Intergalactic_Captain
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1,4-Dioxane - Anyone here use it?
I'm in need of an ether for an upcoming synthesis, EtBr -> EtNO2 via NaNO2. From what I've read thus far, DMF is the best but Et2O works in its
place. I'd try DMSO, but I'm not in need of acetaldehyde.
So, considering the ease of preparation, use, and storage as compared to other ethers, 1,4-Dioxane seems to be my best bet. I've got the documents
regarding its preparation and physical properties, but am stumped as to what to use to stabilise it. I've thumbed through what I could find here, and
there are mixed views on the copper-wire in the jar method. BHT was recommended, but I don't believe I could get any without jumping through hoops.
I haven't had much luck finding anything else, so I'm asking for practical input from anyone who's used it before.
1. If you've got a bottle, what's the stabiliser?
2. How long can I safely store it (with and without stabiliser)
3. I know it's volatile, but is it anything like Et2O?
4. Anyone ever try using it for nitroalkanes?
5. Regarding Grignards - It reportedly works well, but I've never seen it in general use in the literature...Is there any reason for this besides the
availibility of slightly better/cheaper/more common ethers?
I'm planning on making a batch within the next couple of days, and would like any availible input - I'm not worried about the synthesis killing me so
much as opening the bottle when I use it next week...Oh, and this stuff won't sit around past August - I make it a point to destroy anything even
remotely unstable before I go back to school at the end of each summer...So, I'm not talking long term storage, I just need to stabilize it for a
couple of months.
Thanks in advance
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Nicodem
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1. I don't live in a country where chemists are paranoid about "ethers forming dangerous peroxides" so we do not use any special additives or
precautions when storing, distilling or using 1,4-dioxane.
2. I used commercial dioxane that was over 20 years old without problems. It does not degrade upon standing except for the slight oxidation from
oxygen.
3. It is not particularly volatile unless you consider something with the bp of water as volatile.
4. I assume you mean the reaction you mentioned (EtBr + NaNO2)? I don't think NaNO2 is particularly soluble in dioxane and even if it is, dioxane does
not have proper solvent properties for such a reaction.
5. It has the bp too high for being apropriate for preparing the Grignard reactions (the Mg insertion reaction is too exothermic and needs diethyl
ether or THF for removing heat by reflux).
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not_important
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More than the boiling point, 1,4-dioxane doesn't work well for Grignard purposes as it favours the formation of MgX2 and MgR2 over MgRX (Schlenk
equilibrium); I believe this is because MgX2 have low solubilities in dioxane.
The more volatile ethers also help keep atmospheric oxygen and moisture away from the reaction mix.
It's also more toxic than the simple mono-ethers.
The glycol ethers and diethers, such as glyme and butyl diglyme, are also used as Grignard solvents; the diglymes are favoured where higher
temperatures are needed. Methylal and ethylal, dialkoxy-methanes R-O-CH2-O-R, are also used; they have a lesser tendency to form peroxides, and the
diethyl has a low enough affinity for water that drying is often not or only minimally needed .
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not_important
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And I was off topic. For what you are trying to do, the solubility of the reagents will be imporant, you'll need to compare DMF to alternative
solvents.
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Intergalactic_Captain
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Hmmm....Sounds like a mixed blessing. I guess I can stop worrying about peroxides, at least. I'm not planning any grignard reactions any time soon
(it was more of a "what can I do with it" question), so that much at least isn't too much of a downer. I'll check into the NaNO2 solubility a little
more though, that part slipped my mind when I wrote the thread.
I guess I'll run a batch tomorrow, though, just for something to do...I'm still waiting for my week-late paycheck to purchase some chems, and I need
something to do tomorrow. I never quite realized how boring summer is when I've got no projects to work on.
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chemrox
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wouldn't acetonitrile be a good choice here?
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JohnWW
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I have used 1,4-dioxane as a polar aprotic solvent before (not just because of its odor!), as part of an effort to identify an unknown organic
compound. Being cyclic, it would be less reactive than most ethers. It is fully miscible with water. However, like other ethers, it would be
protonated by acids to give a disubstituted oxonium cation on both oxygen corners of the molecule, and under suitable conditions would react with
carbocations to give tertiary oxonium salts.
