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Product Name: Tetramethyl Orthosilicate
Synonyms: TMOS, Tetramethoxysilane, Silicon Tetramethoxide
CAS Number: 681-84-5
Recommended Use: Precursor for silica, crosslinking agent, catalyst for organic synthesis
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Emergency Phone Number: [Relevant Emergency Contact]
GHS Classification: Flammable Liquid (Category 2), Acute Toxicity Oral (Category 3), Acute Toxicity Inhalation (Category 2), Skin Corrosion/Irritation (Category 1B), Serious Eye Damage/Irritation (Category 1), Specific Target Organ Toxicity - Single Exposure (Category 3)
Pictogram: Flame, Skull and Crossbones, Exclamation Mark, Corrosion
Signal Word: Danger
Hazard Statements: Highly flammable liquid and vapor; fatal if inhaled; toxic if swallowed; causes severe skin burns and eye damage; may cause respiratory irritation
Precautionary Statements: Keep away from heat, sparks, open flames, and hot surfaces; wear protective gloves/clothing and eye/face protection; do not breathe vapors or mist; wash hands thoroughly after handling; use only outdoors or in well-ventilated area
Chemical Name: Tetramethyl Orthosilicate
CAS Number: 681-84-5
Concentration: ≥ 98%
Inhalation: Move person to fresh air immediately; call emergency medical services if breathing is difficult; administer oxygen if available; provide artificial respiration if not breathing
Skin Contact: Remove contaminated clothing and wash skin thoroughly with soap and water for at least 15 minutes; seek medical attention for burns or ongoing irritation
Eye Contact: Rinse cautiously with water for several minutes, remove contact lenses if present and easy to do, continue rinsing, seek immediate medical attention
Ingestion: Do not induce vomiting; rinse mouth and drink water if person is alert; seek immediate medical advice
Important Symptoms: Burning sensation, cough, sore throat, redness, pain, severe eye irritation, blistering forming
Suitable Extinguishing Media: Dry chemical, foam, carbon dioxide
Unsuitable Extinguishing Media: Water jet
Specific Hazards: Vapors are heavier than air and may spread along floors; forms explosive mixtures with air; thermal decomposition releases toxic vapors such as silicon oxides, methanol, and formaldehyde
Protective Equipment for Firefighters: Self-contained breathing apparatus and full protective gear required; evacuate personnel to safe area
Firefighting Procedures: Isolate hazard area; fight fire from safe distance or protected location; use water spray to cool containers exposed to fire
Personal Precautions: Evacuate area and keep unprotected persons away; avoid breathing vapors; ventilate area; remove all ignition sources
Environmental Precautions: Prevent further leakage or spillage if safe to do so; do not let product enter drains, sewers, or watercourses
Methods for Cleanup: Contain and collect spillage with inert, non-combustible absorbent material (such as sand or earth); transfer to a suitable, tightly closed, labeled container for disposal; wash contaminated surfaces with plenty of water; wear appropriate protective equipment including gloves, eye protection, and respirator
Safe Handling: Use only non-sparking tools; ground and bond containers during transfer; avoid inhalation, ingestion, and contact with skin and eyes; work in well-ventilated spaces; never handle near ignition sources; strictly avoid static discharge; handle in designated flammable liquid area
Safe Storage: Store in cool, dry, well-ventilated location; keep away from heat sources and direct sunlight; keep container tightly closed and properly labeled; store away from oxidizers, acids, bases, and water; use corrosion-resistant containers
Special Requirements: Use explosion-proof electrical equipment; provide spill control and secondary containment; limit quantities stored in areas without proper fire suppression
Control Parameters: OSHA PEL for methanol (potential decomposition product): 200 ppm TWA; ACGIH TLV: 200 ppm TWA
Engineering Controls: Use chemical fume hoods, process enclosures, local exhaust ventilation to control exposure; minimize vapor generation
