Sciencemadness Discussion Board

Very old Ethyl Ether

angelhair - 19-4-2008 at 20:18

I have a ten year old bottle of ethyl ether that has never been opened, never been taken out of the box, never seen the light of day. I want to open it. Would you open it?

Sauron - 19-4-2008 at 21:32

You are concerned about peroxide formation being present.

Treat the Et20 with anhydrous KOH pellets.

No more peroxides, if any were present. Store it over a few pellets, in a light-tight air-tight container in a cool place.



[Edited on 20-4-2008 by Sauron]

Mr. Wizard - 19-4-2008 at 21:47

Peroxides can form under the threads of the cap, and explode when you open it. Satisfy your curiosity by taking some KI starch paper and moistening it with 1 M HCl and touching it to the thread area. A big blue dark spot means peroxides or at least some sort of oxidizer. The classic case of old ether in the lab = boom and fire. I wouldn't open it if it's very old.

http://ehs.ucdavis.edu/sftynet/sn-23.cfm
added link to safety info

[Edited on by Mr. Wizard]

Sauron - 19-4-2008 at 22:55

The ether (and THF) cans I recall had no threads for exactly that reason. Even the 5 liter cans had small (3/8" or so) sealed necks with a snap cap over. Good practice was to procure sizes convenient to use in one go. Bad practice was to return a partially emptied tin to the shelf. VERY BAD practice was/is to return an almost empty tin to the shelf.

If this container is small, then take the advice and dispose of it.

Small = 1 L or less.

If it's 5 L, then maybe it is worth trying to figure out a protocol to open it, treat for peroxides, and rebottle.

But, in even of a worst case, which explosion and fire would you rather be in?

smuv - 19-4-2008 at 23:40

I think you are fine. To form peroxides ether needs oxygen; the very very small amount of headspace above the ether does not provide enough oxygen to produce much peroxides (assuming the manufacturer did not store the ether under nitrogen as is common). Maybe be careful when you are opening it and test it with KI or similar but if they have never been oppened I would not worry too much.

YT2095 - 20-4-2008 at 01:59

Personally I wouldn`t touch this thing, and get it disposed of professionally.
it`s not a risk I would take.

BromicAcid - 20-4-2008 at 06:56

Big question is the container, is it the standard metal container? Usually those are used because they help inhibit peroxide formation. If the seal is still intact, there are no signs of rust or corrosion, and everything looks fine I don't see a big risk in opening it. Usually in my experience the peroxides are in the bottles that have been opened and improperly stored though it is possible for them to be present in maufacturer sealed bottles it usually takes a long time for them to accumulate to any significant degree.

If you are really worried about taking off the cap and unscrewing the threads to test for peroxides, gently flip the can over and take a bottle opener to the bottom and puncture it then test for peroxides through that hole. You will ruin the can but that is the standard way to do it where I came from.

Nick F - 20-4-2008 at 07:04

1L of ether: £5
Damage caused by raging inferno: more, + death.

Well, that's just the way I see this.

BromicAcid - 20-4-2008 at 07:14

It is quite the inferno too, I wonder if there is a movie on YouTube or something for it, I once saw a can of diethyl ether explode in a safety video and it was pretty impressive. Aditionally I had one explode from peroxides myself, thankfully all the ether was drained out of it at the time, still was impressive though.

I just hardly consider 10 years to be any considerable length of time for an unopened manufacturers bottle.

Sauron - 20-4-2008 at 07:48

Overall I agree, but I think that if is a larger can, unopened, intact then it is worth thinking about how the contents can be accessed, tested, transferred, de-poroxided if necessary and repacked (or used) all under conditions that offer minimal, acceptable levels of hazard.

1. What is the size of the can (volume ether?) If 1 L I'd say, dispose of it.

2. How about making a small puncture for a syringe entry at a point unlikely to be a peroxide buildup point? Remove an aliquot, test with starch-iodide paper. If positive, dispose of it. If not, open it. Purify by standard methods and repackage preferably under N2 or Ar. (Small aerosol cans of inert gas are sold for preserving wines after opening. Check vintners.)

