Struggling with slow-dissolving resins or fast-evaporating solvents? Discover why Cyclohexanone is the industrial workhorse you need. Alliance Chemical provides an in-depth analysis of this powerful solvent.
What is cyclohexanone?
Cyclohexanone is a six-carbon ring ketone, formula C6H10O, made industrially by catalytic air oxidation of cyclohexane or by hydrogenating phenol. It is mostly an intermediate: more than 96% of the cyclohexanone produced is oxidized to adipic acid (for nylon 6,6) or converted to caprolactam (for nylon 6), according to the Hazardous Substances Data Bank. The remainder is sold as a high-boiling solvent.
In the vast world of industrial chemicals, some compounds work tirelessly behind the scenes, playing a crucial role in the manufacturing of countless everyday products. Cyclohexanone is one such unsung hero. This powerful organic compound, a colorless to pale yellow oily liquid with a distinctive sweet odor, is a cornerstone of modern chemical synthesis and a solvent with remarkable versatility. Its ability to dissolve a wide array of substances makes it invaluable across numerous sectors, including the production of paints, lacquers, and plastics.
But what truly makes cyclohexanone stand out? Its unique properties as a ketone within a six-carbon ring structure give it superior solvency power for high-molecular-weight polymers where other solvents fail. At Alliance Chemical, we understand the importance of leveraging high-performance chemicals to achieve optimal results. This guide will explore the exceptional solvent properties of cyclohexanone, its critical applications, how it compares to other common solvents, and the essential safety protocols for its handling.
What is the structure of cyclohexanone?
Cyclohexanone is a saturated six-membered carbon ring with one ring carbon double-bonded to oxygen. Five ring carbons are CH2 (methylene) groups and the sixth is a carbonyl carbon, so the formula is C6H10O, the condensed formula is (CH2)5CO, and the SMILES string is C1CCC(=O)CC1.
PubChem describes it as "cyclohexane bearing a single oxo substituent." That C=O makes the molecule polar enough to dissolve resins that hydrocarbons cannot, and to dissolve partly in water.
| Identifier | Cyclohexanone |
|---|---|
| Molecular formula | C6H10O |
| Condensed formula | (CH2)5CO |
| SMILES | C1CCC(=O)CC1 |
| CAS number | 108-94-1 |
| Molar mass | 98.14 g/mol |
| Functional group | Ketone (C=O inside a carbon ring) |
Is cyclohexanone a ketone, and is it aromatic?
Yes, it is a ketone, and no, it is not aromatic. The carbonyl carbon is bonded to two other carbons, which is the definition of a ketone, and the ring holds no C=C double bonds at all, so it has none of the alternating pi system that makes benzene or toluene aromatic. Its only double bond is the C=O.
What is another name for cyclohexanone?
The NIOSH Pocket Guide lists anone, cyclohexyl ketone and pimelic ketone as synonyms. You will also see oxocyclohexane and ketohexamethylene on older labels and in PubChem. All of them mean the same compound, CAS 108-94-1.
Cyclohexanone properties: boiling point, solubility and flash point
Cyclohexanone boils at 155.6 °C (312 °F) at atmospheric pressure (HSDB and NIOSH figures, sources listed under References), freezes at about -31 °C, has a density of 0.948 g/cm3 at 20 °C, and flashes at 44 °C (111 °F) closed cup. Boiling far above acetone (56 °C) and MEK (80 °C) is why it evaporates slowly.
| Property | Value |
|---|---|
| Boiling point | 155.6 °C (312 °F) at 760 mmHg |
| Melting / freezing point | -31 °C |
| Density | 0.9478 g/cm3 at 20 °C (floats on water) |
| Flash point | 44 °C (111 °F), closed cup |
| Explosive limits in air | 1.1% (at 212 °F) to 9.4% |
| Vapor pressure | 5 mmHg at 26.4 °C |
| Solubility in water | Sources differ: about 25 g/L (25 °C) to 87 g/L (20 °C); 150 g/L at 10 °C, 50 g/L at 30 °C |
| Odor | Peppermint- or acetone-like |
Is cyclohexanone soluble in water?
