[vmelkon]

Hello,
I asked this on sciencemadness.org 2 days ago and I had some replies but I guess my thread has been deleted.

After reading about it at some sites, I'm scared. Apparently, anything that is 1 month old should be discarded. Anything older than 1 year, you should call the bomb squad. There is also information out there about testing for the presence of peroxides. Reading http://en.wikipedia.org/wiki/Diethyl_ether#Safety
that gives the impression that testing the wet or liquid stuff is safe and can be done by anyone.

My question was, why is NaOH or KOH added to the diethyl ether? Someone replied saying that "it destroys the peroxides". According to http://en.wikipedia.org/wiki/Diethyl_ether#Safety
it forms a precipitate but I don't know if wikipedia is reliable.

Another question : labs seem to store it in a brown bottle. Is the cap on those bottles good? Perhaps they let in fresh air.

[Organic_lover*]

Hey vmelkon!

As a researcher, I will tell you that I don't trust in Wikipedia, because I already seen some information wrong posted there. So for chemical products information, you have to search the MSDS of the product (Material Safety Data Sheet).

http://www.sciencelab.com/msds.php?msdsId=9927164

Here's a link for diethyl ether

Hope this helps. Bye bye o/

[408]

it is still on scimad...conclusion: peroxides in either are overrated. 

[fledarmus]

I'm afraid you're panicking a little unnecessarily.

All of the commercial diethyl ether that I've seen contains a peroxide inhibitor. These can be stored unopened for quite a while. I have no idea how old that bottles that I receive have been, but I've never seen any trace of peroxides in previously unopened bottles.

Once the bottle is opened, there is a chance that oxygen is present, and the bottle should not be stored longer than six months after that. In our lab, we date the bottle when it is received and when it is opened, and discard it six months after opening. There is still some discussion about how long we should store unopened bottles, but it looks like we will probably settle on one year. That way we won't have to test for peroxides; a year in an unopened bottle isn't long enough to form a significant amount.

If you are distilling ether, you have to be more careful; distillation removes the ether from the stabilizers. When I was working with distilled ether, we maintained the ether (over sodium for drying) in the pot, and distilled off only as much as we needed, discarded whatever distillate wasn't used that day. Now, the anhydrous ether is clean enough I haven't needed to use distilled ether in a long time.

Finally, peroxides are only an issue when they are dry. You can test the solution for the presence of peroxides with no problems. IF there are peroxides present, you don't want to use that ether, because as the ether evaporates the peroxides will precipitate. If your ether tests positive for peroxides, do something about it - quench it and discard, or you can try some of the methods for breaking the peroxides and redistilling the ether if you absolutely have to keep it. Adding the appropriate stabilizers, of course.

If you see crystals forming in the bottle, however, you now have a dangerous situation, and at that point the bomb squad might be a good idea...

[vmelkon]

Thanks for the replies.
That link from sciencelab.com just downloads a php file. Perhaps it is because I'm using firefox

I was thinking of preparing ether myself from ethanol. It won't be anytime soon. I could prepare and use it for something immediately I suppose.
I was wondering why actual labs can't store it pure, without any BHT or NaOH/KOH, if you can just put your bottle in a dark box instead of letting it sit on a shelf with plenty of sunlight or fluorescent.

So from what I understand, it is safe to test for peroxides as long as there aren't crystals of the peroxides and that the peroxide is slightly soluble in the ether.

[Wastrel]

I am under the impression the peroxides that form in ether are liquids and when present form a danger mainly during the final stages of distilling (for example from a product).

Keeping the ether dry with sodium metal would probably avoid peroxide problems altogether.  Otherwise seal away from oxygen as best you can and follow something like a "Purification of laboratory chemicals" method close to the time you want to use it.

Ether has practical hazards that far exceed the risk of peroxide formation in normal use and missing from or not highlighted in the sciencelab MSDS.  It is an anaesthetic, the vapour at high concentration, such as would be found near the liquid or close to something soaked in it can render you unconscious in 10's of seconds.  Do not attempt to deal with a spill, evacuate.  The very flammable vapour is also heavy, which means it crawls along benches and reaches out to sources of ignition.

When making your own the temptation would be to avoid draughts so as to prevent what little ether you make from evaporating away, which is the kind of behaviour that increases the amateur chemistry body count.  Plan, use the right glassware, ventilate, do it properly.  For extractions, chromatography etc, try to find a safer solvent.