What Butyl Acetate Is
Butyl acetate (CAS 123-86-4) is an ester formed from acetic acid and n-butanol. It is a colourless liquid with a characteristic fruity odour, widely used as a medium-volatility solvent in coatings, printing inks, adhesives and nail products. It is miscible with ethanol, ether and most common organic solvents and only sparingly soluble in water, with solubility below 1 g per 100 mL. The technical grade is normally supplied at an ester content of 99 percent or higher, with controlled acidity and water content.
Recognised Hazards
Under the harmonised European classification, butyl acetate carries two main hazard statements: H226, flammable liquid and vapour, and H336, may cause drowsiness or dizziness. It is not classified as acutely toxic by inhalation, nor as severely corrosive to skin, although repeated contact defats the skin and contact with the eyes causes irritation. Because supplier documents in the market sometimes copy hazard statements that do not match the harmonised entry, buyers should treat the regulatory classification for the substance, and the safety data sheet issued for the specific batch, as the reference point.
| Hazard | Code | Practical meaning |
|---|---|---|
| Flammable liquid and vapour | H226 | Flash point near 22 C; keep away from ignition sources |
| May cause drowsiness or dizziness | H336 | Central nervous system effect at high vapour concentration |
Exposure Limits and Workplace Controls
Occupational limits are set by jurisdiction. Widely referenced values for n-butyl acetate include a time-weighted average of 50 ppm and a short-term exposure limit of 150 ppm, while other national systems apply a ceiling value of 150 ppm. In practice, the controls that matter are local exhaust ventilation at mixing and spraying stations, closed transfer of solvent from drums or intermediate bulk containers, bonding and earthing to prevent static discharge, and solvent-resistant gloves and eye protection. Air monitoring confirms whether the chosen controls actually hold the vapour concentration below the applicable limit.
Fire, Storage and Transport
Butyl acetate has a flash point of about 22 C in a closed cup and an autoignition temperature above 400 C. It is a flammable liquid for transport purposes and is normally classified in packing group III, with the standard entry covering butyl acetates. Storage areas should be cool, well ventilated, free of ignition sources and separated from oxidising agents such as peroxides and nitrates. Mild steel drums are suitable for normal storage, and stainless steel or lined vessels are used where colour and acidity must be held to tight limits. Empty containers retain vapour and must be treated as hazardous until they have been cleaned or purged.
Quality Control and Purchase Specifications
Purchase specifications for butyl acetate usually cover ester content, acidity expressed as acetic acid, water content, colour and non-volatile residue. The national industrial standard defines the grades in that way, and gas chromatography is the ordinary method for purity and for the isomer distribution, which distinguishes n-butyl acetate from isobutyl acetate and sec-butyl acetate. Water is measured by Karl Fischer titration. Buyers should specify the isomer required, because the three butyl acetates differ in boiling point and in solvent power, and a substitution changes drying time and film formation in a coating formulation.
Frequently Asked Questions
Q: Is butyl acetate dangerous to handle?
A: It is a flammable liquid that can cause drowsiness at high vapour concentrations, so it requires ventilation and ignition control, but it is not classified as acutely toxic or as severely corrosive to skin.
Q: What is the flash point of butyl acetate?
A: About 22 C in a closed cup, which places it among flammable liquids and makes vapour control and earthing of transfer equipment important.
Q: Is butyl acetate soluble in water?
A: Only sparingly. Solubility is well below 1 g per 100 mL, while the ester mixes freely with ethanol, ether, esters and aromatic solvents.
Q: How is the purity of the solvent verified?
A: By gas chromatography for ester content and isomer identity, by titration for acidity, and by Karl Fischer titration for water content, in line with the grade requirements of the industrial standard.
Q: Which packaging is used for bulk supply?
A: 180 kg or 200 kg steel drums, 1000 litre intermediate bulk containers and road tankers for full loads, all with the flammable liquid label and transport documentation.
Q: Does the isomer matter when ordering?
A: Yes. n-Butyl, isobutyl and sec-butyl acetate have different boiling points and solvent strengths, and the wrong isomer changes evaporation rate and film quality in a coating or ink.
Q: How should spills be managed?
A: Remove ignition sources, ventilate, absorb the liquid with inert material, and collect it as hazardous waste rather than flushing it to drains where it would add to the volatile organic load.