The above is just a suggestion for a protocol.

3. Describe the cap. Screw cap or sealed tin? If former, do not open screw cap till contents have been tested.

Nick F - 20-4-2008 at 16:00

"but I think that if is a larger can"

I just think that any can of old ether has the potential to really ruin your week. If you have any doubt, then why not just buy more?!

I don't know if the dangers of old ether are exagerrated or not, but if there's a risk which can be so easily avoided...

evil_lurker - 20-4-2008 at 16:20

Quote:
Originally posted by Nick F
"but I think that if is a larger can"

I just think that any can of old ether has the potential to really ruin your week. If you have any doubt, then why not just buy more?!

I don't know if the dangers of old ether are exagerrated or not, but if there's a risk which can be so easily avoided...


I've had some unstabilized ether at room temp with a little bit of water and some "head space" in a clear bottle and it hit 25ppm within a few days according to the test strips I was using at the time.

But, some other ether, left in the fridge for a month had no detectable amounts of peroxide.

So its a crap shoot.

But, I tend to agree with the other posters. A bottle of ether is not worth a trip to the ER or worse, lost body parts.

Dispose of it properly.

S.C. Wack - 20-4-2008 at 17:44

Does anyone have an actual documented example of ethyl ether exploding upon opening, not heresay?

woelen - 20-4-2008 at 22:56

I'm also quite reluctant to believe that diethyl ether is that bad. Over here in NL it is an OTC chemical, and it can be purchased in many drugstores. It is used for degreasing all kinds of things, as a much-less toxic alternative to volatile chlorinated hydrocarbons which were used till the mid 80's of the previous century. If there even were only ONE explosion of an ether bottle upon opening, then the product would be taken from the shelves immediately. And I am 100% sure, that 99.9% of the people, who buy this ether, never ever have heard of the peroxide risk (although it is mentioned on the bottle), otherwise they would not want it anymore, given all the chemophobia of the moment.

I do believe though, that the product in NL is stabilized with some other volatile agent (I do not know what). This stabilizer, however, does not affect normal usage of the ether, no residue is left, when the liquid evaporates.

Nicodem - 20-4-2008 at 23:13

Ethyl ether peroxide is liquid and volatile. I can't imagine such a scenario where friction from opening a screwcap would cause it to blow up.
I also find it strangely suspicious that the ether peroxide scareshit is only mediated by propaganda and that is localized to some countries only. Why would ethers be more dangerous in one country than the others? And why the scientific community does not take the incredible dangers of ethers seriously if it is really such a big deal? The only time you hear about dangers of peroxides in academic articles is in the green chemistry ideological papers where the use of a different solvent is being proposed for an old method (and a couple of lab manuals and old papers from the time when oxidation inhibitors were not added to diethyl ether).
I have heard of ethers exploding but it was because of vapors ignited by a spark or palladium, or for example working up reaction mixtures of THF with certain oxidizers like H2O2 causing terrible runaways resulting in serious injury. Yet, I never heard of ethers exploding due to their build up peroxide levels. Them blowing up during distillations is only possible with Et2O since other ethers have a high enough bp for the peroxides to decompose before concentrating (unless vacuum is used).
Throwing away an unopened bottle of ether just because of propaganda sounds a bit strange, especially considering that oxidation inhibitors are added to such solvents. I have regularly used bottles of diisopropyl ether old about 25 years and never even considered any peroxides. Actually I have only heard about this propaganda being reproduced in this forum, never heard about it from real life.

[Edited on 21/4/2008 by Nicodem]

Sauron - 21-4-2008 at 00:28

I generally do not read anything labelled "green chemistry" as the very term sets my teeth on edge.

But the following are not propaganda:

ACS "Prudent Practices"

Various manuals on purification of reagents

Organic Synthesis

and so on.

Diethyl ether is not the worst peroxide former. THF is worse, dioxane is worse. Di-isopropyl ether is perhaps the worst.

The countermeasures are simple. The risk is real but manageable. It is not imaginary.

