| Identification | More | [Name]
METHYL MERCAPTAN | [CAS]
74-93-1 | [Synonyms]
4Q 1998
FEMA 2716
MERCAPTAN C1
MERCAPTOMETHANE
METHANETHIOL
METHYL MERCAPTAN
METHYL SULFHYDRATE
THIOMETHANOL
THIOMETHYL ALCOHOL
CH3SH
Mercaptan methylique
mercaptanmethylique
mercaptanmethylique(french)
Methaanthiol
Methanethiole
methanethiolvialwith25ml
Methanthiol
Methvtiolo
Methyl thioalcohol
Methylmercaptaan | [EINECS(EC#)]
200-822-1 | [Molecular Formula]
CH4S | [MDL Number]
MFCD00004866 | [Molecular Weight]
48.11 | [MOL File]
74-93-1.mol |
| Chemical Properties | Back Directory | [Appearance]
Methyl mercaptan is a colorless gas or white
liquid with a disagreeable odor like garlic or rotten cabbage. Shipped as a liquefied compressed gas. The odor
threshold is 0.002 ppm. | [Melting point ]
−123 °C(lit.)
| [Boiling point ]
6 °C(lit.)
| [density ]
0.8665 | [vapor density ]
1.66 (vs air)
| [vapor pressure ]
1536 mm Hg ( 20 °C)
| [FEMA ]
2716 | [refractive index ]
1.4020 (estimate) | [Fp ]
<71℃ | [solubility ]
Soluble in alcohol, ether (Weast, 1986), and petroleum naphtha (Hawley, 1981) | [form ]
liquid | [pka]
10.3(at 25℃) | [Odor]
at 0.01 % in propylene glycol. decomposing cabbage garlic | [Stability:]
Stable. Highly flammable-note low flash point. Reacts vigorously or explosively with a wide variety of materials-consult a full MSDS data sheet before using. Incompatible with strong oxidizing agents, alkali and alkaline earth metals, epoxides, hydrazines, ketones, lead, mercury (II) oxide, azo-and diazo-compounds, copp | [explosive limit]
21.8% | [Odor Threshold]
0.00007ppm | [Odor Type]
sulfurous | [Water Solubility ]
23.30 g/L at 20 °C (quoted, Windholz et al., 1983)
0.330 mol/L at 25 °C (Hine and Weimar, 1965) | [JECFA Number]
508 | [Merck ]
13,5983 | [BRN ]
1696840 | [Henry's Law Constant]
3.03 (Hine and Weimar, 1965) | [Exposure limits]
TLV-TWA 0.5 ppm (～1.0 mg/m3 ) (ACGIH
and MSHA); ceiling 10 ppm (OSHA); IDLH
400 ppm (NIOSH); the revised IDLH is 150
ppm in analogy to H2S. | [LogP]
0.72 | [Uses]
Synthesis, especially of methionine, jet fuel
additives, fungicides; also as catalyst. | [CAS DataBase Reference]
74-93-1(CAS DataBase Reference) | [EPA Substance Registry System]
Methyl mercaptan (74-93-1) |
| Safety Data | Back Directory | [Hazard Codes ]
F+,T,N | [Risk Statements ]
R12:Extremely Flammable.
R23:Toxic by inhalation.
R50/53:Very Toxic to aquatic organisms, may cause long-term adverse effects in the aquatic environment . | [Safety Statements ]
S16:Keep away from sources of ignition-No smoking .
S25:Avoid contact with eyes .
S60:This material and/or its container must be disposed of as hazardous waste .
S61:Avoid release to the environment. Refer to special instructions safety data sheet . | [RIDADR ]
UN 2037 2.3
| [WGK Germany ]
3
| [RTECS ]
PB4375000
| [F ]
13-27 | [HazardClass ]
2.3 | [Safety Profile]
Poison by inhalation.
Mutation data reported. A common air
contaminant. Very dangerous fire hazard
when exposed to heat or flame; can react
vigorously with oxidzing materials.
