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Author: Subject: Dichloromethane ?
simba
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[*] posted on 21-9-2011 at 08:34


Quote: Originally posted by jamit  

I think its pure, it was coming over at ~40C.


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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[*] posted on 24-9-2011 at 09:43


Quote: Originally posted by neutrino  
I don't think they'd sell it if it really was a known carcinogen.


*(cough) Asbestos *(cough)
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[*] posted on 26-9-2011 at 07:32


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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[*] posted on 27-2-2012 at 15:33
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&reg;</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&ndash;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>&trade; bottles with PTFE-lined caps. I will leave very little headspace in the bottles, and &ndash; as with all my chemicals &ndash; I will wrap <em>Parafilm M</em>&reg; around the cap to prevent loosening of the cap and subsequent leakage. I'm aware that the <em>Parafilm M</em>&reg; 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>&reg;</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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[*] posted on 27-2-2012 at 16:15


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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[*] posted on 27-2-2012 at 17:09


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. :P




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[*] posted on 27-2-2012 at 17:17


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...




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Magic Muzzlet
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[*] posted on 27-2-2012 at 17:47


Quote: Originally posted by bfesser  
I'm using the opportunity to practice with the rotavap.

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. :P


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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[*] posted on 29-2-2012 at 19:28


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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[*] posted on 29-2-2012 at 19:56


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.




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[*] posted on 1-3-2012 at 06:38


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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13-3-2012 at 05:21
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[*] posted on 30-11-2012 at 16:16


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?

ewar.jpg - 233kB

[Edited on 1-12-2012 by thefoxeffect]
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[*] posted on 10-2-2013 at 12:17


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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[*] posted on 10-2-2013 at 12:26


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.




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[*] posted on 10-2-2013 at 12:48


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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[*] posted on 13-2-2013 at 09:17


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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[*] posted on 13-2-2013 at 12:00


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...




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[*] posted on 13-2-2013 at 13:24


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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[*] posted on 13-2-2013 at 14:02


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.



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[*] posted on 14-2-2013 at 09:26


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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[*] posted on 31-8-2013 at 08:50


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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[*] posted on 31-8-2013 at 08:51


http://www.homedepot.com/catalog/pdfImages/5e/5e960aaf-5ec6-... this is the Jasco paint remover i used
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[*] posted on 31-8-2013 at 14:44


- 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]




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[*] posted on 31-8-2013 at 16:38


Chloroform is found in many cough syrups. DCM is less of a cancer risk than chloroform.
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[*] posted on 31-8-2013 at 17:17


Quote: Originally posted by sonogashira  
Chloroform is found in many cough syrups.
I have never heard of this before. Could you give a few examples, please?



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