A German Ph.D. organicker formerly with Dynamit Nobel, and a frequent gues in my house, told me that a colleague of his lost the fingers of both hands and hearly bled to death when a flask he was removing from a rotavap exploded due to peroxides while he was working late at night alone. Because he had lost his fingers he could not dial the phone to summon help. He passed out on the floor. Fortunately a security guard found him in time.

You can dismiss that as anecdotal if you like. But the next time my friend is here shall I get you the name of the hapless chemist? The year that this happened?

I trust my friend, a professional energetics chemist now in senior management, more than I trust your skepticism.

S.C. Wack - 21-4-2008 at 00:48

You are talking about concentration of peroxide by distillation of the more volatile ether, we are talking about opening cans.

Nicodem - 21-4-2008 at 00:59

Sauron, you are misinterpreting what I said. I'm well aware of what happens when you try to distill diethyl ether full of peroxides and I even explicitly mentioned that. If you try to rotavap it under reduced pressure, well, then so much worse since the peroxides will not decompose to any appreciable extent and will accumulate in their entirety. Yet if you distill diisopropyl ether at normal pressure no peroxide will survive to accumulate as the terribly explosive residue.
What I was saying is that the scare of peroxides is crap since nobody considers them as a rational subject but only as some scary ghosts out there to kill you (obviously certain people have a lot of interest in promoting this fear and I don't mean only of the academic green chem parasites). I find it suspiciously strange that the ones who promote this fear usually can't even draw the structure of the peroxides formed. I find the warnings in lab manuals like Vogel's, etc. quite rational (obviously, since they were made by and for chemists), but what I read about peroxides on some less professional hazmat homepages, and even this forum, is straight propaganda (or at least its reproduction).

PS: Ask your guest what kind of a reaction that unfortunate colleague was working up. I'm quite sure he was working up an oxidation reaction where the peroxides formed as side reaction product rather than resulting from using old diethyl ether (unless of course if we are talking about the time before the producers started adding 2,6-di-tert-butyl-4-methylphenol by default as the radical oxidation inhibitor). I have heard of a similar (recent) case involving the use of THF in an oxidation that had as a result a nearly fatal injury of a poor guy rotavaping the worked up reaction (but, as I said in my previous post, this is not related to the peroxides formed from oxygen oxidation of improperly stored ether solvents).

Sauron - 21-4-2008 at 01:14

All right, I take your point. And I agree with you.

Viz., overpriced sylvan as a replacement for THF. I bet sylvan formes peroxides, too, why wouldn't it?

I was all for opening the can, especially if it was more than a trivial size. I said so.

Now, what was the thread author going to do with the ther once opened?

Now or later he was going to use it, and having done, at some point he will want to strip it off. My point was, it would be prudent to test it for peroxides and purify it if any are present. That's all. Destroying peroxides in ether is easy.

[Edited on 21-4-2008 by Sauron]

angelhair - 21-4-2008 at 17:13

2.5L in a Brown bottle. Looks like this is a very polarizing issue. Half of you would take the risk. I'm still 50/50, even though it's not worth the risk.

panziandi - 23-4-2008 at 07:35

I would open the bottle.

I believe that diethyl ether stored in an airtight amber glass bottle in the dark would carry very little risk of forming peroxides. In addition I expect that the diethyl ether would 1) contain a stabilizer and 2) be under nitrogen or its own vapour. Also IIRC traces of ethanol in diethyl ether also inhibits peroxide formation.

I would then test it with perhaps the iodide-starch method then treat accrodingly although I doubt it would give a strong positive result. Also if you are not going to use the full2.5L in 6 months then perhaps consider decanting into smaller more usable bottles or flood the bottle with nitrogen or argon after use.

I have a 500mL bottle of ether to dispense from and I went to use it about a year and half later, the bottle was two thirds filled and i tested for peroxides, I obtained a strong positive test with iodide although I do not worry about it seeping and crystalising around the threads, since the bottle has never been tilted. Before I use this ether I'd treat to destroy the peroxides.

Either way it would be interesting to hear if your ether was peroxide-free it would perhaps clear a lot of the confusion on how sensitive ethers arfe to peroxide formation.

