74-93-1 structure, CH4S






Basic Info

Methanethiol (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 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 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.

Molecular Weight
Exact Mass







FEMA 2716


methyl mercaptane




4Q 1998


expand collapse


Appearance & Physical State
colourless gas with a garlic-like or rotten cabbage-like smell
Boiling Point
Melting Point
Flash Point
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, hydrazi
Vapor Density
1.66 (vs air)
Vapor Pressure
1536 mm Hg ( 20 °C)

Safety Info

Safety Statements
S16; S25; S60; S61
WGK Germany
Risk Statements
HS Code
UN 2037 2.3
Hazard Class
Caution Statement
P210; P261; P273; P311; P410 + P403; P501
Hazard Declaration


SDS 1.0
expand collapse
Download/Modify | Technical supported by XiXisys.com. For US version, EU version (23 languages) and more, please refer to xixisys.com/en/sds/search


According to Globally Harmonized System of Classification and Labelling of Chemicals (GHS) - Sixth revised edition

Version: 1.0

Creation Date: Aug 16, 2017

Revision Date: Aug 16, 2017


1.1 GHS Product identifier

Product name methanethiol

1.2 Other means of identification

Product number -

1.3 Recommended use of the chemical and restrictions on use

Identified uses For industry use only. Volatile organic compounds
Uses advised against no data available

1.4 Supplier's details

Company MOLBASE (Shanghai) Biotechnology Co., Ltd.
Address Floor 4 & 5, Building 12, No. 1001 North Qinzhou Road,
Xuhui District, Shanghai, China
Telephone +86(21)64956998
Fax +86(21)54365166

1.5 Emergency phone number

Emergency phone number +86-400-6021-666
Service hours Monday to Friday, 9am-5pm (Standard time zone: UTC/GMT +8 hours).

2.Hazard identification

2.1 Classification of the substance or mixture

Gases under pressure: Compressed gas

Flammable gases, Category 1

Acute toxicity - Inhalation, Category 3

Hazardous to the aquatic environment, short-term (Acute) - Category Acute 1

Hazardous to the aquatic environment, long-term (Chronic) - Category Chronic 1

2.2 GHS label elements, including precautionary statements

Signal word


Hazard statement(s)

H220 Extremely flammable gas

H331 Toxic if inhaled

H410 Very toxic to aquatic life with long lasting effects

Precautionary statement(s)

P210 Keep away from heat, hot surfaces, sparks, open flames and other ignition sources. No smoking.

P261 Avoid breathing dust/fume/gas/mist/vapours/spray.

P271 Use only outdoors or in a well-ventilated area.

P273 Avoid release to the environment.


P377 Leaking gas fire: Do not extinguish, unless leak can be stopped safely.

P381 In case of leakage, eliminate all ignition sources.

P304+P340 IF INHALED: Remove person to fresh air and keep comfortable for breathing.

P311 Call a POISON CENTER/doctor/…

P321 Specific treatment (see ... on this label).

P391 Collect spillage.


P410+P403 Protect from sunlight. Store in a well-ventilated place.

P403 Store in a well-ventilated place.

P403+P233 Store in a well-ventilated place. Keep container tightly closed.

P405 Store locked up.


P501 Dispose of contents/container to ...

2.3 Other hazards which do not result in classification


3.Composition/information on ingredients

3.1 Substances

Chemical name Common names and synonyms CAS number EC number Concentration
methanethiol methanethiol 74-93-1 none 100%

4.First-aid measures

4.1 Description of necessary first-aid measures

General advice

Consult a physician. Show this safety data sheet to the doctor in attendance.

If inhaled

Fresh air, rest. Artificial respiration may be needed. Refer for medical attention.

In case of skin contact

Remove contaminated clothes. Refer for medical attention . ON FROSTBITE: rinse with plenty of water, do NOT remove clothes.

In case of eye contact

First rinse with plenty of water for several minutes (remove contact lenses if easily possible), then refer for medical attention.

If swallowed

Never give anything by mouth to an unconscious person. Rinse mouth with water. Consult a physician.

