| Ethanethiol[1] | |
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Ethanethiol |
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Other names
Ethyl mercaptan |
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| 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, 125 K, -234 °F |
| Boiling point |
35 °C, 308 K, 95 °F |
| Acidity (pKa) | 10.6 |
| Hazards | |
| R-phrases | 11-20-50/53 |
| S-phrases | 16-25-60-61 |
| Main hazards | Nauseating |
| Related compounds | |
| Related compounds | Methanethiol Ethanol thiophenol |
| (verify) (what is: /?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) |
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| Infobox references | |
Ethanethiol (EtSH) is an organic compound with the formula CH3CH2SH. It consists of an ethyl group, CH3CH2, attached to a thiol group, SH. Its structure parallels that of ethanol, but with S instead of O. The presence of S leads to many different properties, most notably the infamous odour of EtSH. Ethanethiol is also 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 odourless gas products such as liquefied petroleum gas (LPG) to help warn of gas leaks. At these concentrations, ethanethiol is not harmful.
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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 odour resembles that of leeks or onions. Ethanethiol is intentionally added to butane and propane (see: LPG) to impart an easily noticed smell to these odourless fuels, that otherwise pose the threat of fire or explosion.
According to the 2000 edition of the Guinness Book Of World Records, ethanethiol is the "smelliest substance" in existence. Other more specialised chemicals were probably not examined, however. Most volatile thiols are comparably offensive. Thiols can be oxidized to ethyl sulfonic acid, which does not have a smell, using bleach or related strong oxidants. Weaker oxidants, such as ferric oxide, will cause the formation of diethyl disulfide.
Ethanethiol is a valued reagent in organic synthesis. In the presence of sodium hydroxide, it forms the powerful nucleophile NaSEt. The salt can also be generated quantitatively by reaction with sodium hydride.[2]
Mild oxidation of EtSH gives the disulfide, diethyl disulfide:
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.