:D

garage chemist - 23-4-2008 at 07:47

There is no danger in opening the bottle, that's for sure!
You're not taking any risk in opening it.
I would not hesistate doing so.
Ethyl ether does not form enough peroxides to be a danger without concentration by distillation.

I would even go as far as saying there's a chance it doesn't contain any peroxides. I once had a nearly empty bottle of Et2O that was over 2 years old, and it was still peroxide free. It was ordinary reagent grade ether. The stabilizer sure does its job.

[Edited on 23-4-2008 by garage chemist]

BromicAcid - 23-4-2008 at 13:29

I have two examples of bottles of ethyl ether exploding. One is relevant and the other only slightly so.

First one, one of my ex-coworkers was working at a cleanout of a college lab down in Texas. There were bottles and cans of diethyl ether 40 years and older in various states of ruin. Procedure for that situation was to walk them out away from people and put them behind a poly shield and hook them to a bottle opener. Which basically seemed to be a drill with an attachement on it to hook it to a bottle cap. It looked like it was cheap but cost a lot of money basically. It also clamped down on the bottom of the container. You stand back a distance and activate the machine with a push button. Slowly it would unscrew the top. I used a machine a few times myself but nothing exploded. On this trip though one did explode. He described it as spectacular, the blast shield held up and the ether pretty much exploded back and up, the field caught on fire, etc. But no one was hurt.

Second example was at a different site where they had plenty of older cans of diethyl ether. Standard procedure is to flip them upside down carefully then use a can opener to puncture a hole at the bottom and test for peroxides. Several of the cans were heavily rusted. Some didn't hardly test at all, light blue on the peroxide strips. Some were blue and others black. No matter the peroxide test we would dump it into the fuels drum, I mean, they were already open. One of those cans that turned pitch black was emptied as usual into the drum. I tossed it about 10 feet into the trash drum and "Bang!" The bottle shot off into the air. When I looked at the bottle the metal neck of it had inverted into the bottle and the metal lid was completely gone and the bottom ripped. It was pretty impressive.

So it can happen without concentration, just takes somewhat extreme situations. Though the care that people took for ether at my college (or lack thereof) makes it seem like it could happen much faster if the person handling the fresh ether is a lackwit.

[Edited on 4/23/2008 by BromicAcid]

Nicodem - 25-4-2008 at 00:13

I coincidently stumbled at this paper while searching for something else and thought to post it. It is more like of historical interest, but still an interesting read:

THE AUTOXIDATION OF ETHYL ETHER
A. M. Clover
J. Am. Chem. Soc., 44 (1922) 1107-1118.
DOI: 10.1021/ja01426a024

Attachment: The autoxidation of ethyl ether.pdf (804kB)
This file has been downloaded 1652 times

YT2095 - 25-4-2008 at 00:35

it`s interesting to note where it says that "Light isn`t indispensable".
that would explain why it can form inside tin cans too.

syntelman - 25-4-2008 at 05:28

When did suppliers/manufacturers start adding stabilizers to diethyl ether? And as they did unstabilized diethyl ether must (or atleast should) have some issues with peroxide formation and their dangers. (Pure curiosity, I have no oppionion wheter opening the bottle or not is safe)


[Edited on 25-4-2008 by syntelman]

VTchem - 25-4-2008 at 13:54

I have heard that 6 months after opening and you should get rid of it or de-peroxide it. Now thats AFTER you open it and then that was not in reference to 10 year old stuff either. I would open it with some kind of barrier between me and the bottle, I would use some kind of replacement for my hands, I only have two and none to spare. Having an extinguisher handy would probably be a good idea too.

Thats just my opinion though, its your diethyl ether.

vulture - 25-4-2008 at 13:58

I've opened ether bottles from 1993 which were already opened and used recently. No explosions. Just don't distill the stuff.

