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Name: 1,3-Cyclopentadiene
Chemical Formula: C5H6
Molecular Weight: 66.10 g/mol
Appearance: Clear, colorless to slightly yellow volatile liquid with a sharp, unpleasant odor
Common Uses: Intermediate in organic synthesis, diene in Diels-Alder reactions, laboratory research
Synonyms: Cyclopenta-1,3-diene
GHS Classification: Highly flammable liquid, acute toxicity (oral, inhalation, dermal), skin and eye irritant
Hazard Statement: Liquid catches fire easily, releases vapors that form explosive mixtures with air, acts as a significant irritant to mucous membranes and may harm central nervous system with repeated exposure
Signal Word: Danger
Pictograms: Flame, skull and crossbones, exclamation mark
Major Risks: Flammable vapors spread quickly, inhalation irritates nasal passages and lungs, can cause drowsiness, headaches, dizziness, prolonged skin contact leads to redness, blistering, and cracking
Chemical: 1,3-Cyclopentadiene
CAS Number: 542-92-7
Concentration: Usually pure in laboratory reagent bottles
Impurities: Often contains minor amounts of dicyclopentadiene due to dimerization if stored improperly, which complicates safe storage and safe use
Inhalation: Move affected person into fresh air, encourage slow deep breathing, provide oxygen if breathing seems difficult, seek medical attention quickly if symptoms persist like dizziness or headache
Skin Contact: Strip away contaminated clothing, rinse skin with plenty of water for fifteen minutes, soap can be used if available, persistent irritation demands medical evaluation
Eye Contact: Rinse cautiously with water for at least fifteen minutes, keep eyelids open, always get medical advice swiftly
Ingestion: Rinse mouth repeatedly, never induce vomiting, keep individual calm and seek medical assistance
Suitable Extinguishing Media: Use dry chemical, foam, carbon dioxide; avoid water stream directly on the fire as this can spread flammable material
Hazards From Burning: Produces toxic vapors including carbon monoxide, carbon dioxide, irritating organic fumes
Precautions: Wear self-contained breathing apparatus and full protective firefighting gear; stay upwind as vapors travel long distances, escalate to explosion in poorly ventilated spaces
Personal Precautions: Evacuate unnecessary personnel, shut off ignition sources, increase ventilation, avoid breathing vapors, wear chemical-resistant gloves and splash goggles
Spill Response: Cover drains, absorb liquid using inert materials like sand, earth, or vermiculite, collect residue into tightly sealed chemical waste containers
Environmental Protection: Prevent entry into waterways or soil, as toxic effects accumulate in aquatic organisms and persist in the environment
Handling Practices: Always open in fume hood, ground all equipment due to static electricity risks, use spark-proof tools
Storage Conditions: Store in tightly closed glass containers under nitrogen or argon, refrigerate to avoid dimerization, keep away from flame, avoid direct sunlight, chemical oxidizers, and heat sources
Storage Hazards: Vapor escapes easily at room temperature, leading to dangerous concentrations. Regular inspection of containers helps catch leaks and polymerization before they get dangerous
Engineering Controls: Use chemical fume hood, install local exhaust ventilation at points of vapor generation
Personal Protective Equipment: Safety goggles with side shields, chemical-resistant gloves, flame-resistant lab coats, avoid wearing synthetic fibers that melt on contact with liquid
Respiratory Protection: Use NIOSH-approved half-mask organic vapor respirator in non-routine settings or when exposures exceed regulatory limits. Lab work typically demands at least this level of protection
Appearance: Colorless, mobile liquid
Odor: Strong, sharp, tar-like
Boiling Point: Around 42 °C (rapid evaporation happens at room temperature)
Melting Point: -47 °C
Flash Point: -17 °C (closed cup)
Solubility: Insoluble in water, miscible with organic solvents
Vapor Pressure: Elevated at room temperature, compounding risk of inhalation and flammability
Density: About 0.8 g/cm³
Potential for Dimerization: Spontaneous, especially above 20 °C, which is why refrigerated storage matters
Chemical Stability: Unstable at room temperature, dimerizes rapidly, forms dicyclopentadiene
Incompatible Materials: Strong oxidizing agents, acids, halogens
Hazardous Decomposition Products: Forms toxic fumes during thermal breakdown (carbon monoxide, carbon dioxide, formaldehyde)
Polymerization Risks: Exothermic reaction occurs quickly above recommended storage temperature, risk increases with improper container sealing
Acute Effects: Inhalation leads to headache, nausea, lightheadedness; oral exposure irritates mouth and stomach lining; skin contact triggers redness and dryness
Chronic Effects: Extended exposure may depress central nervous system, lead to memory loss, negatively influence liver function
Sensitization: No evidence for allergic reactions, but consistent irritation possible with frequent contact
Carcinogenicity: Not classified as human carcinogen by IARC, but potential risks from impurities not fully settled
Immediate Symptoms: Eye watering, throat discomfort, drowsiness after short exposures
Aquatic Toxicity: Highly toxic to fish and aquatic invertebrates, disrupts reproductive cycles, bioaccumulates in food chains
Persistence: Degrades slowly in surface water and soil, with environmental hazards extending over months
Bioaccumulation: Detected in terrestrial and aquatic life after prolonged low-level releases, examples from chemical plant spills show damage to fish populations in affected rivers
Other Hazards: Vapor pollutes air, contributes to smog and ground-level ozone, volatile organic compound status
Disposal Methods: Collect all liquid and residue, incinerate in licensed chemical waste facility with proper flue gas cleaning
Environmental Release: Strictly prohibited, even dilute concentrations can create severe long-term issues for aquatic organisms and human water supplies
Container Rinsing: Triple rinse with compatible solvents before disposal, avoid pouring into drains or municipal trash, always separate from general waste streams
UN Number: UN1993
Proper Shipping Name: Flammable Liquid, n.o.s. (1,3-Cyclopentadiene)
Hazard Class: 3 (Flammable Liquids)
Packing Group: I (highest hazard)
Transport Precautions: Ship only in approved steel drums or glass with secondary containment, consistent temperature control keeps dimerization in check, always affix proper hazard labeling
OSHA Hazard: Listed as a hazardous chemical, workplace exposure limits strictly enforced
SARA Reporting: Listed under Emergency Planning and Community Right-to-Know Act for storage above threshold quantities
Environmental Protection Agency: Identifies as hazardous air pollutant due to toxic emissions and ozone formation
Personal Liability: Improper handling, accidental release, or inadequate storage attracts severe penalties and cleanup requirements
