Product Name: Methyl Ethyl Ketone Peroxide
Common Synonyms: MEKP
CAS Number: 1338-23-4
Recommended Uses: Initiator and hardener for polyester resins, fiber-reinforced composites, automotive body repair, boat building, and other industrial processes.
Supplier/Manufacturer: Company contact information and emergency phone numbers listed directly on the container label
Emergency Phone: Chemtrec, local emergency services
Classification: Organic peroxide, type D; acute toxicity, category 4; skin corrosion/irritation, category 1; serious eye damage/eye irritation, category 1; specific target organ toxicity, single exposure, category 3
Signal Word: Danger
Hazard Statements: Causes severe skin burns and eye damage; harmful if inhaled, swallowed, or in contact with skin; may cause respiratory irritation; fire and explosion hazard.
Pictograms: Corrosive (GHS05), Explosive (GHS01), Health Hazard (GHS07)
Precautionary Statements: Avoid release to the environment; keep away from heat/sparks/open flames/hot surfaces; avoid all sources of ignition; wash hands thoroughly after handling; wear protective gloves/protective clothing/eye protection/face protection.
Hazards Not Otherwise Classified: Reacts violently with reducing agents, acids, amines, metals, and organic material.
Substance: Methyl Ethyl Ketone Peroxide
Chemical Formula: C8H18O6
CAS Number: 1338-23-4
Concentration Range: 30%–60% MEKP in phlegmatizer (often dimethyl phthalate or similar dilute solution)
Other Ingredients: Solvent or plasticizer (example: dimethyl phthalate, CAS 131-11-3, 40%–70%)
Impurities/Additives: Water and stabilizers up to several percent to minimize decomposition risk
Eye Contact: Rinse cautiously with water for several minutes; remove contact lenses if present; continue rinsing; seek immediate medical attention; risk of blindness if not treated rapidly.
Skin Contact: Immediately remove contaminated clothing; rinse skin with plenty of water and soap; seek medical attention for burns; do not use solvents to remove from skin.
Inhalation: Move person to fresh air; avoid breathing vapors or fumes; if experiencing symptoms such as cough, dizziness, headache, shortness of breath, seek medical attention.
Ingestion: Do not induce vomiting; rinse mouth with water; seek medical help immediately; risk of corrosive injury to mouth, throat, esophagus.
General Advice: Call physician or poison center if ill effects develop; show product label or safety data sheet to medical personnel; provide oxygen if breathing is difficult; perform CPR if not breathing.
Suitable Extinguishing Media: Water spray, foam suitable for organic peroxides, dry chemical; never use carbon dioxide or halogenated extinguishers as they may react with product.
Specific Hazards: Releases oxygen when heated or contaminated, feeding combustion; risk of explosion; high temperatures or shock can cause violent decomposition; toxic fumes of carbon oxides, ketones, and acids possible.
Protective Equipment for Fire Fighters: Full chemical protective clothing and self-contained breathing apparatus; fire may spread rapidly.
Special Techniques: Cool containers with water from a distance; evacuate area; control run-off to prevent environmental contamination; remove undamaged containers from fire area if safe.
Explosion Data: May detonate if heated or subject to severe mechanical shock.
Personal Precautions: Evacuate non-essential personnel; keep ignition sources away; ventilate area; use non-sparking tools; wear chemical splash goggles, gloves, and protective clothing.
Environmental Precautions: Prevent further leakage or spillage if safe; avoid discharge into drains, water courses, or soil.
Containment Methods: Absorb spill with inert material (such as sand, vermiculite); avoid combustible absorbents; collect spill with non-sparking equipment and place in suitable container for disposal.
Cleaning Methods: Wash spill site after material pick-up; ventilate the area aggressively; do not flush to sewer.
Decontamination Notes: Decompose diluted residue with reducing agent such as sodium thiosulfate under controlled conditions; neutralize acidic residue before discarding.
Handling Precautions: Keep container tightly closed; avoid contact with heat, sparks, open flames; never return unused material to original container; always open containers slowly to release internal pressure; use only outdoors or in well-ventilated area.
Safe Storage Conditions: Store away from acids, bases, reducing agents, and combustibles; keep separate from other chemicals; refrigerate if possible (do not allow freezing); store away from direct sunlight; maximum storage temperature usually 30°C (86°F) unless otherwise specified.
Container Requirements: Use container specifically designed for organic peroxides and clearly labeled; do not store in glass or metal containers unless recommended by supplier.
Incompatibilities: Strong acids, alkalis, amines, metal salts, oxidizing/reducing agents, accelerators.
Other Recommendations: Ground and bond transfer containers to prevent static electricity build-up; keep storage area clearly labeled and well-ventilated; emergency showers and eye wash stations close to work area.
Occupational Exposure Limits: No OSHA PEL established for MEKP; ACGIH TLV: 0.2 ppm TWA as organic peroxide; supplier recommendations should be followed.
Engineering Controls: Local exhaust ventilation preferred; use explosion-proof electrical equipment; fume hood for laboratory use.