[Edited on 25-4-2008 by vulture]

Mr. Wizard - 25-4-2008 at 14:46

Evolution in Action


borrowed from an anonymous source

Fatal Accidents: The bright side

Every day some new do-gooder is trying to save us from ourselves. We have so many laws and safety commissions to ensure our safety that it seems nearly impossible to have an accident. The problem is that we need accidents, and lots of them.
Danger is nature's way of eliminating stupid people. Without safety, stupid people die in accidents. Since the dead don't reproduce, our species becomes progressively more intelligent (or at least less stupid).
With safety, however well-intentioned it may be, we are devolving into half-witted mutants, because idiots, who by all rights should be dead, are spared from their rightful early graves and are free to breed even more imbeciles.
Let's do away with safety and improve our species. Take up smoking. Jaywalk. Play with blasting caps. Swim right after a big meal. Stick something small in your ear. Take your choice of dangerous activity and do it with gusto. Future generations will thank you.

CyrusGrey - 25-4-2008 at 15:14

Quote:
Let's do away with safety and improve our species. Take up smoking. Jaywalk. Play with blasting caps. Swim right after a big meal. Stick something small in your ear. Take your choice of dangerous activity and do it with gusto. Future generations will thank you.


Or at least tell everyone else that so my genes have less competition! :D

But seriously, think of the value of your health compared to the value of a tin of ether. We need the highly intelligent people of this forum to be in good health, and to think about sex more, so we can have at least some intelligent people in our next generation.

Vogelzang - 27-4-2008 at 17:03

https://www.hyperlab.info/inv/index.php?s=6bcf9808b6dd476be3...

Jdurg - 27-4-2008 at 18:41

I can tell you that Ether itself has a pretty invisible flame. I had a flash fire with diethyl ether take away my eyebrows for a good long while. (Reason #1 why you don't smoke a cigarette after organic lab where ether was spilled on your jacket).

Klute - 28-4-2008 at 11:05

First hand experience:

A 2.5L amber bottle of THF (SDS, stabilized with 0.025% BHT), opened over a year ago, over 3/4 full and keep in the dark at room temp (15-25°C), without any inert atmosphere, but with a few coils of copper added, proved to give a negative test with KI/Starch paper, moistened with water after a minute, or acidified with a drop of GAA before adding the drop of THF.

And THF is said to be more suceptible at forming peroxides than diethyl ether is :cool:

panziandi - 6-9-2008 at 11:27

Just thought I'd add this post to this thread to save opening another.

I use THF way more than diethyl ether and never have issues with the peroxide, but I found an old bottle of diethyl ether in my cupboard. It's 500mL bottle perhaps 400mLs left. It is LR 98% and i held it up to the light and noticed very little tiny (not lots mind) of crystaline precipitate. Not sure if this ppt is a peroxide or if it's just an impurity. I'm guessing here but I likely purchased it about 2 yrs ago. Now it does give a positive test with KI, but i don't wanna loose it :( ... so I am thinking of shaking 100mL portions with acid ferrous sulphate, drying with CaCl2, then with Na wire and storing in smaller bottles over maybe Cu wire, Na wire or hydroquinone. Can I have peoples thoughts please? I know that hydroperoxides are removed by FeSO4 but IIRC dialkyl peroxides aren't, would this not be worth it?

Klute - 6-9-2008 at 12:58

I should think FeSO4 would be perfectly suitable, bisulfite is another option too.

smuv - 6-9-2008 at 13:16

Peroxides of diethyl ether are oily liquids.

panziandi - 6-9-2008 at 13:31

Yes, I am currently shaking it with FeSO4... It's just I never noticed these crystals in the bottom of the bottle before! As I hardly use diethyl ether anymore (THF is my friend :D) I'm going to divide it into smaller bottles I think. Would you suggest storing it over Cu wire, Na, NaK, NaOH or KOH etc? Which do people find the best here?

Klute - 6-9-2008 at 15:11

I personally keep my recycled ethers (THF mainly) over a few Cu shots and with a dash of hydroquinone. KOH makes the ether all opaque with fine precipitate, I only keep it over KOH prior to drying/distilling over NaH.

