[1]
Inorganosulfur chemistry, hydrogen disulfide adds toalkenes to givedisulfides andthiols.[3]
Thedeuterated form of hydrogen disulfide, deuterium disulfideD−S−S−D (dideuterodisulfane), has a similar geometry toH−S−S−H, but its tunneling time is slower, making it a convenient test case for thequantum Zeno effect, in which frequent observation of a quantum system suppresses its normal evolution. Trost and Hornberger[4] have calculated that while an isolatedD−S−S−D 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 momentarychirality and so suppressing spontaneous evolution to the other chiral state.[5]
In high concentrations, it can cause dizziness, disorientation and ultimately unconsciousness.[6]
