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Author: Subject: How fast does Diethyl Ether form Peroxides? Reuse Ether Indefinitely
LuckyWinner
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[*] posted on 30-8-2020 at 11:08
How fast does Diethyl Ether form Peroxides? Reuse Ether Indefinitely


i checked other threads already and no clear answers were given.

assume you have 250ml of diethyl ether,
made by sulfuric acid and ethanol,
neutralized with naoh solution,
dried over CaCl, and
re-distilled at 35-39C.

this solution is stored in a brown bottle at -18C
with a GL45 plastic thread, blue cap.

how long can this be stored in the freezer till dangerously high levels
of peroxides form that will detonate upon
-movement
-extraction evaporation
-general handling


I plan to use this ether to extract aldehydes from solutions.
this ether will then be distilled in a water bath and recollected
to yield the aldehyde inside the evaporaration flask.

how can this ether be reused, cleanly and safely?

?simply store it over CaCl like before and reuse indefinitely?

I know KoH is used to prevent peroxide formation but
just a bit of water in the ether will cause the KoH to spread
all around the bottle and polymerize my aldehyde once in contact..

had this happen, ether had yellowish precipitate and
caused my aldehyde solution to turn pink/purple upon contact.
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[*] posted on 30-8-2020 at 13:28


Diethyl ether doesn't form peroxides that quickly - you should store it over some FeSO4 in order to minimize the rate in which it does. Stored in a cool environment without access to oxygen it should last long years. If you're concerned about the peroxide formation, test your Et2O using KI and starch.
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[*] posted on 30-8-2020 at 23:09


I have Et2O for over 10 years and it still has no detactable peroxides. I store it in a glass bottle, with a cap with an aluminium foil liner.
Where I live, Et2O is sold OTC in little glass bottles of 100 ml to the general public. I never heard or read about explosion of such a bottle. People are warned about its extreme flamability. There is a remark on the bottle that ether can form peroxide, but no big fuzz is made about that. If it really were a big risk, then this product certainly would not be sold to the general public OTC.

If you intend to use the ether for distillation to dryness, then I would first treat it with some reducing agent, just to be sure. Iron(II) salts indeed are suitable for this.




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[*] posted on 31-8-2020 at 02:26


It also depends what you are using the ether for.
If i was using it to wash lubricating oil + dust off old clocks or something I'd not worry about peroxides.
When I distilled the dirty ether to recover the solvent , the oil + dirt would be left behind along with any peroxides.
But the peroxides would (very probably) be so dilute that, even if they decomposed, it wouldn't matter.

Having said that, in the circumstances, I'd use acetone or "petroleum ether".

The classic way to prevent peroxidation was to keep some copper gauze in the bottle.I have no idea how well this worked.
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[*] posted on 31-8-2020 at 03:10


Put some copper wire or such into it, this prevents formation of peroxides.
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[*] posted on 31-8-2020 at 04:39


You can get a lifetime supply of BHT on eBay for <$10. https://www.ebay.com/sch/i.html?_from=R40&_trksid=p20476...

Most suppliers sell diethyl ether (or any other solvent prone to forming peroxides) with 1-50 ppm BHT as a peroxide inhibitor. It shouldn't interfere with your reactions since it's in such a small concentration, but you can always freshly distill it and then add additional BHT if you're recycling your solvent.

[Edited on 8-31-2020 by monolithic]
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Maurice VD 37
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[*] posted on 31-8-2020 at 07:09


What is BHT ?
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[*] posted on 31-8-2020 at 09:50


Quote: Originally posted by Maurice VD 37  
What is BHT ?

Wikipedia has a short description, basically it's used to prevent formation of organic peroxides in solvents. https://en.wikipedia.org/wiki/Butylated_hydroxytoluene#React...

If you look at non-HPLC peroxide forming solvents like diethyl ether or 1,4-dioxane on Sigma Aldrich, etc. they will note that it is sold as solvent with several ppm BHT. You can see an example here, it's sold with 1 ppm BHT. https://www.sigmaaldrich.com/catalog/product/sial/296082?lan...
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[*] posted on 31-8-2020 at 11:16


I have 7 years old aluminum bottles of ether and I just recently used it for extraction. All commercial products contain inhibitors because they are practically free and prevent peroxidation, and as I refill the used ether back to the bottle and it is only a small amount I used, the concentration of inhibitors remain decent for pretty long.

Fancy sidenote: the ether bottles were still completely full after years of storage in hot warehouse. Aluminum is impermeable and apparently the plastic stopper is so thick and/or lined with such plastic that it pretty much prevents leaching. I also found a bottle of toluene which was apparently evaporated by most part, but I found out that other person using the warehouse had used up the toluene for some random low-value occupation, probably cleaning car parts or something. Pity, as there was unrefined thinner solvent next to it, and he had to use up the purified, fractional distilled one.
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