4.2 Most important symptoms/effects, acute and delayed

Can cause death by respiratory paralysis. It is an eye and respiratory tract irritant. Exposure results in pulmonary edema and hepatic and renal damage. (EPA, 1998)

4.3 Indication of immediate medical attention and special treatment needed, if necessary

Immediate first aid: Ensure that adequate decontamination has been carried out. If patient is not breathing, start artificial respiration, preferably with a demand-valve resuscitator, bag-valve-mask device, or pocket mask, as trained. Perform CPR as necessary. Immediately flush contaminated eyes with gently flowing water. Do not induce vomiting. If vomiting occurs, lean patient forward or place on left side (head-down position, if possible) to maintain an open airway and prevent aspiration. Keep patient quiet and maintain normal body temperature. Obtain medical attention. /Sulfur and related compounds/

5.Fire-fighting measures

5.1 Extinguishing media

Suitable extinguishing media

Stop flow of gas before extinguishing fire. Use water spray to control fire by preventing its spread and absorbing some of its heat.

5.2 Specific hazards arising from the chemical

Combustion produces irritating sulfur dioxide. Flash back along vapor track may occur. Very dangerous when exposed to heat, flame, or oxidizers. On decomposition it emits highly toxic fumes of sulfur oxides. It 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, it 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. (EPA, 1998)

5.3 Special protective actions for fire-fighters

Wear self-contained breathing apparatus for firefighting if necessary.

6.Accidental release measures

6.1 Personal precautions, protective equipment and emergency procedures

Use personal protective equipment. Avoid dust formation. Avoid breathing vapours, mist or gas. Ensure adequate ventilation. Evacuate personnel to safe areas. Avoid breathing dust. For personal protection see section 8.

6.2 Environmental precautions

Evacuate danger area! Consult an expert! Personal protection: self-contained breathing apparatus. Ventilation. Do NOT let this chemical enter the environment.

6.3 Methods and materials for containment and cleaning up

Stop or control the leak, if this can be done with undue risk. Use water spray to cool and disperse vapors, protect personnel, and dilute spills to form nonflammable mixtures. Control runoff and isolate discharged material for proper disposal.

7.Handling and storage

7.1 Precautions for safe handling

Avoid contact with skin and eyes. Avoid formation of dust and aerosols. Avoid exposure - obtain special instructions before use.Provide appropriate exhaust ventilation at places where dust is formed. For precautions see section 2.2.

7.2 Conditions for safe storage, including any incompatibilities

Fireproof. Separated from strong oxidants and acids. Cool. Store in an area without drain or sewer access.Separate from oxidizing materials. Store in a cool, dry, well-ventilated location.

8.Exposure controls/personal protection

8.1 Control parameters

Occupational Exposure limit values

Recommended Exposure Limit: 15 Minute Ceiling Value: 0.5 ppm (1 mg/cu m).

Biological limit values

no data available

8.2 Appropriate engineering controls

Handle in accordance with good industrial hygiene and safety practice. Wash hands before breaks and at the end of workday.

8.3 Individual protection measures, such as personal protective equipment (PPE)

Eye/face protection

Safety glasses with side-shields conforming to EN166. Use equipment for eye protection tested and approved under appropriate government standards such as NIOSH (US) or EN 166(EU).

Skin protection

Wear impervious clothing. The type of protective equipment must be selected according to the concentration and amount of the dangerous substance at the specific workplace. Handle with gloves. Gloves must be inspected prior to use. Use proper glove removal technique(without touching glove's outer surface) to avoid skin contact with this product. Dispose of contaminated gloves after use in accordance with applicable laws and good laboratory practices. Wash and dry hands. The selected protective gloves have to satisfy the specifications of EU Directive 89/686/EEC and the standard EN 374 derived from it.

Respiratory protection

Wear dust mask when handling large quantities.

