FriendlyFinger
Hazard to Self
Posts: 64
Registered: 14-3-2005
Member Is Offline
Mood: No Mood
|
|
IPA extraction question
If a had a block of a fairly anhydrous mix of MeHN2/NH4HCl, from a hexamine/HCl reaction and extract that with 88% IPA, how much NH4Cl should I expect
to be extracted along with MeNH2.HCl noting that NH4Cl is soluble in water (W/W) 39.6% at 80 deg C?
|
|
|
Vitus_Verdegast
Hazard to Others
Posts: 297
Registered: 5-12-2004
Location: Ottoman Empire
Member Is Offline
Mood: tea time
|
|
Why don't you dry your IPA? Isn't NH4Cl almost insoluble in dry IPA?
Use 3A molecular sieves. They are cheap and easy.
Sic transit gloria mundi
|
|
|
bio2
Hazard to Others
Posts: 447
Registered: 15-1-2005
Member Is Offline
Mood: No Mood
|
|
Benzene or toluene as entrainer will
remove the water as ternary azeotrope.
It's somewhat tedious but doesn't need much attention once running and sure beats drying kilos of sieves or silica gel which may get contaminated as
well if recycling your solvents.
It takes a LOT of sieves or silica gel to remove that much water and a pre-treatment with a high capacity
drying agent is helpful if you go this route.
|
|
|
Organikum
resurrected
Posts: 2339
Registered: 12-10-2002
Location: Europe
Member Is Offline
Mood: frustrated
|
|
Why make things so complicated?
Just salt the water out. Add heaps of table salt, separate the layers and the resulting IPA is good enough for this extraction.
Your question Friendly Finger makes me think your problems with the alcohol/hexamine/HCl route to methylamine are fairly basic ones, not so much
related to the procedure but....
Look, if you really ever did this you would have seen that IPA and the residual water form two layers anyways after the extraction. The IPA layer
containing almost only methylamine and the lower salt-loaded layer consisting of methylamine, ammoniumchloride and - water. Provided that you actually
did this you obviously just didn´t really LOOK.
Some older chemistry book states that extraction with 95% EtOH gives already 98%+ methylamine. Just so.
/ORG
[Edited on 15-6-2006 by Organikum]
|
|
|
bio2
Hazard to Others
Posts: 447
Registered: 15-1-2005
Member Is Offline
Mood: No Mood
|
|
.....pre-treatment with a high capacity
drying agent is helpful ........
Like salt (NaCl) maybe for IPA, .
Somehow Joe always seems to end up with mixed alcohols so has saved the same mixture of the 3 lower alcohols for many a
recrystallization.
After being a near fanatic for water removal of the HCl he;s decided to take your advice and gorget drying the salt and just gassing it into the
alcohol for the amination.
|
|
|
S.C. Wack
bibliomaster
Posts: 2419
Registered: 7-5-2004
Location: Cornworld, Central USA
Member Is Offline
Mood: Enhanced
|
|
His IPA cannot be dried further with NaCl, as the top layer from this is 87% IPA. It can however be dried beyond 91% with NaOH and the top layer
distilled for the anhydrous product.
|
|
|
Organikum
resurrected
Posts: 2339
Registered: 12-10-2002
Location: Europe
Member Is Offline
Mood: frustrated
|
|
It´s not drying but salting out and the top layer is more then 87% IPA, it´s more like 98%. We are not talking about azeotropes here.
/ORG
[Edited on 16-6-2006 by Organikum]
|
|
|
S.C. Wack
bibliomaster
Posts: 2419
Registered: 7-5-2004
Location: Cornworld, Central USA
Member Is Offline
Mood: Enhanced
|
|
It is nice to see you posting outside of whimsy again, but I will argue anyways.
Removing water is drying whether it is salted out or absorbed.
If you are so sure that the layer is 98%, then I suggest that you take some 91% IPA and shake it with salt. Shake by hand until a brine layer forms. A
drop is fine. You will be typing with one hand for quite some time, because the 87% number did not come out of thin air. If it was 98% IPA, that would
leave nothing for the 2% of salt to dissolve in, and there is definitely salt in the top layer. Where there is salt there is water. If you try this
with NaOH like I said, you will observe very different results. Of course the NaOH will dissolve some in the IPA, but not fast and that is what the
distillation is for.
After 434 posts, every one outside of whimsy when they were posted, I'm seen as some bullshit poster talking out of my ass, not taking posting
seriously like so many others.
[Edited on 16-6-2006 by S.C. Wack]
|
|
|
12AX7
Post Harlot
Posts: 4803
Registered: 8-3-2005
Location: oscillating
Member Is Offline
Mood: informative
|
|
| Quote: | Originally posted by S.C. Wack
After 434 posts, every one outside of whimsy when they were posted, I'm seen as some bullshit poster talking out of my ass, not taking posting
seriously like so many others.
|
Maybe because you don't deposit the bullshit in the appropriate receptacle as everyone else does? 
(Whether or not there actually *IS* BS (which, if none of your posts actually are in Whimsy, I commend you ) is independent of this argument, of course.)
