Benzoyl peroxide (BPO), with the chemical formula C₁₄H₁₀O₄ and CAS number 94-36-0, is a vital organic peroxide widely used in industrial and chemical processes. This white crystalline powder, characterized by a faint almond-like odor, serves as a powerful oxidizing agent, initiator, and crosslinking agent across diverse sectors.
🔬 Chemical and Physical Properties
Molecular Weight: 242.23 g/mol
Melting Point: 105°C (decomposes explosively above this point)
Density: 1.334 g/cm³
Solubility:
Highly soluble in acetone, chloroform, and benzene
Slightly soluble in ethanol and methanol
Negligible solubility in water
Reactivity: Extremely unstable when dry. Sensitive to heat, friction, impact, and contaminants. Reacts violently with strong acids, bases, reducing agents, and metals.
Safety Note: Commercial BPO is stabilized with 25–30% water to mitigate explosion risks during storage and transport.
⚙️ Key Industrial Applications
1. Polymerization Initiator
BPO is the primary free-radical initiator for synthesizing polymers like:
PVC, polyacrylonitrile, and acrylate resins
Unsaturated polyesters and organic glass adhesives
Its decomposition into reactive radicals (around 70–90°C) drives chain-growth polymerization.
2. Crosslinking Agent
Rubber Vulcanization: Accelerates curing in silicone and fluorocarbon rubbers, enhancing elasticity and durability.
Polyethylene Modification: Improves thermal stability and mechanical strength.
3. Bleaching and Oxidation
Historically used to bleach flours, oils, and waxes. Banned in food (e.g., EU, China since 2011) due to toxicity concerns.
Non-Food Uses: Cosmetic formulations, textile whitening, and organic wastewater treatment.
4. Pharmaceutical and Chemical Synthesis
Intermediate in manufacturing antibiotics (e.g., penicillin) and dermatological treatments (acne gels).
Catalyst for dye synthesis and high-performance coatings.
⚠️ Safety and Handling Protocols
Hazards:
Classified as UN 3108 (5.2 Organic Peroxide).
Acute toxicity (Rat oral LD₅₀: 7,710 mg/kg).
Skin/eye irritant; may cause sensitization.
Storage: Keep at 2–25°C in ventilated, non-reactive containers. Avoid light, heat, and contamination.
Fire Response: Use water spray, foam, or CO₂. Never use sand (explosion risk).
♻️ Environmental and Regulatory Status
Ecotoxicity: Moderate aerobic/anaerobic biodegradability. Potential bioaccumulation (BCF: 250).
Regulations:
Listed in WHO IARC Group 3 (not carcinogenic to humans).
Banned in food additives globally; restricted under REACH for consumer products.
🔮 Future Outlook
Research focuses on:
Safer Alternatives: Encapsulated BPO for controlled-release applications.
Environmental Remediation: Advanced oxidation processes for pollutant degradation.
Benzoyl peroxide (CAS 94-36-0) remains indispensable in polymer science and specialty chemistry, though its use demands rigorous safety protocols. As industries prioritize sustainability, innovations in BPO delivery systems and eco-friendly applications will shape its future role.