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Sandmeyer
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Being cyclic is not a guarantee
| Quote: | Originally posted by JohnWW
Being cyclic, it would be less reactive than most ethers. It is fully miscible with water. |
For example, diethylether being acyclic is more resistant to buli than cyclic THF (which mechanisticly speaking undergoes an retro-[2+3] cycloaddition
leading to ethylene and acetaldehyde enolate fragments).
[Edited on 17-5-2007 by Sandmeyer]
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Ozone
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It is a very interesting modifier to use with gradient liquid chromatography. It is not only PAP like THF, it also facilitiates transient bonding with
polar stationary phases (or un-capped silica)--it acts like a "bridge". Very unique selectivity can be had this way.
I have found the effects difficult to predict and variable from one column manufacturer to the next. It's either solid gold or runny crap.
It should facilitate the separation of ion pairs (gegenions, specifically) in ionic polymerization--but, the temperatures are usuallly so low that the
stuff would be a block in the flask .
It does not seem to desorb carbon very well (DMF and DMSO are great).
How would it do as a more inert substitute for, say, glyme or carbitol?
As for the stabilizer question, I'll check my bottle tomorrow. I keep it in the freezer and thaw when needed. As for volatility--101°C gives it a
nil. I would not make anything in it that was not a)insoluble in water or b) easily distilled.
As far as I know, it does not do ring opening polymerization (and can actually be the product, rather than polymer, in some cases).
Cheers,
O3
[Edited on 17-5-2007 by Ozone]
-Anyone who never made a mistake never tried anything new.
--Albert Einstein
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Nicodem
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Dioxane is quite a useful solvent, but I'm afraid it will soon follow the similar path of many other solvents (notably benzene) given that it gained a
bad reputation due to its (low potential) carcinogenicity.
As far as the issue about the reactivity of cyclic vs. non-cyclic ethers, I would say that for most reaction mechanisms (if not all!) the cyclic
ethers are more reactive than the non-cyclic. Their constrained oxygen lone pairs makes them more exposed and nucleophilic and they will tend to react
faster in reactions involving polar or radical mechanisms. (For example, HCl slowly reacts with THF giving 4-chlorobutanol while diethyl ether is much
more inert toward HCl.)
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Intergalactic_Captain
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Anyone know where I could find info on solubilities for this stuff? I haven't been able to find anything except for viscosity and miscibility info,
along with a buch of vapor-phase equilibrium stuff.
I ran a batch yesterday according to frogfots procedure, only using 1L of EG and 100mL H2SO4 - Same ratios, just scaled up 30x...I wasn't babysitting
it as well as I should (I was digging up clay and checking it about every ~30 minutes), and collected way too much towards the end. Smells a bit like
acetaldehyde, though I'm not sure how much is in there. I plan on redistilling it tomorrow to clean it up. One Q though - Adding NaHCO3 didn't cause
a phase separation (though frogfot may have used Na2CO3, thus explaining it)...Rather, it just settled too the bottom and clogged my sep. funnel. I'm
thinking of adding a handful of dehydrated MgSO4 to bind any water when I distill it - Anyone see any problems with this? I've got about 650mL of
crude, piss-yellow distillate to run off, and unsure how much of it is what I'm after...Hopefully more than 500mL, though I'm not holding my breath
just yet...
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Klute
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Don't leave the MgSO4 in the flask while distilling, at those temperatures it will release most of the water it absorbed... Dry it before,
decant/filter, and then distill.
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Intergalactic_Captain
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All right, sounds like thats what I'll do. I'm not sure why I didn't do it first - I keep some MgSO4 floating around my lab for drying organics, and
it never occurred to me to just use that first. I'm guessing frogfots method would have worked had I had a cleaner product...Not sure if I'll get
around to it today, but I'll post a writeup when I finish everything up. I may do another run to optimize my method a bit too...This stuff isn't
exactly nice, but it's the friendliest of the "dangerous carcinogens" that I've made thus far.
