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Chemical Name: 1,4-Cyclohexadiene
Synonyms: Para-cyclohexadiene, 1,4-CHD
CAS Number: 628-41-1
Appearance: Colorless, typically liquid at room temperature, familiar to labs with a slightly aromatic odor that triggers quick action for ventilation.
Main Uses: Known for hydrogen donor properties, widely tapped in organic synthesis, especially by chemists after versatile ring compounds.
Relevant Industries: Organic synthesis, pharmaceuticals, academic research.
GHS Classification: Flammable liquid (Category 3), acute oral toxicity (Category 4), skin and eye irritant.
Hazards: Catches fire readily if ignition sources linger; building vapor cloud in a poorly ventilated workroom is a genuine risk I’ve seen cause near misses. Breathing in vapors can lead to dizziness. Getting it on skin delivers irritation that lasts longer than expected. Swallowing a modest amount brings nausea and discomfort.
Signal Words: “Warning” signs matter here, not just on paper.
Name: 1,4-Cyclohexadiene
Concentration: Usually sold as >98% pure
Impurities: Trace amounts of benzene, possible residuals from synthesis—important since low-level benzene carries its own headaches for workplace safety.
Inhalation: Remove person to open air—breathing becomes easier quickly, but confusion and headaches show up if exposed longer.
Skin Contact: Wash off with soap and lots of water, keep rinsing even if irritation feels minor.
Eye Contact: Flush eyes under running water, don’t rub—this one stings surprisingly bad.
Ingestion: Rinse mouth, seek medical help without delay. Do not try to make someone vomit as that’s never gone well.
Symptoms: Dizziness, sore throat, nausea, skin rashes that flare up several hours later.
Suitable Extinguishing Media: Foam often works best, CO2 extinguishers provide backup; water fog is useful to cool drums but not to douse flames directly.
Hazards During Fire: Vapors form explosive mixtures with air—witnessing a solvent cabinet catch light brings home just how dramatic this hazard is.
Special Protective Equipment: Full protective gear, self-contained breathing apparatus should be standard for anyone dousing these fires. Wearing cotton over synthetics is smart.
Personal Protection: Gloves and goggles come first—never mop with bare hands. Use a fume hood if possible.
Spill Cleanup: Soak up with inert absorbents like vermiculite; scoop into chemical waste containers. Ventilate area right away.
Environmental Caution: Avoid letting runoff reach building drains—company I worked at got fined for less. Dikes or barriers stop it spreading to waterways.
Handling: Closed systems and local exhaust keep vapors at bay; carelessness lands people in trouble faster than most expect.
Storage: Store in cool, dry, shaded spots—away from flames, oxidizers, and sunlight. Use only containers with tight seals. Flammable cabinets with self-closing doors aren’t just bureaucratic—they prevent catastrophe if accidents happen.
Exposure Limits: No specific OSHA or ACGIH value, but best handled per general solvent limits. Benzene traces mean using the stricter standard is smart.
Engineering Controls: Fume hoods or plenty of local exhaust help minimize inhalation risks.
Personal Protection: Safety goggles, nitrile gloves, and long sleeves; lab coat or apron for splash resistance.
Hygiene Tips: Wash exposed skin quickly; don’t eat near work area. Remove contaminated clothing right away and launder before reuse.
Boiling Point: Around 80–83°C—quick to evaporate.
Melting Point: Circling 5–8°C.
Flash Point: Approximately 18°C; one spark and vapors alight.
Solubility: Negligible in water, readily dissolves in organic solvents.
Odor: Slightly sweet, aromatic—a scent you won’t forget after a spill.
Vapor Density: Heavier than air, so accumulation in low spaces is a real concern.
Vapor Pressure: Noticeably high under room conditions, which means bottles left uncapped evaporate quickly.
Chemical Stability: Stable under typical storage, but dislikes heat and light, which brings risk of peroxidation over time.
Incompatibles: Oxidizing agents, strong acids—they set off reactions that go sideways fast.
Decomposition Products: Fumes of carbon monoxide, carbon dioxide, irritant hydrocarbons come off in fires.
Hazardous Reactions: Polymerizes in contact with acids; needs stabilizing agent sometimes.
Routes of Entry: Inhalation, skin, eyes, ingestion
Main Effects: Respiratory irritation, headaches, dizziness, dermatitis, gastrointestinal distress
Sensitization: No confirmed allergenic action, yet regular users often report delayed skin reactions.
Long Term: No strong evidence for carcinogenicity, but data on chronic exposure is limited. I’ve always pushed for using it in the hood and limiting exposure because you just can’t know if there’s a risk lurking.
Aquatic Impact: Toxic to fish and aquatic life even at low concentrations; years in water testing showed persistent effects downstream of spills.
Persistence and Degradability: Not especially persistent, tends to break down over weeks to months, but any hydrocarbon in the wild raises red flags.
Bioaccumulation: Limited, but no reason to be complacent.
Mobility: Spreads over surface water, can seep through some soils.
Precaution: Contain and collect accidental releases with respect for streams and wastewater systems—rehabilitating affected areas runs up big bills and headaches.
Waste Handling: Collect all residues and contaminated materials in approved solvent waste drums.
Disposal Method: Send to incineration or specialized chemical disposal facilities. Never pour down the drain; local waste authorities either fine or shut down operations for that violation.
Container Cleaning: Triple rinse after use; treat washings as hazardous.
Regulatory Aspect: Follow regional hazardous waste regulations without shortcuts—inspection fines are costly.
UN Number: 1993 (Flammable liquids, n.o.s., often cited for mixed solvent shipments)
Transport Hazard Class: 3 (Flammable liquid—drivers know this means real risk in event of a crash)
Packing Group: II or III, depending on precise flash point and blend.
Labeling: Flammable, always visible on containers; turning up with unmarked drums lands shipments in quarantine.
Special Precautions: Secure packaging tightly; temperature controls help avoid pressure build-up—damage in transit sparks insurance woes more often than admitted.
Classifications: Listed as hazardous under GHS, recognized in transport regulations.
Reporting Requirements: Spill reporting thresholds exist in many regions; exceeding a released amount triggers mandatory notification.
Labeling Laws: Labels showing hazard pictograms and warnings required in workplace and transit.
Workplace Duties: Safety training, access to up-to-date safety data, and incident reporting keep teams safe and in line with compliance standards.
Regulatory Listings: Some jurisdictions regulate as an air or water pollutant due to volatile nature and aquatic toxicity.
