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simba
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The azeotrope of dcm with methanol is 37.8 ºC and 38.3 ºC with water (according to magpie's post), so boiling temp is not a good thing to be based
on in this case.
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Takron
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*(cough) Asbestos *(cough)
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peach
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Asbestos is well controlled in the UK, as I'm aware of things it's not allowed in any new installations, only being used for some gaskets on things
like centrifuges. Although that may be being phased out as well. I seem to remember most asbestos mines have been closed too.
Benzene is the known carcinogen, it is in List 1 of the IARC tables, which means it is known to positively caused cancer in humans,
as opposed to suspected. DCM bottles now have the warning on. I believe that it is a suspected carcinogen due to it showing activity in some animal or
cell tests.
Washing paint stripper / grill cleaner first with water also has the benefit of removing any polymers used to thicken the DCM. If not removed first,
and they are present, they will stick to the inside of your boiling flask and not come back off with any commonly available solvent.
It will gradually go through plastic. Most common halogenated solvents will at least cause the plastic to swell, or extract things from the plastic;
PTFE included. So it's usually stored in glass or metal.
DCM is being phased out of UK paint strippers. The new kind is a thick water based gel and contains no DCM.
One neat thing about DCM is that it's boiling point is only a few degrees over body temperature and it comes in metal cans. You can distil it directly
out of the can provided you can make some semi-decent seal on the top and attach a condenser.
| Quote: | | I think they will all have the polymer in them, it probably keeps it from evaporating instantly and causing people to pass out. Not the kind of bad
publicity you want for a product. |
It's to make it stick. DCM on it's own is like water and pours off anything that isn't perfectly flat. And it boils off very quickly.
The polymer makes it easier to paint onto door frames and other vertical surfaces.
If you're stripping small parts, the best way to get maximum bang for buck is to paint it on and then wrap the objects up in foil and bags so the
solvent has a harder time boiling off, then leave it until it's well blistered.
The new stripper is admittedly much nicer to use. DCM based versions burn like a twat when they make skin contact, they melt brushes and gloves, and
go clean through the 'chemically resistant gloves' the DIY shops sell.
The new stuff is like painting on emulsion. No burning, no stench, stays put easily and it entirely washes off with a jet washer; it comes off like a
soap.
[Edited on 26-9-2011 by peach]
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bfesser
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Stabilizers for Long-Term Storage of Dichloromethane
By coincidence, I have the next three days off of work and am feeling a bit under the weather. I've decided to raise my spirits by setting up my
rotavap to isolate dichloromethane (DCM) from some <a
href="http://www.homedepot.com/catalog/pdfImages/ae/ae03e56d-3b90-4169-8968-69657bb63201.pdf">Klean-Strip®</a> I purchased last year.
I plan to dilute the product with distilled water before stripping (pun intended) off the DCM. I will use a
CO<sub>2</sub><em>(s.)</em>/acetone–chilled trap between the rotavap and my precious virgin <a
href="http://www.sciencemadness.org/talk/viewthread.php?tid=17008">ULVAC G-10DA(S)</a> rotary vane vacuum pump.
The recovered crude product will be fractionally distilled and dried to remove any remaining alcohols and residual water, as per this and the threads
listed at the end of this post. I plan to divide the product into scrupulously cleaned and dried 125 mL amber glass
<em>I-Chem</em>™ bottles with PTFE-lined caps. I will leave very little headspace in the bottles, and – as with all
my chemicals – I will wrap <em>Parafilm M</em>® around the cap to prevent loosening of the cap and subsequent leakage.
I'm aware that the <em>Parafilm M</em>® is "<a href="http://www.parafilm.com/FloraTapeHome.aspx?Menu=2&Prod=Med">not
recommended for use with [chlorinated], non-polar aliphatic and aromatic solvents</a>." I do not believe that this will be an issue, however.
The bottles of DCM will finally be stored in a refrigerator designated for laboratory chemical storage. The DCM will likely sit undisturbed for up to
several years before use.
Immediately upon purchase of the paint stripper last year, I pipetted a small sample of the viscous mixture into one of the bottles I plan to use for
storage of the DCM. This was to test the resistance of the PTFE liner to swelling and absorbtion. I haven't yet checked on the cap, but I have not
detected any sign of leakage (odor). The MSDS for the product states that it should be used within 6 months of opening, to avoid deterioration of the
can.
