Material Safety Data Sheet – Dimethyl Diselenide

Identification

Product Name: Dimethyl Diselenide
Chemical Formula: C2H6Se2
CAS Number: 7101-31-7
Other Names: DMDS, Bis(methyl) diselenide
Recommended Use: Used as a reagent and intermediate in chemical synthesis
Manufacturer Contact: Emergency telephone number and address should be obtained directly from supplier

Hazard Identification

Classification: Acute Toxicity (Oral, Dermal, Inhalation); Skin Irritant; Eye Irritant; Environmental Hazard, especially aquatic life
Label Elements: Danger symbol, signal word "Danger"
Hazard Statements: Toxic if inhaled, swallowed, or absorbed through skin; causes skin and eye irritation; very toxic to aquatic life
Precautionary Statements: Avoid breathing vapors; wash hands thoroughly after handling; do not eat, drink, or smoke when using; avoid release to the environment; wear protective clothing and gloves; use only outdoors or in well-ventilated areas

Composition / Information on Ingredients

Chemical Name: Dimethyl Diselenide
Concentration: >98% by weight
Impurities: Trace amounts of elemental selenium and organoselenium byproducts, usually under 2%
Chemical Family: Organoselenium compounds

First Aid Measures

Inhalation: Move exposed person to fresh air; keep airway open; seek medical attention immediately if symptoms such as coughing, headache, or nausea occur
Skin Contact: Remove contaminated clothing; wash skin thoroughly with soap and plenty of water; get medical attention if irritation persists
Eye Contact: Rinse immediately with plenty of water for at least 15 minutes; seek medical advice
Ingestion: Do not induce vomiting; rinse mouth; give water if conscious; seek immediate medical help
Most Important Symptoms: Headache, dizziness, respiratory difficulties, nausea, skin redness, eye irritation
Special Instructions: Physician should monitor for respiratory distress and possible organ dysfunction

Fire-Fighting Measures

Suitable Extinguishing Media: Dry chemical, carbon dioxide, foam; avoid using water directly on the chemical due to contamination risk
Specific Hazards: Produces toxic selenium fumes, carbon oxides, and irritating vapors if combusted
Protective Equipment: Firefighters should use self-contained breathing apparatus and full protective gear
Firefighting Procedures: Remove containers from area if safe to do so; use water spray to cool exposed containers; avoid allowing run-off from fire control or dilution to enter drains
Unusual Fire Hazards: Vapors may travel to ignition source and flash back

Accidental Release Measures

Personal Precautions: Evacuate unprotected personnel; ventilate area; use approved personal protective equipment including respirator, gloves, goggles, chemical suit
Environmental Precautions: Prevent entry into drains, waterways, or soil; contain spill with dikes if safe
Cleanup Methods: Absorb with inert material (e.g., dry sand or earth); collect in suitable, clearly labeled containers for disposal; decontaminate spill site after material pickup
Further Measures: Alert appropriate authorities if environmental contamination occurs

Handling and Storage

Safe Handling: Handle inside chemical fume hood, avoid inhalation, contact with skin or eyes; do not eat, drink, or smoke during use; employ adequate ventilation
Storage Recommendations: Keep in tightly closed container; store in cool, dry, well-ventilated area away from incompatible substances such as strong oxidizers and acids; keep away from direct sunlight and heat sources
Incompatible Materials: Avoid contact with strong acids, oxidizing agents, and bases
Special Provisions: Store away from foodstuffs and animal feed; ensure secondary containment

Exposure Controls and Personal Protection

Exposure Limits: Occupational exposure limits for selenium compounds generally apply; consult local regulations for specific values; recommended limit for selenium compounds is 0.2 mg/m³ (ACGIH TLV)
Engineering Controls: Use chemical fume hood, eye wash station, and safety shower; utilize explosion-proof equipment
Personal Protection: Wear appropriate gloves (nitrile, neoprene), chemical goggles, face shield, lab coat or coveralls, and NIOSH-approved respirator if airborne concentrations risk exposure
Hygiene Measures: Remove and wash contaminated clothing before reuse; avoid touching face or exposed skin with contaminated gloves; wash hands after handling

Physical and Chemical Properties

Appearance: Clear to pale yellow liquid
Odor: Strong garlic-like
Melting Point: -29°C
Boiling Point: 179°C
Flash Point: 63°C (closed cup)
Vapor Pressure: 0.6 mmHg at 25°C
Solubility: Slightly soluble in water; soluble in most organic solvents
Density: 1.946 g/cm³ at 20°C
Viscosity: Not determined
Partition Coefficient: log Kow ~ 2.3
Autoignition Temperature: 270°C
Evaporation Rate: Not available

Stability and Reactivity

Chemical Stability: Stable under recommended storage and handling conditions
Reactivity: May react with strong oxidizers and acids; forms toxic gases in combustion
Hazardous Reactions: Releases hydrogen selenide and methyl selenol under severe decomposition
Conditions to Avoid: Heat, flames, sparks, direct sunlight, incompatible materials
Incompatible Materials: Strong acids, oxidizing agents, bases
Hazardous Decomposition Products: Selenium oxides, carbon monoxide, carbon dioxide, hydrogen selenide

Toxicological Information

Routes of Exposure: Inhalation, ingestion, skin and eye contact
Acute Toxicity: Oral LD50 (rat): 25 mg/kg; Inhalation LC50 (rat/4h): not established, but known to be toxic at low concentrations
Chronic Effects: Exposure can lead to selenium accumulation, causing symptoms such as garlic breath, gastrointestinal distress, headache, nervous system effects, and in severe cases, organ damage
Sensitization: May cause allergic skin and respiratory reactions
Other Effects: Chronic inhalation may result in respiratory tract irritation or lung effects; repeated skin contact may produce dermatitis

Ecological Information

Ecotoxicity: Very toxic to aquatic organisms; may cause long-term adverse effects in aquatic environments
Persistence and Degradability: Not expected to readily degrade in the environment; selenium may bioaccumulate
Bioaccumulative Potential: Possible, since organoselenium compounds can accumulate in aquatic life
Mobility in Soil: Potential for leaching to groundwater exists, especially in poorly managed spills
Other Adverse Effects: Selenium contamination may disrupt plant and microbial communities

Disposal Considerations

Safe Disposal Methods: Dispose of according to local, regional, and national regulations for hazardous waste; incinerate at approved facility using appropriate off-gas treatment
Container Disposal: Triple-rinse containers, then puncture and send to licensed drum reconditioner or dispose of as hazardous waste
Do Not: Flush into waterways, sewer systems, or open environment
Contaminated Packaging: Handle as hazardous material; do not reuse

Transport Information

UN Number: UN 3283
UN Proper Shipping Name: Selenuim compound, liquid, n.o.s. (Dimethyl Diselenide)
Transport Hazard Class: 6.1 (Toxic substance)
Packing Group: II
Marine Pollutant: Yes
Special Precautions: Transport with proper labeling and placarding; avoid transport with food or animal feed; notify authorities if spillage occurs during transit

Regulatory Information

TSCA: Listed
DSL/NDSL: Listed in Canada
REACH Status: Exempted or pre-registered in the EU (check supplier data)
OSHA Status: Regulated hazardous material in workplace
SARA 313: Subject to reporting under Section 313 (Selenium compounds)
WHMIS Classification: Class D1B (Toxic Material), Class D2B (Other Toxic Effects)
Other Information: Subject to appropriate risk assessment and compliance with the Control of Substances Hazardous to Health Regulations and other national chemical safety directives