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Common name: 1,4-Benzenediol Other names: Hydroquinone, p-Dihydroxybenzene CAS number: 123-31-9 Typical appearance: White crystalline solid with a faint aromatic odor Uses: Photography, polymerization inhibitor, skin lightening creams, dye manufacturing Chemical formula: C6H6O2 Synonyms often show up on labels; it pays to know these for any workplace or lab situation involving this chemical.
Main classification: Acute toxicity (oral, dermal, inhalation), eye irritation, skin sensitization Hazard symbols: Skull and crossbones (toxic), exclamation mark (irritant), environment (aquatic toxicity) Health risks: Skin and eye irritation, allergic skin reactions, possible organ damage with prolonged exposure, may cause respiratory tract irritation Environmental risks: Harmful to aquatic life, danger of bioaccumulation Users should understand the seriousness of these risks, as repeated unprotected exposure can lead to lasting complications.
Single ingredient: 1,4-Benzenediol purity above 98% in most preparations Other possible components: <1% impurities like phenol derivatives from manufacturing processes Mixed formulations: Cosmetic or technical grades may include stabilizers or buffering agents in trace amounts Contamination or improper labeling can add risk, especially where handling pure chemicals and knowing what is in your jar matters.
Inhalation: Move to fresh air and monitor for breathing difficulty, coughing, or dizziness Skin contact: Wash immediately with plenty of water and soap, remove contaminated clothing Eye contact: Rinse eyes cautiously with water for several minutes; seek medical attention if irritation persists Ingestion: Rinse mouth, do not induce vomiting, seek prompt medical care First aid supplies and training are vital; quick action makes all the difference when accidents happen.
Suitable extinguishing media: Water spray, dry chemical, foam, carbon dioxide Specific hazards: Releases toxic fumes (carbon monoxide, carbon dioxide) in fire Protective equipment: Full-face respirator and chemical-resistant clothing Cool exposed containers with water; firefighters need to protect themselves from fumes and splashing Knowing your flammables and keeping extinguishing agents nearby reduces risk in storage rooms and labs with this compound.
Personal precautions: Wear gloves, protective goggles, NIOSH-approved respirators Environmental precautions: Prevent entry into waterways, soil, and drains to avoid contamination Cleanup methods: Sweep up spilled material without generating dust, place in suitable containers for disposal Decontamination: Wash spill area thoroughly; ventilate confined spaces Many accidents come from rushing or lack of preparation; proper tools and containment help limit environmental and personal harm.
Handling: Use in well-ventilated areas, minimize contact and inhalation, avoid creating dust Storage: Keep in tightly sealed containers, store in cool, dry, well-ventilated spaces away from heat and incompatible substances (oxidizers, bases) Segregation: Do not store with strong acids or oxidizing agents Labeling: Clearly label containers to avoid confusion; mishandling can lead to severe consequences in even small-scale settings.
Exposure limits: Occupational exposure limit (OEL) values set by OSHA and ACGIH (TWA 2 mg/m3) Engineering controls: Local exhaust ventilation, enclosed systems Personal protective equipment: Chemical-resistant gloves, goggles, lab coat or chemical apron, NIOSH-approved respirators for high concentrations Hygiene: No eating or drinking near work areas; wash hands after use Commitment to protective measures saves health in environments where these fine powders and crystals are handled daily.
Physical state: Solid Color/Odor: White crystals, faint odor Melting point: Around 172°C Boiling point: 287°C (decomposes) Solubility: Miscible in hot water, alcohol, and ether Vapor pressure: Low at room temperature pH: Weakly acidic in solution Having a handle on these properties helps with safe handling and predicting chemical compatibility during process changes.
Stability: Stable in cool, dry storage conditions Reactivity: Reacts with strong oxidizers, bases, and can auto-oxidize in air to form brown products Decomposition products: Releases toxic gases (phenols, carbon oxides) under heating or fire Storage: Protect from moisture and light to prevent degradation Ignoring stability often leads to ruined chemicals or messy and dangerous reactions, so regular inspection reduces surprises down the road.
Short-term effects: Irritation of eyes, skin, respiratory tract; headache, nausea possible with inhalation Long-term effects: Allergic skin reactions, possible kidney and liver damage, methemoglobinemia from significant or chronic exposure Routes of entry: Inhalation, ingestion, dermal absorption Toxicity data: Oral LD50 in rats around 320 mg/kg Personal stories of mishaps in graduate labs have highlighted why respecting these adverse effects is more than a paperwork requirement.
Aquatic toxicity: Highly toxic to aquatic organisms; even small amounts can have serious environmental impact Persistence: Does not readily break down in the environment; potential to accumulate Bioaccumulation: Recognized potential to build up in tissues of aquatic life Disposal and accidental release into water vital to prevent, as once in the ecosystem, the damage may last decades and spread far beyond the initial spill site.
Disposal methods: Incinerate in approved facility; do not pour into drains, watercourses, or regular trash Contaminated packaging: Handle as chemical waste; triple rinse and puncture containers Follow local and federal waste disposal regulations—chemicals dumped down the drain do not just disappear, they come back as public health problems or environmental crises.
Proper shipping name: 1,4-Benzenediol Transport hazard class: Class 6.1 (toxic substances) Packing group: III (moderate hazard) Environmental hazard: Marine pollutant Shipping containers require proper labeling and handling; everybody from the truck driver to the dock worker needs clear hazard cues for safety.
Chemical subject to reporting and monitoring under federal and local chemical safety regulations, including TSCA and REACH Workers and users must follow hazard communication rules, including safety training and access to Safety Data Sheets Employers responsible for exposure monitoring, reporting accidental releases, and ensuring all staff know the risks and required protections Regulations exist out of necessity; years of experience with industrial chemicals show that skipping even minor rules creates big headaches for companies, workers, and communities alike.
