Product Name: Tetramethyl Orthosilicate
Synonyms: TMOS, Tetra(methyl) Silicate, Methyl Silicate
CAS Number: 681-84-5
Manufacturer: Common chemical suppliers, found worldwide
Recommended Use: Used in organic synthesis, production of silicones, cross-linking agent
Contact Information: Listed on product packaging or supplier website
GHS Classification: Flammable liquid (Category 3), Acute toxicity (oral and inhalation, Category 3), Skin and eye irritation (Category 2), Specific target organ toxicity, single exposure (respiratory tract irritation, Category 3)
Label Elements: Danger
Hazard Statements: Flammable liquid and vapor. Toxic if swallowed or inhaled. Causes skin irritation and serious eye irritation. May cause respiratory irritation.
Pictograms: Flame, Skull and Crossbones, Exclamation Mark
Precautionary Statements: Keep away from heat or open flame. Do not breathe vapors. Avoid contact with skin, eyes, or clothing. Use only outdoors or in a well-ventilated area. Wear protective gloves, eye protection, and face protection.
Chemical Name: Tetramethyl Orthosilicate
Common Name: TMOS
Concentration: Usually 98% or greater
Impurities: Minor possible impurities could include methanol and silanol-containing compounds
Molecular Formula: Si(OCH3)4
Molecular Weight: 152.22 g/mol
Inhalation: Move to fresh air immediately, call for medical attention if symptoms like throat irritation, coughing, or difficulty breathing appear
Skin Contact: Remove contaminated clothing, wash skin with soap and plenty of running water for at least 15 minutes
Eye Contact: Rinse cautiously with water for several minutes. Remove contact lenses if present, rinse again, seek medical advice
Ingestion: Do not induce vomiting. Rinse mouth with water if victim is conscious. Seek urgent medical assistance
Most Important Symptoms: Irritation to eyes, skin, and respiratory system, nausea, headache, dizziness, systemic toxicity due to methanol formation in the body
Notes for Physician: Provide symptomatic and supportive care. Observation recommended due to possible delayed effects
Suitable Extinguishing Media: Dry chemical, foam, carbon dioxide, water spray
Unsuitable Extinguishing Media: Solid water stream as it might spread the fire
Specific Hazards: Vapors may form explosive mixtures with air. Containers may rupture from pressure build-up
Hazardous Combustion Products: Carbon monoxide, carbon dioxide, silicon oxides, formaldehyde, methanol
Special Protective Equipment: Full protective gear and self-contained breathing apparatus for firefighting staff
Firefighting Advice: Cool containers with water spray and remove from fire area if safe to do so
Personal Precautions: Wear chemical-resistant gloves, eye protection, and respirator. Evacuate unnecessary personnel
Environmental Precautions: Prevent entry into waterways, drains, basements or confined areas
Methods for Containment: Absorb with dry earth, sand, or non-combustible material
Cleanup Procedures: Collect absorbed material in a closed container for disposal. Use spark-proof tools and explosion-proof equipment
Decontamination: Wash spill area with plenty of water to remove any residues
Handling: Use only with local exhaust or adequate ventilation. Avoid breathing vapors and contact with skin, eyes, or clothing. Keep away from sources of ignition, no smoking
Storage: Store in cool, dry, well-ventilated area, in tightly closed original container. Keep away from heat, sparks, open flame. Segregate from oxidizers and acids. Store in a flameproof cabinet if possible. Avoid moisture ingress to prevent hydrolysis to methanol and silica.