KOH in Et2O

tapira1 - 6-9-2008 at 17:33

I suppose that your fine precipitate formed when you drop some KOH into Et2O is due to attack of the KOH to the glass of the bottle. These bottles are usually type III or IV of glass (very likely to be attacked by alkalis). KOH does not prevent formation of peroxides in Et2O;on the contrary, attending to the reaction mechanism, it should help their formation (besides it is regular practice to store ether like solvents over KOH before distillation to produce the anhydrous grade solvent.

Klute - 6-9-2008 at 17:59

No, no definitively from the KOH as it forms over an hour or so and the glass (Duran bottles) is intact after. I don't think the THF contains much water, it isn't anhydrous grade but not technical either... And only rarely opened.

Et2O stabilization

tapira1 - 6-9-2008 at 18:37

THF is stabilized with phenolic-type compounds, which are picked up by the KOH when you store the solvent before distillation, but ether usually has some EtOH for stabilization; I don't think "NaEtO" is formed and conveys turbidity to the Et2O.
BtW: Have you tried to "isolate" this white stuff and get something like a melting point? Do you know if, when isolated, is hygroscopic? This may tell you something about the nature of this. I cannot figure out what else can it be. Et2O is "sulfuric ether" because it is usually manufactured by dehydration of EtOH.

Klute - 6-9-2008 at 18:42

Well, the amount of precipitate formed when adding KOH to THF is pretty large compared to the <5ppm BHT present... I will take a picture next time.

Concerning the white solids in Et2O, I'm sure I have been told to be on the look out for traces of white solids on th erim of old empty bottles, as the remaining ether evaporates out..Are all possible Et2O peroxides oils?

Et2O

tapira1 - 6-9-2008 at 18:59

Not in my opinion; as far as I know, Et2O peroxides are liquids (oily). But I have where to find out for sure... Will see next Monday.

panziandi - 6-9-2008 at 19:49

I know the usual peroxides are oily but these peroxides are polymeric so in heavily peroxidised material I would imagine they would crystalise I also seem to recall hearing that they are not that soluble in ether! Although I do not recall where I read or heard that. My plan is this currently half way through it:

Ether 115mL shaken with FeSO4 5g/25mL with H2SO4 added. Aqueous layer removed, saline wash. Ether dried with CaCl2 or Na2SO4. Ether decanted and dried with alkali-metal dessicant (I have not decided which), bottle into 100mL bottle purged with argon and stored over either Cu wire or Na.

The remainder of the bottle I will repeat as above but likely will store some with hydroquinone or an alcohol perhaps?!

Formatik - 6-9-2008 at 20:49

Quote:
Originally posted by Klute Concerning the white solids in Et2O, I'm sure I have been told to be on the look out for traces of white solids on th erim of old empty bottles, as the remaining ether evaporates out..Are all possible Et2O peroxides oils?


The ether autoxidation is as shown in the diagram below as from the reference: Modellversuche zur Autoxydation der Äther in Angewandte Chemie 49(5):101-103.

Oxidized diethyl ether may contain H2O2 and acetaldehyde and their accumulation products: oxyethyl hydroperoxide CH3.CH(OH).OOH or dioxyethyl peroxide, CH3.CHOH.OO.CHOH.CH3, some ethanol, and a small amount of AcOH.

The intermediate peroxide, the hydroperoxy diethyl ether, CH3.CH.(OOH)OC2H5 is a colorless, inviscid oil of a pleasent odor. This deflagrates weakly when heated forming an acidic fog, which smells like acetic acid. Barely sol in water, easily soluble in almost all organic solvents. Decomposed by NaOH soln or ferrosulfate.

The polymeric ethylidene peroxide [CH3.(CH-)OO-]x, is a viscous liquid similar to glycerin in consistency. It is very friction sensitive and exceedingly explosive. It also has a very high brisance, 4 mg of it was enough that during a micro-C-H-determination it blew the "Verbrennungsrohr" (tube for determination) to pieces.