Tim
|
|
|
Organikum
resurrected
Posts: 2339
Registered: 12-10-2002
Location: Europe
Member Is Offline
Mood: frustrated
|
|
If I find the time I will dig up the related article for you Mr Wack and you are wrong by the way - salting out and drying with a salt are two
different processes - well if you are VERY generous you might regard salting out as a subgroup of what is usually called drying but thats just
nitpicking.
Maybe I have expressed myself a little bit to sloppy: One adds enough salt, NaCl, preferably dishwasher regeneation salt and not table salt for
impurtities to saturate the water in the IPA. Brine in difference to water mixes almost not with IPA.
This is decidedly another principle then to remove water by adding a salt like CuSO4 which sucks the water off.
This yields IPA which is perfectly useful for extracting methylamine and that was what was asked for - nothing else.
The 87% you are talking of are nonsense IMHO. Sounds more like the azeotrope water/IPA but I am to lazy to look this now up, do it yourself if you are
interested.
/ORG
PS: The standard procedure was always to add the salt, to shake or stirr and to let sit for some days. Yields a clear upper layer - if not your salt
was dirty. And thats pretty old.
[Edited on 16-6-2006 by Organikum]
|
|
|
S.C. Wack
bibliomaster
Posts: 2419
Registered: 7-5-2004
Location: Cornworld, Central USA
Member Is Offline
Mood: Enhanced
|
|
I'm really quite familiar with salting 70% IPA, having used the result for natural product extractions. I've mentioned this here before. Again I say,
shake 91% IPA with salt. Don't call bullshit on me again until you see two layers.
Looking forward to your article. Here is more nonsense bullshit.
http://pubs.acs.org/cgi-bin/abstract.cgi/jacsat/1932/54/i04/...
Take your meds.
|
|
|
Organikum
resurrected
Posts: 2339
Registered: 12-10-2002
Location: Europe
Member Is Offline
Mood: frustrated
|
|
The article you provided says: | Quote: | | The distillate has so nearly the composition of the 91% azeotropic mixture... |
The MERCK though states the
azeotrope of water/IPA contains 87,7% IPA w/w. The last paragraph makes not much sense to me anyways - at least not the part where they talk about
salting out + distillation yielding about the same concentration as distillation of the azeotrope. Then salting out would be obsolete as first step.
I suppose the authors of the article just didn´t wait long enough to allow a complete separation of brine and IPA.
The preparation of anhydrous IPA with NaOH sounds good, but I cannot say if it´s actually valid.
/ORG
|
|
|
Organikum
resurrected
Posts: 2339
Registered: 12-10-2002
Location: Europe
Member Is Offline
Mood: frustrated
|
|
Here is the related thread from the-hive including some practical tips:
Attachment: salting out.html (38kB)
This file has been downloaded 1123 times
|
|
|
S.C. Wack
bibliomaster
Posts: 2419
Registered: 7-5-2004
Location: Cornworld, Central USA
Member Is Offline
Mood: Enhanced
|
|
This makes perfect sense to me as they are talking about concentrating dilute IPA. It makes no sense to distill a liter when you could shake with salt
and distill 500 ml. The 91% figure is the same as 190 proof/95% grain alcohol is here in the US - volume measurement with the wt. % being a little
lower.
|
|
|
Organikum
resurrected
Posts: 2339
Registered: 12-10-2002
Location: Europe
Member Is Offline
Mood: frustrated
|
|
It seems to me that the time it takes to salt the water out and the effort involved is much higher then the time it takes to bring one liter IPA/water
to boil in difference to 500ml. The plain distillation time is exactly the same methinks - the azeotrope comes first and thats that.
/ORG
|
|
|
bio2
Hazard to Others
Posts: 447
Registered: 15-1-2005
Member Is Offline
Mood: No Mood
|
|
I tried PhMe, benzene and hexanes to form the ternary azeotrope for water removal. Benzene works best and
although toluene entrains more water the temperature is too close to the binary water azeo with IPA. Even with a 150mm
steel sponge packed column the separation is far from ideal.
Dealing with the binary azeotrope of IPA and the entrainer
isn't necessary if only a small amount is used, refluxing hard
over a Dean Stark.
When trying to dry many liters of alcohol I find this much better than dealing with kilos of salt and all that entails.
The NaOH method works fine but it might end up costing more than the Isopropanol unless it's acquired in 50lbs bags.
|
|
|
gil
Unregistered
Posts: N/A
Registered: N/A
Member Is Offline
|
|
recycling NaOH would bring overall cost down
|
|
|
nightflight
Hazard to Self
Posts: 82
Registered: 23-5-2006
Member Is Offline
Mood: pyrophoric
|
|
I think there was a paper calling for 1-butyl(oh), I´ll post a citation if I find it.
What´s the fun in using Me(OH) over Et(oh) or n-butyl(OH) or a Et(OH)/ME(OH)-mix anyway?
|
|
|
![[*]](images/xpblue/default_icon.gif){kind=icon}
