Acetic anhydride

  • Acetyl oxide
  • Ethanoic anhydride
  • Acetic acid anhydride
Formula
(CH3CO)2O
Structure
Description
Clear, colorless liquid with a strong, pungent, sour vinegar-like odor, lachrymator.
Uses
In manufacture of acetyl compound, cellulose acetates, acetylizer and solvent in examining wool fat, glycerol, fatty & volatile oils, resins, detection of rosin, in organic synthesis, eg as dehydrating agent in nitrations, sulfonations and other reactions where removal of water is necessary.

Registry Numbers and Inventories.
CAS
108-24-7
EC (EINECS/ELINCS)
203-564-8
EC Index Number
607-008-00-9
EC Class
Flammable; Harmful; Corrosive
R 10 20/22 34
S 26 36/37/39 45
RTECS
AK1925000
RTECS class
Primary Irritant
UN (DOT)
1715
Merck
13,57
Beilstein/Gmelin
385737
Beilstein Reference
4-02-00-00386
EPA OPP
44007
Swiss Giftliste 1
G-1619
Canada DSL/NDSL
DSL
US TSCA
Listed
Austrailia AICS
Listed
New Zealand
Listed
Japan ENCS (MITI)
Listed
Korea ECL
Listed

Properties.
Formula
C4H6O3
Formula mass
102.09
Melting point, °C
-73
Boiling point, °C
139.9
Vapor pressure, mmHg
4 (20 C)
Vapor density (air=1)
3.52
Saturation Concentration
3950 (0.4%); 5260 ppm (0.53%) at 20 C (calculated)
Evaporization number
0.46 (butyl acetate = 1)
Odor Threshold Odor threshold 0.56 mg/m3
Critical temperature
333
Critical pressure
39.48
Density
1.08 g/cm3 (20 C)
Solubility in water
Slowly soluble
Viscosity
0.971 cp @ 15C
Surface tension
32.7 g/s2 @ 20 C
Refractive index
1.3904 (20 C)
Dielectric constant
20.7 (19 C)
Heat of vaporization
52.0 kJ/mol
Heat of combustion
-1805 kJ/mol

Hazards and Protection.
Storage
Protect against physical damage. Store in a cool, dry well-ventilated location, away from any area where the fire hazard may be acute. Outside or detached storage is preferred. Separate from incompatibles. Containers should be bonded and grounded for transfers to avoid static sparks. Storage and use areas should be No Smoking areas. Use non-sparking type tools and equipment, including explosion proof ventilation. Keep away from water. This material is corrosive to steel, galvanized iron, copper and copper alloys. Containers of this material may be hazardous when empty since they retain product residues (vapors, liquid); observe all warnings and precautions listed for the product.
B3 D1A E
Handling
Remove contaminated clothing and wash before reuse. Do not allow water to get into the container because of violent reaction. Ground and bond containers when transferring material. Use spark-proof tools and explosion proof equipment. Do not breathe dust, vapor, mist, or gas. Do not get in eyes, on skin, or on clothing. Empty containers retain product residue, (liquid and/or vapor), and can be dangerous. Avoid contact with heat, sparks and flame. Use with adequate ventilation. Discard contaminated shoes. Do not pressurize, cut, weld, braze, solder, drill, grind, or expose empty containers to heat, sparks or open flames. Keep from contact with moist air and steam.
Protection
Eyes: Wear appropriate protective eyeglasses or chemical safety goggles as described by OSHA's eye and face protection regulations in 29 CFR 1910.133 or European Standard EN166. Skin: Wear impervious protective clothing, including boots, gloves, lab coat, apron or coveralls, as appropriate, to prevent skin contact. Rubber and neoprene are recommended materials for personal protective equipment.
Respirators
If the exposure limit is exceeded and engineering controls are not feasible, a full facepiece respirator with organic vapor cartridge may be worn up to 50 times the exposure limit or the maximum use concentration specified by the appropriate regulatory agency or respirator supplier, whichever is lowest. For emergencies or instances where the exposure levels are not known, use a full-facepiece positive-pressure, air-supplied respirator. WARNING: Air purifying respirators do not protect workers in oxygen-deficient atmospheres.
Small spills/leaks
Absorb spill with inert material, (e.g., dry sand or earth), then place into a chemical waste container. Avoid runoff into storm sewers and ditches which lead to waterways. Clean up spills immediately, using the appropriate protective equipment. Remove all sources of ignition. Use a spark-proof tool. Provide ventilation. Do not expose spill to water. Spill may be neutralized with lime. Cover with material such as dry soda ash or calcium carbonate and place into a closed container for disposal. A vapor suppressing foam may be used to reduce vapors.
Stability
Stable under normal shipping and handling conditions. Combines vigorously or explosively with water.
Incompatibilities
Water, steam, mineral acids, oxidizing materials, alcohols, or amines may cause violent reaction. Contact with strong caustics will cause violent reaction and spattering. Corrosive to copper, brass, bronze, and iron.
Decomposition
Carbon monoxide, irritating and toxic fumes and gases, carbon dioxide.