But the same authors of the above paper, also wrote in Ber. 1939, 72, 1933 detailed Bayer and Villiger who made an oil from H2O2, acetaldehyde, and H2SO4, which after heated and cooled gave an exceedingly explosive crystalline mass which they called ethylidene peroxide*, and wasn't investigated further due to its dangerous nature. The authors then suspect that their crystal comprised of mainly dimeric, next to polymeric ethylidene peroxides.

The dimer has an acetaldehyde-like stench, and has a very high vapor pressure. It is insoluble in water, but soluble in most organic solvents, and pretty stable towards hydrolysis. They say the polymer decomposes in the heat, to depolymerise to the volatile dimer. Usually in a destillation of diethyl ether where explosions have resulted, it is the polymeric which is responsible, on gentle heating this compound can depolymerise but the authors above have had quite a few detonations in those procedures.

*But in the gesammelte Werke, Bayer &c., call the oil diacetaldehyde peroxide hydrate, and the crystals diacetaldehyde diperoxide. Bayer &c. must have also had some real bitter experiences with it, to have just quit analysing it. This is a very dangerous compound, also about 110% as strong as TNT following the peroxy aldehydes thread.

[Edited on 7-9-2008 by Schockwave]

etheroxidationperoxid.jpg - 12kB

Et2O peroxides

tapira1 - 7-9-2008 at 05:02

Contrary to what I was told during years, yesterday night and today I am learning about the instability of ether peroxides against Na/KOH. It is good to know this. However, the mistery of the solids formed is still around.

smuv - 7-9-2008 at 08:26

Isopropyl ether peroxides are solid...I think it has just been a confusion over the years. If your ether is stabilized and tightly caped; you will not get significant peroxide formation. In order for peroxides to form there needs to be oxygen present and the amount of oxygen in the head space above the liquid is trivial.

Like Klute I store recycled ether over copper wire. If I have had unstabalized ether sitting around for a while before distilling/evaporating to dryness, I allow it to stand over a sodium bisulphite or metabisulphite solution for a few hours.

Also amber glass bottles on their own are probably effective inhibitors although I don't use them as much as I probably should.

Saber - 7-9-2008 at 08:36

When you add a NaOH to peroxide conatining ether it will precipitate the hydroperoxide with the ether. This is much less explsoive however still dangerous.
It should be removed by filtration.

[Edited on 7-9-2008 by Saber]

Klute - 7-9-2008 at 10:01

I remember certain notes going around about drying THF with KOH being an explosion hazard if peroxides were not detroyed before adding the KOH. Apparently, explosions happened enough times for people to get concerned about it and start warning other labs about this..

http://www.orglist.net/archive/2003/0083.html

Hum, can't find the article/note I'm taling about...


Here is a very complete document on peroxide-forming chemicals and their handling (in French though :) ):
http://www.inrs.fr/INRS-PUB/inrs01.nsf/inrs01_catalog_view_v...

matei - 7-9-2008 at 12:25

From "Inorganic Syntheses", Vol. XII:

