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Chemical Name: p-Phenylenediamine free base
Common Names: 1,4-diaminobenzene
Appearance: Usually white or slightly purple crystalline solid with a faint aromatic odor
Uses: Strong presence in hair dyes, polymer production, rubber chemicals, textile dyes, gasoline additives
CAS Number: 106-50-3
Molecular Formula: C6H8N2
Synonyms: PPDA, para-phenylenediamine
Hazard Classes: Acute toxicity (oral, dermal, inhalation); skin sensitization; eye irritation
GHS Label Elements: Skull and crossbones, exclamation mark
Routes of Exposure: Skin contact, inhalation, ingestion
Main Risks: Allergic reactions, skin irritation, eye damage, respiratory harm; contact dermatitis is common among people exposed through use in hair dye; ingestion brings risk of systemic toxicity
Symptoms: Skin rashes, redness, swelling, difficulty breathing, headache, nausea, potential for methemoglobinemia with substantial exposure
Long-term Effects: Prolonged exposure links to chronic dermatitis and possibly kidney or liver impacts
Main Component: p-Phenylenediamine (usually at purity above 98%)
Impurities: Trace residual aniline, tars, or diaminobenzene isomers, depending on supplier and grade
No stabilizing additives
Inhalation: Move to fresh air; give supplemental oxygen if breathing feels labored; immediate medical attention required for difficulty breathing
Skin Contact: Remove contaminated clothing; rinse skin with running water for 15 minutes; call a doctor if irritation or rash persists
Eye Contact: Rinse eyes gently with lukewarm water for 15 minutes holding lids open; see an ophthalmologist for persistent redness or pain
Ingestion: Rinse mouth; do not induce vomiting; medical attention is critical, as systemic poisoning can develop quickly
Suitable Extinguishing Media: Carbon dioxide, foam, or dry powder extinguishers recommended for solids fires; avoid high-pressure water sprays that might spread contamination
Hazards from Combustion: Burns create toxic fumes, especially carbon monoxide, nitrogen oxides, and aniline vapors; smoke is often acrid
Protective Measures: Firefighters need full gear and positive-pressure SCBA; run-off water from fire efforts can cause environmental harm downstream
Personal Precautions: Wear nitrile gloves, chemical goggles, apron, and proper respirator
Environmental Precautions: Keep product out of drains and waterways; sweep up spills with non-sparking tools
Containment: Avoid dust generation; place waste in tightly closed chemical waste containers; label for hazardous waste disposal
Safe Handling: Use in well-ventilated fume hood; do not eat, drink, or smoke when handling; always wash hands thoroughly after use
Storage Conditions: Store in tightly closed bottles, away from direct sunlight, moisture, and oxidizers; temperature below 30°C recommended; keep container securely labeled
Incompatible Materials: Avoid contact with strong acids, strong bases, and oxidizing agents such as hydrogen peroxide or sodium hypochlorite
Engineering Controls: Local exhaust or fume hood required in lab environments; process handling equipment should minimize dust
Personal Protection: Chemically resistant gloves, splash goggles, lab coat with closed sleeves, appropriate respirator if dust or fumes possible
Exposure Limits: Occupational limits differ by country; ACGIH sets TLV at 0.1 mg/m³ (skin absorption significant)
Hygiene Measures: No food or drink in work area; shower and change clothes after exposure
Physical State: Crystalline powder or flakes
Color: White to pale purple, susceptible to darkening from air oxidation
Melting Point: About 145–147°C
Boiling Point: 267°C (decomposes)
Solubility: Soluble in hot water, alcohol, and ether
Odor: Lightly aromatic or amine-like
Vapor Pressure: Low at room temperature
Chemical Stability: Stable under recommended storage conditions, but prone to oxidation in air
Reactivity: Reacts with strong oxidizers; product may darken or degrade in moist or acidic conditions
Hazardous Decomposition: Yields aniline, nitrogen oxides, and benzene derivatives if burned or heated excessively
Acute Toxicity: Moderate to high acute toxicity by oral, dermal, or inhalation routes
Symptoms: Allergic skin and respiratory reactions common; accidental ingestion brings rapid systemic effects, including dizziness, headache, and cyanosis
Chronic Risk: Long-term skin exposure raises risk for chronic eczema, kidney changes, or methemoglobinemia—hair dye workers and salon staff at increased risk
Sensitization: Sensitizing potential is high, leading to lifelong allergic response in some exposed workers
Aquatic Toxicity: Harmful to aquatic organisms; disrupts fish gill function, impacts plant root systems in runoff
Persistence and Degradability: Degrades slowly in soil and water; can build up in sediment
Bioaccumulation: Tends not to concentrate significantly in higher organisms; still poses risk from repeated low-level exposures in contaminated environments
Effect on Microbes: May alter microbial community in exposed soils, affecting natural breakdown processes
Waste Handling: Treat as hazardous chemical waste; incinerate using facilities equipped for nitrogen compounds; do not landfill with regular garbage
Container Disposal: Rinse and handle containers as hazardous material; avoid releasing residues into wastewater
Regulatory Requirement: Disposal rules defer to national and local hazardous waste authorities; strict record-keeping enforced in many jurisdictions
UN Number: Classified under UN 1673 for shipping
Hazard Class: Often classed as a toxic solid, organic, n.o.s.
Packing Group: II or III, depending on jurisdiction
Labeling: Requires warning for poison and skin sensitization; regulated as Dangerous Goods under ADR, IATA, IMO; restrictions common for air shipment due to acute toxicity
Handling Notes: Shipping containers must be sealed, labeled, and handled only by trained personnel
Chemical Restrictions: Use restricted or banned in cosmetics and hair care in several regions, including parts of the European Union
Worker Protection: Occupational safety rules demand ventilation, protective gloves, and skin monitoring in workplaces
Inventory Listings: Appears on most major chemical inventories such as TSCA, EINECS
Public Health Notices: Government advisories emphasize risk for sensitization, especially in products for direct skin contact; ongoing review for tighter regulation