Thermal hazards

no data available

9.Physical and chemical properties

Physical state colourless gas with a garlic-like or rotten cabbage-like smell
Colour Water-white liquid when below boiling point, or colorless gas
Odour Odor of rotten cabbage
Melting point/ freezing point 2ºC
Boiling point or initial boiling point and boiling range 6°C(lit.)
Flammability Flammable GasExtremely flammable.
Lower and upper explosion limit / flammability limit Lower flammable limit:3.9% by volume; Upper flammable limit:21.8% by volume
Flash point -18°C
Auto-ignition temperature no data available
Decomposition temperature no data available
pH no data available
Kinematic viscosity no data available
Solubility 2 % (NIOSH, 2016)
Partition coefficient n-octanol/water (log value) log Kow = 0.78 (est)
Vapour pressure 1536 mm Hg ( 20 °C)
Density and/or relative density 0.8665
Relative vapour density 1.66 (vs air)
Particle characteristics no data available

10.Stability and reactivity

10.1 Reactivity

no data available

10.2 Chemical stability

Stable under recommended storage conditions.

10.3 Possibility of hazardous reactions

Very dangerous, when exposed to heat, flame; can react vigorously with oxidizing materials.The gas is heavier than air and may travel along the ground; distant ignition possible.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].

10.4 Conditions to avoid

no data available

10.5 Incompatible materials

Can react dangerously with strong oxidizing agents and mercury (II) oxide.

10.6 Hazardous decomposition products

Upon decomposition, emits highly toxic fumes of /sulfur oxides/.

11.Toxicological information

Acute toxicity

  • Oral: LD50 Mouse oral 61 mg/kg
  • Inhalation: LC50 Mouse inhalation 1,664 ppm/4 hr
  • Dermal: no data available

Skin corrosion/irritation

no data available

Serious eye damage/irritation

no data available

Respiratory or skin sensitization

no data available

Germ cell mutagenicity

no data available


no data available

Reproductive toxicity

no data available

STOT-single exposure

no data available

STOT-repeated exposure

no data available

Aspiration hazard

no data available

12.Ecological information

12.1 Toxicity

  • Toxicity to fish: no data available
  • Toxicity to daphnia and other aquatic invertebrates: no data available
  • Toxicity to algae: no data available
  • Toxicity to microorganisms: no data available

12.2 Persistence and degradability

AEROBIC: Aerobic degradation of methyl mercaptan is insignificant compared to anaerobic degradation(1).

12.3 Bioaccumulative potential

An estimated BCF of 3 was calculated in fish for methyl mercaptan(SRC), using an estimated log Kow of 0.78(1) and a regression-derived equation(1). According to a classification scheme(2, this BCF suggests the potential for bioconcentration in aquatic organisms is low(SRC).

12.4 Mobility in soil

Using a structure estimation method based on molecular connectivity indices(1), the Koc of methyl mercaptan can be estimated to be 13(SRC). According to a classification scheme(2), this estimated Koc value suggests that methyl mercaptan is expected to have very high mobility in soil. Gaseous methyl mercaptan has been observed to partition to soils(3). For example, when gaseous methyl mercaptan was passed over six air-dried and moist (50% field capacity) soils, 2.4-32.1 mg/g and 2.2-21.4 mg/g of methyl mercaptan rapidly adsorbed to the dry and moist soils, respectively(3). Neither the capacity or rate of sorption was correlated to soil pH, organic matter content, or clay content; sterile controls ruled out the involvement of microorganisms(3); it was suggested that adsorption to soil surfaces might be an environmental sink for gaseous methyl mercaptan(3).

12.5 Other adverse effects

no data available

13.Disposal considerations

13.1 Disposal methods


The material can be disposed of by removal to a licensed chemical destruction plant or by controlled incineration with flue gas scrubbing. Do not contaminate water, foodstuffs, feed or seed by storage or disposal. Do not discharge to sewer systems.

Contaminated packaging

Containers can be triply rinsed (or equivalent) and offered for recycling or reconditioning. Alternatively, the packaging can be punctured to make it unusable for other purposes and then be disposed of in a sanitary landfill. Controlled incineration with flue gas scrubbing is possible for combustible packaging materials.