Explosive in the form of vapor when
exposed to heat or flame. Reacts with water,
steam, or acids to produce toxic and
flammable vapors. Violent reaction with
mercury(II) oxide. To fight fire, use alcohol
foam, CO2, dry chemical. Upon
decomposition it emits highly toxic fumes of
SOx. | [Hazardous Substances Data]
74-93-1(Hazardous Substances Data) | [Toxicity]
LC50 (inhalation) for mice 6,530 μg/m3/2-h, rats 675 ppm (quoted, RTECS, 1985). | [IDLA]
150 ppm |
| Hazard Information | Back Directory | [Reactivity Profile]
METHYL MERCAPTAN is a reducing agent--can react vigorously with oxidizing agents. Dangerous fire or explosion hazard when exposed to heat, flame, sparks or strong oxidizing agents (e.g., calcium hypochlorite). When heating to decomposition emits highly toxic fumes of oxides of sulfur [Lewis, 3rd ed., 1993, p. 862]. Violent reaction with mercury(II) oxide [Klason P., Ber., 1887, 20, p. 3410]. | [Air & Water Reactions]
Highly flammable. Reacts with water, steam or acids to produce toxic, flammable vapors [Lewis]. | [Hazard]
Flammable, dangerous fire risk. Explosive
limits in air 3.9–21.8%. Strong irritant. Liver damage. | [Health Hazard]
Can cause death by respiratory paralysis. It is an eye and respiratory tract irritant. Exposure results in pulmonary edema and hepatic and renal damage. | [Potential Exposure]
Methyl mercaptan is used in methionine synthesis, and widely as an intermediate in pesticide
manufacture. A foul-smelling odorant usually added to
chemicals, including pesticides. | [Fire Hazard]
Combustion produces irritating sulfur dioxide. Flash back along vapor track may occur. Very dangerous when exposed to heat, flame, or oxidizers. On decomposition METHYL MERCAPTAN emits highly toxic fumes of sulfur oxides. METHYL MERCAPTAN will react with water, steam or acids to produce toxic and flammable vapors; and can react vigorously with oxidizing materials. Irritating sulfur dioxide is produced upon combustion. When heated to decomposition, METHYL MERCAPTAN emits highly toxic fumes and flammable vapors. Incompatible with mercuric oxide and oxidizing materials. Avoid direct sunlight, and areas of high fire hazards. Hazardous polymerization may not occur. | [First aid]
If this chemical gets into the eyes, remove any
contact lenses at once and irrigate immediately for at least
15 minutes, occasionally lifting upper and lower lids. Seek
medical attention immediately. If this chemical contacts the
skin, remove contaminated clothing and wash immediately
with soap and water. Seek medical attention immediately.
If this chemical has been inhaled, remove from exposure,
begin rescue breathing (using universal precautions, including resuscitation mask) if breathing has stopped and CPR if
heart action has stopped. Transfer promptly to a medical
facility. When this chemical has been swallowed, get medical attention. Give large quantities of water and induce
vomiting. Do not make an unconscious person vomit.
Medical observation is recommended for 24 to 48 hours
after breathing overexposure, as pulmonary edema may be
delayed. As first aid for pulmonary edema, a doctor or
authorized paramedic may consider administering a drug or
other inhalation therapy. If frostbite has occurred, seek
medical attention immediately; do NOT rub the affected
areas or flush them with water. In order to prevent further
tissue damage, do NOT attempt to remove frozen clothing
from frostbitten areas. If frostbite has NOT occurred, immediately and thoroughly wash contaminated skin with soap
and water. | [Shipping]
UN1064 Methyl mercaptan, Hazard Class: 2.3;
Labels: 2.3-Poisonous gas, 2.1-Flammable gas, Inhalation
Hazard Zone C. Cylinders must be transported in a secure
upright position, in a well-ventilated truck. Protect cylinder
and labels from physical damage. The owner of the compressed gas cylinder is the only entity allowed by federal
law (49CFR) to transport and refill them. It is a violation
of transportation regulations to refill compressed gas cylinders without the express written permission of the owner. | [Incompatibilities]
Violent reaction with strong oxidizers,
bleaches, copper, nickel and their alloys; aluminum. Reacts
with acids producing flammable and toxic hydrogen
sulfide | [Description]
Methanethiol (also known as methyl mercaptan) is a colorless gas with a smell like rotten cabbage. It is a natural substance found in the blood and brain of humans and other animals as well as plant tissues. It is disposed of through animal feces. It occurs naturally in certain foods, such as some nuts and cheese. It is also one of the main chemicals responsible for bad breath and the smell of flatus. The chemical formula for methanethiol is CH3SH; it is classified as a thiol. It is sometimes abbreviated as MeSH. It is very flammable. | [Chemical Properties]
colourless gas with a garlic-like or rotten cabbage-like smell | [Chemical Properties]
Methyl mercaptan has an objectionable odor of decomposing cabbage or garlic | [Chemical Properties]
Methyl mercaptan has an objectionable odor of decomposing cabbage. May be prepared by heating an aqueous solution of potassium methyl sulfate and KHS; from sodium methyl sulfate and
potassium sulfhydrate; also from methanol and hydrogen sulfide
in the presence of a catalyst.
| [Chemical Properties]
Methyl mercaptan is a colorless gas or white
liquid with a disagreeable odor like garlic or rotten cabbage. Shipped as a liquefied compressed gas. The odor
threshold is 0.002 ppm. | [Waste Disposal]
Return refillable compressed
gas cylinders to supplier. Consult with environmental regulatory agencies for guidance on acceptable disposal practices. Generators of waste containing this contaminant
(≥100 kg/mo) must conform to EPA regulations governing
storage, transportation, treatment, and waste disposal.
Incineration followed by effective scrubbing of the effluent
gas. | [Physical properties]
Colorless gas with a garlic-like or rotten cabbage odor. An experimentally determined odor
threshold concentration of 2.1 ppbv was reported by Leonardos et al. (1969). A detection odor
threshold concentration of 81 μg/m3 (41 ppbv) was determined by Katz and Talbert (1930). | [Occurrence]
Methanethiol is released from decaying organic matter in marshes and is present in the natural gas of certain regions, in coal tar, and in some crude oils.
