Material Safety Data Sheet for Sodium Methyl Mercaptide (SMM)

Identification

Product Name: Sodium Methyl Mercaptide
Chemical Formula: CH₃SNa
CAS Number: 5188-07-8
Synonyms: Sodium Methanethiolate, Methanethiol, sodium salt
Recommended Uses: Used in organic synthesis, pharmaceuticals, agrochemicals
Supplier Details: Manufacturer or importer’s name, physical address, contact phone number, emergency contact information
Emergency Telephone: Local emergency response center or company hotline

Hazard Identification

Classification: Flammable liquid, toxic upon inhalation and skin contact, corrosive to metals and tissue, environmental hazard
Signal Word: Danger
Hazard Statements: Causes severe skin and eye burns, toxic if inhaled, contact with water releases toxic gases, may cause respiratory irritation, highly flammable, harmful to aquatic life with long-lasting effects
Precautionary Statements: Avoid all inhalation, use protective equipment, keep away from water and incompatible materials, prevent environmental release, do not eat, drink, or smoke when handling this material
Hazard Pictograms: Skull and crossbones, Corrosive, Exclamation mark, Flame, Environment

Composition / Information on Ingredients

Chemical Name: Sodium Methyl Mercaptide
Concentration: 95% or higher (remaining is solvent or small amount of impurities)
Chemical Formula: CH₃SNa
CAS Number: 5188-07-8
Impurities/Additives: Water (<1%), possible organic solvent traces

First Aid Measures

Inhalation: Remove person to fresh air immediately, do not give mouth-to-mouth, provide oxygen if breathing is difficult, seek medical attention right away
Skin Contact: Remove contaminated clothing, rinse affected area with plenty of water for at least 15 minutes, obtain immediate medical attention
Eye Contact: Rinse cautiously with water for several minutes, remove contact lenses if present, continue rinsing, get emergency medical assistance
Ingestion: Do not induce vomiting, rinse mouth with water, never provide anything orally to an unconscious person, arrange emergency medical help
Most Important Symptoms/Effects: Severe irritation, chemical burns, respiratory distress, nausea, headache, drowsiness, risk of fatality if inhaled in high concentrations

Fire-Fighting Measures

Extinguishing Media: Dry chemical powder, foam, carbon dioxide, never use water
Hazards from Combustion: Toxic gases including sulfur oxides, sodium oxides, methyl mercaptan
Specific Fire Hazards: Gas/air mixtures may explode, reacts dangerously with water, intense heat may rupture containers
Protective Equipment: Self-contained breathing apparatus, full-body chemical protection suit, stand upwind, evacuate non-essential personnel from immediate area
Special Precautions: Approach fire from upwind side, use water spray only to cool fire-exposed containers, not for extinguishing

Accidental Release Measures

Personal Precautions: Restrict area, ventilate if possible, avoid breathing vapors, wear chemical gloves, flame-resistant clothing, and face/eye protection
Emergency Procedures: Evacuate unnecessary personnel, shut off sources of ignition, contain and control entry to spill area
Spill Containment: Neutralize with dilute acid under controlled conditions, absorb with dry earth, lime, or sand
Environmental Precautions: Prevent entry into drains, sewers, surface waters, and soil; report significant releases to environmental authorities
Clean-Up Methods: Collect spilled material in labeled corrosion-resistant containers, secure for appropriate disposal, decontaminate surfaces with mild bleach solution after safe neutralization

Handling and Storage

Handling: Always use closed systems, prevent contact with water or humidity, use in chemical fume hood, keep away from ignition sources, avoid inhaling vapors or allowing contact with skin or clothing
Storage Requirements: Keep tightly closed in a cool, dry, well-ventilated, and non-acidic area, store in corrosion-resistant containers under inert atmosphere (e.g., nitrogen or argon), segregate from acids, oxidizers, and water
Special Considerations: Post warning signs, inspect containers regularly, ensure spill control materials are nearby, train workers on proper procedures

Exposure Controls and Personal Protection

Exposure Limits: No specific occupational exposure limits set for this compound by OSHA or ACGIH, but treat with strict control due to high toxicity
Engineering Controls: Use explosion-proof exhaust ventilation, local fume extraction, maintain negative pressure in work area
Personal Protective Equipment: Wear chemical splash goggles or face shield, impermeable gloves (e.g., butyl rubber), flame-resistant laboratory coat, chemical-resistant apron, use respiratory protection (half mask with organic vapor and acid gas cartridges or supplied-air respirator in emergencies), no open skin exposure permitted
Hygienic Measures: Change contaminated clothing and monitor work area for gases, wash hands before eating, drinking or leaving the lab, shower after handling large amounts

