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Common Name: Methylacetoacetate.
Chemical Name: Methyl 3-oxobutanoate.
CAS Number: 105-45-3.
Molecular Formula: C5H8O3.
Physical Appearance: Clear, colorless liquid with a characteristic sweet odor.
Uses: Manufacturers often turn to methylacetoacetate as a building block for pharmaceuticals, agrochemicals, and flavors. Its presence in the lab or on an industrial site means workers will regularly encounter it during synthesis or formulation work.
GHS Classification: Flammable liquid, Irritant.
Signal Word: Warning.
Hazard Statements: It catches fire easily. The vapor may irritate eyes or skin if people come into direct contact with it or breathe it in.
Routes of Entry: Inhalation, skin and eye contact, ingestion possible in high-risk environments.
Symptoms of Exposure: Headaches, dizziness, skin redness, eye watering, sometimes nausea for folks working with larger quantities.
Component: Methylacetoacetate nearly always shows up as pure or with minor impurities, so people seldom need to worry about mixed exposures in most work settings.
Purity: Typically over 98% in commercial samples.
Impurities: Trace amounts of related esters or solvents can show up depending on how carefully it’s made and stored.
Inhalation: People who’ve breathed the vapors should move to fresh air. Trouble breathing calls for medical help.
Skin Contact: Any spills on hands or exposed skin should get rinsed off with plenty of soap and water. Sensitive folks or those with open wounds face higher risk, so they should take care.
Eye Contact: Eyes need gentle rinsing with water for many minutes, sometimes with eyelids held open, to flush out the chemical.
Ingestion: Drinking water or rinsing the mouth helps if someone accidentally swallows it, but going to a doctor is the safest move, especially if any symptoms show up.
Suitable Extinguishing Media: Foam, dry chemical powder, carbon dioxide.
Hazardous Combustion Products: As this chemical burns, it can make carbon monoxide and carbon dioxide.
Firefighting Advice: Those fighting fires involving methylacetoacetate should wear gear that includes a self-contained breathing apparatus. Closed containers may build up pressure and burst, so cooling them with water spray often helps.
Special Risks: If tanks or big storage drums heat up, they may explode.
Personal Precautions: Good ventilation matters, and workers need gloves, eye protection, and sometimes face shields when cleaning up leaks or spills to avoid breathing in vapors or touching their skin or eyes.
Environmental Precautions: People need to avoid letting methylacetoacetate run off into drains, sewers, lakes, or streams because it can upset aquatic life.
Cleanup Methods: Small spills get soaked up with sand or absorbent materials, but bigger leaks call for a proper chemical spill kit and safe waste disposal measures to avoid breathing in harmful fumes or touching the skin.
Handling: Avoid contact with skin, eyes, and clothing, and use only with adequate ventilation. Keeping food and drinks out of work spaces where methylacetoacetate is handled helps to minimize risks.
Storage: Store methylacetoacetate in cool, well-ventilated places away from sources of ignition such as open flames or sparks. Metal drums or glass bottles work well as storage containers. Sealing containers tightly after every use helps keep vapors from escaping, and storing them away from strong oxidizers cuts down on the chance of unexpected reactions.
Engineering Controls: Fume hoods or local exhaust ventilation work best for people who handle this chemical day in and day out.
Personal Protective Equipment: Nitrile or neoprene gloves, chemical splash goggles or face shields, and lab coats shield the skin and eyes from exposure.
Respiratory Protection: If workplace air tests show high vapor levels, a respirator with organic vapor cartridges is a must.
Workplace Hygiene: Workers should wash hands and face after handling methylacetoacetate and remove any contaminated clothing before leaving the area.
Physical State: Liquid.
Color: Colorless to pale yellow.
Odor: Sweet, fruity.
Boiling Point: About 170°C.
Melting Point: Roughly -39°C.
Flash Point: About 63°C (closed cup).
Density: Around 1.05 g/cm³.
Solubility: Mixes well with organic solvents; only slightly soluble in water.
Vapor Pressure: Moderate at room temperature, so fumes can spread in the workspace.
Chemical Stability: On its own and kept cool, methylacetoacetate holds up well over time.
Conditions to Avoid: High temperatures, open flames, or contact with oxidizing agents can trigger dangerous reactions or catch fire.
Hazardous Reactions: Mixing with strong oxidizers sometimes causes violent reactions. Prolonged storage in poorly sealed containers can boost risk of evaporation or accidental release.
Decomposition Products: Heating or burning produces carbon monoxide and carbon dioxide.
Acute Toxicity: Swallowing large amounts or breathing in concentrated vapors can trigger headaches, dizziness, or nausea. High exposures rarely occur outside labs or factories with poor ventilation.
Skin Irritation: Direct exposure to undiluted methylacetoacetate irritates most people after a short time.
Eye Irritation: Vapors in the air, or a splash, cause watering, redness, and discomfort.
Long-term Effects: Long-term health data on this compound isn't as robust as some other industrial chemicals, but routine safe practices keep risk low for most workers.
Aquatic Toxicity: Accidental spills into lakes or rivers can damage aquatic life, particularly fish and smaller organisms sensitive to chemicals.
Persistence: Methylacetoacetate breaks down in water and air with time, but surface spills in a factory or during transport threaten immediate harm to local wildlife.
Bioaccumulation: Current studies suggest little risk of methylacetoacetate building up in fish or animals, but repeated spills can cause problems in a local ecosystem.
Waste Disposal: Most waste handlers collect methylacetoacetate in labeled containers and send it for incineration at chemical waste facilities. Pouring it down the drain or dumping it in landfills contaminates water and soil.
Precautions for Disposal: Proper disposal keeps workers, the environment, and the surrounding community safe. Workers handling disposal need the same gloves and goggles they use during transfer or cleanup.
Transport Classification: Flammable liquid under international and domestic transport guidelines.
Packaging Advice: Tightly sealed drums or bottles lower the risk of leaks or spills while in transit. Shipments must travel with hazard labeling so transport workers spot dangers right away.
Spill Response in Transit: Those working in shipping need emergency kits for small leaks and fire extinguishers as part of their standard equipment.
Hazard Labeling: Workers and safety officers should make sure the chemical comes with GHS-compliant hazard pictograms and warning statements.
Workplace Rules: Many safety agencies, including OSHA and international bodies, require clear records of volume, storage, and worker training. Inspectors sometimes check for emergency eyewash stations, ventilation, and personal protection gear.
Environmental Rules: Local governments often set limits for chemical discharge into water, so facility managers need to keep close watch on waste and air emissions.
