NIOSH Publication No. 2005-151:

NIOSH Pocket Guide to Chemical Hazards

September 2005

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] See: 79209
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
(See protection)
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
Important additional information about respirator selection
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   See ICSC CARD: 0507