-jeffB
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Aniline and its salts: buying and storing
I note that Chemsavers has both aniline hydrochloride and aniline sulfate in their "closeout" section at an attractive price., with ORM-D shipping
also fairly cheap. I'd like to enter the world of diazo reactions at some point, but probably not in the immediate future, and I'm wondering if I
should jump on one or the other.
I probably have enough authority through my place of work to order straight aniline through a normal supplier, but:
a) it's pretty expensive
b) it's volatile, insidious, deadly, etc, etc, etc.
c) it doesn't age especially well
d) it has to be shipped OMG-DIE POISON-PAK HAVE SOMEONE ESCORT THE TRUCK ON FOOT RINGING A BELL, which adds considerably to its expense
So, my questions:
How much better do the salts keep than the free amine?
How easy is it to liberate the aniline from its salts in a useful form?
Is it worth the bother?
Back in my ambitious and clueless days, I made a few ml of nitrobenzene, tried to reduce it with iron powder and HCl, got an unbreakable suspension,
and tried to separate it in my Gilbert Chemcraft plastic centrifuge. The centrifuge broke, and smashed the test-tube and its contents into the
cinder-block basement wall, which promptly absorbed the mixture. I'd just as soon not repeat that little goof...
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garage chemist
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If you can make or get benzene in useful amounts, you can make aniline yourself with minimal cost...
The emulsion you get from the reduction isn't meant to be separated, its meant to be steamdistilled and aniline separated from unreacted nitrobenzene
by extraction with aqueous acid.
EDIT: Ordenblitz has written a good documentation, as has Magpie:
https://sciencemadness.org/talk/viewthread.php?tid=462&p...
[Edited on 16-4-2008 by garage chemist]
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Klute
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The freebase would be easily libezrated from it's salt by simple treatment with conc NaOH followed by seperation and extraction if you want to get all
of it out.
And usually salts of amines store very well when in a dry, cool atmosphere.
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-jeffB
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| Quote: | Originally posted by garage chemist
If you can make or get benzene in useful amounts, you can make aniline yourself with minimal cost...
The emulsion you get from the reduction isn't meant to be separated, its meant to be steamdistilled and aniline separated from unreacted nitrobenzene
by extraction with aqueous acid.
EDIT: Ordenblitz has written a good documentation, as has Magpie:
https://sciencemadness.org/talk/viewthread.php?tid=462&p...
[Edited on 16-4-2008 by garage chemist] |
Great, now all I have to do is send this tip back in time 30 years to my younger self.  (Along with a steam-distillation setup!) I think I was looking at a lab manual detailing the reduction with tin (which I couldn't get),
and read that it was done industrially with iron (which I had).
Getting aniline HCl or sulfate looks easier and cheaper than getting or making benzene and nitric acid, doing the nitration, reduction, separation,
and purification. Of course, the journey is the reward, but I'm happy to skip certain particular parts of the journey at this stage of my life.
Oh, and thanks for the link! I'd come across that thread in my search, but I hadn't appreciated how nice Ordenblitz's procedure was.
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-jeffB
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| Quote: | Originally posted by Klute
The freebase would be easily libezrated from it's salt by simple treatment with conc NaOH followed by seperation and extraction if you want to get all
of it out.
And usually salts of amines store very well when in a dry, cool atmosphere. |
That's what I was hoping, although I'm not sure just how cool and dry I can keep things.
Is there a reason to prefer the sulfate over the hydrochloride, or vice versa? I seem to remember someone saying that the hydrochloride is extremely
hygroscopic; is the sulfate any less so? It seems like it would be equally easy to recover aniline from either salt, and the weight percentage of
aniline is comparable.
I wonder if it would be possible to diazotize without first releasing the aniline? In the preps I remember, the first thing you do is mix the aniline
with sulfuric or hydrochloric acid; it seems that starting with the salt would put you further ahead...
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