Methanethiol
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| Names | |||
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Preferred IUPAC name
Methanethiol
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| Other names
Methyl mercaptan
Mercaptomethane Methiol Thiomethyl alcohol Methylthiol |
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| Identifiers | |||
74-93-1 
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| 3D model (Jmol) | Interactive image | ||
| ChEBI |
CHEBI:16007
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| ChemSpider |
855
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| ECHA InfoCard | 100.000.748 | ||
| KEGG |
C00409
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| UNII |
2X8406WW9I
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| Properties | |||
| CH4S | |||
| Molar mass | 48.11 g·mol−1 | ||
| Appearance | colorless gas | ||
| Odor | Rotten cabbage, flatulence | ||
| Density | 0.9 g/mL (liquid at 0°C) | ||
| Melting point | −123 °C (−189 °F; 150 K) | ||
| Boiling point | 5.95 °C (42.71 °F; 279.10 K) | ||
| 2% | |||
| Solubility | alcohol, ether | ||
| Vapor pressure | 1.7 atm (20°C) | ||
| Acidity (pKa) | ~10.4 | ||
| Hazards | |||
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EU classification (DSD)
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 F+  T  N
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| R-phrases | R12, R23, R50/53 | ||
| S-phrases | S16, S25, S33S60, S61 | ||
| NFPA 704 | |||
| Flash point | −18 °C; 0 °F; 255 K | ||
| Explosive limits | 3.9%-21.8% | ||
| Lethal dose or concentration (LD, LC): | |||
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LD50 (median dose)
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60.67 mg/kg (mammal) | ||
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LC50 (median concentration)
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3.3 ppm (mouse, 2 hr) 675 ppm (rat, 4 hr) |
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| US health exposure limits (NIOSH): | |||
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PEL (Permissible)
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C 10 ppm (20 mg/m3) | ||
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REL (Recommended)
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C 0.5 ppm (1 mg/m3) [15-minute] | ||
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IDLH (Immediate danger)
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150 ppm | ||
| Related compounds | |||
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Related compounds
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Ethanethiol | ||
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Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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 (what is  ?) |
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| Infobox references | |||
Methanethiol /ˈmɛθeɪnˈθaɪɒl/ (also known as methyl mercaptan) is an organosulfur compound with the chemical formula CH
3SH. It is a colorless gas with a distinctive putrid smell. It is a natural substance found in the blood and brain of humans and animals, as well as in plant tissues. It is disposed of through animal feces. It also occurs naturally in certain foods, such as some nuts and cheese. It is one of the main compounds responsible for bad breath and the smell of flatus. Methanethiol is classified as a thiol and is sometimes abbreviated as MeSH. It is very flammable.
The molecule is tetrahedral at carbon, like methanol. It is a weak acid, with a pKa of ~10.4, but is about a million times more acidic than methanol. The colorless salt can be obtained in this way:
The resulting thiolate anion is a strong nucleophile.
It can be oxidized to dimethyl disulfide:
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