Ethyl Ether Safety Alert
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Ethyl ether (a.k.a. diethyl ether) presents an extreme fire
hazard. It is highly volatile and has a flash point of -49°F and a lower explosive limit of
only 1.9% by volume in air. An open beaker of ether on a lab bench next to an
ignition source (e.g., spark from wall outlet, oven relay, etc.) will ignite.
Its density is 2.5 times that of air; therefore, ether vapors can
"fall" from a lab bench to the floor and travel to a spark source
which can result in a flashback to the source. Also, vapors can easily accumulate
in sufficient concentration in a closed space (e.g. refrigerator) to explode
with the slightest spark (e.g. refrigerator condenser comes on). Refrigerated
storage does not suppress the formation of ether vapors.
More important to consider is the fact that, upon exposure
to air and light, ether tends to form unstable peroxides. These compounds will concentrate by
evaporation of the ether and may detonate with a violent explosion when
disturbed by shock or friction. The friction produced by simply unscrewing the
cap of a container of peroxidized ether may cause an explosion. One incident
documented in the literature involved an "empty" 250-cc bottle which
had held ethyl ether that exploded when the lid was loosened.
Some brands of ether are "stabilized" by the
manufacturer. This will be stated on the
label. As long as they are unopened,
stabilized containers of ether are usually OK for about 1-2 years. Once exposed to the air, however, the ether
may form peroxides within a matter of a couple of months. Unstabilized ether may form peroxides in less
than two weeks and must be handled with extreme care. There is no evidence that
refrigerated storage will prevent formation of peroxides.
To prevent fire and explosion hazards associated with ethyl
ether, follow these precautions:
1.
Purchase ether in a quantity that can be used within
12 months.
2.
Date the ether to indicate the date received and the
date the container was opened.
3.
Dispose of any ether that is older than one year.
4.
Dispose of ether remaining in squeeze bottles that
has not been consumed after 2-3 days.
5.
Keep ether in a metal can or amber glass bottle to
prevent its exposure to light.
6.
Store bottles or cans of ether only in approved
explosion-proof flammable cabinets.
7.
Dispose of unused unstabilized ether within 2-3 days
after opening container.
8.
Do not store ether in the laboratory fume hood or in
a household style refrigerator or freezer.
9.
Always use ether in a properly functioning chemical
fume hood.
10. Make sure there are no open flames
or ignition sources present when ether is in use.
If you are ever interested in determining if ether contains
peroxides, you can test it as follows:
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Add 1 ml of freshly prepared 10% potassium iodide
solution to 10 ml of ethyl ether in a 25 ml clear glass- stoppered flask that
has been wrapped to protect it from light.
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Shake for one minute, then let it stand for one
minute.
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Unwrap the flask and view against a white background.
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Yellow color indicates the presence of peroxides.
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