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Author: Subject: Dichloromethane ?
Chris The Great
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[*] posted on 5-9-2005 at 22:40


Quote:
Originally posted by Magpie
Chris the Great:

I noticed your post about a successful distillation of dichloromethane from paint thinner in Whimsy. I will be needing some of this most useful solvent. Will you please let us know what brand you of thinner you used and what if any problems you had with the distillation. Thanks. ;)


I used 'Recochem' brand Paint and Varnish Remover. They are a Canadian company, so you might not find the brand in places other than Canada. It has a green and blue label.

There was a goo mixed into it to thicken it, however there was no problems in distillation. I simply heated the stuff in a waterbath with some pottery chips tossed in for boiling chips. I kept the DCM cool with a small amount of salt-ice mix.
The only problem was that now all the goo is a near solid mass in my jar. I haven't tried to get it out but it dissolves in most solvents (gasoline etc) so I think it can just be scooped out. However, it could not be removed from the inside of the metal can the stuff originally came in, so I had to use another metal can (I had an empty acetone can from the same company and used that). I could not get the goo stuff out with any solvents. Keep that in mind, because you'll probably need a new container for your DCM.

One thing I was expecting was more of other chemicals to come over in the distillation, as it listed dichloromethane, methanol and toluene on the back. My end product smells neither of methanol oir toluene, though I think it might have a bit of methanol in it. So, even if other stuff is listed in the ingredients, it's not a problem in my experience.

I ended up with about 3.25L of DCM and 0.5L of goo from roughly 4L of paint and varnish remover. I spilled some DCM on the floor while pouring it into the new container, since it was ackward to pour it out of my 4L pickle jar reciever, and I think that was the main loss.
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Magpie
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[*] posted on 6-9-2005 at 07:57


Thanks Chris the Great for that detailed description. I was hoping your source did not have the polymer crap in it.

Mendeleev mentioned that Jasco brand is a a likely good source (also has polymer). I am pretty sure I have seen this at Home Depot.

When I was active in sailing I used to go to BC almost every summer - but those days appear to be over. My son and 1st mate has moved to, of all places, NYC. :(




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Chris The Great
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[*] posted on 6-9-2005 at 14:36


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.

However, I suppose the polymer would cause more of a problem in a nice ground-joint glass setup than in my improvised copper condenser and jam jar still I used! Nice big jar mouth means it is easy for me to scoop it out. I would imagine it would be much more problematic if one had to scoop it out through a 24/40 female joint.
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Quantum
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[*] posted on 8-11-2005 at 21:10
Compleat write up on distillation of DCM with pics


This is my second post in this thread and what a difference there is; more then a year has gone by and I have gone from being a newbee to well not being a newbee;) still not exactly an experianced amature chemist but the Sandmeyer reaction was unthinkable for me then and now is in my very near future:D

In preparation for a large extraction I needed much more DCM then I have now and so spent the day distilling some from the same can of paint thinner I have had all last year.

"Klean-Strip Paint Stipper" was the type used - a goopy polymer mess if there ever was one. I donned the butyl gloves and plop plop plot the mess was poured into my 1 liter RBF 24/40. I made some boiling stones from pottery and dropped them in there and turned on the heat after assembling a standard distillation setup using a liebig condenser with ice water and a 500ml RBF to collect the distillate.





The distillate came off at 40! and slowly rose as the distillation progressed untill it was stopped when the temp got to about 44! This took about 2h 20min in total and mostly involved me watching the distillation and reading General Chemistry by Pauling.

I disconnected the dflask and quickly flushed it with equal volume of cold water. This greatly helped in getting out the gooey junk left over. I advice this for every DCM distillation where polymers are present.

I then cleaned out all the glassware very well and redistilled the DCM and discarded the leftover 30ml or so that was attempting to come over at much higher then 40!

I then refluxed the DCM over anny MgSO<sub>4</sub> using a CaCl drying tube on top of the condenser. This was done for about an hour and a half and then the warm DCM was poured into its final resting place - a HDPE bottle - through a filter.







I have read that DCM can offgas through this sort of container so soon I am going to transfer this solvent into a glasswalled home.

Paintstripper is a viable source of dichloromethane given access to proper distillation equipment. Once taken out of the polymer mess DCM is easy to work with generally speaking.

Now to read Flatlanders and browse the forum.:D




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Magpie
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[*] posted on 9-11-2005 at 20:13


Quantum that is nice work! Thanks for the complete write-up. I almost missed it with all my screwing around with Waldo over in Whimsy. This write-up will make it easy for me.

I see you are keeping a notebook. I just started doing this too.




