MrHomeScientist
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Explosive Peroxide Testing and Prevention
In researching tetralin (re: my experience here), I've found that is has potential to form explosive peroxides on long term storage. Admittedly, this (and the fact that it smells) is
something I should have looked into before purchasing it.
I found a document that details a procedure for testing for peroxides and stabilizing against their formation, which I've also attached below for
posterity.
An excerpt regarding the iodine test and stabilization:
| Quote: | Method B (Iodide Test)
The iodide test (6) is suitable for the testing any peroxide forming chemical.
1. Wear chemical resistant gloves, a laboratory coat and eye protection. Work in a fume hood.
2. Dissolve 100 mg of potassium iodide in 1 ml of glacial acetic acid.
3. Add the mixture to 1 ml of the chemical being tested. Use a 10 ml graduated cylinder.
4. Determine the color of the resulting mixture by looking through the side of the cylinder with a piece of white paper behind the cylinder.
• A pale or barely discernable yellow color indicates a peroxide concentration of 0.001 – 0.005%.
• A bright yellow or brown indicates a peroxide concentration of 0.01% or greater.
If the peroxide concentration is less than 0.001% (10 ppm), go to the next step. If the peroxide concentration exceeds 0.001% (10 ppm), the chemical
must be stabilized prior to collection by EH&S; see Step 5.
4. Stabilization of peroxides by laboratory personnel
Even if the concentration of peroxides is less than 0.001% (10 ppm), you should periodically stabilize your chemical from additional formation of
peroxides if feasible. To do so, add at least 1 gram of butylated hydroxytoluene (BHT) per liter of chemical. BHT is an antioxidant that slows the
oxidation of peroxide forming chemicals. BHT will not destroy peroxides already present.
Once you have stabilized the chemical, label the substance with the peroxide concentration and indicate the date that you stabilized it. Store the
substance properly or manage as hazardous waste.
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This appears to be a good document for general peroxide formation, testing, and prevention information, so I thought it deserved its own thread.
Attachment: peroxideguidelines.pdf (150kB)
This file has been downloaded 356 times
==============================
That document does not cover how to destroy any peroxides after they form, however. I did find this document that has some instruction on that:
| Quote: | Removal of peroxides with ferrous sulfate:
ROOH + 2Fe<sup>2+</sup> + 2H<sup>+</sup> --> ROH + 2Fe<sup>2+</sup> + H<sub>2</sub>O
A solution of 6 g of FeSO4 · 7H2O, 6 mL of concentrated sulfuric acid, and 11 mL of water is stirred with 1 L of water-insoluble solvent until the
solvent no longer gives a positive test for peroxides. Usually only a few minutes are required.
Diacyl peroxides can be destroyed by this reagent as well as by aqueous sodium hydrogen sulfite, sodium hydroxide, or ammonia. However, diacyl
peroxides with low solubility in water, such as dibenzoyl peroxide, react very slowly. A better reagent is a solution of sodium iodide or potassium
iodide in glacial acetic acid. |
I'll likely be trying both the test and destruction methods on my tetralin in the near future.
[Edited on 2-29-2016 by MrHomeScientist]
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Tdep
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Not every thread has to be general and applicable to everyone aga, let's just talk about peroxides and tetralin in this thread.
I have ~100ml of tetralin that I've used for a few failed runs and is now in storage, I did not know it could form explosive peroxides. Is there
anything else other than BHT that I could add to prevent for,action, as it may be in storage for another year or so before I work up the courage to
crack that potassium synth again
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aga
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OK. Fair 'nuff. Message deleted and thread added to the wiki.
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UC235
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Tetralin hydroperoxide is probably one of tamest peroxides out there. Here's a procedure to make a whole bucket of it. http://www.orgsyn.org/Content/pdfs/procedures/CV4P0895.pdf
All benzylic and allylic hydrocarbons are susceptible, some more than others. Ethylbenzene (makes up about 15% of commercial xylenes) is also used as
a model compound for peroxidation. Benzylic, Allylic and secondary alcohols are all susceptible as are lots of alkenes like styrene,
dicyclopentadiene, vinyl acetate, and butadiene. Obviously ethers are susceptible as well though tertiary and methyl ethers seem to be fine (like
MTBE)
Here's a paper on preparation (from alcohols) and various reduction techniques to give alcohols from hydroperoxides. This can actually be a useful
preparative technique. For example, alpha-tetralol could be made from tetralin in 2 steps.
I have used the above ferrous sulfate technique on diethyl ether and it worked well. However, I now have some glyme that turns a starch-iodide strip
quite blue and it's water-miscible. I'm not sure what the best approach is. Maybe to just add the ferrous sulfate solution and deal with the suck of
drying the solvent back out after.
Attachment: davies1958.pdf (632kB)
This file has been downloaded 339 times
[Edited on 1-3-2016 by UC235]
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MrHomeScientist
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Thanks, UC235, that's interesting.
Another concern I have is disposal. How do you dispose of or otherwise chemically react tetralin into something less harmful? I briefly searched for
tetralin disposal procedures but all the links basically just say "let someone else handle it."
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UC235
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Quote: Originally posted by MrHomeScientist  | Thanks, UC235, that's interesting.
Another concern I have is disposal. How do you dispose of or otherwise chemically react tetralin into something less harmful? I briefly searched for
tetralin disposal procedures but all the links basically just say "let someone else handle it." |
It's a hydrocarbon just like xylene or toluene. I'd just burn it. It'll be sooty but that's expected of aromatics. It will need heating beforehand to
combust well, so maybe it's best to add it into a wood fire already in progress.
Unless you bubble air into it in storage it's not going to turn into hydroperoxides. I recently tested some THF that had been in storage for years and
it was fine because it was in a relatively temperature stable place in the dark with the lid on tightly. Tetralin isn't going to form touch-sensitive
crystalline peroxides anyway.
I mean, huge amounts of toluene and xylene just evaporate every day in use as degreasers for electronics and automotive work. If you're feeling mildly
irresponsible, let it evaporate outside.
Boiling KMnO4 solution will turn it into phthalic acid but you'd need a lot of KMnO4 for even a small amount.
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