Physical and Chemical Properties

Appearance: Colorless to pale yellow liquid or solid (depending on temperature and concentration)
Odor: Strong, unpleasant odor resembling rotten cabbage or sulfur gases
Boiling Point: Approximately 80–100 °C (varies with concentration)
Melting Point: Can be below room temperature, forms liquid above ~10 °C
Flash Point: Below 23 °C (highly flammable)
Vapor Pressure: Moderate at room temperature
Solubility: Soluble in water, reacts slowly to release toxic fumes
Specific Gravity: About 1.1–1.2 (varies with purity)
pH: Strongly basic in water solution
Stability: Unstable when exposed to moisture, sunlight, heat, or acids

Stability and Reactivity

Chemical Stability: Unstable in moist air, decomposes to release corrosive and toxic vapors
Reactivity: Reacts violently with water, acids, strong oxidizing agents, may ignite on contact with air
Hazardous Reactions: Contact with acids liberates methyl mercaptan gas, strong exothermic reaction with water, danger of explosion if heated or mixed with incompatible chemicals
Decomposition Products: Methanethiol, hydrogen sulfide, oxides of sodium and sulfur
Incompatible Materials: Acids, water, oxidizers, strong reducing agents, metals like zinc, aluminum

Toxicological Information

Routes of Exposure: Inhalation, skin absorption, eye contact, ingestion
Acute Toxicity: Toxic following inhalation, ingestion, or skin contact; rapid onset of coughing, headache, eye and throat burn, chemical pneumonia likely following inhalation
Skin/Eye Corrosion: Causes severe burns to skin and eyes, permanent damage possible
Long-Term Effects: Possible central nervous system depression with chronic exposure, no confirmed carcinogenicity from animal data
Sensitization: May cause allergic skin reaction in sensitive individuals
Symptoms: Nausea, vomiting, chest tightness, difficulty breathing, drowsiness, dizziness, severe pain

Ecological Information

Aquatic Toxicity: Extremely hazardous to aquatic life even at low concentrations, fish and invertebrates most susceptible
Persistence/Degradability: Reacts with water and decomposes quickly but may cause acute toxicity during the breakdown process
Bioaccumulation: No significant bioaccumulation expected due to rapid degradation, but methyl mercaptan released may affect local environment
Mobility in Soil: High mobility possible due to solubility and vapor pressure, can contaminate soil and groundwater
Other Effects: Water treatment required for any release, regional authorities should be notified in case of major spill

Disposal Considerations

Disposal Methods: Dispose of as hazardous chemical waste following local, regional, and national regulations, neutralize under controlled conditions only by trained personnel in permitted facilities
Container Disposal: Decontaminate empty containers thoroughly before disposal or recycling, never reuse containers for other materials
Precautions: Prevent accidental release to environment during handling and transfer, do not dispose of in regular trash or by pouring into drains

Transport Information

UN Number: 3267
Shipping Name: Corrosive liquid, basic, organic, n.o.s. (contains Sodium Methyl Mercaptide)
Hazard Class: 8 (Corrosive), subsidiary risk: 3 (Flammable), packing group II
Transport Labels: Corrosive, Flammable
Special Handling: Use leak-proof containers, label clearly, avoid transport with food or incompatible substances, secure containers during movement, emergency response info and spill kits should accompany shipment
Regulatory Agencies: Subject to DOT, IMDG, IATA hazardous materials requirements

Regulatory Information

TSCA Status: Listed on the United States Toxic Substances Control Act inventory
OSHA Status: Covered under hazardous chemical exposure standard
EPA Status: Classified hazardous under the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), reportable quantity rules apply
WHMIS (Canada): D1A (very toxic), D2A (other toxic), E (corrosive)
EU Classification: T+ (Very toxic), C (Corrosive), N (Dangerous for the environment), R10/26/34/50 (Risk phrases for flammability, inhalation toxicity, burns, aquatic risk)
Other Regulations: Consult applicable country and state/provincial regulations before manufacturing, handling, or disposing, be prepared for periodic safety audits and reporting