My questions are these:<ul><li>Do I need to add a stabilizer, as is necessary with trichloromethane?</li><li>I don't remember
the exact date I opened the can to take the sample. From the outside, the can appears to be intact. What reactions might the DCM have with the metal
of the can in the presence of atmospheric oxygen, moisture, and other constituents of the paint stripper mixture listed in the
MSDS?</li><li>Will standard <a
href="http://www.carolina.com/product/tubing,+red+vacuum-pressure,+lab+grade,+1-4+in+bore,+1-8+in+wall.do">red rubber vacuum tubing</a>
suffice between the rotavap and trap, or do I need to use something else like <a
href="http://books.google.com/books?id=mdmTGNrREK8C&pg=PA35&lpg=PA35&dq=tygon+dichloromethane&source=bl&ots=xp7yZMzSMV&sig=oBF
1TFJuI5cTlaq6cHp8Fp_xHI4&hl=en#v=onepage&q=tygon%20dichloromethane&f=false"><em>Tygon</em>®</a>?</li>&l
t;/ul>
Related DCM threads:
<em><a href="http://www.sciencemadness.org/talk/viewthread.php?tid=18824">nasty klean strip</a></em>
<em><a href="http://www.sciencemadness.org/talk/viewthread.php?tid=14401">Storage Bottle for Dichloromethane</a></em>
<em><a href="http://www.sciencemadness.org/talk/viewthread.php?tid=10306">Dichloromethane Distillation/Azeotropes</a></em>
<em><a href="http://www.sciencemadness.org/talk/viewthread.php?tid=7338">Dichloromethane otc product</a></em>
<em><a href="http://www.sciencemadness.org/talk/viewthread.php?tid=2363">Dichloromethane from paint remover</a></em>
[Edited on 2/28/12 by bfesser]
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Magic Muzzlet
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Hey, you are thinking way too hard about this simple procedure.
I don't see the point of purifying it so rigorously anyway if it's being stored for so long, it will need to be purified again if you want it up to
the same standards...
I never had problems using it between dist setup and PTFE pump, pumping vapor throug occasionally. Don't worry about it.
Who knows what happened in the can, just distill it!
But wow! Just such an effort to get some CH2Cl2!!
[Edited on 28-2-2012 by Magic Muzzlet]
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bfesser
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I'm using the opportunity to practice with the rotavap. And by virgin, I didn't mean PTFE. I meant that I haven't yet exposed the pump to anything
but dry air. As for the red rubber vacuum tubing, it was hard for me to source and was relatively expensive. I'd rather destroy cheap tubing from
the hardware store by leaching plasticizers than damage my precious vacuum tubing.
I know I may be over planning things, but that's just my nature. I can't (yet) help being OCD. It's also in my nature to question everything. I
believe that inquiry is the whole point of this forum, and of science as a whole. (Please do not drag this thread off topic by discussing the nature
of science further.)
I thank you, however, for your advice. I <em>do</em> worry about <em>everything</em>. But, hey! That's what medication is
for. 
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bahamuth
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Quote: Originally posted by bfesser  | | As for the red rubber vacuum tubing, it was hard for me to source and was relatively expensive. I'd rather destroy cheap tubing from the hardware
store by leaching plasticizers than damage my precious vacuum tubing. |
Your red rubber tubing will be crackled and elswhere degraded by light and air before you can kill it with some DCM, if it is anywhere the same stuff
I bought from Sigma and VWR. Even think it was Kartell brand. Latex has a expiration date of not more than a year or so.
If it is butyl or similar you don't have to worry about either DCM or air/light for quite some time..
Other than that a rotavap usually can't build extreme vacuums so a regualr thick/stiff walled tube will last you longer and usually is cheaper than
the red latex crap.
PS. the ultra vacuum really thick walled Tygon tubes goes real cheap on Ebay once in a while...
Any sufficiently advanced technology is indistinguishable from magic.
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Magic Muzzlet
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Yes, I figured that's why you wanted to use it. I understand, I would be more than happy to use my own, if I had one!
| Quote: | And by virgin, I didn't mean PTFE. I meant that I haven't yet exposed the pump to anything but dry air. As for the red rubber vacuum tubing, it was
hard for me to source and was relatively expensive. I'd rather destroy cheap tubing from the hardware store by leaching plasticizers than damage my
precious vacuum tubing.
I know I may be over planning things, but that's just my nature. I can't (yet) help being OCD. It's also in my nature to question everything. I
believe that inquiry is the whole point of this forum, and of science as a whole. (Please do not drag this thread off topic by discussing the nature
of science further.)
I thank you, however, for your advice. I <em>do</em> worry about <em>everything</em>. But, hey! That's what medication is
for. |
I worded my post badly, I meant I have used the red vacuum tubing with a PTFE pump, this detail added to emphasize no trap was used and lots of vapor
went through. The tubing was fine for a very long time, it was not the CH2Cl2 that I ended up ruining it with.
As for stabilizers, well, there is info in the threads so you can read and decide for yourself if you want to use them or not.
I hope you are worrying about the health effects of CH2Cl2 though, that is worth worrying about.
Have fun with your rotovap!
