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Name: Acetonitrile
Chemical Formula: C2H3N
Chemical Family: Nitrile, organic solvent
Other Names: Methyl cyanide, Cyanomethane
Packing: Usually found in tightly sealed glass or high-density polyethylene containers to limit evaporation and contamination.
Main Hazards: Highly flammable liquid and vapor, acute toxicity by inhalation or absorption, irritating to eyes, skin, and respiratory system, may cause central nervous system depression, harmful if swallowed.
Signal Word: Danger
GHS Classification: Flammable liquids (Category 2), Acute toxicity (Category 4), Eye irritation (Category 2A)
Pictograms: Flame, exclamation mark, health hazard
Chemical: Acetonitrile
Concentration: Typically over 99% for ACS grade
CAS Number: 75-05-8
Impurities: Usually less than 1% water or other organics, but always check the certificate of analysis for specifics.
Inhalation: Move affected person to fresh air, keep warm and provide rest, seek medical attention.
Skin Contact: Remove contaminated clothing, rinse skin thoroughly with water and soap, get medical help if irritation persists.
Eye Contact: Rinse immediately with plenty of water, lift eyelids occasionally, get medical advice promptly.
Ingestion: Rinse mouth, do not induce vomiting, seek urgent medical help. Immediate assistance is critical as acetonitrile is easily absorbed.
Extinguishing Media: Use alcohol-resistant foam, dry chemical, or carbon dioxide. Water spray can help cool exposed containers but may not put out the flame.
Hazards from Combustion: Produces toxic gases including hydrogen cyanide, nitrogen oxides, and carbon monoxide.
Protective Equipment: Firefighters need self-contained breathing apparatus and full protective gear in vapor-rich environments.
Personal Precautions: Evacuate non-essential personnel, put on gloves and goggles, avoid breathing vapors.
Environmental Precautions: Prevent spills from entering drains, sewers, or surface waters.
Cleanup: Absorb on sand or inert material, collect in suitable container for disposal, ventilate area. Wash spill area with plenty of water after removal.
Handling: Always use in a well-ventilated hood, avoid inhaling vapor, prevent skin contact by wearing proper protective equipment, keep away from heat, sparks, and open flames, never use near smoking materials. After many years working in laboratories, I’ve seen first-hand how even a small lapse—like leaving a container open—can lead to headaches, eye irritation, and potentially dangerous conditions.
Storage: Store in tightly closed containers in a cool, dry, and well-ventilated area, away from incompatible substances such as strong acids or bases, oxidizers, and reducing agents. Good storage practice cuts down on risks of unexpected reactions or leaks.
Engineering Controls: Chemical fume hood or local exhaust ventilation is essential. I have never once worked with acetonitrile outside a hood without discomfort or concern for long-term health effects.
Personal Protective Equipment: Safety goggles, chemical-resistant gloves (like nitrile or neoprene), lab coat, closed-toe shoes. Respirators required if ventilation is inadequate.
Exposure Limits: OSHA PEL: 40 ppm, ACGIH TLV: 20 ppm
Hygiene Measures: Wash hands, face, and any exposed areas thoroughly after handling, don’t eat, drink, or smoke during use.
Appearance: Clear, colorless liquid
Odor: Ether-like, somewhat sweet odor—I’ve found the smell noticeable even at low concentrations, which can help with early leak detection if you’re paying attention.
Boiling Point: 81.6°C
Melting Point: -45°C
Density: 0.786 g/cm³ at 20°C
Solubility: Miscible with water, ethanol, ether
Vapor Pressure: 97 hPa at 20°C
Flash Point: 2°C
Stability: Stable under recommended storage and handling conditions. In the real world, heat or extended exposure to air or light can break down the compound.
Incompatibilities: Reacts with acids, strong oxidizing agents, reducing agents, chlorinated solvents. Mixing with these can give off hazardous byproducts.
Hazardous Decomposition: Hydrogen cyanide, nitrogen oxides, carbon monoxide.
Conditions to Avoid: Heat, sparks, flames, and sources of ignition.
Acute Effects: Causes headache, dizziness, nausea, weakness, shortness of breath; can depress the central nervous system.
Chronic Exposure: Prolonged or repeated exposure may affect the liver, kidneys, or thyroid, though studies in humans remain limited. Decades of published toxicology work confirm the need for diligent control of exposure.
Routes of Entry: Inhalation, skin absorption, ingestion.
LD50 (oral, rat): Roughly 2,733 mg/kg
Symptoms of Overexposure: Anxiety, confusion, convulsions, unconsciousness.
Toxicity to Fish: Harmful, with LC50 values for some species in the tens of milligrams per liter.
Mobility: High in soil and water; does not stay in one place if released.
Persistence and Degradability: Biodegradable over weeks, but spills persist long enough to cause harm.
Bioaccumulation: Not likely to accumulate in food chains, but immediate impact on aquatic life is real. Years working with environmental risk analysts have shown that routine laboratory use, even in cities, becomes a problem when disposal and clean-up procedures are neglected.
Waste Disposal Techniques: Collect in labeled hazardous waste containers, never pour down the drain. Contract with a licensed chemical disposal service.
Regulatory Scrutiny: Many local jurisdictions have strong enforcement on acetonitrile disposal, and I’ve seen fines issued for improper handling.
Recycling: Possible for larger scale, but not routine for bench use. Most labs do not reclaim this solvent due to purity concerns.
UN Number: 1648
Proper Shipping Name: Acetonitrile
Hazard Class: 3 (Flammable liquid)
Packing Group: II
Environmental Hazards: Watch for accidental leaks—any shipment requires special labeling, emergency procedures, and documentation.
High Concern under Federal Chemical Safety Laws: Included in inventories such as TSCA, subject to SARA reporting and OSHA regulation.
Workplace Controls: Compliance with exposure limits set by OSHA and ACGIH required. My experience has shown regulators sometimes audit these chemicals specifically because of their safety record in industry.
Labeling Requirements: Strict hazard and precautionary statements often required by law, and failure to follow rules can lead to occupational health citations.
