Ethanethiol

**Ethanethiol**^[1]^[2]
Names
	IUPAC name Ethanethiol
	Other names Ethyl mercaptan, Mercaptoethane, Ethyl sulfhydrate
Identifiers
CAS Number	75-08-1 ;
3D model (JSmol)	Interactive image;
ChemSpider	6103 ;
ECHA InfoCard	100.000.762
PubChem CID	6343;
RTECS number	KI9625000;
UNII	M439R54A1D ;
UN number	2363
CompTox Dashboard (EPA)	DTXSID9026394 ;
	InChI InChI=1S/C2H6S/c1-2-3/h3H,2H2,1H3 Key: DNJIEGIFACGWOD-UHFFFAOYSA-N ; InChI=1/C2H6S/c1-2-3/h3H,2H2,1H3 Key: DNJIEGIFACGWOD-UHFFFAOYAW;
	SMILES CCS;
Properties
Chemical formula	C2H6S
Molar mass	62.13404 g·mol−1
Appearance	Colorless liquid
Odor	Rotten cabbage, flatulence, skunk-like
Density	0.8617 g·cm−3
Melting point	−148 °C (−234 °F; 125 K)
Boiling point	35 °C (95 °F; 308 K)
Solubility in water	0.7% (20°C)
Vapor pressure	442 mmHg (20°C)
Acidity (pKa)	10.6
Hazards
	Occupational safety and health (OHS/OSH):
Main hazards	Nauseating
NFPA 704 (fire diamond)	2 4 0
Flash point	−48 °C; −55 °F; 225 K
Explosive limits	2.8%-18.0%
	Lethal dose or concentration (LD, LC):
LD50 (median dose)	682 mg/kg (rat, oral)
LC50 (median concentration)	4410 ppm (rat, 4 hr); 2770 (mouse, 4 hr)
	NIOSH (US health exposure limits):
PEL (Permissible)	C 10 ppm (25 mg/m3)
REL (Recommended)	C 0.5 ppm (1.3 mg/m3) [15-minute]
IDLH (Immediate danger)	500 ppm
Related compounds
Related compounds	Methanethiol; Butanethiol; Ethanol; thiophenol
	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

Ethanethiol, commonly known as ethyl mercaptan, is a colorless gas or clear liquid with a distinct odor. It is an organosulfur compound with the formula CH₃CH₂SH. Abbreviated EtSH, it consists of an ethyl group (Et), CH₃CH₂, attached to a thiol group, SH. Its structure parallels that of ethanol, but with S instead of O. The odor of EtSH is infamous. Ethanethiol is more volatile than ethanol due to a diminished ability to engage in hydrogen bonding. Ethanethiol is toxic. It occurs naturally as a minor component of petroleum, and may be added to otherwise odorless gaseous products such as liquefied petroleum gas (LPG) to help warn of gas leaks. At these concentrations, ethanethiol is not harmful.

Preparation

Ethanethiol is prepared by the reaction of ethylene with hydrogen sulfide over a catalyst. The various producers utilize different catalysts in this process. It has also been prepared commercially by the reaction of ethanol with hydrogen sulfide gas over an acidic solid catalyst, such as alumina.^[5]

Report by mrkarkai.

Ethanethiol was originally reported by Zeise in 1834.^[6] Zeise treated calcium ethyl sulfate with a suspension of barium sulfide saturated with hydrogen sulfide. He is credited with naming the C₂H₅S- group as mercaptum.

Ethanethiol can also be prepared by a halide displacement reaction, where ethyl halide is reacted with aqueous sodium bisulfide. This conversion was demonstrated as early as 1840 by Henri Victor Regnault.^[7]

Odor

Ethanethiol has a strongly disagreeable odor that humans can detect in minute concentrations. The threshold for human detection is as low as one part in 2.8 billion parts of air.^{[citation needed]} Its odor resembles that of leeks, onions, durian or cooked cabbage, but is quite distinct. Ethanethiol is intentionally added to butane and propane (see: LPG) to impart an easily noticed smell to these normally odorless fuels that pose the threat of fire, explosion, and asphyxiation.

Reactions

Ethanethiol is a valued reagent in organic synthesis. In the presence of sodium hydroxide, it gives the powerful nucleophile SEt⁻. The salt can be generated quantitatively by reaction with sodium hydride.^[8]

Ethanethiol can be oxidized to ethyl sulfonic acid, using bleach and related strong aqueous oxidants. Weaker oxidants, such as ferric oxide give the disulfide, diethyl disulfide:

2 EtSH + H₂O₂ → EtS-SEt + 2 H₂O

Like other thiols, it behaves comparably to hydrogen sulfide. For example, it binds, concomitant with deprotonation to "soft" transition metal cations, such as Hg²⁺, Cu⁺, and Ni²⁺ to give polymeric thiolato complexes, Hg(SEt)₂, CuSEt, and Ni(SEt)₂, respectively.

