Product Name: N-Octadecylmethyldimethoxysilane
Chemical Formula: C22H48O2Si
Synonyms: Octadecyl(Methyl)Dimethoxysilane, Stearyl Methyldimethoxysilane
CAS Number: 16699-66-4
Manufacturer: Usually supplied by specialty chemical producers, lab supply houses, and industrial distributors
Recommended Use: Surface treatment and coupling agent for glass, ceramics, and minerals; water repellents; hydrophobic coatings
GHS Classification: Flammable Liquid, Category 3; Eye Irritation, Category 2A; Specific Target Organ Toxicity (Single Exposure), Category 3 (narcotic effects)
Pictograms: Flame, Exclamation Mark
Signal Word: Warning
Hazard Statements: Causes eye irritation; may cause drowsiness or dizziness; flammable liquid and vapor
Precautionary Statements: Keep away from ignition sources; use explosion-proof equipment; avoid inhalation of vapors; use outdoors or in a well-ventilated area; wear eye protection
Chemical Name: N-Octadecylmethyldimethoxysilane
CAS Number: 16699-66-4
Concentration: 98-100% pure (remaining minor impurities include nonhazardous organosilicon derivatives)
Impurities: Not expected to affect classification; typical trace quantities only
Inhalation: Remove to fresh air, keep person at rest, seek medical attention if breathing difficulty or dizziness develops
Skin Contact: Wash thoroughly with water and mild soap, remove contaminated clothing, consult physician if irritation or discomfort persists
Eye Contact: Rinse immediately with plenty of running water for at least 15 minutes, lifting eyelids to ensure thorough flushing, obtain medical advice if irritation continues
Ingestion: Do not induce vomiting, rinse mouth, drink water if conscious, seek immediate medical attention
Most Important Symptoms and Effects: Eye redness, stinging, headache, drowsiness; repeated overexposure may suppress central nervous system
Suitable Extinguishing Media: Alcohol-resistant foam, dry chemical, carbon dioxide, water fog (avoid straight water streams)
Specific Hazards: Vapors heavier than air; risk of flashback; can generate toxic fumes, including carbon oxides and silicon oxides, under fire conditions
Special Protective Equipment for Firefighters: Self-contained breathing apparatus, full protective clothing
Firefighting Instructions: Cool containers exposed to fire with water spray; evacuate area, fight fire from upwind position, prevent runoff from entering waterways or drains
Personal Precautions: Wear protective gloves, goggles, and impervious clothing; avoid breathing vapors; ensure adequate ventilation
Environmental Precautions: Contain spillage to prevent entry into soil, drains, groundwater, or surface water
Methods for Cleanup: Absorb with non-combustible material (sand, earth, diatomaceous earth); collect in suitable containers for disposal; ventilate area; wash affected areas after cleanup; dispose of according to regulations
Safe Handling: Use non-sparking tools; keep away from heat, flames, and sources of static; avoid contact with eyes, skin, clothing; do not breathe vapors or spray; wash hands after handling and before breaks or meals
Storage Conditions: Store in tightly sealed, original container in a cool, dry, well-ventilated area; keep away from direct sunlight, incompatibles (oxidizing agents, acids); ground all equipment; store separate from food and beverages; maintain temperature below 35°C to preserve material integrity
Occupational Exposure Limits: Not established for N-Octadecylmethyldimethoxysilane
Engineering Controls: Provide local exhaust to minimize vapor exposure; eye wash station and safety shower required in work area
Personal Protective Equipment: Chemical-resistant gloves (nitrile, neoprene), splash-proof goggles, face shield for large quantities, lab coat or chemical apron, approved respirator if ventilation is inadequate
Hygiene Measures: Wash hands, face, and exposed skin after handling; remove contaminated clothing and wash thoroughly before reuse
Appearance: Clear to pale yellow liquid
Odor: Faint, characteristic
Melting Point/Freezing Point: -5°C
Boiling Point: ~210°C
Flash Point: 84°C (closed cup)
Auto-Ignition Temperature: >250°C
Flammability: Flammable liquid
Vapor Pressure: <0.10 mmHg at 25°C
Relative Density: 0.85–0.89 g/cm³ at 25°C
Solubility: Insoluble in water; miscible in common organic solvents
Viscosity: 6–12 cSt at 25°C
Chemical Stability: Stable under recommended handling and storage
Conditions to Avoid: Excessive heat, ignition sources, exposure to air and moisture
Incompatible Materials: Strong oxidizers, acids, water (hydrolyzes slowly, forming methanol)
Hazardous Decomposition Products: Methanol, silicon dioxide, carbon oxides, formaldehyde (incomplete combustion)
Reactivity: Reacts with water or humid air, liberating methanol and silanols; avoid mixing with reactive chemicals
Acute Toxicity: Low acute toxicity expected; estimated oral LD50 (rat) >2000 mg/kg
Skin Corrosion/Irritation: May cause mild skin irritation on prolonged contact
Eye Damage/Irritation: Causes moderate to serious eye irritation
Respiratory or Skin Sensitization: Not classified as a sensitizer
Chronic Toxicity: Repeated inhalation of vapors may cause headaches, dizziness, or drowsiness; prolonged skin contact may dry skin
Carcinogenicity: Not listed as carcinogenic by IARC, NTP, or OSHA
Other Information: Hydrolyzes in moist conditions, producing methanol, which is toxic if inhaled or absorbed in significant amounts
Toxicity (Aquatic): No acute aquatic toxicity data available; hydrolysis product (methanol) is moderately toxic to aquatic organisms
Persistence and Degradability: Reacts with water forming silanols and methanol; silanols further polymerize and bind to soil particles
Bioaccumulation Potential: Not expected to bioaccumulate significantly
Mobility in Soil: Limited mobility due to hydrolysis and soil binding; may persist as bound siloxanes
Other Adverse Effects: Avoid discharge to waterways due to possible methanol release during hydrolysis
Waste Disposal Methods: Incinerate in accordance with local, regional, national regulations; do not pour into drains, soil, or water bodies
Disposal of Containers: Triple rinse before recycling or disposal; puncture and dispose of in licensed landfill or by incineration
Precautions for Disposal: Follow all relevant guidelines and avoid any open burning or uncontrolled discharge
UN Number: UN 1993
Proper Shipping Name: Flammable Liquid, n.o.s. (contains N-Octadecylmethyldimethoxysilane)
Hazard Class: 3 (Flammable liquid)
Packing Group: III (minor hazard)
Marine Pollutant: No specific classification, but prevent exposure to marine environments
Special Precautions for Transport: Secure tightly capped containers upright, segregate from oxidizers and foods, follow all applicable road, rail, air, marine regulations; emergency response guides should accompany shipment
TSCA Status: Listed on US Toxic Substances Control Act Inventory
REACH Registration: Imported/manufactured in EU subject to REACH notification and potential registration
Canada (DSL/NDSL): Present on Domestic Substances List
OSHA Hazard Communication: Flammable liquid and irritant under OSHA Hazard Communication Standard
SARA Title III: Not listed as extremely hazardous; methanol (hydrolysis product) is subject to reporting requirements at certain thresholds
California Proposition 65: Methanol from hydrolysis appears on the list; exposure should be minimized
Other Applicable Laws: Users should verify compliance with local workplace safety, chemical handling, and waste management standards applicable to their jurisdiction