Fire.
Flash Point,°C
49
Autoignition, °C
330
Upper exp. limit, %
10.3
Lower exp. limit, %
2.7
Fire fighting
Wear a self-contained breathing apparatus in pressure-demand, MSHA/NIOSH (approved or equivalent), and full protective gear. During a fire, irritating and highly toxic gases may be generated by thermal decomposition or combustion. Water Reactive. Material will react with water and may release a flammable and/or toxic gas. Use water spray to keep fire-exposed containers cool. Wear appropriate protective clothing to prevent contact with skin and eyes. Wear a self-contained breathing apparatus (SCBA) to prevent contact with thermal decomposition products. Containers may explode in the heat of a fire. May ignite or explode on contact with steam or moist air. Extinguishing media: Use dry sand or earth to smother fire. If water is the only media available, use in flooding amounts. DO NOT USE WATER! Do NOT use straight streams of water.
Fire potential
Moderately flammable.
Hazards
Above flash point, vapor-air mixtures are explosive within flammable limits noted above. Sealed containers may rupture when heated. Vapors can flow along surfaces to distant ignition source and flash back. A violent exothermic reaction occurs with water. Sufficient heat may be produced to ignite combustible materials. Sensitive to static discharge.
Combustion products
Irritating vapors are generated when heated.
Health
3
 
Flammability
2
 
 
Reactivity
1
 

Health.
Exposure limit(s)
TLV: 5 ppm; 21 mg/m3 (as TWA) (ACGIH 1993-1994). OSHA PEL: TWA 5 ppm (20 mg/m3) NIOSH REL: C 5 ppm (20 mg/m3) NIOSH IDLH: 200 ppm
Poison_Class
3
Exposure effects
Effects may be delayed. Prolonged skin contact may be painless and cause redness and subsequently a white appearance of the skin accompanied by wrinkling. Skin burns may be delayed. Persons with pre-existing skin disorders or eye problems, or impaired respiratory function may be more susceptible to the effects of the substance.
   Ingestion
May cause severe and permanent damage to the digestive tract. Causes gastrointestinal tract burns. May cause perforation of the digestive tract. May be harmful if swallowed. Ingestion of large amounts may cause CNS depression. May cause systemic effects.
   Inhalation
Harmful if inhaled. Causes severe irritation of upper respiratory tract with coughing, burns, breathing difficulty, and possible coma. Causes chemical burns to the respiratory tract. May cause lung damage. Aspiration may lead to pulmonary edema. Vapors may cause dizziness or suffocation. May cause systemic effects. May cause burning sensation in the chest.
   Skin
Contact with skin causes irritation and possible burns, especially if the skin is wet or moist. Prolonged skin contact may be painless with reddening of the skin followed be a white appearance of the skin. Skin burns may be delayed. May cause cyanosis of the extremities. May cause skin rash (in milder cases), and cold and clammy skin with cyanosis or pale color.
   Eyes
Eye damage may be delayed. Contact with liquid is corrosive to the eyes and causes severe burns. When substances becomes wet or comes in contact with moisture of the mucous membranes, it becomes an irritant. May cause chemical conjunctivitis and corneal damage.

First aid
 
   Ingestion
Do NOT induce vomiting. If victim is conscious and alert, give 2-4 cupfuls of milk or water. Never give anything by mouth to an unconscious person. Get medical aid immediately.
   Inhalation
Get medical aid immediately. Remove from exposure to fresh air immediately. If breathing is difficult, give oxygen. DO NOT use mouth-to-mouth respiration. If breathing has ceased apply artificial respiration using oxygen and a suitable mechanical device such as a bag and a mask.
   Skin
Get medical aid. Immediately flush skin with plenty of soap and water for at least 15 minutes while removing contaminated clothing and shoes. Wash clothing before reuse. Discard contaminated clothing in a manner which limits further exposure. If water-reactive products are embedded in the skin, no water should be applied. The embedded products should be covered with a light oil.
   Eyes
Get medical aid immediately. Do NOT allow victim to rub or keep eyes closed. Extensive irrigation is required (at least 30 minutes).

Transport.
UN number
1715
Response guide
Hazard class
8
Packing Group
II
 
USCG CHRIS Code
ACA
 
11 Organic anhydrides
HS Code
2915 24 00
 
Std. Transport #
4931304
 
IMO Chemical Code
17
IMO Pollution Category
D
IMO Hazard code
S