Hydrogen selenide

Hydrogen selenide
Structural diagram of the hydrogen selenide molecule	Space-filling model of the hydrogen selenide molecule
Names
	IUPAC name Hydrogen selenide
	Other names Hydroselenic acid; selane; selenium hydride
Identifiers
CAS Number	7783-07-5 ;
3D model (JSmol)	Interactive image;
ChEBI	CHEBI:16503 ;
ChemSpider	518 ;
ECHA InfoCard	100.025.071
EC Number	231-978-9;
KEGG	C01528 ;
PubChem CID	533;
RTECS number	X1050000;
UNII	V91P54KPAM ;
UN number	2202
CompTox Dashboard (EPA)	DTXSID20872822 ;
	InChI InChI=1S/H2Se/h1H2 Key: SPVXKVOXSXTJOY-UHFFFAOYSA-N ; InChI=1/H2Se/h1H2 Key: SPVXKVOXSXTJOY-UHFFFAOYAF;
	SMILES [SeH2];
Properties
Chemical formula	H2Se
Molar mass	80.98 g/mol
Appearance	Colorless gas
Odor	decayed horseradish[1]
Density	3.553 g/dm3
Melting point	−65.73 °C (−86.31 °F; 207.42 K)
Boiling point	−41.25 °C (−42.25 °F; 231.90 K)
Solubility in water	0.70 g/100 mL
Solubility	soluble in CS2, phosgene
Vapor pressure	9.5 atm (21°C)[1]
Acidity (pKa)	3.89
Conjugate acid	Selenonium
Conjugate base	Selenide
Structure
Molecular shape	Bent
Hazards
	Occupational safety and health (OHS/OSH):
Main hazards	Extremely toxic and flammable
	GHS labelling:
Pictograms
Signal word	Danger
Hazard statements	H220, H280, H330, H410
Precautionary statements	P210, P260, P271, P273, P284, P304+P340, P310, P320, P377, P381, P391, P403, P403+P233, P405, P410+P403, P501
NFPA 704 (fire diamond)	4 4 0
Flash point	flammable gas
	Lethal dose or concentration (LD, LC):
LCLo (lowest published)	0.3 ppm (guinea pig, 8 hr); 5.9 ppm (rat, 1 hr)[2]
	NIOSH (US health exposure limits):
PEL (Permissible)	TWA 0.05 ppm (0.2 mg/m3)[1]
REL (Recommended)	TWA 0.05 ppm (0.2 mg/m3)[1]
IDLH (Immediate danger)	1 ppm[1]
Safety data sheet (SDS)	ICSC 0284
Related compounds
Other anions	H2O; H2S; H2Te; H2Po
Other cations	Na2Se; Ag2Se
Related compounds	Arsine
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). verify (what is ?) Infobox references

Hydrogen selenide is an inorganic compound with the formula H₂Se. This hydrogen chalcogenide is the simplest and most commonly encountered hydride of selenium. H₂Se is a colorless, flammable gas under standard conditions. It is the most toxic selenium compound[3] with an exposure limit of 0.05 ppm over an 8-hour period.[4][5] Even at extremely low concentrations, this compound has a very irritating smell resembling that of decayed horseradish or 'leaking gas', but smells of rotten eggs at higher concentrations.

Structure and properties

H₂Se adopts a bent structure with a H−Se−H bond angle of 91°. Consistent with this structure, three IR-active vibrational bands are observed: 2358, 2345, and 1034 cm⁻¹.

The properties of H₂S and H₂Se are similar, although the selenide is more acidic with pK_a = 3.89,[6] and the second pK_a = 11,[6] or 15.05 ± 0.02 at 25 °C.[7]

Preparation

Industrially, it is produced by treating elemental selenium at T > 300 °C with hydrogen gas.[8] A number of routes to H₂Se have been reported, which are suitable for both large and small scale preparations. In the laboratory, H₂Se is usually prepared by the action of water on Al₂Se₃, concomitant with formation of hydrated alumina. A related reaction involves the acid hydrolysis of FeSe.[9]

Al₂Se₃ + 6 H₂O ⇌ 2 Al(OH)₃ + 3 H₂Se

H₂Se can also be prepared by means of different methods based on the in situ generation in aqueous solution using boron hydride, Marsh test and Devarda's alloy. According to the Sonoda method, H₂Se is generated from the reaction of H₂O and CO on Se in the presence of Et₃N.[10] H₂Se can be purchased in cylinders.

Reactions

Elemental selenium can be recovered from H₂Se through a reaction with aqueous sulfur dioxide (SO₂).

2 H₂Se + SO₂ ⇌ 2 H₂O + 2 Se + S

Its decomposition is used to prepare the highly pure element.

Applications

H₂Se is commonly used in the synthesis of Se-containing compounds. It adds across alkenes. Illustrative is the synthesis of selenoureas from cyanamides.[11]

H₂Se gas is used to dope semiconductors with selenium.