Exposure Limits: OSHA PEL for methanol: 200 ppm TWA, ACGIH TLV for methanol: 200 ppm TWA, 250 ppm STEL
Engineering Controls: Provide sufficient mechanical exhaust and ventilation to keep airborne concentrations below permissible exposure limits
Personal Protective Equipment: Chemical-resistant gloves (nitrile recommended), safety goggles, face shield, and lab coat. For large scale or uncontrolled exposures, positive-pressure respirator recommended
Hygiene Measures: Wash hands before breaks and after handling. Remove contaminated clothing and shoes promptly
Appearance: Clear, colorless liquid
Odor: Strong, unpleasant
Odor Threshold: Not established
pH: Not applicable (not water soluble)
Melting Point: -2°C (28°F)
Boiling Point: 121°C (250°F)
Flash Point: 19°C (66°F), closed cup
Evaporation Rate: Not determined
Flammability: Flammable liquid
Upper/Lower Explosion Limits: Upper: 18.8%, Lower: 1.3% (estimated)
Vapor Pressure: 8.1 mmHg (25°C)
Vapor Density: 5.2 (air = 1)
Relative Density: 1.03 g/cm³ (20°C)
Solubility: Poor in water, reacts slowly; miscible with organic solvents
Partition Coefficient (n-octanol/water): 1.2 (estimated)
Auto-ignition Temperature: 210°C (410°F)
Decomposition Temperature: Not established
Viscosity: 0.59 mPa•s (20°C)
Chemical Stability: Stable under recommended storage conditions in closed containers
Hazardous Reactions: Reacts with water or moisture, generating methanol and silica; risk of flammable vapor accumulation
Incompatible Materials: Strong oxidizers, acids, strong bases, moisture
Hazardous Decomposition Products: Methanol, formaldehyde, silicon oxides, possible carbon oxides
Conditions to Avoid: Heat, flame, static discharge, sources of ignition, humidity
Routes of Exposure: Inhalation, ingestion, skin contact, eye contact
Acute Toxicity: LD50 Oral (rat): 850 mg/kg, LD50 Dermal (rabbit): 2000 mg/kg, LC50 Inhalation (rat): 4300 mg/m³ / 4hr
Symptoms: Headache, dizziness, drowsiness, nausea, respiratory irritation, eye and skin redness. In severe cases: methanol poisoning (blurred vision, blindness, death)
Sensitization: Not classified as a sensitizer
Chronic Effects: Chronic exposure affects central nervous system, may damage eyes, liver, and kidneys due to methanol
Carcinogenicity: Not listed by NTP, IARC, or OSHA
Mutagenicity: No evidence found
Reproductive Toxicity: Risk due to methanol byproduct; possible fetal toxicity
Ecotoxicity: Toxic to aquatic organisms, may cause long-term adverse effects in aquatic environment. Methanol byproduct adds further risk
Persistence and Degradability: Hydrolyzes in moisture to methanol and silica; methanol is biodegradable, silica remains persistent
Bioaccumulation Potential: Low for methanol, low expected for parent compound
Mobility in Soil: High mobility expected until hydrolysis occurs
Other Adverse Effects: Spillage can harm aquatic life if allowed to reach water bodies
Waste Disposal: Send to licensed hazardous waste disposal facility. Material and containers are considered hazardous waste. Incineration in approved facility preferred
Container Disposal: Rinse and triple-wash containers, then remove all identifying labels before disposal. follow all local and national regulations
Contaminated Packaging: Handle as hazardous waste
Precautions: Avoid release into the environment or sewage system
UN Number: UN 1992
Proper Shipping Name: Tetramethyl orthosilicate, flammable, toxic, liquid
Transport Hazard Class: 3 (Flammable Liquids), 6.1 (Toxic Substances)
Packing Group: II
Label Requirements: Flammable Liquid, Toxic
Special Provisions: Avoid shipment with incompatible substances. Use tightly sealed, chemical-resistant containers
Emergency Response Guide Number: 132
US Regulations: Covered under TSCA. SARA Title III Sections 302/304 (not listed), Section 313 (methanol component)
OSHA: Hazardous Chemical per OSHA Hazard Communication Standard
EPA: RCRA hazardous waste due to ignitability and toxicity (methanol byproduct)
Canada: WHMIS Classification: B2 (Flammable Liquid), D1B (Toxic)
EU: Classified as hazardous under Regulation (EC) No. 1272/2008 (CLP); included in REACH regulation
Other Regulations: Refer to country and local laws for handling, storage, transport, and disposal