Purification of Tetrahydrofuran

It has been reported that serious explosions may occur when
impure tetrahydrofuran is treated with solid potassium hydroxide or with concentrated aqueous potassium hydroxide, as has been recommended widely for the purification of tetrahydrofuran; see Organic Syntheses, Coll. 4,* 474, 792 (1963); 40, 94 (1960). There is evidence that the presence of peroxides in the tetrahydrofuran being purified was causal. It is strongly recommended, therefore, that this method not be used to dry tetrahydrofuran, if the presence of peroxides is indicated by a qualitative or quantitative test with acidic aqueous iodide solution. Traces of peroxide can be removed by treatment with copper (I) chloride (cuprous chloride) see Organic Syntheses, 46, 57 (1965). The safety of this operation should be checked first on a small scale (1-5 ml.). It is recommended that tetrahydrofuran containing larger than trace amounts of
peroxides be discarded by flushing down a drain with tap water. It must be kept in mind that mixtures of tetrahydrofuran vapor and air are easily ignitable and explosive; purification is best carried out in a hood which is well exhausted and which does not contain an ignition source.
The best procedure for drying tetrahydrofuran appears to be
distillation (under nitrogen) from lithium aluminum hydride.
This operation should not be attempted until it is ascertained
that the tetrahydrofuran is peroxide-free and also not grossly
wet. A small-scale test can be carried out in which a small
amount of lithium aluminum hydride is added to ca. 1 ml. of the tetrahydrofuran to determine whether a larger-scale drying operation with lithium aluminum hydride would be too vigorous for safe operation. Tetrahydrofuran so purified rapidly absorbs both oxygen and moisture from air. If not used immediately, the purified solvent should be kept under nitrogen in a bottle labeled with the date of purification. Storage for more than a few days is not advised unless 0.025% of 2,6-di-t-butyl-4-methylphenol is added as an antioxidant. There are no indications that peroxide-free, but moisturecontaining, tetrahydrofuran cannot safely be predried over potassium hydroxide. However, even this operation should be attempted only after a test-tube-scale experiment to make sure that a vigorous reaction does not occur.
A peroxide-free grade of anhydrous tetrahydrofuran (stabilized by 0.025 % of 2,6-di-t-butyl-4-methylphenol)i n 1-lb. bottles is available currently (1970) from Fisher Scientific Co. This product as obtained from freshly opened bottles has been found to be suitable for reactions, such as the formation of Grignard reagents, in which purity of solvent is critical (Du Pont Company, unpublished observations). It is standard practice in at least one laboratory to use only tetrahydrofuran (Fisher) from freshly opened bottles and to discard whatever material is not used within 2 to 3 days.

[Edited on 7-9-2008 by matei]

DNA - 30-9-2008 at 04:59

Just another thing about the peroxides I just read in a book:

To test for peroxides:

A more quantative method involves adding 1 mL of the liquid to an equal volume of a 10% sodium iodide in glacial acetic acid solution. A yellow color indicates a low peroxide concentration, whereas a brown color indicates a high peroxide concentration. If the concentration of peroxide is not too great, the material can be salvaged by shaking with aquous ferrous sulfate. In the case of a water-soluble ether, solid CuCl may be used to remove traces of peroxides.* Large amounts of peroxides may be removed by storing the liquid over activated alumina or by running the liquid through an activated alumina column. CAUTION: Do not allow the alumina to dry completely. The adsorbed peroxides may be removed by washing the alumina with an aqueous ferrous sulfate solution.

Ref. The manipulation of air-sensitive compounds. 2nd edition, D.F Shriver, M.A Drezdzon. p86-87
* Organic Synteses, 45, 57 (1965).

[Edited on 30-9-2008 by DNA]

Vogelzang - 1-10-2008 at 13:29

see
https://www.hyperlab.info/inv/index.php?s=2ee6fc02dcbb5efbce...

cristiro - 18-12-2012 at 10:53

http://ccc.chem.pitt.edu/wipf/Web/16340.pdf

ScienceHideout - 18-12-2012 at 14:03

I store mine over KOH. Had it for 7+ months, never had a problem.

The rumour of ether in China

chem_haruka - 17-5-2015 at 20:33

In China,I heard that,if you open a bottle of ether which placed in reagent cabinet for a long time,it may explode when you open it. Because the air could oxidate ether(some bottles aren't hermetic).However,the peroxide of ether is stable at r.t. ，and only explode under heating.
Please tell me that,is it dangerous when someone open it？

Zombie - 17-5-2015 at 20:44

There is a good thread on that here... http://www.sciencemadness.org/talk/viewthread.php?tid=10380

It's worth reading because you heard correctly.

mnick12 - 17-5-2015 at 21:37

Ya it is not a rumor,

Luckily most ether has BHT or something similair to scavenge for reactive oxygen species. The case where this doesnt happen is when the ether is meant for grignards or analytical chemistry, then it could be full of peroxides.

If you have an open bottle of ether the best way to check is with iodide and acetic acid. Dissolve some KI or NaI in acetic acid, and add an equal portion of ether. If the color is yellow, then you have some peroxide but are probably OK. If it is brown or black, then you need to call whoever deals with your organic lab waste.

diggafromdover - 18-5-2015 at 06:50

Lovely thread gents!