What Is the CAS Number of Butyl Acetate?
Butyl acetate has the CAS number 123-86-4. The full name is n-butyl acetate, written on older documents as butyl ethanoate or acetic acid n-butyl ester. It is an ester formed from acetic acid and n-butanol, with the molecular formula C6H12O2 and a molecular weight of 116.16 g/mol. The liquid is colourless and transparent with a strong fruity odour, it mixes with ethanol and ether in any proportion, and it dissolves in most organic solvents.
Water solubility is limited: roughly 0.7 g per 100 mL dissolves at 20 °C, and the ester itself takes up about 1.2% water. That partial water rejection, together with a moderate evaporation rate, is exactly what formulators want when they need a solvent that flows out well but still dries to a hard, defect-free film.
Physical and Chemical Properties
| Property | Typical value |
|---|---|
| CAS number | 123-86-4 |
| Formula | C6H12O2 |
| Molecular weight | 116.16 g/mol |
| Appearance | Colourless liquid, fruity odour |
| Density at 20 °C | 0.88 g/cm3 |
| Boiling point | 126.5 °C |
| Freezing point | -77.9 °C |
| Flash point (closed cup) | 22 °C |
| Water solubility at 20 °C | 0.7 g/100 mL |
| Transport classification | UN 1123, Class 3, Packing Group III |
The ester is stable under normal storage conditions but is incompatible with strong oxidising agents, strong acids and strong bases, all of which can hydrolyse it back to acetic acid and butanol. It should be kept in a flammables store in closed containers, and transfers must be bonded and grounded.
Industrial Applications
Nitrocellulose lacquers: butyl acetate is a classic active solvent for nitrocellulose systems, giving good flow, blush resistance and film clarity in wood, metal and plastic coatings.
Artificial leather, fabric and plastics processing: it is used in coating and finishing lines where a medium-evaporating solvent with a mild odour is preferred.
Resin solvency: the ester dissolves cellulose acetate butyrate, ethyl cellulose, chlorinated rubber, polystyrene and methacrylic resins, as well as natural resins such as manila gum and damar.
Printing inks and adhesives: it controls viscosity and drying in gravure and flexographic inks and in solvent-borne adhesive systems.
Perfumery and personal care: the fruity note is used in fragrance blends, and the solvent is common in nail-care and coating products.
Flavour formulations: under GB 2760-2024, the national food safety standard for the use of food additives, butyl acetate is permitted as a flavouring substance and is used in banana, pear, pineapple, apricot, peach and berry type flavours.
General industrial cleaning: it removes resins, inks and grease from equipment and printed surfaces.
Quality Specifications and Supply Options
Assay by gas chromatography: 99.5% minimum for standard grade, 99.8% and above for high-purity grade.
Water content: 0.10% maximum, measured by Karl Fischer titration.
Acidity: 0.01% maximum expressed as acetic acid; colour: 10 Hazen maximum; non-volatile residue: 0.005% maximum.
Food-grade lots are produced and documented against the requirements for flavouring substances, with traceable raw materials and dedicated production campaigns.
Packaging: 180 kg drums, 900 kg intermediate bulk containers and dedicated tankers for contract volumes.
Documents issued per lot: certificate of analysis, safety data sheet, technical data sheet, and route-of-synthesis or analytical method statements when a project requires them.
The product meets EU REACH requirements for export shipments and is produced under ISO 9001 and ISO 14001 certified management systems.
Handling, Storage and Regulatory Notes
Butyl acetate is a flammable liquid with a closed-cup flash point of 22 °C and an explosive range of roughly 1.4% to 8% by volume in air. Vapour is heavier than air, so ventilation should be designed to remove it from low points and pits. Prolonged skin contact defats the skin, and the vapour irritates the eyes and respiratory tract at high concentrations.
Store in a flammables area, in closed containers, away from heat, ignition sources, strong oxidisers, strong acids and strong bases.
Use closed transfer systems, bonding and grounding, and local exhaust ventilation at filling and mixing points.
Wear chemical goggles, solvent-resistant gloves and, where concentrations are uncontrolled, suitable respiratory protection.
The substance is listed in the Chinese inventory of existing chemical substances and registered under REACH for European deliveries; the workplace exposure limit in most jurisdictions is 150 ppm as an eight-hour time-weighted average, with a 200 ppm short-term limit.
Frequently Asked Questions
Q: What is the CAS number of butyl acetate?
The CAS number of butyl acetate is 123-86-4, corresponding to n-butyl acetate with the formula C6H12O2.
Q: What is butyl acetate used for?
It is used in nitrocellulose lacquers, artificial leather and fabric coatings, printing inks, adhesives, resin solutions, fragrances and permitted flavour formulations.
Q: Is butyl acetate soluble in water?
Only slightly: about 0.7 g dissolves in 100 mL of water at 20 °C. It mixes freely with ethanol, ether and most organic solvents.
Q: What is the boiling point and flash point of CAS 123-86-4?
The boiling point is 126.5 °C and the closed-cup flash point is 22 °C, which classifies the material as a Class 3 flammable liquid, Packing Group III, UN 1123.
Q: Which resins does butyl acetate dissolve?
It dissolves cellulose acetate butyrate, ethyl cellulose, chlorinated rubber, polystyrene, methacrylic resins, manila gum and damar.
Q: How should butyl acetate be stored?
Keep it in closed, grounded containers in a cool, ventilated flammables store, away from ignition sources, strong oxidising agents, strong acids and strong bases.