MSDS List Commentary for P-Hydroxybenzoic Acid

Identification

Chemical Name: P-hydroxybenzoic acid
Synonyms: 4-Hydroxybenzoic acid, para-hydroxybenzoic acid
Chemical Formula: C7H6O3
Molecular Weight: 138.12 g/mol
Recommended Use: Intermediary for pharmaceuticals, preservatives, and polymer production
Recognized Appearance: White crystalline powder with a faint odor
Industries Served: Pharmaceutical synthesis, cosmetic preservatives, plastic manufacturing

Hazard Identification

Hazard Classes: Irritant to eyes, skin, and respiratory tract
Main Risks: Eye redness and pain, skin discomfort, coughing, throat irritation
Exposure Concerns: Individuals regularly handling powders risk skin and eye contact; inhalable dust forms with frequent transferring
Label Elements: Exclamation mark pictogram aligns with chemical irritation
Critical Symptoms: Associated redness, swelling, and short-term discomfort upon contact or inhalation

Composition / Information on Ingredients

Main Ingredient: P-hydroxybenzoic acid (>99%)
CAS Number: 99-96-7
Impurities: Trace residual solvents or related aromatic compounds depending on synthesis route, typically less than 1%
Physical Form: Solid, homogeneous powder

First Aid Measures

Eye Contact: Rinse eyes with gentle stream of water for several minutes; seek medical attention for persistent irritation
Skin Contact: Wash exposed area with soap and water, remove contaminated clothing
Inhalation: Move to fresh air; respiratory symptoms like coughing or discomfort typically resolve quickly
Ingestion: Rinse mouth, seek medical advice if significant quantities swallowed
Workplace Practices: Immediate access to eyewash stations and emergency showers where large-scale handling occurs

Fire-Fighting Measures

Suitable Extinguishing Media: Water spray, foam, dry chemical, carbon dioxide
Special Hazards: Combustion releases irritating fumes, including carbon oxides
Protective Equipment: Firefighters use self-contained breathing apparatus
Fire Behavior: Dust dispersions ignite at high temperature, commonly above 540°C
Response Concerns: Nearby combustibles and dust accumulation escalate incident severity

Accidental Release Measures

Personal Precautions: Minimize dust formation, ventilate area
Cleanup Techniques: Collect spilled material with damp cloth or vacuum using HEPA filter
Disposal: Deposit in chemical waste container compatible with aromatic acids
Environmental Release: Do not allow runoff into stormwater drains; collect residues even from hard-to-reach crevices
Workplace Training: Teams trained to control dust, avoid open sweeping or forced air

Handling and Storage

Handling: Use closed transfer systems where possible, avoid direct contact and production of airborne particles
Storage: Store in tightly sealed containers, cool and dry conditions, away from oxidizers and strong bases
Segregation: Dedicated acid storage cabinets reduce risk of incompatibility reactions
Container Materials: P-hydroxybenzoic acid tolerates glass, some robust plastics, coated metals
Worker Training: Emphasize routine use of gloves, safety goggles, and good housekeeping

Exposure Controls and Personal Protection

Engineering Controls: Local exhaust at powder weighing, enclosed process equipment
Personal Protection: Chemical splash goggles, acid-resistant gloves, laboratory coats or coveralls
Respiratory Protection: Dust mask or particulate respirator above occupational exposure limits
Hygiene Measures: Wash hands after handling, prohibit food and drink in process area
Facility Practice: Routine inspection of ventilation systems, regular environmental monitoring for airborne particulates

Physical and Chemical Properties

Appearance: White or off-white crystalline powder
Melting Point: Range between 213-216°C
Odor: Negligible aromatic scent
Solubility: Low in cold water, greater in hot water and common polar organic solvents
Vapor Pressure: Practically nonexistent at room temperature
Partition Coefficient: Moderate, log P generally around 1.6
Other Features: Stable under recommended storage, dust formation increases with agitation or sieving of large batches

Stability and Reactivity

Chemical Stability: Highly stable under ambient storage conditions
Incompatibility: Reacts with strong oxidizing agents, bases—releases heat and can splatter
Decomposition: Generates irritating vapors (phenols, carbon monoxide) upon strong heating or combustion
Polymerization: Does not self-react under typical handling
Best Practice: Avoid mixing with other reactive powders or storing close to incompatible materials

Toxicological Information

Acute Effects: Mild to moderate irritation of skin, eyes, and respiratory tract
Chronic Exposure: No significant evidence of carcinogenicity or chronic toxicity in normal workplace handling
LD50 (Oral, Rat): Published values near 2000 mg/kg
Occupational Hazards: Prolonged exposure contributes to dishydrosis or dermatitis in susceptible individuals
Medical Surveillance: Sensitive workers benefit from routine skin and respiratory health checks

Ecological Information

Aquatic Toxicity: Low, but larger releases risk pH alteration in small water bodies
Environmental Persistence: Biodegradable by soil and water microorganisms
Bioaccumulation: Minimal; structure not prone to accumulate in aquatic organisms
Disposal Impacts: Improper discharge into wastewater streams disrupts treatment systems and downstream flora
Research Observation: Good degradation profile under aerobic conditions in standard environmental testing

Disposal Considerations

Recommended Disposal: Incineration in approved facility where feasible; otherwise, landfill consistent with local regulations
Recyclability: Not practical; once contaminated, not suitable for reprocessing
Avoided Practices: No direct flushing to drains, no routine mixing with general garbage
Container Cleaning: Decontaminate before recycling or disposal, adhere to regional hazardous waste handling practices
Industry Commitment: Traceable chain of custody for hazardous residues supports responsible stewardship

Transport Information

UN Number: None assigned for the pure compound
Class: Not regulated as hazardous for land, sea, or air freight under typical shipping scenarios
Packing Group: Not classified as dangerous cargo, special provisions unnecessary for sealed primary containers
Transport Precautions: Handle large drums with equipment to prevent breakage or spills; ship upright inside secondary outer box to avoid loss of integrity
Emergency Advice: Carriers briefed on spill containment; documentation includes hazard brief for in-transit incidents

Regulatory Information

Inventory Status: Listed under major global chemical inventories based on established safety
Workplace Safety: OSHA and other jurisdictional standards apply for dusts and irritants
Environmental Regulations: Waste handlers comply with local and national hazardous waste laws for disposal
Reporting Requirements: No mandatory toxics release inventory reporting for this substance in most major regulatory jurisdictions
Labeling Practices: Shipping packs include required hazard statements, precautionary pictograms, and disposal instructions aligned with best practices in chemical manufacturing