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vmelkon
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the dangers of diethyl ether
From what I gather, on exposure to oxygen and uv-light, diethyl ether peroxide forms.
It seems to me that if you take away one or the other, then you can store diethyl ether forever.
Why do laboratories store in brown bottles instead of a cardboard box?
Why bother putting in NaOH? What does it even do? Dissolve in the ether or does it absorb water?
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Dr.Bob
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Quote: Originally posted by vmelkon  | From what I gather, on exposure to oxygen and uv-light, diethyl ether peroxide forms.
Why do laboratories store in brown bottles instead of a cardboard box?
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The ether leaks out of cardboard boxes...
Sorry, I had to do that. If you keep ether out of oxygen, that makes peroxide formation impossible. Also, light is needed to form the free radicals
needed to make the peroxide, so the brown bottles filter out the UV needed for radical formation.
Most fire codes forbid storing paper and cardboard with flammable chemicals, with the idea that they fuel fires.
NaOH might help absorb water. BHT and other anti-oxidants can slow down perioxide formation and/or buildup. But they also can mess up many
reactions. According to some lab legends, water will somewhat slow down the build up of peroxides, not sure why, myself. In my experience, ethyl
ether will keep for a year or more if opened but keep under nitrogen, without detectable peroxides by test paper. Sealed cans and bottles should be
good for longer, but will start forming peroxides if opened or the cap leaks.
The bigger hazard for peroxides are more complex ethers like diisopropyl or di-tert-butyl ether, which form them much more readily according to the
literature. See Brethrick's for details.
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UnintentionalChaos
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I remember hearing that NaOH precipitates the initial hydroperoxide as it's sodium salt. Iron and supposedly copper also seem to be fairly potent
inhibitors of peroxide formation.
Department of Redundancy Department - Now with paperwork!
'In organic synthesis, we call decomposition products "crap", however this is not a IUPAC approved nomenclature.' -Nicodem
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entropy51
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The formation and dangers of ether peroxides is one of the favorite subjects on Science Madness. It's been discussed before in many other threads.
Did you even try to search for existing threads before starting a new one, or do you just know that your ideas are so original that they must be novel
and deserving of a new thread?
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Adas
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NaOH is used to destroy the peroxides formed.
Rest In Pieces!
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vmelkon
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| Quote: Originally posted by entropy51 | The formation and dangers of ether peroxides is one of the favorite subjects on Science Madness. It's been discussed before in many other threads.
Did you even try to search for existing threads before starting a new one, or do you just know that your ideas are so original that they must be novel
and deserving of a new thread?
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I did search but I didn't find exactly what I was looking for.
This one seemed nice since there is a link to wikimedia
https://www.sciencemadness.org/whisper/viewthread.php?tid=14...
Anyway, the point is that is there a better way than keeping it in a brown bottle 1 month and testing it for peroxide or just throwing away anything 1
month old. There was one site that said produce the ether and use it right away to avoid storage.
They make it sound like there is no better solution.
I didn't find an explanation to why NaOH should be added.
As an amateur, I could just fill a 710 mL PETE coke bottle all the way to the top with diethyl ether. Is this a good idea or is it dangerous?
[Edited on 28-1-2012 by vmelkon]
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entropy51
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| Quote: Originally posted by vmelkon | As an amateur, I could just fill a 710 mL PETE coke bottle all the way to the top with diethyl ether. Is this a good idea or is it dangerous?
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Storing ether in a coke bottle does not sound like a good idea. It doesn't even sound amateurish. It just
sounds dumb.
Is there a better way than just storing it in a brown bottle? Of course there is. Fill the head space of the bottle with nitrogen, add an inhibitor
of peroxide formation, and store the bottle in a dark cabinet.
The peroxides that form upon short storage in ethyl ether are only dangerous when distilled to dryness. Higher ethers are another story altogether.
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Nicodem
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Thread Moved
29-1-2012 at 03:24 |
Hexavalent
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Unfortunately, ether peroxides are colourless and it is almost impossible to tell if they are present visually. To do so, add some KI crystals to a
test tube and dissolve in some water. Then, add 3ml of ether and look for a pink/purple colour in the ether layer. If peroxides are present, then they
will oxidise the iodide ions to elemental iodine which will migrate to the ether layer and thus produce the said purple colour.