Partly, and published figures differ. Near room temperature they run from about 25 g/L at 25 °C (DrugBank) to about 87 g/L at 20 °C (ILO International Chemical Safety Card), NIOSH lists 15%, and the Hazardous Substances Data Bank gives 150 g/L at 10 °C falling to 50 g/L at 30 °C, so it dissolves better in cold water than in warm. Past its limit the mixture splits into two layers, with the cyclohexanone layer on top.
For process work, plan on a few percent at your operating temperature. It dissolves in acetone, ethanol, ether and other common organic solvents.
Is cyclohexanone the same as cyclohexane?
No. Cyclohexane (C6H12, CAS 110-82-7) is a plain hydrocarbon ring with no oxygen; cyclohexanone (C6H10O, CAS 108-94-1) is the same ring carrying a C=O ketone group. The oxygen changes almost everything: cyclohexanone boils about 75 °C higher, has a much higher flash point (44 °C against -18 °C, though both are flammable liquids), and dissolves partly in water, while cyclohexane does not.
The two are linked in industry: catalytic air oxidation of cyclohexane is one of the main routes to cyclohexanone.
| Feature | Cyclohexanone | Cyclohexane |
|---|---|---|
| Formula | C6H10O | C6H12 |
| CAS number | 108-94-1 | 110-82-7 |
| Compound class | Cyclic ketone | Cycloalkane (saturated hydrocarbon) |
| Boiling point | 312 °F (155.6 °C) | 177 °F (81 °C) |
| Flash point | 111 °F (44 °C) | 0 °F (-18 °C) |
| Water solubility (NIOSH) | 15% | Insoluble |
| OSHA PEL (8-h TWA) | 50 ppm | 300 ppm |
| Main use | Nylon intermediate; resin and PVC solvent | Raw material for cyclohexanone and nylon; nonpolar solvent |
Chapter 1: The Superior Solvent at Work
The true power of cyclohexanone lies in its exceptional ability to act as a high-boiling, slow-drying solvent. Its chemical structure allows it to be miscible with most common organic solvents and effectively dissolve a vast range of materials that other solvents struggle with. This makes it a go-to choice in many complex formulations.
What is cyclohexanone used for?
Mostly for nylon. More than 96% of cyclohexanone is oxidized to adipic acid (nylon 6,6) or converted to caprolactam (nylon 6). The rest is used as a solvent: the Hazardous Substances Data Bank lists it as a solvent for cellulose acetate, nitrocellulose, vinyl resins, PVC polymers and copolymers, lacquers, waxes, natural resins, shellac and crude rubber, and as a metal degreasing solvent and leather spot remover.
Its slow evaporation is the reason to choose it over acetone or MEK: the film stays wet long enough to level. ACGIH also lists paint removal and printing inks among its uses.
Key Solvent Applications:
- Paints, Coatings, and Varnishes: Cyclohexanone is critical in the coatings industry for dissolving high-molecular-weight resins like vinyls and epoxies, improving flow and preventing "blushing" in lacquers for a smooth, durable finish.
- Nylon and Polymer Production: Its single largest use is as the primary chemical precursor for adipic acid and caprolactam, the essential building blocks for producing Nylon 6 and Nylon 6,6.
- Resins and Adhesives: It is an excellent solvent for a variety of synthetic resins, including vinyl resins and cellulose esters. This property is vital for the production of plastics and for adhesives where its slow evaporation rate is a major benefit.
- Cleaning and Degreasing: Its strong solvency makes it a powerful ingredient in industrial cleaning solutions and metal degreasers, effectively removing heavy oils, fats, and waxes from surfaces.
- Agricultural formulations: Cyclohexanone has been used as a solvent in crop-protection formulations.
