neutrino - 21-1-2006 at 21:39
Does anyone know of any cheap OTC sources of glymes? For those of you who have never heard of these compounds, here is a good page on them.
I have heard of glymes used in cleaning products; can anyone list any specific ones? Has anyone seen them in any other common products?
densest - 28-1-2006 at 22:59
I looked for glymes for a while. Spectrum sells them but that's not OTC. Butyl diglyme may be available through prospecting/gold recovery supply
places - a couple of sites reference it as one method of purifying gold.
frogfot - 29-1-2006 at 10:12
Whow, that's a very interesting stuff! If it's used in cleaning products than it shouldn't be as hazardous as crown ethers..
Synth of such things shouldn't be that hard: any alcohol ROH + ethylene glycol in acidic conditions or in presence of some funky catalyst.. the point
is to avoid formation of polymers and just dioxane..
Btw, I've seen somewhere a lithium salt being used as a catalyst in some crawn ether type compound (I'll post more info when my memory comes back..)..
mentioned this somewhere..
neutrino - 30-1-2006 at 08:33
Actually, what we want is a polymer. The long (-CH<sub>2</sub>CH<sub>2</sub>O-) chains bind the ions, although not as well as
crowns. This is to our advantage because crowns tend to dissolve alkali metals, forming alkalide anions. Glymes should not have this problem.
The alkali cations are commonly used as templates in the syntheses of crowns. If you add a lithium salt to a reaction mixture that produces crowns,
you will get mainly crowns with a central region the right size to bind lithium cations. The same goes for other alkalis.
Here is a brief JCE article about a PEG (HO(CH<sub>2</sub>CH<sub>2</sub>O)<sub>n</sub>H) and its use as a ligand.
edit: too big to attatch, I will try to fix that.
[Edited on 30-1-2006 by neutrino]
neutrino - 1-2-2006 at 16:39
I finally figured out how to make a pdf into a multipage djvu, so here is that article. It's a little fuzzy, but it's certainly not bad for the
compression (1.9M --> 65K).
Would PEG itself work for this electrolysis? A PEG or PEO (same thing, different name) with a very high molecular mass (in the neighborhood of 10,000)
should dissolve an alkali salt easily. When the alkali metal is formed some will react back with the PEG to form an alkoxide, but with a
high-molecular weight PEG this won't be so significant. (The higher the molecular weight of a sample, the fewer OH groups a given mass will have.)
Esterification is also a possibility if one gets some PEG. This way a normal molecular weight (in the hundreds) will suffice. I guess I should change
the original question of this thread; does anyone know of any good sources of high-molecular weight polyethylene glycols/oxides?
Before I forget here is that article.
Attachment: PEG_crown.djvu (65kB)
This file has been downloaded 758 times
BromicAcid - 1-2-2006 at 20:50
Frogfot, I remember lithium perchlorate being used for the template in the preparation of a 'nifty little crown' from furan and acetone, though its
application is limited.
These linear crown ethers are not as good as actual crown ethers, they have decreased solubility as opposed to their counterparts but they are good
for phase transfer catalysts (that's all from memory). The longest ethylene glycol chain I've seen readily avalible OTC is diethylene glycol from
those alcohol lamps for heating food. PEG is occasionally used in all sorts of preparations though never in useful amounts (as far as I have found).
None the less you can procure small amounts of it for various purposes online, photography, wood stabilizing (huh?). If you have the uncapped version
though, i.e., hydroxyl groups on the end, and n (where n = the number of ethylene glycol units) equals 6, then I think it would be a simple matter of
heating it with some potassium salt and something to remove the water from the condensation and you would end up with 18-crown-6. Anyway, I digress.
Like frogfot said, these should be preparable from OTC ingredients and should be useful for the regular Joe backyard chemist.
sparkgap - 2-2-2006 at 05:15
I remember someone in the board already mentioned the brand Simple Green being a short-chain glyme.
sparky (~_~)
frogfot - 3-2-2006 at 15:35
Bromic, yes I was also thinking about furan/acetone crown, the memory comes back. I have that synth somewhere in an ebook. IIRC, the reaction proceeds
without lithium too but somewhat slower.