"Success is going from failure to failure without loss of enthusiasm." Winston Churchill
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ScienceSquirrel
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| Quote: Originally posted by Hexavalent | | Unfortunately, ether peroxides are colourless and it is almost impossible to tell if they are present visually. To do so, add some KI crystals to a
test tube and dissolve in some water. Then, add 3ml of ether and look for a pink/purple colour in the ether layer. If peroxides are present, then they
will oxidise the iodide ions to elemental iodine which will migrate to the ether layer and thus produce the said purple colour.
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Solutions of iodine in diethyl ether are brown!
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entropy51
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| Quote: Originally posted by Hexavalent | | Unfortunately, ether peroxides are colourless and it is almost impossible to tell if they are present visually. To do so, add some KI crystals to a
test tube and dissolve in some water. Then, add 3ml of ether and look for a pink/purple colour in the ether layer. If peroxides are present, then they
will oxidise the iodide ions to elemental iodine which will migrate to the ether layer and thus produce the said purple colour.
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The standard test also calls for acidification of the KI solution with dilute HCl. A positive test is
yellow to brown. You only get a purple to black color if some starch is also added to the KI.
The misinformation just keeps on coming.
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woelen
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Another misinformation is that diethylether forms peroxides very easily. Over here in the Netherlands we can buy diethylether over the counter in
drugstores without any problem and this already is true for many many years. All kinds of people use this as a relatively non-toxic (somewhat smelly)
way of degreasing things and cleaning things. People without any chemistry background store the diethyl ether in bottles with screw caps for years and
years and never ever did I hear or read about a peroxide explosion in a household. This only needs to happen once in order to get diethyl ether
removed from the shelves in every Dutch store.
The only real issue with diethyl ether is its extreme flammability and people are warned for that.
It becomes another matter when diethyl ether is dried and distilled. In such cases there is a chance of buildup of concentration of peroxides, but in
normal household applications, and also when used as a solvent, I do not expect any serious issues. I also have diethyl ether around, a 1 liter
bottle, which is 80% full and I have this around for more than 5 years already.
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Dr.Bob
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I agree that diethyl ether is not a huge hazard, but I would also guess that most sold for consumer use (in the US it is sometimes available as
starter fluid) probably has some sort of inhibitor in it as well. I have seen sealed cans of ether for anesthesia which were probably 30+ years old
that still appeared to be full and undamaged, although it would be hard to detect peroxides inside a can. But if the ether is still there, not much
air could have gotten in, or the ether would have evaporated. So if the ether is either 1) sealed well, 2) inhibited with BHT or the like, 3)
contains water, base, or other peroxide destroying compounds or 4) is keep in the dark, then it is likely fine for many years.
The bigger risk is with anhydrous, distilled ether which does not contain any inhibitor and is not sealed well, and is in the light. Then it will
slowly form them, but as you stated, they are most hazardous if concentrated, especially under heat. I would be careful with any ether like that
which is over 1-2 years old.
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dann2
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Also used as starter fluid in Europe.
I should know, I have a vehicle that has a diethyl ether addiction!
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Hexavalent
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What did I say about ether tests? See 4.43.
http://www.youtube.com/watch?v=hlR3UWLyxEU&feature=g-use...
"Success is going from failure to failure without loss of enthusiasm." Winston Churchill
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AirCowPeaCock
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Say I wanted to make diethyl ether peroxide, would I add concentrated hydrogen peroxide set out in the sun? Or should I add HCl as a catalyst like
AP?
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woelen
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You don't want to make diethyl ether peroxide if you value your hands and other body extensions.
But from a theoretical point of view one of course can speculate about this reaction. I don't think that the mechanism of formation of ether peroxide
resembles the mechanism for acetone peroxide. So, I do not expect that addition of HCl will accelerate formation of ether peroxide.
The mechanism is described in this picture:
Wikipedia also has an article about this subject.
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entropy51
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Please don't quote boob tube as a
scientific reference. We do have standards here, you know. Try Vogel's book in the forum library.