Safety

Hydrogen selenide is hazardous, being the most toxic selenium compound[3] and far more toxic than its congener hydrogen sulfide. The threshold limit value is 0.05 ppm. The gas acts as an irritant at concentrations higher than 0.3 ppm, which is the main warning sign of exposure; below 1 ppm, this is "insufficient to prevent exposure", while at 1.5 ppm the irritation is "intolerable".[5] Exposure at high concentrations, even for less than a minute, causes the gas to attack the eyes and mucous membranes; this causes cold-like symptoms for at least a few days afterwards. In Germany, the limit in drinking water is 0.008 mg/L, and the US EPA recommends a maximum contamination of 0.01 mg/L.[8][12]

Despite being highly toxic, no human fatalities have yet been reported. It is suspected that this is due to the gas' tendency to oxidise to form red selenium in mucous membranes; elemental selenium is less toxic than selenides are.[4]

References

NIOSH Pocket Guide to Chemical Hazards. "#0336". National Institute for Occupational Safety and Health (NIOSH).
"Hydrogen selenide". Immediately Dangerous to Life or Health Concentrations (IDLH). National Institute for Occupational Safety and Health (NIOSH).
http://www.epa.gov/ttnatw01/hlthef/selenium.html, US Environmental Protection Agency, Air Toxins website
https://www.cdc.gov/niosh/idlh/7783075.html, Documentation of Immediately Dangerous to Life or Health Concentrations: Hydrogen Selenide, The National Institute for Occupational Safety and Health
https://www.cdc.gov/niosh/docs/81-123/pdfs/0336.pdf Occupational Health Guideline for Hydrogen Selenide, The National Institute for Occupational Safety and Health, 1978
William M. Haynes; David R. Lide; Thomas J. Bruno, eds. (2017). CRC handbook of chemistry and physics : a ready-reference book of chemical and physical data (97th ed.). Boca Raton, Florida. ISBN 978-1-4987-5429-3. OCLC 957751024.
Levy, D. E.; Myers, R. J. "Spectroscopic Determination of the Second Dissociation Constant of H₂Se and the Activity Coefficients and Spectral Shifts of Its Ions" J. Phys. Chem. 1990, 94(20), 7842-1847. http://pubs.acs.org/doi/pdf/10.1021/j100383a020
Bernd E. Langner "Selenium and Selenium Compounds" in Ullmann's Encyclopedia of Industrial Chemistry, 2005, Wiley-VCH, Weinheim. doi:10.1002/14356007.a23_525.
Féher, F. In "Handbook of Preparative Inorganic Chemistry"; Brauer, E., Ed.; Academic: New York, 1963; 1, p 418.
Sonoda, N.; Kondo K.; Nagano, K.; Kambe, N.; Morimoto, F. Angewandte Chemie International Edition English 1980, vol. 19, page 308
Cohen, V.I. (1980). "A Convenient Synthesis of Mono-, N,N′-Di-, and Trisubstituted Selenoureas from Methyl Carbamimidothioates (S-Methylpseudothioureas)". Synthesis. 1980: 60–63. doi:10.1055/s-1980-28927.
https://www.osha.gov/dts/chemicalsampling/data/CH_246700.html, OSHA GENERAL INDUSTRY PEL: 0.05 ppm, 0.2 mg/m3 ,OSHA CONSTRUCTION INDUSTRY PEL: 0.05 ppm, 0.2 mg/m3 TWA

External links

This article is issued from Wikipedia. The text is licensed under Creative Commons - Attribution - Sharealike. Additional terms may apply for the media files.

[PGCH-1] NIOSH Pocket Guide to Chemical Hazards. "#0336". National Institute for Occupational Safety and Health (NIOSH).

[2] "Hydrogen selenide". Immediately Dangerous to Life or Health Concentrations (IDLH). National Institute for Occupational Safety and Health (NIOSH).

[EPA-3] ttp://www.epa.gov/ttnatw01/hlthef/selenium.html, US Environmental Protection Agency, Air Toxins website

[IDLHC-4] ttps://www.cdc.gov/niosh/idlh/7783075.html, Documentation of Immediately Dangerous to Life or Health Concentrations: Hydrogen Selenide, The National Institute for Occupational Safety and Health

[OHG-5] ttps://www.cdc.gov/niosh/docs/81-123/pdfs/0336.pdf Occupational Health Guideline for Hydrogen Selenide, The National Institute for Occupational Safety and Health, 1978

[:0-6] William M. Haynes; David R. Lide; Thomas J. Bruno, eds. (2017). CRC handbook of chemistry and physics : a ready-reference book of chemical and physical data (97th ed.). Boca Raton, Florida. ISBN 978-1-4987-5429-3. OCLC 957751024.

[7] Levy, D. E.; Myers, R. J. "Spectroscopic Determination of the Second Dissociation Constant of H₂Se and the Activity Coefficients and Spectral Shifts of Its Ions" J. Phys. Chem. 1990, 94(20), 7842-1847. http://pubs.acs.org/doi/pdf/10.1021/j100383a020

[Ullmann-8] Bernd E. Langner "Selenium and Selenium Compounds" in Ullmann's Encyclopedia of Industrial Chemistry, 2005, Wiley-VCH, Weinheim. doi:10.1002/14356007.a23_525.

[9] Féher, F. In "Handbook of Preparative Inorganic Chemistry"; Brauer, E., Ed.; Academic: New York, 1963; 1, p 418.

[10] Sonoda, N.; Kondo K.; Nagano, K.; Kambe, N.; Morimoto, F. Angewandte Chemie International Edition English 1980, vol. 19, page 308

[11] Cohen, V.I. (1980). "A Convenient Synthesis of Mono-, N,N′-Di-, and Trisubstituted Selenoureas from Methyl Carbamimidothioates (S-Methylpseudothioureas)". Synthesis. 1980: 60–63. doi:10.1055/s-1980-28927.

[12] ttps://www.osha.gov/dts/chemicalsampling/data/CH_246700.html, OSHA GENERAL INDUSTRY PEL: 0.05 ppm, 0.2 mg/m3 ,OSHA CONSTRUCTION INDUSTRY PEL: 0.05 ppm, 0.2 mg/m3 TWA