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Product Name: Tetraethyl Orthosilicate
Synonyms: Tetraethoxysilane, TEOS
Chemical Formula: Si(OC₂H₅)₄
CAS Number: 78-10-4
Recommended Use: Used in the synthesis of silica and other industrial chemistry applications, semiconductor manufacturing, and as a crosslinking agent
Supplier Information: Manufacturer and distributor details available on shipping labels and purchase documentation
Emergency Contact Number: Available through chemical supplier or company’s EHS office
GHS Classification: Flammable liquid (Category 3), Acute toxicity, Inhalation (Category 4), Skin irritation (Category 2), Eye irritation (Category 2A), Specific target organ toxicity, single exposure; respiratory tract irritation (Category 3)
Signal Word: Warning
Hazard Statements: Flammable liquid and vapor, harmful if inhaled, causes skin and eye irritation, may cause respiratory irritation
Pictograms: Flame, Exclamation Mark
Precautionary Statements: Keep away from heat and open flames, use only outdoors or in well-ventilated area, avoid breathing vapors, wear protective gloves and eye protection, wash skin thoroughly after handling
Label Elements: GHS label with hazard information and codes displayed on containers
Chemical Name: Tetraethyl Orthosilicate
Common Name: TEOS
Concentration: 98-100%
CAS Number: 78-10-4
Impurities: Small traces of ethanol and ethyl silicate homologs may be present, depending on manufacturer and storage conditions
Additives: No stabilizers or preservatives intentionally added
Inhalation: Move person to fresh air, keep at rest in a position comfortable for breathing, seek medical advice if symptoms persist such as coughing or shortness of breath
Skin Contact: Remove contaminated clothing, wash skin with plenty of water and soap for at least 15 minutes, seek medical attention for irritation
Eye Contact: Rinse eyes cautiously with water for at least 15 minutes, remove contact lenses if present, call a physician immediately
Ingestion: Rinse mouth, do not induce vomiting, seek immediate medical attention
Symptoms: Respiratory tract irritation, skin redness, eye tearing and burning, dizziness at high vapor concentrations
Notes for Physician: Treat symptomatically, monitor for delayed respiratory effects, support vital functions where needed
Suitable Extinguishing Media: Use alcohol-resistant foam, dry chemical powder, carbon dioxide, water spray for larger fires (avoid direct water jets)
Specific Hazards: Produces flammable vapors, may form explosive mixtures with air; combustion generates silicon oxides, carbon monoxide, carbon dioxide, fumes of ethanol
Protective Equipment for Firefighters: Wear full protective gear, self-contained breathing apparatus, avoid inhaling decomposition products
Special Procedures: Remove containers from fire area if safe, cool exposed containers with water spray
Explosion Data: Vapors may travel and ignite at distant sources, risk of explosive vapor-air mixture, ensure thorough ventilation post-fire
Personal Precautions: Evacuate area, clear personnel not involved in response, use appropriate PPE including chemical resistant gloves, goggles, respirator if ventilation is not strong
Environmental Precautions: Prevent runoff into drains, surface water, and soil; alert environmental authorities if widespread contamination occurs
Cleanup Methods: Ventilate area, remove all ignition sources, absorb with inert material such as sand or earth (avoid combustible absorbents), place waste in suitable closed containers, clean area with water after material pick-up, dispose of contaminated materials as hazardous waste
Handling Large Spills: Use non-sparking tools, establish diking or diversion if possible, contain spillage
Handling: Use only in well-ventilated workspace, avoid breathing vapors or contact with skin and eyes, ground and bond containers when transferring to avoid static spark, use non-sparking equipment
General Hygiene: Do not eat, drink, or smoke where chemical is handled, wash hands after handling, remove contaminated clothing and wash before reuse
Storage Conditions: Store in cool, dry, well-ventilated area, tightly closed in original container, away from direct sunlight, incompatible materials such as acids, water, oxidizers, and sources of ignition
Storage Temperature: Maintain below 25°C (77°F), avoid freezing and humidity
Incompatible Materials: Moisture, strong acids, bases, oxidizers—reacts to form flammable ethanol and silica gel
Container Requirements: Use containers made of compatible materials: steel drums lined with protective coatings, glass bottles with Teflon-lined caps
Exposure Limits: No established OSHA PEL or ACGIH TLV; manufacturers recommend TWA exposure below 10 ppm for occupational safety due to volatile ethanol byproduct
Engineering Controls: Local exhaust ventilation, general dilution ventilation, keep airborne concentrations below recommended limits