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BromicAcid
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Back when I was in the business of hazardous waste disposal we often ran across old-very old containers of diethyl ether. Very often the usual
storage container was an aluminum / tin / or stainless steel can with a plastic or plastic coated lid. Standard procedure for these older cans was to
invert the bottle then take a can opener and puncture the bottom of the can. Theory was that any wet peroxide crystals at the bottom are less
sensitive than any dry peroxide crystals. A peroxide test strip was then dipped into the can and the contents tested.
Ninety percent (out of a hundred or so cans) tested negative for peroxides. Of the remaining 10 cans 9 gave weak peroxide results. That leaves the
one in a hundred can. Upon puncturing the bottom and testing the contents the peroxide strip which is normally white turned black. (This was >400
ppm if I recall correctly) Since it was being dumped into a 55 gallon drum of flammable waste and seeing as there was <250 mL of ether I dumped it
into the drum after calling over a co-worker to show off the intensity of the response (dilution is the solution).
Without a second thought I tossed the can the ten or so feet into the other 55 gallon drum which was accumulating empty bottles and such. There was a
resounding *Bang* and the sound of glass falling. Inspecting the drum containing the empty bottles many of the bottles inside were pulverized more
than would be expected and a cloud hung out near the drum. The aluminum bottle that the ether had been inside was tore to pieces. Based on the
evidence I did find it looked like the explosion had been concentrated in the head of the can. My theory being that it was not tightly screwed down
and allowed a constant infusion of air with expulsion of ether as the barometric pressure and temperature changed throughout the day. And there the
crystals grew.
These units were from college labs, most of the students never having been instructed in proper ether usage. Actually on the whole from my own
experience in college handling technique is pretty far from most people's mind in early chemistry labs since it seems like everyone and their brother
are required to take those labs. Considering how badly those bottles were mistreated it's amazing we only had one 'bomb' amongst all the bottles
which we trashed.
The lesson being that it can happen, but with proper handling and packaging the dangers can be subdued, at least in part.
@vmelkon: However I do find your statement "Why do laboratories store in brown bottles instead of a cardboard box?" strange, I have never seen diethyl
ether in glass bottles, only metal cans and metal pour-outs. And some of those cans were fairly old as well. BTW, standard practice 'back in the
day' for disposing of old ether cans was to take them out in the field and shoot them.
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entropy51
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Thanks for sharing your experience BromicAcid. It's invaluable to have someone with your vast practical experience on the forum.
My experience with ethyl ether has been similar. I've used ether out of prevously unopened copper-coated cans that was very old, and never had a
positive peroxide test.
I guess I do worry about amateur chemists who make their own ether, or distill it from starting fluid, and store it in glass bottles, perhaps without
adding an inhibitor.
One place I worked had a couple of cases of very old Eastman-Kodac isopropyl ether, in brown glass bottles. We regularly used it for TLC solvent
systems and never had any problems, but I was more scared of that stuff than I was of the phosgene.
What does concern me is that everyone defecates concrete blocks about ether, but never gives a thought to isopropanol, benzyl alcohol, or cyclohexanol
and several others. My bottles of these reagents sometimes give strongly positive peroxide tests, and I treat them with acidified ferrous sulfate to
remove peroxides before disilling them. There are also literature references to the hazards of these reagents that I beleive I have posted in other
threads.
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AirCowPeaCock
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 . Maybe I should do that before I distil any alcohols next time!
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Vogelzang
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https://www.hyperlab.info/inv/index.php?s=6bcf9808b6dd476be3...
(scroll down and click Продолжить )
http://www.sciencemadness.org/talk/viewthread.php?tid=12158#...
[Edited on 4-2-2012 by Vogelzang]
[Edited on 4-2-2012 by Vogelzang]
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Funkerman23
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Iffy connection but fair enough.
[Edited on 4-2-2012 by Funkerman23]
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entropy51
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Well it won't work for water soluble alcohols such as isopropyl. Dry stannous chloride works for those.
And I have never heard of a peroxide problem with ethanol. It's easy enough to test them for peroxides. The real problem is distilling them to
dryness, assuming, God forbid, that no crystals have formed in the bottom of the bottle. Peroxides are generally not the problem that people think
they are, as Woelen has discussed above.
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AirCowPeaCock
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It would still be a good idea, considering I do it quite frequently
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entropy51
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I hope you don't mean distilling to
dryness.
Better to remain silent and appear a fool than to open your mouth and remove all doubt.
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