Chapter 2: Cyclohexanone vs. The Alternatives: A Solvent Showdown
Choosing the right solvent is critical for process efficiency and product quality. Cyclohexanone's unique balance of high solvency and slow evaporation sets it apart. Here’s a look at how it compares to other common industrial solvents.
| Feature | Cyclohexanone | Acetone | MEK (Methyl Ethyl Ketone) | Toluene |
|---|---|---|---|---|
| Boiling Point | 155 °C (311 °F) | 56 °C (133 °F) | 80 °C (176 °F) | 111 °C (232 °F) |
| Evaporation Rate | Slow | Very Fast | Fast | Medium |
| Primary Use Case | High-solids coatings, nylon precursor, PVC adhesives | General purpose cleaning, paint thinner, nail polish remover | Coatings, adhesives, printing inks | Paints, rubbers, adhesive manufacturing |
| Key Advantage | Excellent solvency for resins/polymers; prevents blushing | Low cost, fast-acting cleaner | Strong solvency with faster evaporation than cyclohexanone | Good solvency for non-polar compounds |
| Key Consideration | Higher boiling point requires more energy for removal | Extremely flammable; can damage sensitive plastics | Highly flammable; regulated VOC | Higher toxicity; regulated as a hazardous air pollutant |
| Solvent Family | Ketone | Ketone | Ketone | Aromatic Hydrocarbon |
This comparison shows that while faster-evaporating solvents like Acetone and MEK are ideal for rapid cleaning, Cyclohexanone excels in applications requiring superior film formation and the dissolution of complex polymers, making it the premier choice for high-performance coatings and specialized industrial synthesis.
Chapter 3: Safety First - Handling Cyclohexanone Responsibly
With great power comes the need for great responsibility. As a flammable and moderately toxic chemical, handling cyclohexanone requires a strict adherence to safety protocols to protect workers and the environment. At Alliance Chemical, we are committed to promoting the highest standards of safety for all our products.
Key Hazard Information
According to the NFPA 704 standard, Cyclohexanone has a flammability rating of 2 (must be moderately heated for ignition) and a health rating of 1 (can cause significant irritation). It is harmful if swallowed, inhaled, or in contact with skin. Always consult the Safety Data Sheet (SDS) before use.
How toxic is cyclohexanone?
Cyclohexanone is a GHS Category 3 flammable liquid (H226) with the EU harmonized classification H332, "harmful if inhaled." OSHA's permissible exposure limit is 50 ppm (200 mg/m3) as an 8-hour TWA, NIOSH recommends 25 ppm (100 mg/m3) with a skin notation, and the IDLH concentration is 700 ppm.
The skin notation matters: NIOSH lists skin absorption as an exposure route, and names the eyes, skin, respiratory system, central nervous system, liver and kidneys as target organs. Read the Safety Data Sheet for first aid and PPE before use.
| Limit | Value |
|---|---|
| OSHA PEL (8-h TWA) | 50 ppm (200 mg/m3) |
| NIOSH REL (10-h TWA) | 25 ppm (100 mg/m3), skin |
| NIOSH IDLH | 700 ppm |
| NFPA 704 | Health 1, Flammability 2, Instability 0 |
| DOT shipping | UN1915, Class 3 flammable liquid |
Is cyclohexanone illegal?
No. Cyclohexanone is legal to buy, sell and use in the United States, and it is not on the DEA's List I or List II of regulated chemicals in 21 CFR 1310.02. It is regulated as a hazardous material in other ways: it ships as UN1915, a Class 3 flammable liquid (its 44 °C flash point is under DOT's 60 °C cutoff in 49 CFR 173.120), and as a waste it is EPA hazardous waste U057 when discarded unused, or F003 when it is a spent solvent (40 CFR 261.33 and 261.31).
Universal Safety Guidelines:
- Ventilation: Always use cyclohexanone in a well-ventilated area. For indoor applications, local exhaust ventilation (e.g., a fume hood) is essential to keep vapor concentrations below permissible exposure limits.
- Personal Protective Equipment (PPE): Appropriate PPE is mandatory. This includes chemical-resistant gloves (Butyl or Silver Shield® are recommended), indirect-vent chemical splash goggles, and protective clothing to prevent skin contact.
- Storage and Handling: Store containers in a cool, dry, well-ventilated area away from heat, sparks, and ignition sources like oxidizing agents. Keep containers tightly closed. All equipment used for transferring the liquid must be properly grounded and bonded.
- Spill Response: In case of a spill, remove all ignition sources. Absorb the liquid with a non-combustible material like sand or vermiculite and place it in a sealed, labeled container for proper disposal according to local regulations.
Chapter 4: Frequently Asked Questions
Is cyclohexanone safe for home or consumer use?