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bfesser
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Ok, so that didn't work out so well. Apparently the vacuum pump was a little overkill. No sign of condensation or even a reflux ring anywhere in the
rotavap condenser, despite the cooling water being barely above freezing. Found the CH<sub>2</sub>Cl<sub>2</sub> condensing
in the dry ice/acetone trap--at least something worked as planned. Slowly released vacuum, then shut off the rotavap. This paint stripper is a pain
in the ass. The waxy residues clean out of the flask with a few alternating washes of acetone and ethanol followed by a final cleaning of lab
detergent and hot water.
Perhaps it'd be worth just purchasing some reagent grade dichloromethane. Or, maybe when it gets warm enough to work outside again, I'll try the
distill-from-can method that seems to work so well for everyone else. If only I had a cold finger style condenser for my rotavap. 
Glassware porn for your viewing pleasure:
<a href="http://www.adamschittenden.com/Evaporation.php"><img
src="http://www.adamschittenden.com/uploads/trotovap/Buchi%20style%20dry%20ice%20condenser.image.jpg"></a>
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Sedit
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Distill from the can is great as a predistillation because all you need to do is solder a copper coil onto a lid and you have the setup you need to do
this for a long time but after you get it cleaned up its best to dry it and run it again because it will not come over clean the first time and wax
will almost without a doubt carry over somewhat.
Knowledge is useless to useless people...
"I see a lot of patterns in our behavior as a nation that parallel a lot of other historical processes. The fall of Rome, the fall of Germany — the
fall of the ruling country, the people who think they can do whatever they want without anybody else's consent. I've seen this story
before."~Maynard James Keenan
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Mailinmypocket
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I have had a few go's at distilling DCM from paint stripper... I eventually got tired of the gunk and hassle and checked on eBay.... Biostain sells
DCM in 250/500/1000 ml sizes at very reasonable prices, they ship worldwide and are based in the UK. I receive my orders in great condition everytime.
They also sell GAA, Toluene and Xylene I believe but I have never ordered the last two.
http://www.ebay.com/itm/Dichloromethane-99-5-Pure-1-Litre-1L...
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ScienceSquirrel
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Thread Pruned
13-3-2012 at 05:21 |
thefoxeffect
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I recently bought a gallon container of Klean Strip Adhesive Remover to distill for the dichloromethane. I did the distillation directly from the
metal can that the Klean Strip came in. After a few hours the temperature started to spike so I stopped the distillation. I then redistilled the
product once more. I have a few questions concerning the process. In other post and forums, it has been said that methanol and dichloromethane, form
an azeotrope, but according to multiple sources I don't think it does,
http://eweb.chemeng.ed.ac.uk/chem_eng/azeotrope_bank.html
It does however from an azeotrope with water, but the % weight is roughly 99.6 methleyne chloride to water, so I am not considering this an issue. So
question, am I wrong about dichloromethane and methanol forming an azeotrope? Should I worry about the azetrope between dichloromethane and water, I
am wanting decently pure chemical reagents.
Also, I posted some pictures of my setup. I would like to try this again, but to try to achieve maximum efficiency. Would doing a fractional
distillation help in this process? The BP of methylene chloride is 39.6 and the BP of methanol is 65. I would like to buy a gallon container of Klean
Strip and do a single distillation, straight from the can and into its storage container; that way losing minimal product, and of course having to
clean less glassware. Any suggestions or ideas?
One more question, the MSDS of dichloromethane says
"To minimize decomposition, all storage
containers should be galvanized or lined with
a phenolic coating. This material may corrode plastic and rubber."
As of now I plan on buying a galvanized paint can at Home Depot to store it, does anyone know of any common storage containers that have a phenolic
coating that might be used? Or would I have to order something like that from online?
[Edited on 1-12-2012 by thefoxeffect]
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luckybot
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I have noticed in my own distillate and in the distillate of another users youtube video that there still appears to be a murky whiteness present. I
am assuming this might be some of the polymer coming over as an azeotrope. How can this be removed? I have tried placing the DCM in the freezer and
this freezes any water present and causes some of the polymer goop to clump together, but it is difficult to filter as the second it starts to warm up
the goop disperses back into the DCM.
[Edited on 10-2-2013 by luckybot]
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Hexavalent
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Have you tried filtering over diatomaceous earth, or boiling the DCM (under reflux, of course) for half an hour/a few hours to help increase the
particle size of the goop, hopefully causing it to clump together?
Personally, I'd do a rough distillation from the can, and then do a fractional distillation in a glass apparatus to maximise purity: if you're
careful, you shouldn't lose too much of your product.
