So I purchased some paint stripper at my local hardware store that contains methanol, toluene and dichloromethane. It has a polymer added to it that
gives it the consistency of gel. Methanol and toluene form and azeotrope so to break it I could add water. But then I encounter the issue of water
forming azeotropes and the solvents already form azeotropes with one another to some degree. Is there a way I can break the azeotropes? I was thinking
of first distilling everything from the gel so that I have easier to work with liquids that are less viscous. Then I thought I could break the
azeotropes through a series of steps. First removing the methanol via water and a sep funnel. Then breaking water's azeotropes with the other solvents
by adding a compound that is soluble in water but not the DCM or toluene and again using the sep funnel. Now that I'm left with the DCM and toluene
which form an azeotrope if I'm not mistaken. I think I could do something similar again by adding something that is soluble in one solvent but not the
other, then letting two layers form in a sep funnel again and separating. Then I would distill the toluene and DCM on their own. Is this a viable
process?Metacelsus - 10-1-2014 at 16:27
There is no azeotrope between toluene and dichloromethane.
Thank you! Other than that is it viable?Metacelsus - 10-1-2014 at 17:28
Yes, probably, although the goo may complicate things (like clogging glassware).thebean - 10-1-2014 at 17:41
The goo won't be too much of an issue because I built a small copper pipe distillation set up so I can distill straight out of the can. This video is similar to what I'm doing.Bot0nist - 10-1-2014 at 17:51
Thats how I get all my DCM too, distilled from its can. I use a kleenstrip gel type and only recover the DCM. The low boiling point makes it pretty
easy with a water bath, then I use my glass apparatus to further purify the DCM and gather the BP at the still head. Dont have to worry about cleaning
the gunk from my RBF then. TheChemiKid - 10-1-2014 at 17:57
Make sure that you wash the DCM with water, then dry and distill it. This is very important because most paint stripper have methanol as well. DCM and
methanol will form an azeotrope with 7.3% methanol. This can mess up reactions in which you use your DCM.Bot0nist - 10-1-2014 at 18:16
Yes, good point, a shake with room temp distilled water and your crude DCM in a sep funnel should fix that. Thanks Chemikid. Sorry I left that out.TheChemiKid - 10-1-2014 at 18:25
Just a tip: Cool all your glassware in the freezer (not including the distillation apparatus), this will reduce losses. You can also test for methanol
with potassium dichromate.thebean - 10-1-2014 at 19:20
First removing the methanol via water and a sep funnel.their own.
I had already covered removing the methanol in my procedure description. Thanks for the part about the methanol detection though, that will come in
handy.Electra - 10-1-2014 at 20:48
Is there a reason you want to do this other than sheer experimentation?
If you are in the USA, Toluene is readily available in pure form OTC if you go to stores that specialize in paint, alternatively you can get it
online. It is regularly used as an additive in nail polish remover, fuel enhancers, paint thinners, etc. I don't see why you're going to all the
unnecessary work. When it comes to chemistry supplies why bother go to mainstream hardware stores like Home Depot, Lowes, etc... all of that stuff is
polluted with a bunch of fancy additives to make it more appeals to everyday consumers. Go to a paint shop, get any quantity of toluene you'd like. I
know many racing hobbyist who buy it by gallon as a fuel additive to increase their octane rating. TheChemiKid - 11-1-2014 at 05:21
Yes, toluene is very available, but DCM isn't for the amateur chemist. When you buy this, you learn how to distill a mix of liquids, use a separatory
funnel, and separate a homogeneous mixture of liquids. This is a great experiment for a beginner, and a great way of getting DCM for almost anyone who
can get their hands on it.blogfast25 - 11-1-2014 at 06:50
Hmm, I didn't see Elemental Scientific had it, but it is still much less easily obtained than toluene. I have never seen any DCM at RC stores. Still,
separation from paint stripper is fun, and it can be found locally. Elemental Scientific is slow at shipping, and has expensive shipping. You would
need to buy lots of DCM from Elemental for it to be more cost efficient. At that point, you should just buy in bulk.thebean - 11-1-2014 at 10:20
I am in the US and normally the store I go to as toluene but they didn't this time and I also wanted DCM, so I thought why not?
DCM from Furniture stripper at Walmart in Canada
GoldGuy - 11-1-2014 at 11:52
I dont distill.
I just pour Sa litre of furniture stripper in a four litre jar.
Add cold water and shake and stir the hell out of it. It separates into three layer: aqueous,gel/junk and DCM.... pure enough for DCM washes. But if I
was going to use the DCM for extracting Id distill it.
Sometimes when I wash DCM with water after the distillation its will turn milky immediately upon water meeting it. Anybody know what Im doing wrong?Bot0nist - 11-1-2014 at 12:12
An impurity causing an emulsion or colloidal suspension, I would dare to guess. A distillation to get crude DCM first should solve this.blogfast25 - 12-1-2014 at 02:10
It separates into three layer: aqueous,gel/junk and DCM.... pure enough for DCM washes.
Assuming your starting product contains toluene (I don't know it does), then that should still be with the DCM in the organic phase, I think.vmelkon - 12-1-2014 at 05:16
It said
dichloromethane
toluene
----------------------
313.2 K 40.05 °C 104.09 °F
----------------------
Zeotropic
Does zeotropic means it doesn't form an azeotrope?TheChemiKid - 12-1-2014 at 05:25
@vmelkon Zeotropic: non-azeotropic
So yes, zeotropic means not the mixture will not form an azeotrope.
It says this right at the top of the page Cheddite Cheese posted.
EDIT: Fixed typo
[Edited on 1-12-2014 by TheChemiKid]hydride_shift - 12-1-2014 at 06:39
Make sure that you wash the DCM with water, then dry and distill it. This is very important because most paint stripper have methanol as well. DCM and
methanol will form an azeotrope with 7.3% methanol. This can mess up reactions in which you use your DCM.
THIS, is very useful information.
The paint stripper I use contains ammonia which is very soluble in DCM, when using a copper retort a small amount of blue copper complex distills
over. Easy solution is to wash with cold HCl and force everything into the aqueous.
[Edited on 12-1-2014 by hydride_shift]thebean - 12-1-2014 at 18:45
I hate to ask a stupid question but when I wash with water to get rid of methanol what layer will be on top? I should think the toluene/DCM will be on
bottom but I could be wrong.Bot0nist - 12-1-2014 at 19:46
Search the density if DCM, and compare that to water's. Then you will have found
your answer.thebean - 12-1-2014 at 19:57
DCM is on the bottom yes? Thanks!
He had a good question
GoldGuy - 12-1-2014 at 22:43
Yes the DCM will most likely be on the bottom but with toulene dissolved in it who knows?
You guys cant buy Stripper that is only DCM and methanol?
What do you guys use to dry your DCM after washing with water?
Then you will have found
your answer.