What Is Cyclohexanone (CAS 108-94-1)?
Cyclohexanone is a colourless liquid ketone with an odour often described as resembling peppermint and acetone. Its CAS number is 108-94-1 and its chemical formula is C6H10O. The compound is very soluble in methanol, ethanol, acetone, benzene, n-hexane, nitrobenzene, diethyl ether, naphtha, xylene, ethylene glycol, isoamyl acetate, diethylamine and most other organic solvents, while its solubility in water remains limited. This balance of polar and non-polar behaviour makes it a strong solvent for resins, polymers and printing systems.
Properties of Cyclohexanone
| Property | Value |
|---|---|
| CAS number | 108-94-1 |
| Chemical formula | C6H10O |
| Molecular weight | 98.15 g/mol |
| Melting point | -47 °C |
| Boiling point | 156.4 °C |
| Vapour pressure | 0.52 kPa at 20 °C |
| Density | 0.9455 g/cm3 |
| Refractive index | 1.4552 |
| Dynamic viscosity | 1.803 mPa·s at 30 °C |
| Specific heat | 1.811 J/g |
| Surface tension | 33.51 mN/m at 30 °C |
| Heat of vaporisation | 44.92 kJ/mol |
| Heat of combustion | -3.521 MJ/mol |
| Flash point | 54 °C |
| Autoignition temperature | 420 °C |
| Solubility in water at 20 °C | 9.0 g/100 g of water |
Common synonyms include pimelic ketone, oxocyclohexane, hexanon and cyclohexyl ketone.
Industrial Uses of Cyclohexanone
Cyclohexanone is an important solvent for the coatings and printing industries. It is a major additive in lacquers and paints, where it helps prevent blushing, and it acts as a solvent for PVC printing inks, giving good flow and film formation on flexible substrates. It also dissolves polyurethane, acrylic and epoxy systems used in industrial finishes and adhesives.
Solvent for PVC and other resin-based printing inks
Anti-blushing additive and flow promoter in lacquers and paints
Carrier in adhesives, sealants and industrial coating formulations
Chemical intermediate for caprolactam and adipic acid, the monomers behind nylon 6 and nylon 6,6
Raw material for herbicides, antihistamines and other fine chemicals
Solubility and Compatibility
Because cyclohexanone mixes freely with alcohols, esters, aromatic and aliphatic hydrocarbons and glycols, formulators can combine it with cheaper diluents without risking phase separation. Its limited water solubility, around 9.0 g per 100 g of water at 20 °C, means it can still tolerate small amounts of moisture in a coating system, which is useful when substrates or pigments carry residual water. Compatibility testing is still recommended whenever a new resin or pigment is introduced, because solvent blends behave differently from single solvents.
Safety and Handling
Cyclohexanone has relatively low acute toxicity but it must still be handled with care. It is irritating to the eyes and respiratory tract and can cause drowsiness or dizziness when vapours accumulate, so good general and local ventilation is essential. Operators should avoid contact with skin and eyes and wear protective gloves and tight-fitting goggles, and inhalation or ingestion must be avoided. If material is swallowed or a person is exposed to excessive amounts, seek immediate medical attention and show the safety data sheet to the physician. With a flash point of 54 °C and an autoignition temperature of 420 °C, the liquid should be kept away from heat and ignition sources, containers should be bonded and earthed during transfer, and spills should be absorbed with inert material and disposed of according to local rules.
Quality, Packaging and Storage
Commercial cyclohexanone is normally supplied in technical grade with a purity specification covering assay, water content, colour and acidity. Buyers should request a certificate of analysis for each lot and keep the material in sealed steel drums or intermediate bulk containers, stored in a cool, dry, well-ventilated area away from strong oxidising agents. Prolonged exposure to air and light can lead to discolouration and peroxide formation, so stock should be rotated and containers kept closed when not in use.
Frequently Asked Questions
Q: What is cyclohexanone used for?
It is used mainly as an industrial solvent for PVC printing inks, lacquers and paints, as an anti-blushing additive, and as a chemical intermediate for caprolactam, adipic acid, herbicides and antihistamines.
Q: What is the CAS number of cyclohexanone?
The CAS number of cyclohexanone is 108-94-1 and its chemical formula is C6H10O with a molecular weight of 98.15 g/mol.
Q: Does cyclohexanone dissolve in water?
Only partly. Its solubility in water is about 9.0 g per 100 g of water at 20 °C, although it mixes freely with most organic solvents such as alcohols, esters and aromatic hydrocarbons.
Q: Is cyclohexanone flammable?
Yes. It is a combustible liquid with a flash point of about 54 °C and an autoignition temperature near 420 °C, so it must be stored away from heat and ignition sources and handled with bonded containers.
Q: What is the smell of cyclohexanone?
Cyclohexanone is a colourless liquid with a sweet, pungent odour often compared with peppermint and acetone. The odour threshold is low, so leaks are usually noticed quickly.
Q: How should cyclohexanone be stored?
Keep it in sealed steel drums or IBCs in a cool, dry, well-ventilated place away from oxidising agents and ignition sources, rotate stock regularly and keep containers closed to limit moisture pickup and peroxide formation.