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Methylmercaptan

Methanethiol
Methanethiol
Ball-and-stick model of the methanethiol molecule
Space-filling model of the methanethiol molecule
Names
Preferred IUPAC name
Methanethiol
Other names
Methyl mercaptan
Mercaptomethane
Methiol
Thiomethyl alcohol
Methylthiol
Identifiers
74-93-1 YesY
3D model (Jmol) Interactive image
ChEBI CHEBI:16007 YesY
ChemSpider 855 YesY
ECHA InfoCard 100.000.748
KEGG C00409 YesY
UNII 2X8406WW9I YesY
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
Extremely Flammable F+ Toxic T Dangerous for the Environment (Nature) N
R-phrases R12, R23, R50/53
S-phrases S16, S25, S33S60, S61
NFPA 704
Flammability code 4: Will rapidly or completely vaporize at normal atmospheric pressure and temperature, or is readily dispersed in air and will burn readily. Flash point below 23 °C (73 °F). E.g., propane Health code 4: Very short exposure could cause death or major residual injury. E.g., VX gas Reactivity code 1: Normally stable, but can become unstable at elevated temperatures and pressures. E.g., calcium Special hazards (white): no codeNFPA 704 four-colored diamond
Flash point −18 °C; 0 °F; 255 K
Explosive limits 3.9%-21.8%
Lethal dose or concentration (LD, LC):
LD50 (median dose)
 60.67 mg/kg (mammal)
3.3 ppm (mouse, 2 hr)
675 ppm (rat, 4 hr)
US health exposure limits (NIOSH):
PEL (Permissible)
 C 10 ppm (20 mg/m3)
REL (Recommended)
 C 0.5 ppm (1 mg/m3) [15-minute]
IDLH (Immediate danger)
 150 ppm
Related compounds
Related compounds
 Ethanethiol
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
YesY  (what is YesYN ?)
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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