"Success is going from failure to failure without loss of enthusiasm." Winston Churchill
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luckybot
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I just poured in the mess straight out of the KS3 Klean Strip can into a 2L RBF and then pretty heavily diluted it with water to try to thin it out,
prolly 50/50 mix. This was stirred and heated on an oil bath using fractional distillation setup. Quite a bit of refluxing was going on and a very
large portion of the polymer was clumped together and spinning at the center of the flask. Distillate was then washed 3 times, each time with equal
volume of water, this reduced the amount of polymer by quite a bit but it seemed to reach a point where additional washes were no longer helping.
After that I placed the DCM in the freezer and returned the next day to find quite a bit of clumped up polymer floating around in it. As far as
filtering goes my attempts were made using a medium frit buchner funnel with and without vacuum, while this certainly removed some polymer it looks
like there is quite a bit that doesn't clump in the freezer and just makes its way straight through the filter. I will look into acquiring some
diatomaceous earth, in the mean time might activated carbon be an option? Thanks.
Update. I went ahead and filtered it through activated carbon, no luck there. Took what I had and redistilled it. Looks even worse after being
redistilled. This stuff is a nightmare. I guess I will be searching for another source of DCM.
[Edited on 11-2-2013 by luckybot]
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luckybot
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Okay, another update. I have found some liquid paint stripper that is a mixture of DCM, methanol, toluene, and acetone. Might be creating more
problems than I am solving switching to this mixture. It starts out as a clear liquid that you can shake to your hearts content and it remains a clear
liquid after shaking. So I fire up the distillation and to my surprise/rage a cloudy white distillate starts to come over, wtf. So I disassemble
everything and start cleaning under the assumption that maybe some gunk is left over from previous attempts. This is when I realize that the
fiberglass that I use to hold up the column packing is looking awfully nasty. Remove that and use the vigreux without glass beads in it, getting
desperate at this point, lol. Finally a clear distillate comes over slightly above the boiling point of DCM and then between DCM and methanols BP.
Proceed to water wash and I am back at a murky white, fail once again. So I check what happens when I water wash the raw paint thinner and the same
thing happens and it appears to be even more murky white. Any ideas what is going on here? I am using distilled water and I left the murky white gunk
over night to see if it would settle out and of course it didn't.
I suppose I will try removing the methanol with CaCl2 next.
[Edited on 13-2-2013 by luckybot]
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mr.crow
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Organic liquids turn white and cloudy when water is dissolved in them. Using CaCl2 is a good idea
Step 1 - Distill crude DCM from paint stripper
Step 2 - Dry with CaCl2 to remove water and methanol. Should turn clear
Step 3 - Distill with clean dry apparatus
Step 4 - Add methanol and put in well sealed dark bottle, etc...
Double, double toil and trouble; Fire burn, and caldron bubble
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luckybot
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So perhaps water washing isn't the best way to go? Do you think it will be practical to remove the 16% methanol azeotrope using only CaCl2 or should I
still water wash and then hopefully clear up the DCM with CaCl2? I suppose I will try both methods. Thanks for the reply, any ideas on what I can use
to hold the column packing up besides fiberglass?
[Edited on 13-2-2013 by luckybot]
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mr.crow
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Copper sponges are supposed to work well for packing material. They can have steel underneath the copper and might rust. Hopefully copper is
compatible with DCM vapors.
Double, double toil and trouble; Fire burn, and caldron bubble
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luckybot
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Copper is working fine, results are looking a lot better. Fast distill with column packed produces clear distillate with at least 16% methanol
probably more. Water wash this and a large chunk of the DCM/Methanol layer goes into the water layer. DCM layer is now murky. Dry using CaCl2, clears
up within a couple shakes. Decant into vacuum filter. Perfectly clear DCM. Thanks for the help.
Also just a tip for anyone working with the goop paint stripper, stuff some wet toilet paper into your rbf and swirl it around as hard as you can,
cleans it up nicely.
[Edited on 14-2-2013 by luckybot]
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Zephyr
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as noted, the best source of DCM is paint stripper. ive tried several paint removersand had the best results with JASCO (75% YIELD) industrial
strenght strippers may have higher concentrations
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Zephyr
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http://www.homedepot.com/catalog/pdfImages/5e/5e960aaf-5ec6-... this is the Jasco paint remover i used
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subsecret
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- Cancer risk of DCM -
Exposure to many hydrocarbons may cause cancer, with cancer risk being (somewhat) proportional to amount of exposure. It seems that exposure to
halogenated hydrocarbons has a greater cancer risk. Chances are that cancer won't occur with limited exposure, but still treat DCM with respect. Use
your own good judgement when choosing PPE.
Also, please understand that I am not a doctor, and my advice should not be used as medical information.
[Edited on 31-8-2013 by Awesomeness]
Fear is what you get when caution wasn't enough.
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sonogashira
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Chloroform is found in many cough syrups. DCM is less of a cancer risk than chloroform.
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bfesser
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I have never heard of this before. Could you give a few examples,
please?
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