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Chemical Name: 4-(2-Pyridylazo)resorcinol
Common Name: PAR
Chemical Formula: C11H9N3O2
Appearance: Deep red or orange crystalline powder, known for its strong color and water solubility which makes it popular in laboratories, especially for detecting metal ions. People working around it should recognize its color and odor, which can stick to surfaces or gloves if not handled carefully.
Physical Hazards: Flammable as a fine dust; users often forget powders spread quickly in air, increasing risk if sparks or open flames are nearby.
Health Hazards: Irritating to skin, eyes, and respiratory system. Some studies report that extended exposure may prompt allergic reactions or breathing discomfort.
Environmental Hazards: Toxic to aquatic life; small spills can damage drains and water systems much faster than people expect. This single trait often catches labs and hobby chemists off guard because a little spill doesn’t look like much until wildlife or plant stress shows up later.
Main Component: 4-(2-Pyridylazo)resorcinol
Chemical Purity: Laboratory grade available commonly in high purity.
Impurities: Trace solvents or related aromatic compounds, often less than 1% by mass. Technicians using it should stay aware of this, as even minor impurities can skew sensitive analyses or contribute unexpected health effects.
Inhalation: Move victim to fresh air, keep at rest; shallow breathing or coughing signals the need for immediate medical help.
Skin Contact: Rinse thoroughly with soap and water. Persistent irritation means get medical advice.
Eye Contact: Rinse with clean water for at least 15 minutes, keeping eyelids apart; rapid action helps prevent longer-term damage.
Ingestion: Rinse mouth without inducing vomiting, seek a doctor since some symptoms show up only after a delay.
Suitable Extinguishing Media: Use dry chemical, CO2, or foam. Water spray only as a last resort and with minimal quantity.
Specific Hazards: Dust explosions can happen if powder clouds form. Decomposition releases nasty fumes, including nitrogen oxides.
Protective Equipment for Firefighters: Wear self-contained breathing apparatus. Even after a small fire, ventilate the area thoroughly. Sprinklers or hoses splash powder, spreading contamination, so avoid unless unavoidable.
Personal Precautions: Avoid breathing dust, ventilate area, keep people away who don’t need to be there. Protect skin and eyes.
Environmental Precautions: Stop spill from entering drains or bodies of water. Contamination travels fast through drains to sensitive wildlife.
Cleanup Methods: Sweep up with a wet cloth or absorbent material, avoid dry sweeping or compressed air. Dispose collected material in a sealed bag or container for hazardous waste pickup.
Handling: Wear gloves and safety goggles, avoid inhaling dust. Weigh amounts carefully, since the color stains hands and benches quickly. Work in a fume hood if possible.
Storage: Keep container tightly closed, stored away from light and moisture. Keep far from sources of ignition, acids, and oxidizers. Use clear, sealed labeling, and store with other organic chemistry reagents, not with food or animal feed.
Engineering Controls: Work in a fume hood or a well-ventilated area. Avoid building up dust in the lab because it settles in unreachable places.
PPE: Use gloves, safety glasses or goggles, and lab coats. Respirators should be available if dust formation gets out of hand.
Hygiene: Wash hands after use. Remove contaminated clothing immediately because powders like this hitchhike onto shared surfaces or home clothes.
Appearance: Orange-red powder
Odor: Faint, chemical-like
Melting Point: Decomposes before boiling
Solubility: Soluble in water and alcohol, less so in most non-polar solvents
Stability: Stable under normal conditions, but avoid heat and strong oxidizing agents. It remains one of those chemicals that never seems to degrade on the shelf, yet reacts quickly with lab metals.
Reactivity: Reacts with strong oxidizers, acids, or bases.
Chemical Stability: Stable under cool, dry conditions; poorly stored material can clump or degrade. Users forget that sunlight and humid air speed up this process.
Hazardous Decomposition: Produces oxides of nitrogen and carbon if burned or exposed to strong heat.
Acute Toxicity: Irritation to skin and eyes; inhaling dust can trigger coughing and breathing difficulty. Reports on luckier users say mild headaches, but more sensitive people might get nausea or dizziness.
Chronic Exposure: Not enough data for cancer risk, though persistent handling without protection traces on skin can lead to allergies or sensitization.
Routes of Exposure: Inhalation and skin absorption. Lab coats and gloves don’t block all chance of contact, so avoid eating or drinking around it.
Persistence and Degradability: Does not break down easily in the environment.
Bioaccumulation Potential: There’s risk it builds up in fish or aquatic insects — environmental monitoring in research labs picked up traces around unused drains and runoff.
Ecotoxicity: Fish and amphibians are particularly sensitive; wastewater treatment does not fully remove it, creating additional risk for zones downstream from discharge points.
Waste Disposal: Collect all waste, including gloves and spill cloths, in sealed bags marked as hazardous.
Drain Disposal: Should never go down the sink, even in tiny amounts, since municipal wastewater treatment fails to catch all of it.
Incineration: Use chemical incinerators with afterburners and scrubbers to prevent harmful gases.
UN Number: Recognized as hazardous for shipping.
Packaging: Ship in tightly sealed, labeled containers that can’t easily break or leak.
Transport Hazard Class: Treat as toxic solid — couriers and handlers should use gloves.
Environmental Hazard: Mark as dangerous for water; accidental releases in transit can have long-term consequences on nearby soils or drainage.
Lab Safety Rules: Most schools, companies, and government agencies require it to be handled only by trained personnel.
Workplace Exposure Limits: No established TLV or short-term exposure maximum, but most labs recommend minimal exposure and strong ventilation.
Environmental Regulations: Many regions prohibit release into public sewers and require tracking and documentation for disposal.
