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Chemical Name: 3,5-Dimethylpyrazole
Synonyms: 3,5-Dimethyl-1H-pyrazole
CAS Number: 67-51-6
Molecular Formula: C5H8N2
Molecular Weight: 96.13 g/mol
Appearance: White to faintly yellow crystalline powder
Odor: Faint, characteristic
Uses: Often used as an intermediate in chemical synthesis, pesticides manufacturing, and specialty chemical research
GHS Classification: Eye irritation Category 2A, Acute Toxicity Oral Category 4
Label Elements: Signal word “Warning”, Exclamation mark pictogram
Hazard Statements: Causes serious eye irritation, harmful if swallowed
Precautionary Statements: Avoid breathing dust, wash hands thoroughly after handling, wear protective gloves and eye protection
Routes of Exposure: Inhalation, dust contact with skin or eyes, accidental ingestion
Substance: 3,5-Dimethylpyrazole
Concentration: 98–100% (by weight)
Impurities: Minor traces of related pyrazoles or solvents, dependent on synthesis
Inhalation: Move person to fresh air, seek medical attention if symptoms such as coughing or difficulty breathing develop
Skin Contact: Remove contaminated clothing, wash affected area with soap and plenty of water
Eye Contact: Rinse cautiously with plenty of water for at least 15 minutes, remove contact lenses if present, continue rinsing if irritation persists, consult a doctor
Ingestion: Rinse mouth with water, do not induce vomiting unless directed by medical personnel, call for medical assistance if feeling unwell
Suitable Extinguishing Media: Carbon dioxide, dry chemical powder, alcohol-resistant foam
Unsuitable Media: Do not use a strong water jet as it might spread the burning powder
Special Hazards: Emits nitrogen oxides, carbon monoxide, and other toxic fumes during combustion
Firefighter Precautions: Wear full protective clothing and self-contained breathing apparatus, avoid breathing smoke and fumes
Personal Protective Actions: Wear appropriate gloves, goggles, and protective clothing to prevent direct contact
Spill Response: Carefully sweep up spilled powder, minimize dust with damp material, place collected material in closed, labeled containers for disposal
Environmental Precautions: Prevent entry into drains, sewers, and waterways to limit environmental exposure
Area Ventilation: Increase air flow in spill area to disperse dust and fumes during cleanup
Handling Recommendations: Work in a well-ventilated area, avoid inhaling dust or allowing contact with skin and eyes, use only with suitable engineering controls
Safe Storage Conditions: Store in tightly closed containers, keep in a cool, dry, and well-ventilated location away from sources of ignition, incompatible materials like strong oxidizers, acids, or bases
Hygiene Measures: Wash hands thoroughly after handling, do not eat, drink, or smoke during use, keep work clothing separate from household clothing
Engineering Controls: Use local exhaust ventilation or process enclosures to limit airborne dust levels
Eye Protection: Wear chemical splash goggles or face shield
Hand Protection: Select gloves resistant to chemicals, such as nitrile or neoprene
Skin Protection: Use long-sleeve shirts and full-length pants, lab coats when handling powder
Respiratory Protection: Use dust masks or respirators if airborne exposure can’t be controlled below occupational limits, especially during bulk transfers or spill cleanup
Occupational Exposure Limits: No established limits for 3,5-Dimethylpyrazole, but minimize exposure to lowest practical levels
Physical State: Solid
Color: White to light yellow
Odor: Slightly pungent, characteristic
Melting Point: Around 135-139°C
Boiling Point: Not applicable (decomposes before boiling)
Solubility: Moderately soluble in water, highly soluble in organic solvents such as ethanol and acetone
Vapor Pressure: Negligible at ambient temperature
Density: About 1.07–1.1 g/cm³
Chemical Stability: Stable under standard temperature and pressure, sensitive to strong oxidizing agents
Hazardous Reactions: Can react with oxidizers to release toxic gases
Hazardous Decomposition Products: Burning or decomposition produces nitrogen oxides, carbon monoxide, and possible organic fragments
Storage Incompatibility: Avoid contact with strong acids, bases, and oxidizing chemicals
Acute Toxicity: Harmful if swallowed; oral LD50 for rats is moderately low, indicating a need for care during handling
Skin Corrosivity: Not classified as corrosive or irritating to skin, though prolonged contact might cause dryness or rash
Eye Irritation: Documented as irritating to eyes, may cause redness, watering, and discomfort
Chronic Effects: Limited long-term exposure data, best practice treats it as a material of unknown chronic toxicity
Sensitization: No widespread reports of skin or respiratory sensitization, but avoid repeated skin contact just in case
Carcinogenicity/Mutagenicity: No evidence in available literature for carcinogenic action or mutagenic effects, but industry standards advise using with care
Persistence: Not easily biodegradable, may linger in the environment
Ecotoxicity: Limited studies on aquatic life, but pyrazoles as a group often show moderate toxicity to fish and invertebrates
Bioaccumulation: Tends not to strongly bioaccumulate; risk to food chains remains low if managed properly
Environmental Precautions: Don’t allow runoff or disposal to contaminate soil, surface, or groundwater, especially near agricultural ecosystems
Disposal Method: Collect waste in labeled, sealed containers for transfer to licensed hazardous waste facility
Small Amounts: Disperse in a suitable solvent and incinerate at approved sites
Waste Classification: Treat as hazardous chemical waste to comply with local and international regulations, avoid sewage discharge
Contaminated Packaging: Dispose of empty packaging through hazardous waste protocols after triple rinsing or as government guidelines require
UN Number: Not classified as dangerous goods for most modes of transport
Transportation Hazards: Solid organic chemicals travel best in sealed, secure containers, protected from moisture and accidental exposure
Environmental Hazards During Transport: No labeling required for marine pollutant, but accidental spillage during transit could cause local harm
Chemical Inventory: Listed on key national and international chemical inventories
Labeling: Must follow GHS and workplace hazard communication standards
Occupational Handling Rules: Comply with local worker protection laws for handling hazardous chemicals
Additional Restrictions: Environmental discharge or waste limits apply in most jurisdictions, regular training and documentation of use recommended
