Hydrogen disulfide

Hydrogen disulfide
IUPAC name Dihydrogen disulfide
Other names Hydrogen disulphide; Hydrogen persulfide; Hydrogen persulphide
Identifiers
CAS number	13465-07-1
PubChem	108196
ChemSpider	97274 Y
ChEBI	CHEBI:33114 Y
Jmol-3D images	Image 1
SMILES SS
InChI InChI=1S/H2S2/c1-2/h1-2H Y Key: BWGNESOTFCXPMA-UHFFFAOYSA-N Y InChI=1/H2S2/c1-2/h1-2H Key: BWGNESOTFCXPMA-UHFFFAOYAV
Properties
Molecular formula	H2S2
Molar mass	66.15 g mol−1
Appearance	yellow liquid
Density	1.334 g cm-3
Melting point	-89.6 °C, 184 K, -129 °F
Boiling point	70.7 °C, 344 K, 159 °F
Hazards
Flash point	flammable
Related compounds
Related compounds	Hydrogen peroxide Hydrogen sulfide
Y disulfide (verify) (what is: Y/N?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Hydrogen disulfide (H₂S₂) is an inorganic compound. This mal-odorous oil decomposes readily to hydrogen sulfide (H₂S).

Structure

The structure of hydrogen disulfide is similar to that of hydrogen peroxide, with two central sulfur atoms and two outer hydrogen atoms. However, the skew angle of the molecule is different, as the H-S-S bond in hydrogen disulfide has a near-standard 90° torsion angle of the syn conformer.

Skew angle in the H₂S₂ molecule is 90.6°, compared with 113.7° in H₂O₂. Molecular dimensions in these two molecules are: O-O, O-H, S-S and S-H bonds have lengths of 1.490, 0.970, 2.055 and 1.352 ångströms respectively.^[1][2]

Synthesis and reactions

Hydrogen disulfide can be synthesised by dissolving alkali or alkali earth metal polysulfides in water. When the solution is mixed with concentrated hydrochloric acid at −15 °C, a yellow oil consisting a mixture of polysulfanes (H₂S_n) will pool below the aqueous layer. Fractional distillation of this oil gives hydrogen disulfide separate from any other polysulfides (mostly trisulfide).^[3][4][5]

Hydrogen disulfide readily decomposes under ambient conditions to hydrogen sulfide and sulfur.^[4] In organosulfur chemistry, hydrogen disulfide adds to alkenes to give disulfides and thiols.^[6]

Health effects

Hydrogen disulfide has been described as "having a severe and irritating odour" that is similar to camphor or sulfur chloride, causing "tears and a smarting sensation in the nostrils".^[4] If it is present in high concentrations, it can cause dizziness, disorientation and ultimately unconsciousness.^[7]

References

1. ^ Davies, D. W. (1974). "Photoelectron spectra of hydrogen peroxide and hydrogen disulfide: ab initio calculations". Chemical Physics Letters 28 (4): 520–522. doi:10.1016/0009-2614(74)80093-X. 
2. ^ P. Lazzeretti and R. Zanasi (1997). "On the calculation of parity-violating energies in hydrogen peroxide and hydrogen disulfide molecules within the random-phase approximation". Chemical Physics Letters 279 (5-6): 349–354. doi:10.1016/S0009-2614(97)01060-9. 
3. ^ De, A. K. (2001-01-15). A Text Book of Inorganic Chemistry. ISBN 9788122413847. http://books.google.com/?id=AzoCJfTmRDsC. 
4. ^ ^{a b c} Walton and Parson; Parsons, Llewellyn B. (1921). "Preparation and Properties of the Persulfides of Hydrogen". J. Amer. Chem. Soc. 43: 2539–48. doi:10.1021/ja01445a008. 
5. ^ Georg Brauer: Handbook of Preparative Inorganic Chemistry Volume I, page 391, Wiley, 1963.
6. ^ Hazardous Reagents, Robinson Brothers
7. ^ Stein, Wilkinson, G (2007). Seminars in general adult psychiatry. Royal College of Psychiatrists. ISBN 9781904671442.