Personal Protection: Respiratory protection: NIOSH-approved organic vapor Cartridge or supplied air respirator for concentrations above exposure limits; Eye protection: chemical splash goggles and face shield; Skin protection: chemical-resistant gloves (nitrile, neoprene), laboratory coat or coveralls, closed footwear
Special Procedures: Emergency eyewash and safety shower available within immediate work area, regular maintenance and fit-testing for protective equipment
Appearance: Colorless, transparent liquid
Odor: Slight, sweet, ethanol-like
Odor Threshold: Not established
pH: Not applicable (hydrolyzes in water)
Melting Point: -77°C (-106.6°F)
Boiling Point: 168-170°C (334-338°F)
Flash Point: 45°C (113°F) closed cup
Evaporation Rate: Slower than butyl acetate
Flammability: Liquid and vapor
Explosive Limits: Lower: 1.3% by volume, Upper: 23% by volume
Vapor Pressure: 3 mmHg at 20°C
Vapor Density: 8.2 (air = 1)
Density/Specific Gravity: 0.933-0.940 at 20°C (water = 1)
Solubility: Slight in water (reacts slowly); miscible with organic solvents such as ethanol, ether, benzene
Coefficient of Partition (n-octanol/water): 1.57
Auto-ignition Temperature: 215°C (419°F)
Decomposition Temperature: 200°C (392°F) with generation of ethanol and silica oxides
Viscosity: 0.73 cP at 25°C
Chemical Stability: Stable under normal conditions and recommended temperatures; decomposes in presence of moisture or water
Possibility of Hazardous Reactions: Hydrolyzes to ethanol and silica gel, can form flammable mixtures
Conditions to Avoid: Heat, flames, sparks, moisture, incompatible chemical contact
Incompatible Materials: Water, acids, bases, strong oxidizers; reacts to form flammable byproducts
Hazardous Decomposition Products: Silicon oxides, ethanol, ethyl silicates, possible aldehydes
Routes of Exposure: Inhalation, dermal contact, eye contact, ingestion
Acute Effects: Irritates mucous membranes, respiratory tract, skin, eyes; inhalation causes coughing, dizziness, possible headaches
Chronic Exposure: Repeated exposure can cause persistent skin irritation, possible liver and kidney impact noted in animal studies
Toxicity Data: Oral LD50 (rat): 6270 mg/kg; Dermal LD50 (rabbit): >5,000 mg/kg; Inhalation LC50 (rat, 4 hr): >16,000 mg/m³
Carcinogenicity: Not listed as a carcinogen by NTP, IARC, or OSHA
Sensitization: No data showing sensitization
Mutagenic or Reproductive Effects: Not mutagenic in tested systems; no data indicating reproductive toxicity
Other Effects: High vapor exposure may cause narcotic effects similar to ethanol
Aquatic Toxicity: Harmful to aquatic life; LC50 (fish, 96 hr): >245 mg/L (practically non-toxic); hydrolysis product, ethanol, has greater aquatic toxicity
Persistence and Degradability: Readily hydrolyzed in water to ethanol and silica; ethanol is biodegradable
Bioaccumulation Potential: Not expected to bioaccumulate; log Kow ~1.57 for parent compound
Soil Mobility: Hydrolysis limits persistence in soil, products bind to particulate matter and eventually form stable silica
Other Adverse Effects: Product can alter water pH on hydrolysis, care required to keep out of natural waterways
Waste Handling: Collect in properly labeled, tightly sealed containers, minimize handling
Disposal Methods: Dispose of as hazardous chemical waste under local, state, and federal regulations; incineration in approved facility, prevent release into sewer, ground, or surface water
Contaminated Packaging: Empty containers may retain product residue; triple rinse, puncture before disposal or recycling consistent with chemical regulations
Precautions: Use licensed waste disposal contractor with access to approved incineration or hazardous landfill facilities
UN Number: UN1292
Proper Shipping Name: Tetraethyl orthosilicate
Transport Hazard Class: Class 3 (Flammable Liquid)
Packing Group: III (Moderate danger)
Labels Required: Flammable liquid, Class 3
Environmental Hazards: Not classified as marine pollutant, though care needed to avoid accidental spillage
Special Precautions: Ensure containers are securely closed, upright, and stowed to prevent leaks; check transport regulations for restrictions
Regulatory Transport Information: Subject to IATA (Air), IMDG (Sea), and DOT (US Land) regulations
U.S. Regulations: Listed on TSCA Inventory; subject to SARA Title III Section 313 (Ethanol byproduct); CERCLA not listed for release reporting
European Union: REACH registered; labeled dangerous for flammability and irritation under CLP
Other International Regulations: Listed in Australian Inventory of Chemical Substances (AICS), Canadian DSL, Japan ENCS, Korea KECI; transportation and workplace handling subject to local chemical control statutes
Labeling Requirements: Containers carry GHS/CLP pictograms and signal word “Warning,” risk and safety advice, prescribed PPE use
Workplace Controls: Employer must provide worker education, MSDS access, and exposure controls as required by OSHA Hazard Communication Standard or corresponding jurisdictions