Protective Equipment: Chemical splash goggles, face shield, acid-resistant gloves (nitrile, neoprene), long-sleeved protective clothing, flame-resistant lab coat where needed
Respiratory Protection: Approved respirator (organic vapor/acid gas type) during handling of large volumes or spill response
Hygiene Measures: Wash hands, face, and contaminated skin thoroughly after handling; remove contaminated clothing and wash before reuse; do not eat, drink, or smoke in work area.
Environmental Controls: Avoid environmental release by using secondary containment in work and storage areas.
Appearance: Clear to pale yellow liquid
Odor: Pungent or acetone-like
Odor Threshold: Not established
pH: Acidic
Melting/Freezing Point: Below 0°C (solvent dependent)
Boiling Point: Decomposes before boiling
Flash Point: Above 60°C as formulated; pure MEKP can be lower
Evaporation Rate: Slower than ether
Flammability: Not itself flammable but enhances burning of combustibles
Upper/Lower Flammability Limit: No data for mixtures; pure MEKP UEL: 21%, LEL: 1.7%
Vapor Pressure: Less than 10 mmHg at 20°C
Vapor Density: Greater than air
Solubility: Miscible with most organic solvents, slightly soluble in water
Partition Coefficient (n-octanol/water): Not available
Autoignition Temperature: Above 350°C (practically, decomposes first)
Decomposition Temperature: Around 60°C–90°C (dependent on formulation)
Viscosity: Variable, generally low to moderate, depending on dilution
Stability: Unstable under heat, contamination, impact, or friction; requires stabilizers
Hazardous Reactions: Violent decomposition with acids, bases, metals, strong reducing agents, or accelerators
Conditions to Avoid: Heat, sparks, open flames, direct sunlight, strong shock, and contamination with incompatible materials
Incompatible Materials: Iron, copper, brass, acids, strong bases, amines, and combustibles
Hazardous Decomposition Products: May release flammable gases, carbon oxides, methyl ethyl ketone, organic acids; decomposition may be explosive
Polymerization: Will not occur; runaway reaction possible with unsuitable catalysts
Acute Toxicity: Harmful if swallowed, inhaled, or absorbed through skin; estimated LD50 (oral, rat): 484 mg/kg; causes severe burns
Chronic Effects: Potential for long-term skin sensitization and chronic respiratory irritation
Skin Contact: Causes severe irritation, chemical burns, possible blistering
Eye Contact: Moderate to severe eye injury or blindness if not rinsed immediately
Inhalation: Throat and lung irritation, cough, headache, dizziness, risk of pulmonary edema
Ingestion: Corrosive injury to mouth, esophagus, gastrointestinal tract, risk of systemic toxicity
Carcinogenicity: Not classified as a carcinogen by IARC, NTP, or OSHA
Reproductive Toxicity: No human data but caution is justified
Mutagenicity: No clear evidence in literature
Other Relevant Effects: May exacerbate asthma and other respiratory disorders; exacerbates dermatitis in sensitive individuals
Ecotoxicity: Toxic to aquatic organisms at moderate concentrations; risk of long-term effects in the aquatic environment; LC50 (fish, 96h): 44 mg/L (MEKP, estimated); EC50 (daphnia, 48h): 16 mg/L
Persistence and Degradability: Decomposes in environment to carbon dioxide, water, organic acids and alcohols; breaks down more slowly in soil
Bioaccumulation: Expected to be low due to reactivity and instability in water and soil
Mobility in Soil: High mobility due to solubility in water
Other Adverse Effects: Strong oxidizer; can change the chemistry of bodies of water rapidly; fish kills possible after accidental spill
Waste Handling: Do not dispose of in landfill or sewage; minimize quantity for disposal; follow local, state, federal regulations strictly
Neutralization: Dilute carefully with water and decompose with reducing agents (e.g., sodium thiosulfate) under controlled conditions
Container Disposal: Rinse thoroughly, neutralize residues, and dispose of as hazardous chemical waste; never reuse empty containers for food or drink
Disposal of Large Quantities: Only specialized hazardous waste contractors should handle bulk residues
Regulatory Requirements: U.S. RCRA hazardous waste number D003 (reactive waste)
UN Number: 3105 or 3109 (depending on formulation)
Proper Shipping Name: Organic Peroxide type D, liquid (Methyl Ethyl Ketone Peroxide with phlegmatizer)
Transport Hazard Class: 5.2 (Organic peroxide)
Packing Group: II
Labels: Organic Peroxide, Corrosive
Special Provisions: Do not transport above specified temperatures; keep packages upright and stable; separate from foodstuffs; only trained personnel should handle
Environmental Hazards: Marine pollutant; do not allow to enter drains or waterways during shipment
Emergency Transport Response Guide: ERG Guide 145
OSHA: Hazardous under Hazard Communication Standard; requires detailed labeling, employee training, Safety Data Sheets on site
EPA: Listed under CERCLA due to potential environmental hazards; subject to release reporting
SARA Title III: Section 311/312 hazard categories: Immediate (acute), Delayed (chronic), Fire, Reactive
TSCA: MEKP included on inventory
Other Regulations: Subject to strict controls for storage and use; international transport regulated by ADR, IMDG, IATA
Right-to-Know: Listed on U.S. state hazardous substance lists (California, Massachusetts, Pennsylvania, New Jersey)
Worker Safety Regulations: Routine use of PPE, proper training, and emergency preparedness plans required by law in facilities handling significant quantities
