METHYL ETHYL KETONE

Methyl ethyl ketone
(2-Butanone, methyl acetone, MEK, butan-2-one)
CAS 78-93-3

CH₃COCH₂ CH₃

Colorless liquid
bp 80 °C, mp -86 °C
Highly soluble in water (25.6 g/100 mL at 20 °C)

Sweet/sharp odor detectable at 2 to 85 ppm (mean = 16 ppm)

2.5 (air = 1.0)

71.2 mmHg at 20 °C

-9 °C

516 °C

LD₅₀ oral (rat) 2737 mg/kg

LD₅₀ skin (rabbit) 6480 mg/kg

LC₅₀ inhal (rat) 23,500 mg/m³(8 h)

PEL (OSHA) 200 ppm (590 mg/m³)

TLV-TWA (ACGIH) 200 ppm (590 mg/m³)

STEL (ACGIH) 300 ppm (885 mg/m³)

Highly flammable

The acute toxicity of methyl ethyl ketone is low. Exposure to high concentrations can cause headache, dizziness, drowsiness, vomiting, and numbness of the extremities. Irritation of the eyes, nose, and throat can also occur. Methyl ethyl ketone is considered to have adequate warning properties.

Repeated or prolonged skin exposure to methyl ethyl ketone can cause defatting of the skin, leading to cracking, secondary infection, and dermatitis. This compound has not been found to be carcinogenic or to show reproductive or developmental toxicity in humans. Methyl ethyl ketone has exhibited developmental toxicity in some animal tests.

Methyl ethyl ketone is extremely flammable (NFPA rating = 3), and its vapor can travel a considerable distance to an ignition source and "flash back." MEK vapor forms explosive mixtures with air at concentrations of 1.9 to 11% (by volume). Carbon dioxide or dry chemical extinguishers should be used for MEK fires.

Fires and/or explosions may result from the reaction of methyl ethyl ketone with strong oxidizing agents and very strong bases.

Methyl ethyl ketone should be handled in the laboratory using the "basic prudent practices" described in Chapter 5.C, supplemented by the additional precautions for dealing with extremely flammable substances (Chapter 5.F). In particular, MEK should be used only in areas free of ignition sources, and quantities greater than 1 liter should be stored in tightly sealed metal containers in areas separate from oxidizers.

In the event of skin contact, immediately wash with soap and water and remove contaminated clothing. In case of eye contact, promptly wash with copious amounts of water for 15 min (lifting upper and lower lids occasionally) and obtain medical attention. If methyl ethyl ketone is ingested, obtain medical attention immediately. If large amounts of this compound are inhaled, move the person to fresh air and seek medical attention at once.

In the event of a spill, remove all ignition sources, soak up the methyl ethyl ketone with a spill pillow or absorbent material, place in an appropriate container, and dispose of properly. Respiratory protection may be necessary in the event of a large spill or release in a confined area.

Excess methyl ethyl ketone and waste material containing this substance should be placed in an appropriate container, clearly labeled, and handled according to your institution's waste disposal guidelines.

The information in this LCSS has been compiled by a committee of the National Research Council from literature sources and Material Safety Data Sheets and is believed to be accurate as of July 1994. This summary is intended for use by trained laboratory personnel in conjunction with the NRC report Prudent Practices in the Laboratory: Handling and Disposal of Chemicals. This LCSS presents a concise summary of safety information that should be adequate for most laboratory uses of the title substance, but in some cases it may be advisable to consult more comprehensive references. This information should not be used as a guide to the nonlaboratory use of this chemical.

Copyright 1995 National Academy of Sciences. All rights reserved.