Absolutely not. Cyclohexanone is a powerful industrial chemical intended for professional use in controlled environments. It is not suitable for household applications due to its flammability and health hazards.
How should I dispose of cyclohexanone waste?
Cyclohexanone waste is considered hazardous. It must be disposed of in accordance with all federal, state, and local regulations. Never pour it down the drain. Contact a licensed environmental services company for proper disposal or recycling.
Can cyclohexanone be mixed with water?
Only up to its solubility limit, which published sources put between about 25 and 87 g/L near room temperature (about 150 g/L at 10 °C, lower in warm water). Below that it forms one clear solution; above it the excess separates as an upper layer. It is miscible with most common organic solvents.
What are the signs of overexposure to cyclohexanone vapors?
Signs of overexposure can include irritation to the eyes, nose, and throat, as well as headache, dizziness, and nausea. If you experience these symptoms, immediately move to fresh air and seek medical attention if they persist.
Related Reading
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Shop Ketone Solvents Speak with a SpecialistReferences & Authoritative Sources
Chemical identity, properties, and safety data sourced from the U.S. National Library of Medicine's PubChem database — the authoritative open-chemistry data resource maintained by the National Institutes of Health.
- PubChem CID 180: Acetone Technical Grade — National Center for Biotechnology Information, U.S. National Library of Medicine. CAS 67-64-1.
- PubChem CID 6569: Methyl Ethyl Ketone (MEK) — National Center for Biotechnology Information, U.S. National Library of Medicine. CAS 78-93-3.
- PubChem CID 1140: Toluene — National Center for Biotechnology Information, U.S. National Library of Medicine. CAS 108-88-3.
- NIOSH Pocket Guide to Chemical Hazards: Cyclohexanone, Centers for Disease Control and Prevention. CAS 108-94-1. Accessed 2026-09-28.
- NIOSH Pocket Guide to Chemical Hazards: Cyclohexane, Centers for Disease Control and Prevention. CAS 110-82-7. Accessed 2026-09-28.
- PubChem CID 7967: Cyclohexanone, National Center for Biotechnology Information, U.S. National Library of Medicine (includes HSDB data). Accessed 2026-09-28.
- Cyclohexanone: phase change data, NIST Chemistry WebBook, SRD 69. Accessed 2026-09-28.
- 21 CFR 1310.02: Substances covered (DEA List I and List II chemicals), Electronic Code of Federal Regulations. Accessed 2026-09-28.
- 40 CFR 261.31: Hazardous wastes from non-specific sources (F003), Electronic Code of Federal Regulations, U.S. EPA. Accessed 2026-09-28.
- 40 CFR 261.33: Discarded commercial chemical products (U057), Electronic Code of Federal Regulations, U.S. EPA. Accessed 2026-09-28.
- 49 CFR 173.120: Class 3, definitions, Electronic Code of Federal Regulations, U.S. DOT PHMSA. Accessed 2026-09-28.
Key numbers and sources
| Fact | Value | Source |
|---|---|---|
| Boiling point of cyclohexanone | 155.6 °C (312 °F) | pubchem.ncbi.nlm.nih.gov |
| Boiling point of acetone | 56 °C (133 °F) | pubchem.ncbi.nlm.nih.gov |
| Boiling point of MEK (Methyl Ethyl Ketone) | 80 °C (176 °F) | pubchem.ncbi.nlm.nih.gov |
| Boiling point of toluene | 111 °C (232 °F) | pubchem.ncbi.nlm.nih.gov |
| NFPA 704 flammability rating for cyclohexanone | 2 (must be moderately heated for ignition) | pubchem.ncbi.nlm.nih.gov (HSDB) |
| NFPA 704 health rating for cyclohexanone | 1 (can cause significant irritation) | pubchem.ncbi.nlm.nih.gov (HSDB) |
| Flash point of cyclohexanone | 44 °C (111 °F), closed cup | cdc.gov/niosh |
| OSHA PEL / NIOSH REL / IDLH for cyclohexanone | 50 ppm / 25 ppm (skin) / 700 ppm | cdc.gov/niosh |
Frequently asked questions
What is the structure of cyclohexanone?
