Gualterio_Malatesta
Harmless
Posts: 24
Registered: 8-1-2010
Member Is Offline
Mood: No Mood
|
|
Steam distillation of aniline.
I have some old, dark brown, almost black aniline.
I want to steam distill it. Any tips guys?
I plan to add water to aniline (1:1) and heat it until it boils, then I'd introduce a steamer outlet into the mixture. Collect the distillate.
Now the question is how would I separate it from water at the end of distillation? Can I salt it out?
|
|
|
Bot0nist
International Hazard
Posts: 1559
Registered: 15-2-2011
Location: Right behind you.
Member Is Offline
Mood: Streching my cotyledons.
|
|
Check out the last half of this video.
http://www.youtube.com/watch?v=oRn7kTiqfaA
EDIT: Fixed link, sorry.
[Edited on 16-7-2011 by Bot0nist]
U.T.F.S.E. and learn the joys of autodidacticism!
Don't judge each day only by the harvest you reap, but also by the seeds you sow.
|
|
|
Gualterio_Malatesta
Harmless
Posts: 24
Registered: 8-1-2010
Member Is Offline
Mood: No Mood
|
|
Hey, that link is totally broken, man.
|
|
|
vulture
Forum Gatekeeper
Posts: 3330
Registered: 25-5-2002
Location: France
Member Is Offline
Mood: No Mood
|
|
I've always wondered, is it really necessary to steam distill aniline? Can't one just use normal (vacuum) distillation? Or for small quantities use
the acidify - basify route?
One shouldn't accept or resort to the mutilation of science to appease the mentally impaired.
|
|
|
IPN
Hazard to Others
Posts: 156
Registered: 31-5-2003
Location: Finland
Member Is Offline
Mood: oxidized
|
|
I never bothered with the steam distillation when preparing aniline from nitrobenzene but this was mostly due to the small scale of the reactions.
Still I see no reason why it would be needed if one is just purifying aniline. It might be useful in large scale reductions where you have a lot of
tin / iron salts and workup by extractions would be too laborious.
|
|
|
Gualterio_Malatesta
Harmless
Posts: 24
Registered: 8-1-2010
Member Is Offline
Mood: No Mood
|
|
So you think steam distilling it is unnecessary? I mean it's really old and dark, pretty much black.
|
|
|
IPN
Hazard to Others
Posts: 156
Registered: 31-5-2003
Location: Finland
Member Is Offline
Mood: oxidized
|
|
From Purification of Laboratory Chemicals, 6th Ed.
| Quote: |
Aniline [62-53-3] M 93.1, f -6.0o, b 68.3/10mm, 184.4o/760mm, d 4 20 1.0220, n D 20 1 . 5 8 5 , n D 25 1.5832, pK25 4.60. Aniline is hygroscopic.
It can be dried with KOH or CaH2, and distilled under reduced pressure. Treatment with stannous chloride removes sulfur-containing impurities,
reducing the tendency to become coloured by aerial oxidation. It can be crystallised from Et2O at low temperatures. More extensive purifications
involve preparation of derivatives, such as the double salt of aniline hydrochloride and cuprous chloride or zinc chloride, or N-acetylaniline (m
114o) which can be recrystallised from water. Redistilled aniline is dropped slowly into a strong aqueous solution of recrystallised oxalic acid.
Aniline oxalate (m 174-175o) is filtered off, washed several times with water and recrystallised three times from 95% EtOH. Treatment with saturated
Na2CO3 solution regenerated aniline which was distilled from the solution, dried and redistilled under reduced pressure [Knowles Ind Eng Chem 12 881
1920]. After refluxing with 10% acetone for 10hours, aniline is acidified with HCl (Congo Red as indicator) and extracted with Et2O until
colourless. The hydrochloride is purified by repeated crystallisation before aniline is liberated by addition of alkali, then dried with solid KOH,
and distilled. The product is sulfur-free and remains colourless in air [Hantzsch & Freese Chem Ber 27 2529, 2966 1894]. Non-basic materials,
including nitro compounds, are removed from aniline in 40% H2SO4 by passing steam through the solution for 1hour. Pellets of KOH are then added to
liberate the aniline which is steam distilled, dried with KOH, distilled twice from zinc dust at 20mm, dried with freshly prepared BaO, and finally
distilled from BaO in an all-glass apparatus [Few & Smith J Chem Soc 753 1949]. Aniline is absorbed through skin and is TOXIC. [Beilstein 12 IV
223.]
|
You should really keep a copy of this book at hand. 
So taking from this, I'd probably do the A/B extractions and then just dry with KOH and distill. Going through all that is described there is overkill
for amateur chemistry work.
|
|
|
Bot0nist
International Hazard
Posts: 1559
Registered: 15-2-2011
Location: Right behind you.
Member Is Offline
Mood: Streching my cotyledons.
|
|
Fixed the link up thread, sorry. Its a good vid.
U.T.F.S.E. and learn the joys of autodidacticism!
Don't judge each day only by the harvest you reap, but also by the seeds you sow.
|
|
|
Gualterio_Malatesta
Harmless
Posts: 24
Registered: 8-1-2010
Member Is Offline
Mood: No Mood
|
|
Thanks everyone!
I haven't decided what I'm gonna do with it yet, it still mostly depends on my laziness
|
|
|
smuv
National Hazard
Posts: 842
Registered: 2-5-2007
Member Is Offline
Mood: Jingoistic
|
|
@vulture, you can vac distill aniline, no need to steam distill. You can even distill aniline at atmospheric and it comes over colorless.
Edit: I never tried acid base for aniline but for p-anisidine (granted more OX sensitive) it did not provide a colorless product.
[Edited on 7-16-2011 by smuv]
"Titanium tetrachloride…You sly temptress." --Walter Bishop
|
|
|
![[*]](images/xpblue/default_icon.gif){kind=icon}