Uses

In the underground mining industry, ethanethiol or ethyl mercaptan is referred to as "stench gas".^[9] The gas is released into underground mine ventilation systems as an early warning system to alert mine workers during an emergency.^[10] In Ontario, mining legislation dictates that "The alarm system in an underground mine shall, consist of the introduction into all workplaces of sufficient quantities of ethyl mercaptan gas or similar gas to be readily detectable by all workers".^[11]

References

^ Merck Index, 12th edition, 3771
^ "ICSC 0470 - ETHANETHIOL".
^ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ NIOSH Pocket Guide to Chemical Hazards. "#0280". National Institute for Occupational Safety and Health (NIOSH).
^ ^a ^b "Ethyl mercaptan". Immediately Dangerous to Life or Health Concentrations (IDLH). National Institute for Occupational Safety and Health (NIOSH).
^ Norell, John; Louthan, Rector P. (1988). "Thiols". Kirk-Othmer Concise Encylclopedia of Chemical Technology (3rd ed.). New York: John Wiley & Sons, Inc. pp. 946–963. ISBN 978-0471801047.
^ Zeise, William Christopher (1834). "Sur le Mercaptan; avec des Observations sur d'autres produits resultant de l'Action des Sulfovinates ainsi que de l'Huile de vin, sur des sulfures metalliques". Annales de Chimie et de Physique. 56: 87–97.
^ Regnault, V (1840). "Ueber die Einwirkung des Chlors auf die Chlorwasserstoffäther des Alkohols und Holzgeistes und über mehrere Punkte der Aethertheorie". Ann. 34: 24–52. doi:10.1002/jlac.18400340103.
^ Mirrington, R. N.; Feutrill, G. I. (1988). "Orcinol Monomethyl Ether". Organic Syntheses{{cite journal}}: CS1 maint: multiple names: authors list (link); Collected Volumes, vol. 6, p. 859.
^ "Stench Gas". Zacon Ltd. Retrieved 20 February 2015.
^ "A Stench Gas Warning System for Information Governance?". Barclay T Blair. Retrieved 20 February 2015.
^ "Occupational Health and Safety Act: R.R.O. 1990, REGULATION 854 MINES AND MINING PLANTS Sect. 26(6)(a)". Ontario Ministry of Labour. Retrieved 20 February 2015.

External links

[1] Merck Index, 12th edition, 3771

[2] "ICSC 0470 - ETHANETHIOL".

[PGCH-3] ^ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ NIOSH Pocket Guide to Chemical Hazards. "#0280". National Institute for Occupational Safety and Health (NIOSH).

[IDLH-4] "Ethyl mercaptan". Immediately Dangerous to Life or Health Concentrations (IDLH). National Institute for Occupational Safety and Health (NIOSH).

[John_Wiley_&_Sons,_Inc-5] Norell, John; Louthan, Rector P. (1988). "Thiols". Kirk-Othmer Concise Encylclopedia of Chemical Technology (3rd ed.). New York: John Wiley & Sons, Inc. pp. 946–963. ISBN 978-0471801047.

[6] Zeise, William Christopher (1834). "Sur le Mercaptan; avec des Observations sur d'autres produits resultant de l'Action des Sulfovinates ainsi que de l'Huile de vin, sur des sulfures metalliques". Annales de Chimie et de Physique. 56: 87–97.

[7] Regnault, V (1840). "Ueber die Einwirkung des Chlors auf die Chlorwasserstoffäther des Alkohols und Holzgeistes und über mehrere Punkte der Aethertheorie". Ann. 34: 24–52. doi:10.1002/jlac.18400340103.

[8] Mirrington, R. N.; Feutrill, G. I. (1988). "Orcinol Monomethyl Ether". Organic Syntheses{{cite journal}}: CS1 maint: multiple names: authors list (link); Collected Volumes, vol. 6, p. 859.

[9] "Stench Gas". Zacon Ltd. Retrieved 20 February 2015.

[10] "A Stench Gas Warning System for Information Governance?". Barclay T Blair. Retrieved 20 February 2015.

[11] "Occupational Health and Safety Act: R.R.O. 1990, REGULATION 854 MINES AND MINING PLANTS Sect. 26(6)(a)". Ontario Ministry of Labour. Retrieved 20 February 2015.

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