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Darkblade48
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[*] posted on 9-11-2005 at 21:05


That's a really nice setup, interestingly enough, I was poking around the basement the other day and found a large glass bottle (about 1L) of methylene chloride :D

Turns out my dad used to use it for melting plastic or something....and now uses it for getting rid of the sticky gunk that labels can sometimes leave behind :O My only comment was to show him a bottle of acetone and told him to use that instead of DCM

Also Quantum: check your inbox, I sent you a PM regarding your reflux setup
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Magpie
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[*] posted on 13-1-2006 at 16:10


I finally got around to buying a gallon of Jasco "Premium Paint & Epoxy Remover" today for around $25. I placed about 250 mL of this goop in a 500 mL RBF and have been distilling (simple) away for over an hour. It is coming over at 36 to 37C. I expected 40C but this could be due to thermometer miscalibration and/or atmospheric low pressure, I suppose.

This stuff is supposed to be 82.4% DCM and 10% methanol. The MSDS lists the remainder as aliphatic hydrocarbons, which must be the white polymer goop.

My handbooks don't list an azeotrope for methanol/DCM. So I don't know what all that talk was about on earlier posts.

This is very time consuming but will provide a reliable supply of this very valuable solvent. Anytime I don't have anything else to do I can just spend a day distilling off DCM. ;)

Edit: The temperature of the distillate finally did rise to 40C right at the end. Yield: 200 mL clear distillate. Is this a mix of DCM and methanol, pure DCM, or what?

[Edited on 14-1-2006 by Magpie]

[Edited on 14-1-2006 by Magpie]




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neutrino
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[*] posted on 13-1-2006 at 19:10


Pure DCM? I would bet that this is a mixture and that the low temp was caused by a lack of intermolecular forces between nonpolar DCM and relatively polar MeOH. To be safe, I'd wash it with water, dry, and redistill. That should get you the pure stuff. :D
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Magpie
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[*] posted on 13-1-2006 at 22:05


Good suggestions, neutrino. ;) I'm also going to do a little library research on a possible DCM/methanol azeotrope.



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[*] posted on 14-1-2006 at 11:51


According to Gmehling's Azeotropic Data DCM does form an azeotrope with methanol: 84%DCM/16%methanol, T=37.8C, P=1atm.

For reference I also noted that it forms one with water:
93.3%DCM/6.7%water, T=38.3C, P=1atm.

So this nicely explains my condensate temperature observations. And yes, I have some cleanup to do.




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Magpie
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[*] posted on 15-1-2006 at 15:08
DCM vs CHCl3 or CCl4


My 1960's college organic chemistry manual never specified DCM as solvent in any of the procedures although it was mentioned in a list of solvents. Chloroform and carbon tetrachloride were occaisionally used as well as, of course, diethyl ether.

Now, during my recent refresher course the lab manual relies very heavily on the use of DCM, and rarely specifies chloroform, carbon tet, or ether.

Surely this must be due to the lower toxicity of DCM vs chloroform and carbon tet. And compared to ether there is the big advantage DCM's non-flammability.

What I'm wondering is: If lower boiling point and somewhat higher solubility in water aren't an issue, is there any reason that DCM can't be generally substituted for these other chlorinated methanes?

For a specific example take the case of the extraction of phenol from water.




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Magpie
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[*] posted on 16-1-2006 at 19:50


I took my ~300 mL of crude DCM (from paint stripper) and washed it twice with about 450 mL water. Then I placed several grams of anhydrous Na2SO4 in it and let it set overnight. The next morning I decanted off the DCM and placed a little CaCl2 in it for a few hours. Then I filtered it and redistilled it. Distillate condensing temperature was 38.3 - 39.5 C. Yield = 216 mL.

This temperature puzzles me as the bp for DCM is 40C, and that for the DCM/methanol azeotrope is 37.8C. So I think I'll do some qualitative testing for the presence of alcohol.




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[*] posted on 17-1-2006 at 07:50


Each mole of CaCl2 should sequester 4 moles of methanol (and 3 moles of ethanol) by forming some sort of complexes. The mole ratios should be correct. Therefore you should not have any alcohol in the DCM if you used sufficient CaCl2. If you're unsure try increasing the amount of CaCl2 used.



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[*] posted on 17-1-2006 at 08:54


Quote:
I used 'Recochem' brand Paint and Varnish Remover. They are a Canadian company, so you might not find the brand in places other than Canada. It has a green and blue label.

There was a goo mixed into it to thicken it


Just FYI, a product called "Plastisolve" can be had from plastics supply places (there is at least one in every good-sized city) that is mostly all DCM and contains no polymer goo...

-z
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[*] posted on 17-1-2006 at 18:33


Thanks for the tip Explosivo.

I measured the density with a hydrometer at 12C: it was 1.315. CRC handbook says 1.335 at 15C. Methanol is 0.791 at 20C.

With simplifying assumptions I can calculate the fraction of methanol as follows:

Let X = fraction methanol
0.791X + 1.335(1-X) = 1.315
X = 0.037, or 3.7% methanol

So, I think I'll leave it as is. If I have a need for some extra pure DCM I can always treat it with CaCl2 as suggested.

