isiahmajor
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Aluminum amalgam problem...Help needed
Good Evening to everybody out there.
i've been doing some interesting organic synthesis in the last time.. yesterday i've tried once again a classic reduction of nitroalkane to the
correspondent amine trough aluminium amalgam but using the far less toxic kalomel ( mercurous chloride) instead of HgCl2.
Now i perfectly know that kalomel is insoluble in alcohol and only slightly soluble in water, but if you lower the water ph to 4,5 - 5 and you mix
really well the alumina with Hg2Cl2 for at least 4 hour it will begin to react forming the amalgam. So i must to admit that yes it is really possible
to substitute HgCl2 with its safer counterpart Hg2Cl2.
Now i've got a question... after been doing the classic work up basifiyng gently the whole mixture with 30 perc. NaOh soln, collecting the upper
layer, extracted it with 2x ether, driying the ether with Na2SO4 , distilled the solvent and collecting the freebase... yeah now i was really
disappointed! in the flask was yes the classic fish smelling freebase but also some crystals...??? yes some white crystal wich after gravity
filtration smelled really like hell.. never seen in all my workups anything like that.
What could this be? anyway at the end also the cristallyzation process failed, i wanted to make the sulphate salt and when i've added the H2SO4
mixture in IPA to IPA + amine freebase ( wich have been freed of those impurity -- see up -- ) result in a crystalization wich have only started and
then incredibly stopped...the formed crystals wich have been formed redissolved again in a matter of seconds leaving me with something smelling again
fishy and of course of Ipa with ph 6-7.
What can i do know? i'm not an expert chemist but just a student wich is still learning and sometimes..this is the case..also need a lill bit of help.
Maybe i can basify again the mixture repeating the whole process from extraction on , distill again the solvent and again trying to get the sulphate
salt?
Any help will be really appreciated... and one special hug to Mr Nicodem.
bye 
[Edited on 30-11-2013 by isiahmajor]
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elementcollector1
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It does help if you describe the problem, for starters.
Elements Collected:52/87
Latest Acquired: Cl
Next in Line: Nd
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Pyro
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I assume he is talking of an Al-Hg amalgam for hydrogenation since he posted in organics.
It probably won't start or reacts too vigorously
all above information is intellectual property of Pyro.  |
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isiahmajor
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Hey guys Sorry i've now edited my post. Thank you in advance!!
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isiahmajor
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anything?
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bfesser
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If you want immediate responses, join us on IRC (#sciencemadness on irc.efnet.org). On a forum, please be patient; it can take anywhere from seconds
to years before you'll get replies. It's best to give it at least a couple days before bumping a topic.
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CycloKnight
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Not sure if I can help here, but just thought I'd wade in and say your 4 hour amalgamation time seems crazy for Hg2Cl2. I've carried out the aluminium
amalgamation procedure more times than I could count over the years (many dozens of times), always using mercurous chloride which I've made by passing
chlorine over mercury in a heated flask (never used mercuric chloride before nor since).
Cut up aluminium pie tins (1cm x 1cm or less) will fully amalgamate in around 20 minutes or less. Its best to warm the methanol beforehand, as it
helps to speed things up.
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Panache
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I have no recent (as in the last decade) experience with forming al/hg amalgum's but like cylco have made my fair share of lots. I do recall that some
al foils alloy a significant amount (5% by memory) of Fe into the mix to add tear strength and this can significantly reduce or impair the bulk of the
al's ability to form self sustaining amalgum's.
To assess if this may be the problem buy some aluminium electrical wire from a electronics store, strip the casing from it and use this is a small
test. Electrical wire aluminium generally never has co-metals alloyed with.
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vmelkon
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Quote: Originally posted by Panache  | I do recall that some al foils alloy a significant amount (5% by memory) of Fe into the mix to add tear strength and this can significantly reduce or
impair the bulk of the al's ability to form self sustaining amalgam's.
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I wonder if processor heat sinks use high purity aluminum. They don't need any alloying agents since the parts is bulky.
I don't think it is 5% Fe. In general, there is 2% or 1% of junk like Fe, Si, Mn, Cu...depending on the alloy.
Also,
https://www.sciencemadness.org/whisper/viewthread.php?tid=21...
this is from a Reynolds faq item, about a year ago:
"Today, Reynolds Wrap is made from 8111 alloy aluminum, at the thickest gauge specifications available in the marketplace. Reynolds Wrap® Aluminum
Foil is 98.5% aluminum. The balance is primarily iron and silicon. These are added to give the strength and puncture resistance obtained only in the
alloy used in Reynolds Wrap® Aluminum Foil."
https://www.rtapublicsales.riotinto.com/En/OurGlobalNetwork/...
http://www.mwswire.com/specialalum.htm
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zed
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Which Nitroalkane? There are possible side reactions. I'm not completely clear about how the reaction proceeds in all dissolving metal reductions.
In some scenarios, the reduction might only be completed to the oxime stage. Probably not the product you want. Further, if for instance, you were
reducing Nitroethane, and a significant portion of your product were to remain as oxime for a while, that oxime could disassociate to acetaldehyde,
and that acetaldehyde would be free to condense with any ethylamine already present to form an imine........Which of course, could be further reduced
to Diethyl Amine. Which I assume you don't want.
In short, your reduction may not be producing a single product. Or, the product you are producing, is not the product you want.
Tell us more.
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chemaddict
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He is more than likely going to reduce a nitropropene because if he was going to reduce a nitroalkane this could be done with tin or zinc and acid or
many other ways .
And if he was going to reduce a terminal nitroalkene he wouldn't need mercury why not just use zinc he is wanting to create the sulphate salt ! i
wonder which phenylethylamine needs to be a sulphate salt. daaaa
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Nicodem
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Thread Moved
8-12-2013 at 07:17 |
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