Caprolactam (CPL) is widely used across various industries, including as an intermediate for organic synthesis, polymer manufacturing, synthetic fibers, paint solvents, and synthetic amino acids. As a highly flammable chemical, improper storage or transportation may lead to serious damage or personal injury. In this article, you’ll learn the key uses, hazards, and proper storage methods of CPL.

 1.   What is Caprolactam? Hazard Classification and Primary Applications

Caprolactam (CPL), HS Code: 2933 7100 002, has the chemical formula (CH₂)₅C(O)NH.
It is classified by the UN under Hazard Class 6.1 (Toxic Substances), UN No. 2811.

Physical Properties :

• Boiling point: 268°C
• Melting point: 69.2°C
• Density: 1.05 g/cm³ (water = 1)
• Solubility: Miscible with water
• Volatility: Low vapor pressure, not easily volatile

Chemical Properties :

• Chemically stable at room temperature
• May react explosively with acetic acid and nitrogen trioxide
• Reacts and decomposes with acidic substances

CPL is a cyclic amide (lactam) derivative. It is synthesized through the following reaction:
Cyclohexanone + Hydroxylamine Sulfate → Cyclohexanone Oxime (dehydrated with sulfuric acid) → Caprolactam

CPL can also be polymerized or derivatized for various purposes:

(1) Polymer Monomer

Caprolactam is the monomer for Nylon 6, the first fully synthetic fiber. Nylon 6 is used in plastics, textiles, parachutes, military ropes, cable ties, plastic films, bristle tapes, and more.

(2) Stable Solvent

CPL is a temperature-stable compound, used in the production of paint solvents, coatings, urea-based structural enhancers, plasticizers, and other organic solvent products.

(3) Derivatives

Caprolactam contains a peptide bond (-CO-NH-) and can be used to synthesize artificial amino acids and proteins. It also reacts with other amino acid compounds like diaminohexanoic acid.

2.   Understanding the Hazards of Caprolactam

Caprolactam may ignite or explode upon contact with reactive substances, releasing toxic fumes and gases. It is harmful to human health and can irritate the eyes, skin, and respiratory system. Immediate medical attention is necessary in case of exposure.

Health Hazards :

• Inhalation: May cause allergic respiratory reactions, pulmonary edema, vomiting, nausea, coughing, CNS depression, and lung damage
• Eye Contact: May result in conjunctivitis or even blindness
• Skin Contact: Can cause burns, redness, blisters, and allergic dermatitis
• Ingestion: May burn the esophagus and be fatal

3.   How to Store Caprolactam Properly: Precautions and Guidelines

(1) Store in Cool, Well-Ventilated Areas

Keep CPL in a shaded, well-ventilated environment. Use opaque, airtight containers to prevent sunlight and air exposure, which may cause degradation. Separate it from strong oxidizers, strong acids (sulfuric, hydrochloric, nitric), acetic acid, and nitrogen trioxide to prevent exothermic or explosive reactions.

(2) Seal Packaging Securely

Without inhibitors, CPL may polymerize upon contact with air or light, leading to pressure build-up and potential container rupture. Given its toxicity, packaging must be sealed, and inhibitors are typically added to maintain stability.

(3) Use Proper Hazard Labels

CPL containers must bear hazardous materials labels to inform personnel of chemical properties and safety handling instructions. These labels help guide emergency response in case of incidents during transit.

Further Reading : What Are Dangerous Goods? A Quick Guide to Hazard Classification and Transport Regulations

(4) Equip Workers with PPE

Personnel handling CPL should wear gloves, protective clothing, safety goggles, and respirators. Professional training is essential for safe handling.

(5) Avoid Spark-Generating Tools

CPL is highly reactive to flame, heat, static, light, and strong oxidizers. Using metal tools may create sparks, risking fire or explosion. Use plastic tools and ensure the environment is fire-safe.

(6) Install Emergency Equipment

Emergency handling equipment should be installed in CPL storage areas to ensure rapid response in case of accidents. MSDS documents must be accessible and placed in clearly visible locations.

Further Reading : How to Understand the MSDS (Material Safety Data Sheet) and Key Details to Watch For

Published Date : January 13, 2025