Well, since the size of the chain-crown seems to be critical (most probably it can't be too big eather), the best thing would be to follow the
references in article posted by neutrino. Experimenting from scratch wouldn't do any good.
Oh, and there seems to be a simple test for chelating ability of the crown, just dissolve it in any org solvent and shake with some KMnO4 solution
Btw, in that article they mention that one of the disadvantages of PEG is it's high water solubility... (if I got it correctly, this decreases it's
carrier ability of salts across aq-org phases??) Couldn't one just protect the alcohol ends of PEG by something less polar, say methoxy or acetyl
group..? Lol, I assume they've tested this already..
[Edited on 3-2-2006 by frogfot]
neutrino - 3-2-2006 at 17:27
I only plan on using any glyme I find for electrolysis of sodium. Water solubility shouldn’t be any kind of problem.
The size of a crown is critical for complexation, true. In this case we are working with very long chains of [CH<sub>2</sub>
CH<sub>2</sub>O], so the length shouldn’t be an issue as long as it’s over some critical value, probably around six oxygens.
I have a lot of research lying around on crowns. If you want anything, I will gladly upload it to the crown thread. It’s mostly related to other
crowns, though.
One more thing, I looked at Simple Green. As far as I can tell the only thing resembling a polyether they have is 2-butoxyethanol and in very small
concentrations. The chain on this is far to short for any use.
ollip - 17-2-2006 at 05:58
Hi there,
just came across your thread on glymes.
I am the author of the web page neutrino has linked to. (www.glymes.com).
We make and sell glymes in commercial volumes. Let me know if you have specific questions about these products.
By the way, monoglyme (n=1) , diglyme (n=2) and triglyme (n=3) are toxic compounds (at least in Europe). the rest is non toxic.
For cleaning applications,in paint removers and in coatings and paint formulations, dipropylene glycol dimethyl ether is used. It is a great
replacement for NMP, too.
Electrolysis of sodium should work well in mon- or diglyme or any glyme with higher MW. PEGs won't work - the OH groups will cause trouble.
JimmyPage - 3-5-2006 at 10:59
One question about glymes that comes to mind is, roughly how much do they cost? A vague and mundane question I know but they look so usefull and it
would be good to know if they fall within the price range available to the average chemistry hobbyist. Are we looking at tens or hundreds of dollars
per litre?
Ollip, funny how I was on your website for hours then came here to find.....well, to find you...the horses mouth so to speak. Very convenient!
[Edited on 4-5-2006 by JimmyPage]
densest - 8-5-2006 at 14:10
The following seems plausible:
ethylene glycol monomethyl ether
ethylene glycol monobutyl ether
are commonly available solvents used in large quantities and available without any trouble (I don't think they are hazardous material for shipping in
the US except for the fire hazard).
c3h7Oc2h4OH dripped into conc. H2SO4 at 100C? Diethylene glycol dibutyl ether (butyl diglyme) is reported to be mostly immiscible with aqueous
things. Would this be likely to make separate into a layer of butyl diglyme over a layer of acid?
ordenblitz - 8-5-2006 at 17:10
I was reading this thread the other day when I suddenly remembered something that happened about 8 years ago.
We use acetone and other solvents by the barrel at work so there are always trucks coming in with a couple of barrels of this and that. One time after
emptying a barrel of acetone I went to get another barrel of it from the warehouse. After popping the seal , unscrewing the cap and dropping in the
pump....I noticed a strange smell. It was then that I actually decided to read the label instead of glancing at it.. it said "PM Acetate" Where had
this come from? I called the distributor and inquired about the mix up. Their dock man had made the same mistake I had, and just glanced at the label,
thinking it was acetone. I asked if they wanted it back and they said that since it was already opened, we could either keep it for free or send it
back on the next truck. Of course I kept it, and promptly forgot it was there. The price at that time for it was $700 something a barrel. Not bad for
free.
Eastman PM Acetate (propylene glycol monomethyl ether acetate) happens to be a glyme, well a diglyme. I had read about the use of glymes for sodium
electrolysis but wondered where to get some. I dug around in the deep dark back of the warehouse... and there it was, fresh as the day it was lost...
well almost.
How cool is that, it was here all the time.
Now what to do with it first?