Siddy - 14-7-2008 at 19:14
Paint stripper was mixed with an equal volume of water and distilled using simple distillation method.
(Paint stripper= 80% DCM, 20% MeOH, NH3, "Hydrocarbons")
After distilling DCM from paint stripper, a opaque (white) liquid with white semi solids floating on top (foaming occurred and went through the
condenser).
crude DCM (80ml) (minus white scunge) loaded into a sep funnel then added 10g/L NaCl solution (40ml), shook and separated -repeated this 5 times
(first time genitally rocking funnel, last time heavy shaking). But the DCM is still a little opaque (but a lot better than crude). 1 or 2 grams of
dry CaCl2 added to the DCM and left to clarify.
Is this the best method for getting the water out of crude DCM? or is there an easier method?
Or was it the fact that the reaction vessel foamed so much that the crude was contaminated so much? How do you stop it from foaming?
hashashan - 14-7-2008 at 21:50
How did you manag to separate DCM from MeOH? they have very close boiling points
Siddy - 14-7-2008 at 22:25
There boiling points differ by 25oC, and the DCM distills first.
Maybe you are referring to the azeotropes?
The crude DCM will have MeOH in it.
MeOH is soluble in water, therefore saline extractions will remove some MeOH.
CaCl2 will also remove some MeOH.
Im not concerned with MeOH contaminants in the DCM, i just want it clear, even the CaCl2 didnt clear it much but needs to be filtered again.
[Edited on 14-7-2008 by Siddy]
497 - 14-7-2008 at 22:59
Wow you are lucky to have paint stripper with such high DCM content, I have only managed to find it locally with less than about 30% IIRC. Its a pain
in the ass, it forms so many azeotropes.
Conc. H2SO4 does a fine job of dehydrating DCM.
I think there is already a thread on this btw.
hashashan - 14-7-2008 at 23:08
Is there no way to get rid of all the MeOH?
I wanted to use that DCM for HNO3 separation, and I guess that the MeOH will be a serious hazard in there.
Klute - 15-7-2008 at 03:38
As mentionned in at least one other thread, and above, washing with brine, water, sat CaCl2, H2SO4 all remove MeOH in (IMHO) increasing order.
Remove it before a final fractional distillation and you are fit to go.
Siddy - 15-7-2008 at 15:08
Thanks for the replies.
After adding 5ml~ 98% H2SO4, shaking and separating the DCM is much clearer, i would say perfectly clear. Boils at 40oC, distills and leaves no
residue!
I suggest 2 or 3 saline extractions from crude, then H2SO4, i doubt CaCl2 is even needed.
Getting the MeOH out is more important than i thought as its the reason why the water is hard to get out.
497: You have to look around, search msds's to find a good stripper, i think most say 40-60%, but contact a FURNITURE REFURBISHER they go through
stripper like crazy and can sell you heavy duty stuff. For example, one brand locally available at an auto store is 40-60% but the company also makes
a "HD" (heavy duty) version only available to business' so if you buy through a small business you can get the HD stuff
Picric-A - 18-7-2008 at 14:12
burning the DCM MeOh mix (after purification) keeps comming to my head but i dont know how you would go about it.
maybe if you slightly heat the mix up to around 30 degrees C then try to ignite any vapours comming off?
o well, just a thoguht 