Cyclohexanone (CAS 108-94-1) is a fundamental cyclic ketone widely used in the global chemical industry, particularly in nylon production, coatings, adhesives, resins, and fine chemical synthesis. Its unique molecular structure determines its physicochemical properties and industrial functionality.
1. Basic Chemical Information of Cyclohexanone
1.1 Chemical Formula and Identification
The molecular formula of cyclohexanone is C₆H₁₀O. Its structure consists of a six-membered carbon ring containing one carbonyl group (C=O).
- CAS Number: 108-94-1
- Molecular Weight: 98.15 g/mol
- Chemical Class: Saturated cyclic ketone
The presence of a carbonyl group provides high reactivity, while the saturated ring structure ensures chemical stability, making cyclohexanone both a stable solvent and an important synthetic intermediate.
1.2 Physical Properties (Typical Industrial Data, 20–25°C)
- Appearance: Colorless to pale yellow liquid
- Odor: Mild acetone-like odor
- Boiling Point: 155–156°C
- Melting Point: approx. −47°C
- Density: ~0.947 g/cm³
- Solubility: Slightly soluble in water (~2–3%), miscible with most organic solvents
- Flash Point: ~44–47°C (flammable liquid)
1.3 Key Chemical Reactions
Cyclohexanone undergoes typical ketone reactions centered on the carbonyl group:
- Oxidation → adipic acid (important for Nylon-66 production)
- Reduction → cyclohexanol
- Oxime formation → caprolactam (via Beckmann rearrangement, Nylon-6 precursor)
- Condensation reactions → hydrazones, acetals, and related derivatives
2. Main Industrial Production Processes
2.1 Cyclohexane Air Oxidation (Main Industrial Route)
Cyclohexane is oxidized with air under controlled temperature and cobalt catalyst to produce KA oil (cyclohexanol + cyclohexanone mixture), followed by separation and purification.
- Advantages: large-scale, cost-efficient
- Limitation: moderate selectivity and by-product formation
2.2 Cyclohexanol Dehydrogenation
Cyclohexanol is catalytically dehydrogenated (e.g., Zn-Cu catalysts) to produce cyclohexanone.
- Higher purity product
- Suitable for fine chemical and pharmaceutical-grade applications
2.3 Emerging Green Technologies
Green production methods such as bio-catalysis, enzymatic oxidation, and low-carbon hydrogenation processes are currently in research and pilot-scale development, aiming to reduce VOC emissions and energy consumption.
3. Industrial Importance and Applications
Approximately 90–95% of global cyclohexanone consumption is directed toward nylon production.
3.1 Nylon Industry (Primary Application)
Cyclohexanone is a key upstream raw material in polyamide production:
- Nylon-6 production → via cyclohexanone oxime → caprolactam
- Nylon-66 production → via oxidation to adipic acid
It plays a critical role in textiles, automotive components, engineering plastics, and packaging materials.
3.2 Industrial Solvent Applications
Due to its high boiling point and moderate evaporation rate, cyclohexanone is widely used as a high-performance solvent:
- Coatings and paints (improves leveling and film formation)
- Adhesives and resins
- Printing inks
- Industrial cleaning and degreasing
Compared with fast-evaporating solvents (e.g., acetone), cyclohexanone provides better solubility for high-molecular-weight resins and improves coating performance.
3.3 Fine Chemical Intermediate
High-purity cyclohexanone is used in:
- Pharmaceutical intermediates (reaction medium and structural precursor)
- Agrochemical formulations (solvent carrier)
- Advanced polymer materials
4. Quality Classification and Safety
4.1 Product Grades
- Industrial grade: ≥98% purity
- High-purity grade: typically ≥99.5% or higher depending on application
4.2 Safety Information
According to OSHA and NIOSH standards:
- Main hazard: vapor exposure may cause dizziness and CNS effects at high concentrations
- Exposure limit: OSHA TWA 50 ppm (8-hour average)
- Not classified as a confirmed carcinogen by IARC (based on current evaluations)
Protection measures:
- Use in well-ventilated areas
- Wear chemical-resistant gloves and goggles
- Avoid ignition sources (flammable liquid category)
4.3 Storage & Transport
- Store in sealed steel or HDPE containers
- Keep at 5–30°C
- Avoid strong oxidizers and acids
- Transport under UN hazardous chemical regulations (flammable liquid classification)
5. Market Trends
The global cyclohexanone market grows at approximately 3–5% annually, driven primarily by demand from nylon industries in Asia-Pacific.
Key trends include:
- Process optimization for higher selectivity
- Closed-loop solvent recovery systems
- Development of bio-based production routes
6. Conclusion
Cyclohexanone has the chemical formula C₆H₁₀O, combining a stable cyclohexane structure with a reactive carbonyl group. This dual nature makes it a vital intermediate in nylon production and a high-performance industrial solvent.
Its mature production technology, stable global demand, and broad application range ensure its continued importance in the chemical supply chain.