Cyclohexanone is a six-membered carbon ring in which five carbons are CH2 groups and one is a carbonyl carbon double-bonded to oxygen. Its molecular formula is C6H10O, the condensed formula is (CH2)5CO, the SMILES string is C1CCC(=O)CC1, and the molar mass is 98.14 g/mol. It is cyclohexane with one CH2 replaced by C=O, which makes it a cyclic ketone.
What is cyclohexanone used for?
Mostly to make nylon. More than 96% of cyclohexanone produced is oxidized to adipic acid for nylon 6,6 or converted to caprolactam for nylon 6, according to the Hazardous Substances Data Bank. The remainder is a slow-evaporating solvent for PVC, vinyl resins, cellulose acetate, nitrocellulose lacquers, shellac, waxes and rubber, and it is used in paint removers, printing inks and metal degreasing.
Is cyclohexanone soluble in water?
Partly, and published values differ. Near room temperature they range from about 25 g/L at 25 °C (DrugBank) to about 87 g/L at 20 °C (ILO chemical safety card), NIOSH lists 15%, and the Hazardous Substances Data Bank gives 150 g/L at 10 °C and 50 g/L at 30 °C, so it dissolves better in cold water. Above its limit the excess separates as an upper layer. It dissolves readily in acetone, ethanol and ether.
What is the boiling point of cyclohexanone?
Cyclohexanone boils at 155.6 °C (312 °F) at atmospheric pressure. It freezes at about -31 °C, has a density of about 0.948 g/cm3 at 20 °C, and has a closed-cup flash point of 44 °C (111 °F). Its high boiling point compared with acetone (56 °C) and MEK (80 °C) is why it evaporates slowly and keeps coatings wet long enough to level.
Is cyclohexanone the same as cyclohexane?
No. Cyclohexane (C6H12, CAS 110-82-7) is a hydrocarbon ring with no oxygen. Cyclohexanone (C6H10O, CAS 108-94-1) is the same ring with a C=O ketone group. Cyclohexanone boils at 155.6 °C versus about 81 °C for cyclohexane, has a 111 °F flash point versus 0 °F, and dissolves partly in water while cyclohexane is insoluble. Oxidizing cyclohexane is one of the main ways cyclohexanone is made.
How toxic is cyclohexanone?
Cyclohexanone is a GHS Category 3 flammable liquid classified in the EU as harmful if inhaled (H332). OSHA's permissible exposure limit is 50 ppm as an 8-hour TWA, NIOSH recommends 25 ppm with a skin notation because it is absorbed through skin, and the IDLH level is 700 ppm. NIOSH lists eyes, skin, respiratory system, central nervous system, liver and kidneys as target organs. Read the SDS before use.
Is cyclohexanone illegal?
No. Cyclohexanone is legal to buy and use in the United States and is not a DEA List I or List II chemical under 21 CFR 1310.02. It is regulated as a hazardous material: it ships as UN1915, a Class 3 flammable liquid, and as waste it is EPA hazardous waste code U057 when discarded unused or F003 when it is a spent solvent.
What is another name for cyclohexanone?
The NIOSH Pocket Guide lists anone, cyclohexyl ketone and pimelic ketone as synonyms for cyclohexanone. Oxocyclohexane and ketohexamethylene also appear in chemical databases and on older labels. Every one of these names refers to the same compound, CAS number 108-94-1, formula C6H10O, which is also identified for shipping by the UN number UN1915.
What safety precautions are needed when handling cyclohexanone?
Keep vapor below OSHA's 50 ppm PEL (NIOSH recommends 25 ppm) with local exhaust ventilation, and use an organic vapor respirator where monitoring shows it is needed. Prevent skin contact because it is absorbed through skin: butyl rubber or laminate film gloves, splash goggles and protective clothing. The flash point is 111 °F (44 °C), so ground and bond transfers and keep ignition sources and oxidizers away.
What is cyclohexanone's role in PVC pipe cement?
Cyclohexanone dissolves PVC. The Hazardous Substances Data Bank lists it as a solvent for PVC polymers and copolymers, which is why it appears in solvent cements that soften the surfaces of a pipe and fitting so the two fuse as the solvent evaporates. Its slow evaporation gives time to assemble the joint. Follow the cement manufacturer's instructions and drying times.
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