NIOSH Pocket Guide to Chemical Hazards

Methyl acetate CAS 79-20-9
CH3COOCH3 RTECS AI9100000
Synonyms & Trade Names
Methyl ester of acetic acid, Methyl ethanoate
DOT ID & Guide
1231 129
Exposure
Limits
NIOSH REL: TWA 200 ppm (610 mg/m3) ST 250 ppm (760 mg/m3)
OSHA PEL: TWA 200 ppm (610 mg/m3)
IDLH 3100 ppm [10%LEL] Conversion 1 ppm = 3.03 mg/m3
Physical Description
Colorless liquid with a fragrant, fruity odor.
MW: 74.1
BP: 135°F
FRZ: -145°F
Sol: 25%
VP: 173 mmHg
IP: 10.27 eV

Sp.Gr: 0.93
Fl.P: 14°F
UEL: 16%
LEL: 3.1%

Class IB Flammable Liquid: Fl.P. below 73F and BP at or above 100F.
Incompatibilities & Reactivities
Nitrates; strong oxidizers, alkalis & acids; water [Note: Reacts slowly with water to form acetic acid & methanol.]
Measurement Methods
NIOSH 1458; OSHA 7
See: NMAM or OSHA Methods
Personal Protection & Sanitation
Skin: Prevent skin contact
Eyes: Prevent eye contact
Wash skin: When contaminated
Remove: When wet (flammable)
Change: No recommendation

First Aid (See procedures)
Eye: Irrigate immediately
Skin: Water flush promptly
Breathing: Respiratory support
Swallow: Medical attention immediately
Respirator Recommendations NIOSH/OSHA
Up to 2000 ppm: (APF = 10) Any chemical cartridge respirator with organic vapor cartridge(s)*/(APF = 10) Any supplied-air respirator*
Up to 3100 ppm: (APF = 25) Any supplied-air respirator operated in a continuous-flow mode*/(APF = 50) Any chemical cartridge respirator with a full facepiece and organic vapor cartridge(s)/(APF = 50) Any air-purifying, full-facepiece respirator (gas mask) with a chin-style, front- or back-mounted organic vapor canister/(APF = 25) Any powered, air-purifying respirator with organic vapor cartridge(s)*/(APF = 50) Any self-contained breathing apparatus with a full facepiece/(APF = 50) Any supplied-air respirator with a full facepiece
Emergency or planned entry into unknown concentrations or IDLH conditions: (APF = 10,000) Any self-contained breathing apparatus that has a full facepiece and is operated in a pressure-demand or other positive-pressure mode/(APF = 10,000) Any supplied-air respirator that has a full facepiece and is operated in a pressure-demand or other positive-pressure mode in combination with an auxiliary self-contained positive-pressure breathing apparatus
Escape: (APF = 50) Any air-purifying, full-facepiece respirator (gas mask) with a chin-style, front- or back-mounted organic vapor canister/Any appropriate escape-type, self-contained breathing apparatus
Exposure Routes inhalation, ingestion, skin and/or eye contact
Symptoms Irritation eyes, skin, nose, throat; headache, drowsiness; optic nerve atrophy; chest tightness; in animals: narcosis
Target Organs Eyes, skin, respiratory system, central nervous system
See also: INTRODUCTION