Peroxide-Forming
Materials
Peroxides
are very unstable and some chemicals that can form them
are commonly used in laboratories. This makes peroxide-forming
materials some of the most hazardous substances found in
a lab. Peroxide-forming materials are chemicals that react
with air, moisture, or impurities to form peroxides. The
tendency to form peroxides by most of these materials is
greatly increased by evaporation or distillation. Organic
peroxides are extremely sensitive to shock, sparks, heat,
friction, impact, and light. Many peroxides formed from
materials used in laboratories are more shock sensitive
than TNT. Just the friction from unscrewing the cap of a
container of an ether that has peroxides in it can provide
enough energy to cause a severe explosion.
Use and Storage of Peroxide-Formers
- Do not open the chemical container if peroxide formation
is suspected. The act of opening the container could
be sufficient to cause a severe explosion. Visually
inspect liquid peroxide-forming materials for crystals
or unusual viscosity before opening. Pay special attention
to the area around the cap. Peroxides usually form upon
evaporation, so they will most likely be formed on the
threads under the cap.
- Date all peroxide forming materials with the date
received, and the expected shelf life. Chemicals such
as diisopropyl ether, divinyl acetylene, sodium amide,
and vinylidene chloride should be discarded after three
months
- Store all peroxide-forming materials away from heat,
sunlight, and sources of ignition. Sunlight accelerates
the formation of peroxides.
- Secure the lids and caps on these containers to discourage
the evaporation and concentration of these chemicals.
- Never store peroxide-forming materials in glass containers
with screw cap lids or glass stoppers. Friction and
grinding must be avoided. Also, never store these chemicals
in a clear glass bottle where they would be exposed
to light.
- Contamination of an ether by peroxides or hydroperoxides
can be detected simply by mixing the ether with 10%
(wt/wt) aqueous potassium iodide solution - a yellow
color change due to the oxidation of iodide to iodine
confirms the presence of peroxides. Small amounts of
peroxides can be removed from contaminated ethers via
distillation from lithium aluminum hydride (LiAlH-4-),
which both reduces the peroxide and removes contaminating
water and alcohols. If you notice crystal formation
in the container or around the cap, do not attempt to
open or move the container. Call the Department of Environmental
Health and Safety at 274-4351 for proper disposal.
- Never distill an ether unless it is known to be free
of peroxides.
List
of Peroxide-Formers available from University of Kentucky
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