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tupence_hapeny
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| Quote: | Nicodem said
1. I don't live in a country where chemists are paranoid about "ethers forming dangerous peroxides" so we do not use any special additives or
precautions when storing, distilling or using 1,4-dioxane. |
hmmmmmm, not "particularly" paranoid about diethylether? This wouldn't be you by any chance?
| Quote: | How Not to Do It: More Diethyl Ether (Now With Extra Hardware)
Posted by Derek
Man, have things changed since I was in grad school. We used to pour all kinds of horrible things down the drain - mind you, this was a good twenty
years ago. But you can't do that now, can you?
A respected University of Washington pharmacology professor became a felon Wednesday when he acknowledged dumping a flammable substance down a
laboratory sink and then trying to conceal his actions.
Daniel Storm, 62, pleaded guilty in federal court to violating the Resource Conservation and Recovery Act by flushing about four liters of the solvent
ethyl ether. He faces a maximum five years in prison and a $250,000 fine when sentenced June 18, although prosecutors have recommended probation under
the terms of a plea agreement.
Well, everywhere I've worked, the safety officers have tried to put the fear of RCRA ("rick-rah") into us, and by gosh, it looks like they may have
had a point. Turns out that Prof. Storm's lab had several elderly containers of ether which turned up in a lab inspection, and he decided to get out
of paying the $15,000 hazardous waste disposal bill. So he decided to take matters into his own hands.
And how: he went after the metal ether cans with an ax, which means that he was lucky not to blow himself up. (A stray spark from the metal could have
done the trick, and who knows how much peroxide was in the stuff, for that matter). Why the Monty Python lumberjack routine? Well, the lids were too
tight, and according to Prof. Strong, the ax just happened to be handy. (How many times have the police heard that old excuse, eh?) Yep, you can't
pour ether down the sink like we used to, and you can't chop open the stuff with an ax like we. . .well, actually, we never used to do that. No one
ever has, most likely.
What really ripped it was when he went on to fake paperwork from a nonexistant waste disposal company to make it look as if the ether had been
properly hauled away. No, if you haven't clicked on that link yet, you'll have to take my word that I'm not making this up as I go along. But you get
the impression that Professor Strong sure was. Makes you wonder if he had been exposed to too many fumes. A spokeswoman for the school says that she's
unware of any similar incidents there, and I'll bet she's telling the truth. No, I've seen some stupid things done with diethyl ether, but this one
threatens to retire the trophy. |
The last quote was lifted (almost in it's entirety from here: http://pipeline.corante.com/archives/2007/03/08/how_not_to_d...)
I quoted it, simply because not even here would anyone believe that story otherwise....
tup
We are all the sum of our experiences, and our reactions to the same
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Intergalactic_Captain
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Damn...That's just horrible, in so many ways. Kind of reminds me of a conversation I heard a couple weeks ago...I work in the graduate chem stockroom
at UB, and hear quite a bit of gossip between my boss and the various professors. Well, there's this one professor that really hates going through
waste disposal channels, and instead instructs his students to dump shit down the sinks. Well, a few years ago the city of Amherst was running
routine water testing and was surprised to find toxic levels of DCM in the sewer system throughout the city - They traced it back to the school, and
secretly went further from there to find that it was coming specifically from his lab. The guy never got fined, fired, or hassled in any way,
although he cost the city hundreds of thousands of dollars trying to find the cause of contamination...Oh, and he still runs his own department. Not
quite sure how, but I thought that one was kind of funny - If I can find the story anywhere I'll post it.
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BromicAcid
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Off topic, but still, from tupence_hapeny's quote:
"Get out of paying the $15,000 hazardous waste disposal bill."
That's over 100x what it should have cost. Seriously, there had to have been a whole lot more than just ether there.
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Eclectic
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There is a whole lot more money to be made sending in the men in space suits and bomb squad gear than there is in telling people to add 20ml/liter 5%
acidified FeSO4 solution to destroy peroxides.
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BromicAcid
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No, seriously, I do this type of disposal, it's my job, that is about 100 x what we would charge.
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Klute
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SO you wear a space suit at work? cool 
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