14.Transport information

14.1 UN Number

ADR/RID: UN1064 IMDG: UN1064 IATA: UN1064

14.2 UN Proper Shipping Name


14.3 Transport hazard class(es)

ADR/RID: 2.3 IMDG: 2.3 IATA: 2.3

14.4 Packing group, if applicable

ADR/RID: unknown IMDG: unknown IATA: unknown

14.5 Environmental hazards

ADR/RID: yes IMDG: yes IATA: yes

14.6 Special precautions for user

no data available

14.7 Transport in bulk according to Annex II of MARPOL 73/78 and the IBC Code

no data available

15.Regulatory information

15.1 Safety, health and environmental regulations specific for the product in question

Chemical name Common names and synonyms CAS number EC number
methanethiol methanethiol 74-93-1 none
European Inventory of Existing Commercial Chemical Substances (EINECS) Listed.
EC Inventory Listed.
United States Toxic Substances Control Act (TSCA) Inventory Listed.
China Catalog of Hazardous chemicals 2015 Listed.
New Zealand Inventory of Chemicals (NZIoC) Listed.
Philippines Inventory of Chemicals and Chemical Substances (PICCS) Listed.
Vietnam National Chemical Inventory Listed.
Chinese Chemical Inventory of Existing Chemical Substances (China IECSC) Listed.

16.Other information

Information on revision

Creation Date Aug 16, 2017
Revision Date Aug 16, 2017

Abbreviations and acronyms

  • CAS: Chemical Abstracts Service
  • ADR: European Agreement concerning the International Carriage of Dangerous Goods by Road
  • RID: Regulation concerning the International Carriage of Dangerous Goods by Rail
  • IMDG: International Maritime Dangerous Goods
  • IATA: International Air Transportation Association
  • TWA: Time Weighted Average
  • STEL: Short term exposure limit
  • LC50: Lethal Concentration 50%
  • LD50: Lethal Dose 50%
  • EC50: Effective Concentration 50%


  • IPCS - The International Chemical Safety Cards (ICSC), website: http://www.ilo.org/dyn/icsc/showcard.home
  • HSDB - Hazardous Substances Data Bank, website: https://toxnet.nlm.nih.gov/newtoxnet/hsdb.htm
  • IARC - International Agency for Research on Cancer, website: http://www.iarc.fr/
  • eChemPortal - The Global Portal to Information on Chemical Substances by OECD, website: http://www.echemportal.org/echemportal/index?pageID=0&request_locale=en
  • CAMEO Chemicals, website: http://cameochemicals.noaa.gov/search/simple
  • ChemIDplus, website: http://chem.sis.nlm.nih.gov/chemidplus/chemidlite.jsp
  • ERG - Emergency Response Guidebook by U.S. Department of Transportation, website: http://www.phmsa.dot.gov/hazmat/library/erg
  • Germany GESTIS-database on hazard substance, website: http://www.dguv.de/ifa/gestis/gestis-stoffdatenbank/index-2.jsp
  • ECHA - European Chemicals Agency, website: https://echa.europa.eu/

Disclaimer: The above information is believed to be correct but does not purport to be all inclusive and shall be used only as a guide. The information in this document is based on the present state of our knowledge and is applicable to the product with regard to appropriate safety precautions. It does not represent any guarantee of the properties of the product. We as supplier shall not be held liable for any damage resulting from handling or from contact with the above product.
expand collapse
Name: Methanethiol 99.5+% Material Safety Data Sheet
Synonym: Thiomethyl Alcohol; Methyl Mercaptan
CAS: 74-93-1
Section 1 - Chemical Product   MSDS Name:Methanethiol 99.5+% Material Safety Data Sheet
Synonym:Thiomethyl Alcohol; Methyl Mercaptan

CAS# Chemical Name content EINECS#
74-93-1 Methyl Mercaptan >99.5 200-822-1
Hazard Symbols: XN F+
Risk Phrases: 12 20