Plastisolve sounds like it's worth looking into.

[Edited on 18-1-2006 by Magpie]

Plastisolve MSDS says it is pure DCM! Now to just find a source.

[Edited on 18-1-2006 by Magpie]




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[*] posted on 10-12-2006 at 23:48


I have a gallon jug of Methylen chloride/methanol in my garage that has been collecting dust for awhile. When I purchased it the Methylene chloride was colorless and now it has darkened a lot. Should I distill the Methylene chloride with Calcium Chloride or should I add water (and hope that the dark crap is water insoluble) distill, then distill again with CaCl2?
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[*] posted on 7-1-2007 at 01:59


Quantum, what was that thing used to supply water to the condenser?
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[*] posted on 15-1-2007 at 13:01


Some paint strippers it's easy to distill DCM out of, but recently one brand that used to be used with success with hot water now distills as a white distillate containing DCM and some type of low boiling polymer (I'm guessing).

Any ideas what it could be?
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[*] posted on 28-1-2007 at 12:41


It was asked before by someone but went unanswered..

What were you gonna use the DCM for, nitric acid extraction? If so, was it successful? Maybe write a write-up on that as there's not much information to be found on that process, or at least I can't seem to find it. Maybe someone can point me in the right direction?
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[*] posted on 29-1-2007 at 05:01


<< Quantum, what was that thing used to supply water to the condenser? >>

It's a garden pond water pump for recirculating water




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[*] posted on 13-9-2011 at 21:47
additive in paint-stripper


I did an initial distillation of paint-stripper and acquired about 750ml of dichloromethane. I washed it with about 1.5l of water, then dried it with calcium chloride overnight.

Next day I redistilled in a 1liter rbf. The distillate started to come over at about 38C and quickly rose to 39.5-40C and stayed there for about 1.5hrs. I collected about 600ml.

Then the temperature rose to above 44C and I collected about 100ml. Then the temperature rose again sharply to about 60C where I collected the rest of the distillate, about 40ml.

My question is: should I discard the last two distillate, the ones collected at temperature of 44C and 60C? What is it that I'm collecting at those high temperature?

The msds of my paint stripper only has dichloromethane, methanol, and some polymer stuff.

Any ideas and suggestions? thanks.
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[*] posted on 13-9-2011 at 22:08


Quote: Originally posted by Magpie  

Now, during my recent refresher course the lab manual relies very heavily on the use of DCM, and rarely specifies chloroform, carbon tet, or ether.

Surely this must be due to the lower toxicity of DCM vs chloroform and carbon tet. And compared to ether there is the big advantage DCM's non-flammability.


The lack of modern references to carbon tet. is probably as much to do with it being banned under the Montreal Protocol as anything else.

[Edited on 14-9-2011 by drago57]
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[*] posted on 20-9-2011 at 21:33
purification of otc dichloromethane


Just wanted to share with the sciencemadness community my result in otc dichloromethane and its purification.

I got great result. I did the initial distillation and got about 600ml of dichloromethane between the temperature of 38C to 44C. My source of OTC dichlormethane had only methylene chloride, methanol, and polymer stuff to thicken it and slow the volatility. The initial distillation probably got rid of all the polymer stuff. dischloromethane forms an azeotrope with methanol (93% and 7%) and with water (97.5% and 2.5%).

I did a second distillation and collected only what came over between 39C to 41C. I got rid of what came over initially and the final 100ml in the initial rbf. I collected about 500ml.

Next, I washed the dichloromethane with equal volume of water in a separatory funnel. YOu want to keep the bottom layer. Dichlormethane is heavier than water.

I did a second water wash and allowed it to stand overnight. Next morning I drained the lowered layer into a container and then added 10g of calcium chloride. I let that settle for several hours and then set up for a final distillation. The distillate started to come over between 39C and quickly rose within minutes to 40C and stood there for about 1.5hrs, til almost the end of the distillation.

I was happy with the result: 450ml of pure dichloromethane!

I think its pure, it was coming over at ~40C.
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[*] posted on 21-9-2011 at 08:20


probably a lot cheaper to buy it

[img]http://www.newhorizonsscientific.ca/catalogsearch/result/?q=dichloromethane[/img]

chemicals_2_39.jpg - 8kB
13.49$ for 500ml
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[*] posted on 21-9-2011 at 08:24


Quote: Originally posted by Steve_hi  
probably a lot cheaper to buy it

[img]http://www.newhorizonsscientific.ca/catalogsearch/result/?q=dichloromethane[/img]


13.49$ for 500ml


I don't know about other countries, but dcm, like many other solvents, is a list II controlled substance and you can't buy decent amounts from supplier without a license.

[Edited on 21-9-2011 by shivas]
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