Ethanethiol
| Ethanethiol[1][2] | |
|---|---|
 | |
 | |
| IUPAC name Ethanethiol | |
| Other names Ethyl mercaptan | |
| Identifiers | |
| CAS number | 75-08-1  |
| PubChem | 6343 |
| ChemSpider | 6103 |
| UNII | M439R54A1D |
| RTECS number | KI9625000 |
| Jmol-3D images | Image 1 |
| |
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| Properties | |
| Molecular formula | C2H6S |
| Molar mass | 62.13404 g·mol−1 |
| Density | 0.8617 g·cm−3 |
| Melting point | −148 °C; −234 °F; 125 K |
| Boiling point | 35 °C; 95 °F; 308 K |
| Acidity (pKa) | 10.6 |
| Hazards | |
| EU classification |  F  Xn  N |
| R-phrases | R11, R20, R50/53 |
| S-phrases | S16, S25, S60, S61 |
| Main hazards | Nauseating |
| NFPA 704 |
 4
2
0
|
| Related compounds | |
| Related compounds | Methanethiol Butanethiol Ethanol thiophenol |
(verify) (what is: / ?)Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa) | |
| 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.[3]
Ethanethiol was originally reported by Zeise in 1834.[4] 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.[5]
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. 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.[6]
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.
References
- ↑ Merck Index, 12th edition, 3771
- ↑ "ICSC 0470 - ETHANETHIOL".
- ↑ 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", Org. Synth.; Coll. Vol. 6: 859