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MESITYL OXIDE
ICSC: 0814
Peer-Review Status: 26.03.1998 Validated
4-Methyl-3-penten-2-one
Methyl isobutenyl ketone 
CAS #: 141-79-7 RTECS #: SB4200000
UN #: 1229
EC #: 606-009-00-1
EINECS #: 205-502-5
    Formula: C6H10O / (CH3)2C=CH-COCH3
Molecular mass: 98.1

TYPES OF
HAZARD /
EXPOSURE
ACUTE HAZARDS / SYMPTOMS      PREVENTION      FIRST AID / FIRE FIGHTING
FIRE Flammable.  NO open flames, NO sparks and NO smoking.  Use AFFF, alcohol-resistant foam, powder, carbon dioxide. 
EXPLOSION Above 25°C explosive vapour/air mixtures may be formed.  Above 25°C use a closed system, ventilation and explosion-proof electrical equipment.  In case of fire: keep drums, etc., cool by spraying with water. 
 
EXPOSURE   STRICT HYGIENE!   
Inhalation Cough. Dizziness. Lethargy. Headache. Shortness of breath. Sore throat.  Use ventilation, local exhaust or breathing protection.  Fresh air, rest. Artificial respiration may be needed. Refer for medical attention. 
Skin MAY BE ABSORBED! Dry skin. Redness. Pain. Further see Inhalation.  Protective gloves. Protective clothing.  Remove contaminated clothes. Rinse and then wash skin with water and soap. Refer for medical attention . 
Eyes Redness. Pain.  Wear face shield or eye protection in combination with breathing protection.  First rinse with plenty of water for several minutes (remove contact lenses if easily possible), then refer for medical attention. 
Ingestion Abdominal cramps. Further see Inhalation.  Do not eat, drink, or smoke during work.  Rinse mouth. Give a slurry of activated charcoal in water to drink. Refer for medical attention . 

SPILLAGE DISPOSAL
PACKAGING & LABELLING
Personal protection: self-contained breathing apparatus. Ventilation. Collect leaking liquid in sealable containers. Absorb remaining liquid in sand or inert absorbent. Then store and dispose of according to local regulations. Do NOT wash away into sewer.   
EC Classification
Symbol: Xn; R: 10-20/21/22; S: (2)-25 
UN Classification
UN Hazard Class: 3; UN Pack Group: III 
GHS Classification
 

EMERGENCY RESPONSE SAFE STORAGE
Transport Emergency Card: TEC (R)-130.
NFPA Code: H3; F3; R0. 
Fireproof. Separated from strong oxidants. Cool. Keep in the dark. 

IMPORTANT DATA
Physical State; Appearance
COLOURLESS VISCOUS LIQUID WITH CHARACTERISTIC ODOUR. DARKENS ON STANDING. 

Physical dangers
No data. 

Chemical dangers
The substance can presumably form explosive peroxides. Reacts violently with strong oxidants. Attacks many plastics. 

Occupational exposure limits
TLV: 15 ppm, 60 mg/m³ as TWA; 25 ppm, 100 mg/m³ as STEL; (ACGIH 1997). 

Routes of exposure
The substance can be absorbed into the body by inhalation of its vapour, through the skin and by ingestion. 

Inhalation risk
A harmful contamination of the air can be reached rather quickly on evaporation of this substance at 20°C. 

Effects of short-term exposure
The substance is irritating to the eyes, skin and respiratory tract. Exposure far above the OEL could cause unconsciousness. 

Effects of long-term or repeated exposure
The liquid defats the skin. The substance may have effects on the liver, kidneys and lungs. 


PHYSICAL PROPERTIES ENVIRONMENTAL DATA
Boiling point: 130°C
Melting point: -41.5°C
Relative density (water = 1): 0.865
Solubility in water, g/100ml at 20°C: 3.3 (moderate)
Vapour pressure, kPa at 20°C: 1.2
Relative vapour density (air = 1): 3.4
Relative density of the vapour/air-mixture at 20°C (air = 1): 1.03
Flash point: 25°C c.c.
Auto-ignition temperature: 340°C
Explosive limits, vol% in air: 1.4-7.2
Octanol/water partition coefficient as log Pow: 1.7  
The substance is harmful to aquatic organisms. 

NOTES
Other melting points: -59°C.
Use of alcoholic beverages enhances the harmful effect.
Depending on the degree of exposure, periodic medical examination is indicated.
Check for peroxides prior to distillation; eliminate if found. 

ADDITIONAL INFORMATION
 

IPCS
International
Programme on
Chemical Safety
WHO ILO EC Prepared in the context of cooperation between the International Programme on Chemical Safety and the European Commission
© IPCS 2004-2012
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    See Also:
       Toxicological Abbreviations