In surface seawater, methanethiol is the primary breakdown product of the algal metabolite dimethylsulfoniopropionate (DMSP). Marine bacteria appear to obtain most of their protein sulfur by the breakdown of DMSP and incorporation of methanethiol, despite the fact that methanethiol is present in seawater at much lower concentrations than sulfate (～0.3 nM vs. 28 mM). Bacteria in oxic and anoxic environments can also convert methanethiol to dimethyl sulfide (DMS), although most DMS in surface seawater is produced by a separate pathway. Both DMS and methanethiol can be used by certain microbes as substrates for methanogenesis in some anaerobic soils.
Methanethiol is a weak acid, with a pKa of ～10.4. This acidic property makes it reactive with dissolved metals in aqueous solutions. The environmental chemistry of these interactions in seawater or fresh water environments such as lakes has yet to be fully investigated.
A material safety data sheet (MSDS) lists methanethiol as a colorless, flammable gas with an extremely strong and repulsive smell. At very high concentrations it is highly toxic and affects the central nervous system. Its penetrating odor provides warning at dangerous concentrations. An odor threshold of 1 ppb has been reported. The United States OSHA Ceiling Limit is listed as 10 ppm. | [Definition]
ChEBI: Methanethiol is an alkanethiol. It has a role as a human metabolite and a Saccharomyces cerevisiae metabolite. | [Preparation]
Methanethiol is prepared commercially by the reaction of methanol with hydrogen sulfide gas over an acidic solid catalyst, such as alumina. It can be prepared by the reaction of methyl iodide with thiourea. | [Aroma threshold values]
Detection: 0.02 to 4 ppb. Aroma characteristics at 1.0%: vegetable oil, alliaceous, eggy, creamy with
savory nuances | [Taste threshold values]
Taste characteristics at 1 ppm: sulfurous, alliaceous, creamy with a surface-ripened cheese top note and a
clean, savory, meaty depth | [Synthesis]
By heating an aqueous solution of potassium methyl sulfate and KHS; from sodium methyl sulfate and potassium sulfhydrate; also from methanol and hydrogen sulfide in the presence of a catalyst | [Source]
Occurs naturally in kohlrabi stems (Brassica oleracea var. gongylodes) and potato plants
(Duke, 1992) | [Environmental Fate]
Biological. After 20 d, methyl mercaptan started to degrade in anaerobic sediments and sludges
producing stoichiometric amounts of methane. Complete degradation was achieved after 20 d. Under
anaerobic freshwater conditions, methyl mercaptan were degraded by methanogenic archea (van
Leerdam et al., 2006).
Photolytic. Sunlight irradiation of a methyl mercaptan-nitrogen oxide mixture in an outdoor
chamber yielded formaldehyde, sulfur dioxide, nitric acid, methyl nitrate, methanesulfonic acid,
and an inorganic sulfate (Grosjean, 1984a).
Chemical/Physical. In the presence of nitric oxide, gaseous methyl mercaptan reacted with OH
radicals forming methyl sulfenic acid and methyl thionitrite. The rate constant for this reaction is
2.1 x 10-11 cm3/molecule?sec at 20 °C (MacLeod et al., 1984).
Forms a crystalline hydrate with water (Patnaik, 1992). | [storage]
Color Code—Red: Flammability Hazard: Store ina flammable liquid storage area or approved cabinet awayfrom ignition sources and corrosive and reactive materials.Prior to working with this chemical you should be trainedon its proper handling and storage. Before entering confinedspace where this chemical may be present, check to makesure that an explosive concentration does not exist. Methylmercaptan must be stored to avoid contact with water,steam, or strong acids (such as hydrochloric, sulfuric, andnitric) because toxic flammable vapors will be released. Itshould not contact oxidizers (such as perchlorates, peroxides, permanganates, chlorates, and nitrates) since violentreactions occur. Store in tightly closed containers in a cool,well-ventilated area away from heat or sparks. Sources ofignition, such as smoking and open flames, are prohibitedwhere methyl mercaptan is handled, used, or stored. Metalcontainers involving the transfer of 5 gallons or more ofmethyl mercaptan should be grounded and bonded. Drumsmust be equipped with self-closing valves, pressure vacuumbungs, and flame arresters. Use only nonsparking tools andequipment, especially when opening and closing containersof methyl mercaptan. Procedures for the handling, use, andstorage of cylinders should be in compliance with OSHA1910.101 and 1910.169, as with the recommendations ofthe Compressed Gas Association. | [Asparagus]
Methanethiol is a byproduct produced by the metabolism of asparagus. The ability to produce methanethiol in urine after eating asparagus was once thought to be a genetic trait. However recent research suggests that the peculiar odor is in fact produced by all humans after consuming asparagus, while the ability to detect it (methanethiol being one of many components in "asparagus pee") is in fact the genetic trait. The chemical components responsible for the change in the odor of urine show as soon as 15 minutes after eating asparagus. |
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