xfusion44
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DCM storage
Hi!
Has anyone found a cheap and reliable way of storing dichloromethane (methylene chloride)? I was thinking about teflon lined gl45 caps or something
similar but I can't find them on ebay or amazon - at least not at low enough price. Solid ptfe bottles are even more expensive... I can get metal cans
with metal lids at low price but they also have some kind of sealant on the edges where they are joined - which again means leakage (unless the
sealant is ptfe or pfa or something like that). I've bought DCM in HDPE bottle which, of course, is not resistant to DCM, so my DCM is now escaping at
a rate of around 100ml/week. I need a quick solution. The only thing I can think of are reagent bottles with glass stopper - but I can't believe
that's the only cheap way of storing it... Standard PP caps are also not resistant to DCM, according to some plastic
chemical resistance tables... I could figure out something with teflon tape but I don't really like the idea of it.
Thanks for your help!
[Edited on 5-8-2017 by xfusion44]
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JJay
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I store mine in the dark stabilized with 1% ethanol in an amber bottle with a PTFE-lined GL 45 cap. I think you could use a Boston round bottle with a
PTFE-lined cap. Dr. Bob may still have some suitable bottles and caps.
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j_sum1
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I store mine as paint stripper and distil when needed. It's an extra effort to remove the methanol but that is not always necessary.
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Texium
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I store my distilled and purified paint stripper in an old 1L Sigma-Aldrich DCM bottle 
(Similarly, my canning and pickling salt is disguised as Flinn Scientific Sodium Chloride)
[Edited on 8-5-2017 by zts16]
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Melgar
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A wine bottle with a screw top, if you need something fast. Also, HDPE bottles are not all created equal. Check wall thickness between different
ones. A glass bottle with a plastic cap is usually ok, since only a tiny fraction of the enclosure area is permeable.
The first step in the process of learning something is admitting that you don't know it already.
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PirateDocBrown
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I use a reagent bottle, with a ground glass stopper.
I store absolute ethanol the same way.
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Dr.Bob
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Simple glass bottles with lined caps are fine. Glass joints will work, but might still have some evaporation for DCm, due to the high vapor
pressure, which a lined caps will contain better. If clear, they are best stored in a dark cabinet, which I do.
I have some brand new clear 125 ml Boston Round glass bottles with PTFE lines caps for $1 each, based on a Ebay find someone pointed out a while back.
I have new amber ones with a plastic covering for $3 each, and a few used but very clean amber ones for $2 each. But any amber bottle with a good
PTFE lining should work fine.
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diddi
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mine is in the freezer in a normal screw cap reagent bottle. I marked level ages ago. never leaked or made smell in freezer
Beginning construction of periodic table display
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byko3y
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I have never had any problems with PP cap or HDPE plug on bottles with DCM. I don't even notice any softening, which happens e.g. with xylene or
benzene.
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Panache
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Quote: Originally posted by j_sum1  | | I store mine as paint stripper and distil when needed. It's an extra effort to remove the methanol but that is not always necessary.
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Distil the vapour stream straight into crushed ice, the methanol largely then partitions into the water layer.
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Panache
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sorry fucked up the quoting thing, anyway....
(....Has anyone found a cheap and reliable way of storing dichloromethane (methylene chloride). I've bought DCM in HDPE bottle which, of course, is
not resistant to DCM, so my DCM is now escaping at a rate of around 100ml/week. I need a quick solution....)
Where do you live? the rub' al khali? That's a phenomenal loss rate (I am of course assuming you have only litres). Understanding the interaction
between polymers and discrete chemicals is complex, getting your head around it takes time. hdpe has absolutely no solubility in dcm. However dcm is
quite labile or soluble in hdpe, so it will diffuse out over time. There's only physical chemistry going on there. That said finding a bottle made
from only hdpe is impossible, there's likely a suite of processing additives that may leach into your dcm solution from the polymer.
(.....Standard PP caps are also not resistant to DCM, according to some plastic
chemical resistance tables... )
That's simply wrong, but again many pp additives would leach, so you can understand the polymer compatibility tables trying to oversimplify.
So on dr bobs point, glass is not ideal because it has no flex, the vapour pressure being high, especially in warmer climates the pressure on the seal
increases substantially and your losses through ground glass could be higher than the equivalent pp bottle that can compensate by bloating out a
little.
If you go to your local mechanic and either ask or take from the trash the empty 20l coolant containers. They clean out perfectly with hot water, are
made of pp, have excellent seals and caps often, provision for a drum tap and are completely free. Don't be disturbed if after filling them and
leaving they look ready to explode, they are nowhere near failure just doing their job.
Another excellent alternative is the standard 15l conc Hcl drum, usually thicker higher mol weight hdpe, washes out perfectly with hot water or steam,
bomb proof.
Finally hdpe jerry cans made to the Aus standard or equivalent, just check the rubber seal it may swell with dcm, in which case replace with Teflon.
Side thought, I cannot be bothered busting out Aiken to check, but if stored under a small layer of water the vapour pressure of that system should be
significantly reduced because the dcm, being only 1% soluble in water would only contribute 1% to the vapour pressure.
Can someone here confirm the plausibility of this please.
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Melgar
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| Quote: Originally posted by Panache | Side thought, I cannot be bothered busting out Aiken to check, but if stored under a small layer of water the vapour pressure of that system should be
significantly reduced because the dcm, being only 1% soluble in water would only contribute 1% to the vapour pressure.
Can someone here confirm the plausibility of this please. |
Except that even if it's only 1% of the top layer, it evaporates much more easily, cooling down the water and preventing THAT from evaporating. I'm
sure you can think of plenty of 50/50 systems, where one component contributes much more to the vapor pressure.
The first step in the process of learning something is admitting that you don't know it already.
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DFliyerz
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I use a 1L reagent bottle with no particularly special cap lining as far as I can tell, along with a circle of aluminum foil cut to fit between the
neck of the bottle and the cap. It's stayed fine for over a year, with absolutely no degradation of the aluminum foil.
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mr.crow
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A trick I use is to wrap the entire cap in aluminum tape, the kind for ducts. After putting the cap on tight wrap it on the bottle to seal it in.
I also do this to normal bottles using electrical tape to stop moisture/air/fumes.
Make sure your cap doesn't have any crappy paper liners.
Double, double toil and trouble; Fire burn, and caldron bubble
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CouchHatter
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The caps on my 1 gal HDPE jugs had crappy paper liners. I noticed the loss too late, and an appreciable amount had disappeared from each bottle,
nearly half. Those lids seemed to loosen themselves even after re-tightening. I never smelled anything either.
Now I store my DCM in a 5 liter HDPE jug with a 1-ft square of aluminum foil doubled over on itself several times until it's the size of the cap. I
cut a circle out slightly larger than the cap and forced it into the cap, then screwed it on tight.
I store that jug in a freezer for good measure, and haven't lost another drop!
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Sulaiman
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| Quote: Originally posted by Panache | ...
So on dr bobs point, glass is not ideal because it has no flex, the vapour pressure being high, especially in warmer climates the pressure on the seal
increases substantially and your losses through ground glass could be higher than the equivalent pp bottle that can compensate by bloating out a
little.
... |
That makes no sense to me at all,
surely the vapour PRESSURE is independant of volume ?
I seem to be doing ok storing DCM in PE-capped glass bottles (ex-chilli sauce)
CAUTION : Hobby Chemist, not Professional or even Amateur
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