Extremely flammable. Harmful by inhalation.
Potential Health Effects
Causes eye irritation.
Causes skin irritation. May be absorbed through the skin.
Causes gastrointestinal irritation with nausea, vomiting and diarrhea. May cause liver and kidney damage. May cause central nervous system depression. Mercaptans may cause nausea and headache.
Exposure to high concentrations of mercaptans can produce unconsciousness with cyanosis (bluish discoloration of skin due to deficient oxygenation of the blood), cold extremities and rapid pulse.
Causes respiratory tract irritation. May cause liver and kidney damage. Exposure produces central nervous system depression. Vapors may cause dizziness or suffocation. Exposure may lead to delirium, convulsions, paralysis, and coma. Exposure to high concentrations of mercaptans can produce unconsciousness with cyanosis (bluish discoloration of skin due to deficient oxygenation of the blood), cold extremities and rapid pulse. Mercaptans may cause nausea and headache. Harmful if inhaled.
May cause liver and kidney damage. Exposure to large doses may cause central nervous system depression.

  Eyes: Flush eyes with plenty of water for at least 15 minutes, occasionally lifting the upper and lower eyelids. Get medical aid immediately. Do NOT allow victim to rub eyes or keep eyes closed.
Get medical aid. Flush skin with plenty of water for at least 15 minutes while removing contaminated clothing and shoes. Wash clothing before reuse.
Do not induce vomiting. If victim is conscious and alert, give 2-4 cupfuls of milk or water. Never give anything by mouth to an unconscious person. Get medical aid immediately.
Get medical aid immediately. Remove from exposure and move to fresh air immediately. If breathing is difficult, give oxygen. Do NOT use mouth-to-mouth resuscitation. If breathing has ceased apply artificial respiration using oxygen and a suitable mechanical device such as a bag and a mask.
Notes to Physician:

  General Information:
As in any fire, wear a self-contained breathing apparatus in pressure-demand, MSHA/NIOSH (approved or equivalent), and full protective gear. Vapors may form an explosive mixture with air.
Vapors can travel to a source of ignition and flash back. During a fire, irritating and highly toxic gases may be generated by thermal decomposition or combustion. Use water spray to keep fire-exposed containers cool. Extremely flammable liquid and vapor. Containers may explode in the heat of a fire. Will be easily ignited by heat, sparks or flame.
Extinguishing Media:
For small fires, use dry chemical, carbon dioxide, water spray or alcohol-resistant foam. For large fires, use water spray, fog, or alcohol-resistant foam. Use water spray to cool fire-exposed containers. Water may be ineffective. Use agent most appropriate to extinguish fire. Do NOT use straight streams of water.

  General Information: Use proper personal protective equipment as indicated in Section 8.
Absorb spill with inert material (e.g. vermiculite, sand or earth), then place in suitable container. Avoid runoff into storm sewers and ditches which lead to waterways. Clean up spills immediately, observing precautions in the Protective Equipment section. Remove all sources of ignition. Use a spark-proof tool. A vapor suppressing foam may be used to reduce vapors. Rinse area for 10 minutes with a strong Sodium Hypochorite (bleach) solution, then reabsorb material.

Section 7 - HANDLING and STORAGE
Wash thoroughly after handling. Remove contaminated clothing and wash before reuse. Ground and bond containers when transferring material. Avoid contact with eyes, skin, and clothing. Empty containers retain product residue, (liquid and/or vapor), and can be dangerous. Keep away from heat, sparks and flame. Avoid ingestion and inhalation. Do not pressurize, cut, weld, braze, solder, drill, grind, or expose empty containers to heat, sparks or open flames.
Keep away from heat, sparks, and flame. Keep away from sources of ignition. Store in a cool, dry place. Keep container closed when not in use. Flammables-area.

