Is Butyl Acetate Classified as a Hazardous Chemical?
Yes. n-Butyl acetate, CAS 123-86-4, is classified as a hazardous chemical because it presents a combination of physical, health and environmental hazards. It is a clear, colourless ester solvent with a characteristic fruity odour, widely used in coatings, printing inks, adhesives and cleaning formulations. Its hazards are well understood and manageable, but they do require documented controls in the workplace rather than informal handling.
In transport and supply, butyl acetate is a flammable liquid. In the workplace it is a respiratory and central nervous system irritant at high vapour concentrations, and it is harmful to aquatic life if released to water. These three hazard families drive the storage, ventilation, personal protective equipment and spill response rules that apply to the material.
Physical Properties and Flammability Data
| Property | Typical value |
|---|---|
| CAS number | 123-86-4 |
| Molecular formula | C6H12O2 |
| Molecular weight | 116.16 |
| Boiling point | About 126 degrees C |
| Flash point | About 22 degrees C, closed cup |
| Auto-ignition temperature | About 421 degrees C |
| Flammable limits in air | About 1.2 to 7.5 percent by volume |
| Relative density | About 0.88 |
| Water solubility | Slightly soluble, under 1 percent |
| Transport classification | UN 1123, Class 3 flammable liquid, packing group III |
A flash point close to normal working temperature is the key fact for risk assessment. At summer ambient conditions, or close to a drying oven, the liquid can release a flammable vapour layer above the surface, and that vapour can travel along the floor to a distant ignition source and flash back.
Fire and Explosion Protection
Keep the material away from open flames, hot surfaces, sparks, welding operations and static discharge.
Use explosion-proof electrical equipment and fittings in any area where vapour can accumulate.
Bond and ground containers, drums and transfer lines during dispensing and tank filling.
Prefer closed transfer systems with local exhaust ventilation over open pouring.
Fit flame arresters on vents and store drums away from oxidising agents such as nitrates, peroxides and concentrated acids.
Provide suitable dry powder, foam or carbon dioxide extinguishing media and train operators in their use.
Water spray may be used to cool containers exposed to fire, but a solid water stream can spread burning liquid and should not be used directly on the product.
Health Effects and Occupational Exposure Limits
Inhalation is the dominant exposure route in industry. At elevated concentrations, butyl acetate vapour irritates the eyes, nose and throat and can cause headache, dizziness, drowsiness and depression of the central nervous system. Contact with the liquid defats the skin, and repeated or prolonged exposure may lead to dermatitis. Eye contact causes irritation and transient corneal injury.
Occupational exposure limits are expressed as an eight hour time-weighted average, typically 150 ppm, equivalent to about 710 milligrams per cubic metre, with a short-term exposure limit of around 200 ppm for periods of fifteen minutes. Where engineering controls cannot hold airborne concentrations below those values, suitable respiratory protection is required. Engineering controls are always preferred and include enclosure of processes, local exhaust ventilation at the point of vapour release, and general dilution ventilation. Health surveillance and pre-placement medical assessment are good practice for regularly exposed operators.
Environmental Behaviour and VOC Emissions
Butyl acetate is harmful to aquatic life and must not be discharged to drains, surface water or soil. It is also a volatile organic compound, so vapour emissions contribute to the formation of ground-level ozone and are controlled by solvent emission regulations in many regions. Practical measures include keeping containers closed when not in use, recovering displaced vapour during tank filling, using low-emission cleaning methods, and routing waste solvent to licensed recovery or incineration rather than disposal with general waste.
Spill response should follow a fixed sequence. Remove ignition sources, ventilate the area, contain the pool with inert absorbent such as vermiculite or sand, place the used absorbent in a labelled closed container, and hand it to a licensed waste contractor. Do not wash the spill into the drainage system with water.
Storage, Transport and Personal Protection
Store butyl acetate in tightly closed steel or approved plastic containers in a cool, dry, well ventilated area, protected from direct sunlight and separated from oxidising agents. Earthing of storage tanks and racking, drip trays under dispensing points, and clear segregation from oxidisers are standard requirements. For transport, the material is carried as UN 1123, Class 3, packing group III, and packages must display the appropriate flammable liquid label and documentation.
Personal protective equipment for routine handling includes chemical safety goggles or a face shield, oil-resistant gloves, antistatic work clothing and safety footwear. Self-contained or air-purifying respiratory protection with an appropriate organic vapour cartridge is required for non-routine tasks such as tank cleaning or work in confined spaces, and operators carrying out those tasks should work under a permit to work system with a second person present.
Frequently Asked Questions
Q: Is butyl acetate hazardous?
Yes. Butyl acetate, CAS 123-86-4, is a flammable liquid with a flash point near 22 degrees C, a respiratory and central nervous system irritant at high vapour concentrations, and harmful to aquatic life, so it is regulated as a hazardous chemical.
Q: What are the main hazards of butyl acetate?
The main hazards are fire and explosion from its vapour, inhalation of vapour causing headache, dizziness and narcotic effects, skin and eye irritation on contact, and toxicity to aquatic organisms if the material is released to water.
Q: What health effects can butyl acetate vapour cause?
At high concentrations the vapour irritates the eyes, nose and throat and can cause headache, dizziness, drowsiness and central nervous system depression. Repeated skin contact with the liquid removes natural oils and can lead to dermatitis.
Q: What is the flash point and why does it matter?
The closed cup flash point is about 22 degrees C, which is close to normal ambient and workshop temperatures. That means flammable vapour can form readily, so ignition control, bonding and grounding, and explosion-proof equipment are essential.
Q: How should butyl acetate be stored?
Keep it in tightly closed containers in a cool, dry, well ventilated area away from heat, direct sunlight and ignition sources, and separate it from oxidising agents. Tanks and racking should be earthed and well labelled.
Q: How should a butyl acetate spill be handled?
Shut off ignition sources and ventilate the area, contain the liquid with inert absorbent, seal the used absorbent in a labelled container, and dispose of it through a licensed waste contractor. Never flush the spill to a drain or watercourse.