pralem
Harmless
Posts: 6
Registered: 31-8-2013
Member Is Offline
Mood: No Mood
|
|
wet hcl gas
I'm trying to crystallize an amine dissolved in a solute gassing it with (supposedly) dry hcl gas. At first, everything was ok and got clouds of
crystals. But then, suddenly, they started to disappear. Surely, that was because of water vapors in the gas.
So, now I have my crystals dissolved in water and the solute. My question is: how to extract those crystals? Obvious answer would be evaporate water
and solute but I don't want to do that because the solution became dark brown after 24 hours. If I distill off the solutes, I will be left with a
black gunk (I guess).
Thanks for any alternative solution!
|
|
|
bfesser
Resident Wikipedian
Posts: 2114
Registered: 29-1-2008
Member Is Offline
Mood: No Mood
|
|
Don't be vague. Nobody can help you unless you specify what your mystery compound is.
Don't make
assumptions like this.
If you're inquiring about the preparation of an illicit substance, just come out with it, we don't 'SWIM' (Someone Who Isn't
Me) here.
If you're preparing anything else, give as many details as possible.
Welcome to Science Madness. 
|
|
|
bfesser
|
Thread Moved
31-8-2013 at 07:45 |
pralem
Harmless
Posts: 6
Registered: 31-8-2013
Member Is Offline
Mood: No Mood
|
|
bfesser, I'm assuming it's water in gas because I found little dots of it in the walls of the beaker. Although my generator follow all good standards
for generating dry gas, I guess my overall environment is too humid.
And yes, it is MDMA. Any tips?
|
|
|
sonogashira
National Hazard
Posts: 555
Registered: 10-9-2006
Member Is Offline
Mood: No Mood
|
|
Did you add enough HCl gas to completely neutralize the amine? Discolouring may be due to oxidation of the freebase amine, if enough HCl wasn't added.
What solvent are you using? Toluene may be dried by partial distillation. If you have enough water to completely dissolve your amine hydrochloride
then maybe you would be better to extract it into water, evaporate the water, then recrystallize the crude product. You can always recrystallize your
amine HCl, even if it is black. (You don't have to incriminate yourself - even if someone asks you to).
[Edited on 31-8-2013 by sonogashira]
|
|
|
bfesser
Resident Wikipedian
Posts: 2114
Registered: 29-1-2008
Member Is Offline
Mood: No Mood
|
|
I didn't ask him to incriminate himself. I just pointed out that vague questions get vague (if any) responses.
|
|
|
pralem
Harmless
Posts: 6
Registered: 31-8-2013
Member Is Offline
Mood: No Mood
|
|
sonogashira, thanks for the tips.
Definitely was added enough gas (most provably, in excess). Any problem if excess gas is added?
Solvent was Toluene, lab grade, dry. I will give it a try on the extraction with water.
About recrystallization, last time I tried with that dark oil, I ended up with brown crystals which, in my opinion, were too impure for any real use.
So, I definitely don't want to evaporate water and toluene to end up with that gunk again. I believe that extraction with water would be better.
(thanks for you clarification, I was really kind of innocent in strictly answering the question)
|
|
|
sonogashira
National Hazard
Posts: 555
Registered: 10-9-2006
Member Is Offline
Mood: No Mood
|
|
Try on a small sample first. You will be able to tell from the colour of your water - but you've made it black already(!), so I wouldn't be too
surprized if you'll need to recrystallize a few times.
[Edited on 31-8-2013 by sonogashira]
|
|
|
Shikimol69
Harmless
Posts: 11
Registered: 16-6-2013
Member Is Offline
Mood: No Mood
|
|
You're right, you contaminated your toluene with water during HCl gassing, what generally results in the brownish solution you observed on the bottom
of your glassware... This is a rookie mistake that you could have easily avoid by drying your freshly generated hydrochlorid gas by bubbling it
through concentrated H2SO4 (96% is the one). Getting around this simple but essential procedure will unvariably lead to the solubilisation of your new
born chlorhydrate salt if the bubbling is not interrupted at the good moment.
It is well known that toluene is more enclined to be contaminated with water than xylene under the same atmospheric conditions, thus you should
consider to use xylene(s) when performing gassing, or titrating your freebase in toluene mixture with a concentrated solution of HCl in isopropyl
alcohol (obtained by bubbling well-dried HCl gas in cold IPA with magnetic stirring). You can also keep on with gassing toluene, but it is always a
good idea to remove as much as residual water with drierite or anhydrous MgSO4 prior salting out...
With your messy solvated X in aromatic solvent, first isolate the brown watery "bubbles" from toluene then evaporate/dessicate under vacuum if
possible > you should recover some of your XTC that should be cleaned up via dual solvent re-crystallization. Titrate the toluene with aqueous or
alcoholic acid solution to pH7 and proceed just like before...
I don't know what kind of HCl generator you finally picked up from litterature, but my preference go with HCl dripped over well-stirred H2SO4, much
more manageable than any other procedures.
|
|
|
pralem
Harmless
Posts: 6
Registered: 31-8-2013
Member Is Offline
Mood: No Mood
|
|
Sonogashira, I will try today with a small sample. Thanks for your help!
Shikimol69, the HCl generator I used was 98% H2SO4 (50ml) dripped over 37% HCl (100ml) + NaCl (50g). The gas passed through a 30cm condenser filled
with CaCl2. Perfect construction, in my opinion, but it seems not enough OR my ambient is too humid and the solution is taking water from the air.
Next time, I will try the bubbling in H2SO4 but if my solution is taking water from the air, even this construction will not work.
Do you know how much HCl can 100ml dry and cold IPA hold? Also, if water is dissolved in HCl + IPA, is there any way to remove it out? It seems that
the MgSO4 will not work because it will react with the HCl...
|
|
|
pralem
Harmless
Posts: 6
Registered: 31-8-2013
Member Is Offline
Mood: No Mood
|
|
Just to let you guys know, my mag stirrer stop working and is still being fixed.
As soon as I have the results, I will post them here.
|
|
|
Mildronate
Hazard to Others
Posts: 428
Registered: 12-9-2009
Member Is Offline
Mood: Ruido sintetico
|
|
make sulphate and forget about it (if its speed).
|
|
|
kingkool
Harmless
Posts: 3
Registered: 12-10-2006
Member Is Offline
Mood: No Mood
|
|
Drop the HCl acid onto the sulfuric acid (not the other way around, which is what you indicated). Sulfuric acid is a great desiccant -- it will absorb
all the water almost immediately, liberating dry HCl gas.
If you need it dryer, set up a secondary flask filled with sulfuric acid and bubble the HCl gas through the secondary sulfuric acid.
|
|
|
![[*]](images/xpblue/default_icon.gif){kind=icon}