  Engineering Controls:
Facilities storing or utilizing this material should be equipped with an eyewash facility and a safety shower. Use process enclosure, local exhaust ventilation, or other engineering controls to control airborne levels.
Exposure Limits CAS# 74-93-1: United Kingdom, WEL - TWA: 0.5 ppm TWA; 1.0 mg/m3 TWA United Kingdom, WEL - STEL: 1.5 ppm STEL; 3.0 mg/m3 STEL United States OSHA: ; 10 ppm Ceiling; 20 mg/m3 Ceiling Belgium - TWA: 0.5 ppm VLE; 0.99 mg/m3 VLE France - VME: 0.5 ppm VME; 1 mg/m3 VME Germany: 0.5 ppm TWA; 1 mg/m3 TWA Malaysia: 0.5 ppm TWA; 0.98 mg/m3 TWA Netherlands: 0.5 ppm MAC; 1 mg/m3 MAC Russia: 0.8 mg/m3 TWA Spain: 0.5 ppm VLA-ED; 1 mg/m3 VLA-ED Personal Protective Equipment Eyes: Wear chemical splash goggles. Wear appropriate protective eyeglasses or chemical safety goggles as described by OSHA's eye and face protection regulations in 29 CFR 1910.133 or European Standard EN166.
Wear appropriate protective gloves to prevent skin exposure.
Wear appropriate protective clothing to minimize contact with skin.
A respiratory protection program that meets OSHA's 29 CFR 1910.134 and ANSI Z88.2 requirements or European Standard EN 149 must be followed whenever workplace conditions warrant respirator use.

Physical State: Liquid
Color: water-white - colorless
Odor: garlic-like odor - unpleasant odor
pH: Not available.
Vapor Pressure: 1520 mm Hg @ 26C
Viscosity: Not available.
Boiling Point: 5.95 deg C
Freezing/Melting Point: -123 deg C
Autoignition Temperature: Not available.
Flash Point: >-18 deg C
Explosion Limits, lower: 3.9
Explosion Limits, upper: 21.0
Decomposition Temperature:
Solubility in water: Slightly soluble.
Specific Gravity/Density: .9000g/cm3
Molecular Formula: CH4S
Molecular Weight: 48.11

  Chemical Stability:
Stable under normal temperatures and pressures.
Conditions to Avoid:
Incompatible materials, ignition sources, excess heat, strong oxidants.
Incompatibilities with Other Materials:
Strong oxidizing agents, strong reducing agents, strong acids, strong bases, copper, copper alloys, halogenated agents, hydrazine, organic peroxides, zinc, ketones (e.g. acetone, acetophenone, MEK, MIBK), epoxides (e.g. butyl glycidyl ether), lead, moisture, organic materials.
Hazardous Decomposition Products:
Irritating and toxic fumes and gases, sulfur oxides (SOx), including sulfur oxide and sulfur dioxide.
Hazardous Polymerization: Has not been reported

CAS# 74-93-1: PB4375000 LD50/LC50:
CAS# 74-93-1: Inhalation, mouse: LC50 = 6530 ug/m3/2H; Inhalation, rat: LC50 = 675 ppm.
Inhalation, rat: Carcinogenicity:
Methyl Mercaptan - Not listed by ACGIH, IARC, or NTP.
See actual entry in RTECS for complete information.

  Other No information available.

  Dispose of in a manner consistent with federal, state, and local regulations.

Not regulated as a hazardous material.
Not regulated as a hazardous material.
Not regulated as a hazardous material.
USA RQ: CAS# 74-93-1: 100 lb final RQ; 45.4 kg final RQ

European/International Regulations
European Labeling in Accordance with EC Directives
Hazard Symbols: XN F+
Risk Phrases:
R 12 Extremely flammable.
R 20 Harmful by inhalation.
Safety Phrases:
S 16 Keep away from sources of ignition - No
S 25 Avoid contact with eyes.
WGK (Water Danger/Protection)
CAS# 74-93-1: 3
CAS# 74-93-1 is listed on Canada's DSL List.
CAS# 74-93-1 is listed on Canada's Ingredient Disclosure List.
CAS# 74-93-1 is listed on the TSCA inventory.



NMR Spectrum 1H NMR : parameter in benzene
expand collapse