Personal Protective Equipment: Wear chemical-resistant gloves (such as butyl rubber); use splash goggles and face shield; wear impervious protective clothing and boots; use approved respirator if exposure limits may be exceeded or during cleanup; eye wash stations and safety showers in work area
Hygiene Measures: Wash hands, forearms, and face thoroughly after handling; remove and wash contaminated clothing before reuse
Appearance: Clear, colorless liquid
Odor: Sharp, sweet, penetrating odor
Odor Threshold: No data available
pH: Not applicable
Melting Point: -2°C
Boiling Point: 121°C
Flash Point: 19°C (closed cup)
Evaporation Rate: No data available
Flammability: Highly flammable
Vapor Pressure: 16 mmHg @ 20°C
Vapor Density: 4.1 (Air = 1)
Relative Density: 1.03 g/cm³ @ 20°C
Solubility: Reacts with water; soluble in organic solvents
Partition Coefficient (n-octanol/water): No data
Auto-ignition Temperature: 220°C
Decomposition Temperature: No data
Viscosity: 0.67 mPa·s @ 20°C
Chemical Stability: Unstable in presence of moisture; stable under recommended storage conditions
Reactivity: Reacts violently with water, acids, bases, and strong oxidizing agents
Conditions to Avoid: Moisture, heat, flames, sparks, static discharge, incompatible materials
Hazardous Decomposition Products: Methanol, silicon oxides, formaldehyde
Hazardous Polymerization: Not expected
Routes of Exposure: Inhalation, skin contact, eye contact, ingestion
Acute Toxicity: Oral LD50 (rat): 740 mg/kg; Inhalation LC50 (rat): 200 ppm/4h
Skin Corrosion/Irritation: Severe burns possible after short exposure
Serious Eye Damage/Irritation: Causes blindness if untreated
Respiratory Sensitization: Can cause coughing, breathing difficulty, chemical pneumonitis
Delayed/Chronic Effects: Repeated exposure may cause skin dryness, cracking, and long-term organ damage
Symptoms: Abdominal pain, drowsiness, dizziness, headache, loss of coordination; blindness or death from methanol formation
Toxicity: Harmful to aquatic life even at low concentrations; possible methanol release increases risk
Persistence and Degradability: Rapid hydrolysis in water to methanol and silica; these breakdown products may persist
Bioaccumulation Potential: Low for tetramethyl orthosilicate but methanol can accumulate in aquatic environments
Mobility in Soil: High, due to low partition coefficient; migrates rapidly in water
Other Adverse Effects: Contributes to chemical oxygen demand in water bodies; fish and other aquatic organisms vulnerable to acute exposure
Waste Disposal Methods: Collect and dispose as hazardous waste in accordance with local, regional, national, and international regulations; incinerate in approved facility where possible; do not pour into drains or natural waters
Contaminated Packaging: Empty containers retain vapors; handle as hazardous waste; triple-rinse containers before disposal or recycling, then puncture and dispose according to regulations
Precautions: Wear proper personal protective equipment; notify authorities if spills contaminate sewers or waterways
UN Number: 1992
UN Proper Shipping Name: Flammable liquids, toxic, n.o.s. (Tetramethyl orthosilicate)
Transport Hazard Class: 3 (Flammable liquids), 6.1 (Toxic substances)
Packing Group: II
Labels/Placards: Flammable Liquid, Toxic
Special Precautions: Ship in tightly closed, properly labeled containers; avoid breakage; transport and handle by trained hazardous materials personnel; comply with all regulations for air, road, rail, or sea transport
OSHA: Hazardous chemical as defined by OSHA Hazard Communication Standard
TSCA Inventory: Listed
SARA Title III: Section 302 Extremely Hazardous: No; Section 313 Toxic Release: No
RCRA Status: Considered hazardous waste based on characteristics
California Proposition 65: Not listed, but methanol is known to the State of California to cause birth defects or other reproductive harm
Other Regulatory Information: Subject to workplace exposure limits and transportation safety requirements in many jurisdictions; users required to comply with all pertinent local, regional, and international legislation
