Introduction to Cumene Hydroperoxide
Cumene hydroperoxide (CHP), also known as cumyl hydroperoxide, is one of the most industrially significant organic hydroperoxides. With the CAS registry number 80-15-9 and molecular formula C₉H₁₂O₂, CHP serves as a critical intermediate in the global production of phenol and acetone via the Hock process, which accounts for over 95% of the world’s phenol production capacity.
Key Facts: Cumene Hydroperoxide (CHP)
- CAS Number: 80-15-9
- Molecular Formula: C₉H₁₂O₂
- Molecular Weight: 152.19 g/mol
- Appearance: Colorless to pale yellow liquid
- Boiling Point: 153°C (decomposes)
- Density: ~1.06 g/cm³ at 20°C
- 10-Hour Half-Life Temperature: ~155°C
- Active Oxygen Content: ~10.5% (theoretical)
- Primary Application: Intermediate for phenol/acetone production (Hock process)
- Global Production: Over 12 million metric tons/year (as intermediate, not isolated)
Physical and Chemical Properties
| Property | Value |
|---|---|
| Appearance | Colorless to pale yellow liquid |
| Odor | Characteristic aromatic odor |
| Density at 20°C | 1.06 g/cm³ |
| Refractive Index (nD²⁰) | 1.522-1.525 |
| Flash Point | ~79°C (closed cup) |
| Vapor Pressure at 20°C | <0.1 hPa |
| Solubility in Water | Slightly soluble (~1.5 g/100 mL) |
| Solubility in Organic Solvents | Soluble in alcohols, ketones, esters, aromatic hydrocarbons |
| SADT | ~80°C |
Production: The Cumene Oxidation Process
CHP is produced industrially by the air oxidation of cumene (isopropylbenzene) in the liquid phase. The reaction proceeds via a free-radical chain mechanism:
C₆H₅CH(CH₃)₂ + O₂ → C₆H₅C(CH₃)₂OOH
The oxidation is typically conducted at 90-120°C and 4-6 bar pressure in a cascade of reactors. Sodium carbonate or sodium hydroxide is added to maintain slightly alkaline conditions (pH 8-10), which suppresses acid-catalyzed decomposition of the CHP product. Cumene conversion is limited to approximately 20-25% per pass to minimize byproduct formation; unreacted cumene is recovered by distillation and recycled.
Primary Applications
1. Phenol and Acetone Production (Hock Process)
The overwhelming majority of CHP produced globally is consumed captively in integrated phenol/acetone plants. The Hock process involves acid-catalyzed cleavage of CHP to phenol and acetone:
C₆H₅C(CH₃)₂OOH → C₆H₅OH + (CH₃)₂CO
This reaction is typically performed using sulfuric acid as the catalyst at 50-90°C. The phenol/acetone ratio is approximately 1:0.62 by weight. Phenol is a key raw material for bisphenol A (polycarbonate and epoxy resins), phenolic resins, caprolactam (nylon 6), and alkylphenols. Acetone is primarily used as a solvent and as a feedstock for methyl methacrylate (MMA) and bisphenol A production.
2. Polymerization Initiator
CHP serves as a high-temperature initiator for free-radical polymerization of styrene, acrylates, and other vinyl monomers. Its high 10-hour half-life temperature (~155°C) makes it particularly suitable for bulk and solution polymerization processes operating at elevated temperatures. CHP is also used as an initiator for the production of ABS (acrylonitrile-butadiene-styrene) resins via mass polymerization.
3. Unsaturated Polyester Resin Curing
In combination with metal accelerators (typically cobalt or manganese salts), CHP can initiate the curing of unsaturated polyester resins at ambient or moderately elevated temperatures. This redox initiation system provides a balance of pot life and cure speed for applications including coatings, adhesives, and castings.
4. Chemical Synthesis
CHP is employed as an oxidizing agent in various organic transformations, including epoxidation of alkenes, oxidation of sulfides to sulfoxides, and the industrial production of propylene oxide via the Sumitomo PO-only process (cumene hydroperoxide epoxidation of propylene).
Safety and Handling
CHP is classified as Organic Peroxide Type E or Type F (UN 3109 or 3110), indicating a lower hazard level compared to many other organic peroxides. However, proper safety precautions are essential:
- Thermal Stability: CHP has relatively high thermal stability for an organic peroxide, but decomposition accelerates rapidly above 100°C. Avoid localized overheating.
- Contamination Sensitivity: CHP is sensitive to contamination by strong acids, which catalyze exothermic decomposition. Equipment must be thoroughly cleaned and free of acid residues.
- Storage: Store at temperatures not exceeding 30°C in original containers. Provide adequate ventilation and secondary containment.
- Fire Fighting: Use water spray or fog for fire suppression. Evacuate area if fire involves CHP in bulk quantities.
- PPE: Chemical-resistant gloves (butyl rubber or PVA), safety goggles, face shield, and flame-resistant clothing.
Frequently Asked Questions
Q: How is CHP different from other organic peroxides in terms of hazard classification?
A: Cumene hydroperoxide is classified as Type E or Type F organic peroxide (depending on concentration/formulation), making it among the least hazardous organic peroxides in terms of fire and explosion risk. This is due to its relatively high thermal stability, high boiling point, and low vapor pressure. However, CHP can still undergo exothermic decomposition if contaminated with strong acids or heated above its SADT.
Q: What is the relationship between CHP and the global phenol market?
A: Essentially all commercially produced phenol is made via the Hock process using CHP as the key intermediate. Approximately 1.35 metric tons of cumene are consumed per metric ton of phenol produced. The global phenol market exceeded 12 million metric tons in 2023, growing at approximately 3-4% annually, driven by demand for bisphenol A, phenolic resins, and polycarbonate plastics. Consequently, CHP demand is directly tied to the health of the phenol/acetone industry.
Key Takeaways
- Cumene hydroperoxide (CHP, CAS 80-15-9) is the primary intermediate in global phenol/acetone production via the Hock process.
- With a 10-hour half-life temperature of ~155°C, CHP exhibits excellent thermal stability relative to other organic peroxides.
- Beyond phenol production, CHP serves as a high-temperature polymerization initiator, UPR curing agent, and oxidizing agent in chemical synthesis.
- CHP is classified as a lower-hazard (Type E/F) organic peroxide, but proper handling and storage practices remain essential.
- The global CHP market is intrinsically linked to phenol demand, which continues to grow with expanding polycarbonate and epoxy resin production.
- Shandong Do Sender Chemicals supplies high-quality cumene hydroperoxide for polymerization and chemical synthesis applications.