CYCLOPENTADIENE

Cyclopentadiene is a colorless liquid with an irritating, terpene-like odor. Bp: 42.5°C; Flash point: 77°F. Density: 0.805 g cm-3.

• Highly Flammable
• Explosive

No rapid reaction with air. No rapid reaction with water.

Excerpt from 128 [Flammable Liquids (Water-Immiscible)]:

HIGHLY FLAMMABLE: Will be easily ignited by heat, sparks or flames. Vapors may form explosive mixtures with air. Vapors may travel to source of ignition and flash back. Most vapors are heavier than air. They will spread along the ground and collect in low or confined areas (sewers, basements, tanks, etc.). Vapor explosion hazard indoors, outdoors or in sewers. Those substances designated with a (P) may polymerize explosively when heated or involved in a fire. Runoff to sewer may create fire or explosion hazard. Containers may explode when heated. Many liquids will float on water. Substance may be transported hot. For hybrid vehicles, 147 (lithium ion batteries) or 138 (sodium batteries) should also be consulted. If molten aluminum is involved, refer to 169 . (ERG, 2020)

Excerpt from NIOSH Pocket Guide for Cyclopentadiene:

Exposure Routes: Inhalation, ingestion, skin and/or eye contact

Symptoms: Irritation eyes, nose

Target Organs: Eyes, respiratory system (NIOSH, 2023)

CYCLOPENTADIENE is incompatible with strong oxidizing agents. Ignites on contact with oxygen (O2) and ozone (O3). Explodes on contact with fuming nitric acid or a mixture of sulfuric acid and nitrogen tetroxide. Reacts vigorously on contact with potassium hydroxide and other strong bases. Mixtures with air are explosive. Presents a moderate explosion hazard when exposed to heat or flame. Decomposes violently at high temperature and pressure. May form explosive peroxides in storage. Undergoes a spontaneous dimerization at room temperature to give DICYCLOPENTADIENE (C10H12, CAS No: 77-73-6), which is a low-melting solid (melting point: 32.5°C). The reaction is strongly exothermic (Hazardous Chemicals Desk Reference, p. 360 (1987)), but occurs sufficiently slowly that cyclopentadiene can be said to be stable at room temperature. The dimerization accounts for the partial or complete solidification of liquid cyclopentadiene in storage. Polymerization occurs more rapidly and extensively at higher temperatures. When heated to 180-200°C, cyclopentadiene gives polycyclopentadiene, a white waxy solid. Stronger heating breaks down polycyclopentadiene and re-generates the monomeric cyclopentadiene as a vapor. The vapor decomposes violently at higher temperatures and pressures.

• Hydrocarbons, Aliphatic Unsaturated
• Conjugated Dienes

Use caution: Liquids with this reactive group classification have been known to react with the absorbent listed below.

• Dirt/Earth

Excerpt from 128 [Flammable Liquids (Water-Immiscible)]:

IMMEDIATE PRECAUTIONARY MEASURE: Isolate spill or leak area for at least 50 meters (150 feet) in all directions.

LARGE SPILL: Consider initial downwind evacuation for at least 300 meters (1000 feet).

FIRE: If tank, rail car or tank truck is involved in a fire, ISOLATE for 800 meters (1/2 mile) in all directions; also, consider initial evacuation for 800 meters (1/2 mile) in all directions. (ERG, 2020)

Excerpt from 128 [Flammable Liquids (Water-Immiscible)]:

CAUTION: The majority of these products have a very low flash point. Use of water spray when fighting fire may be inefficient. CAUTION: For mixtures containing alcohol or polar solvent, alcohol-resistant foam may be more effective.

SMALL FIRE: Dry chemical, CO2, water spray or regular foam.

LARGE FIRE: Water spray, fog or regular foam. Avoid aiming straight or solid streams directly onto the product. If it can be done safely, move undamaged containers away from the area around the fire.

FIRE INVOLVING TANKS OR CAR/TRAILER LOADS: Fight fire from maximum distance or use unmanned master stream devices or monitor nozzles. Cool containers with flooding quantities of water until well after fire is out. For petroleum crude oil, do not spray water directly into a breached tank car. This can lead to a dangerous boil over. Withdraw immediately in case of rising sound from venting safety devices or discoloration of tank. ALWAYS stay away from tanks engulfed in fire. For massive fire, use unmanned master stream devices or monitor nozzles; if this is impossible, withdraw from area and let fire burn. (ERG, 2020)

Excerpt from 128 [Flammable Liquids (Water-Immiscible)]:

ELIMINATE all ignition sources (no smoking, flares, sparks or flames) from immediate area. All equipment used when handling the product must be grounded. Do not touch or walk through spilled material. Stop leak if you can do it without risk. Prevent entry into waterways, sewers, basements or confined areas. A vapor-suppressing foam may be used to reduce vapors. Absorb or cover with dry earth, sand or other non-combustible material and transfer to containers. Use clean, non-sparking tools to collect absorbed material.

LARGE SPILL: Dike far ahead of liquid spill for later disposal. Water spray may reduce vapor, but may not prevent ignition in closed spaces. (ERG, 2020)

Excerpt from NIOSH Pocket Guide for Cyclopentadiene:

Skin: PREVENT SKIN CONTACT - Wear appropriate personal protective clothing to prevent skin contact.

Eyes: PREVENT EYE CONTACT - Wear appropriate eye protection to prevent eye contact.

Wash skin: WHEN CONTAMINATED - The worker should immediately wash the skin when it becomes contaminated.

Remove: WHEN WET (FLAMMABLE) - Work clothing that becomes wet should be immediately removed due to its flammability hazard (i.e., for liquids with a flash point <100°F).

Change: No recommendation is made specifying the need for the worker to change clothing after the workshift. (NIOSH, 2023)

No information available.

Excerpt from NIOSH Pocket Guide for Cyclopentadiene:

Eye: IRRIGATE IMMEDIATELY - If this chemical contacts the eyes, immediately wash (irrigate) the eyes with large amounts of water, occasionally lifting the lower and upper lids. Get medical attention immediately.

Skin: SOAP WASH PROMPTLY - If this chemical contacts the skin, promptly wash the contaminated skin with soap and water. If this chemical penetrates the clothing, promptly remove the clothing and wash the skin with soap and water. Get medical attention promptly.

Breathing: RESPIRATORY SUPPORT - If a person breathes large amounts of this chemical, move the exposed person to fresh air at once. If breathing has stopped, perform artificial respiration. Keep the affected person warm and at rest. Get medical attention as soon as possible.

Swallow: MEDICAL ATTENTION IMMEDIATELY - If this chemical has been swallowed, get medical attention immediately. (NIOSH, 2023)

• CYCLOPENTADIENE
• 1,3-CYCLOPENTADIENE
• PENTOLE
• PYROPENTYLENE
• R-PENTINE