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Methanethiol

Names Preferred IUPAC nameMethanethiolOther names Methyl mercaptanMercaptomethaneMethiolThiomethyl alcohol/ThiomethanolMethylthiolIdentifiers CAS Number74-93-13D model (JSmol)Interactive imageAbbreviations MMMeSH ChEBICHEBI:16007ChemSpider855ECHA InfoCard100.000.748EC Number200-822-1KEGGC00409PubChemCID878RTECS numberPB4375000UNII2X8406WW9IUN number1064 CompTox Dashboard(EPA)DTXSID5026382InChIInChI=1S/CH3SH/c1-2/h2H,1H3Key: LSDPWZHWYPCBBB-UHFFFAOYSA-NInChI=1/CH3SH/c1-2/h2H,1H3Key: LSDPWZHWYPCBBB-UHFFFAOYAWSMILESSCProperties Chemical formulaCH4SMolar mass48.10 g·mol Appearance colorless gas OdorDistinctive, like that of rotten cabbage or eggs Density0.9 g/mL (liquid at 0°C) Melting point−123 °C (−189 °F; 150 K) Boiling point5.95 °C (42.71 °F; 279.10 K) Solubility in water2% Solubilityalcohol, ether Vapor pressure1.7 atm (20°C) Acidity (pKa) ~10.4 Hazards GHS labelling: PictogramsSignal wordDangerHazard statementsH220, H331, H410Precautionary statementsP210, P261, P271, P273, P304+P340, P311, P321, P377, P381, P391, P403, P403+P233, P405, P501NFPA 704 (fire diamond) 441Flash point−18 °C; 0 °F; 255 K Autoignitiontemperature364 °C; 687 °F; 637 K Explosive limits3.9%–21.8% Lethal dose or concentration (LD, LC): LD50 (median dose)60.67 mg/kg (mammal) LC50 (median concentration)3.3 ppm (mouse, 2 hr)675 ppm (rat, 4 hr) NIOSH (US health exposure limits): PEL (Permissible)C 10 ppm (20 mg/m) REL (Recommended)C 0.5 ppm (1 mg/m) [15-minute] IDLH (Immediate danger)150 ppm Related compounds Related chalcogenolsMethanolMethaneselenolMethanetellurolRelated compoundsHydrogen sulfideEthanethiolDimethyl sulfideSodium methanethiolateExcept where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).Nverify ( ?)

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