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NIOSH Publication No. 2005-151:

NIOSH Pocket Guide to Chemical Hazards

September 2005

Acetic anhydride

CAS
108-24-7

(CH3CO)2O

RTECS
AK1925000
Synonyms & Trade Names

Acetic acid anhydride, Acetic oxide, Acetyl oxide, Ethanoic anhydride
DOT ID & Guide
1715 137

Exposure
Limits

NIOSH REL: C 5 ppm (20 mg/m3)
OSHA PEL†: TWA 5 ppm (20 mg/m3)
IDLH
200 ppm See: 108247
Conversion
1 ppm = 4.18 mg/m3
Physical Description
Colorless liquid with a strong, pungent, vinegar-like odor.
MW: 102.1
BP: 282°F
FRZ: -99°F
Sol: 12%
VP: 4 mmHg
IP: 10.00 eV

Sp.Gr: 1.08
Fl.P: 120°F
UEL: 10.3%
LEL: 2.7%

Class II Combustible Liquid: Fl.P. at or above 100°F and below 140°F.
Incompatibilities & Reactivities

Water, alcohols, strong oxidizers (especially chromic acid), amines, strong caustics [Note: Corrosive to iron, steel & other metals. Reacts with water to form acetic acid.]
Measurement Methods
NIOSH 3506; OSHA 82, 102
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 or contaminated
Change: No recommendation
Provide: Eyewash, Quick drench
First Aid
(See procedures)
Eye: Irrigate immediately
Skin: Water flush immediately
Breathing: Respiratory support
Swallow: Medical attention immediately
Respirator Recommendations
NIOSH/OSHA
Up to 125 ppm:
(APF = 25) Any supplied-air respirator operated in a continuous-flow mode£
(APF = 25) Any powered, air-purifying respirator with organic vapor cartridge(s)£
Up to 200 ppm:
(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 = 50) Any powered, air-purifying respirator with a tight-fitting facepiece and 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
Conjunctivitis, lacrimation (discharge of tears), corneal edema, opacity, photophobia (abnormal visual intolerance to light); nasal, pharyngeal irritation; cough, dyspnea (breathing difficulty), bronchitis; skin burns, vesiculation, sensitization dermatitis
Target Organs
Eyes, skin, respiratory system
See also: INTRODUCTION   See ICSC CARD: 0209

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