KidCurry
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Al/Hg workup: IPA/dilute HCl solubility?
Sorry about all the small talk, but have some questions I need answers too. 
Scenario: Amine (from Al/Hg reduction) solved in IPA. Will the addition of dilute hydrochloric acid form two phases, one containing the amine+HCl(aq)
and the other IPA?
And would water washes of a basic solution of amine freebase solved in IPA/xylene get rid of the IPA?
The problem is Al/Hg workup (and the fact that IPA dissolves in xylene), thinking of the optimal way to proceed. The reaction leaves you with the
freebase solved in IPA, and I need to go from there to freebase solved in xylene/toluene without the IPA for gassing.
The easiest way would be to just strip off the IPA, leaving you with the freebase as an oil which could be dissolved in xylene. But then someone wrote
that this is bad since the IPA is basic and it would leave some nasty solid hydroxides. Maybe this really isn't a problem?
If dilute HCl is soluble in IPA, wouldn't the addition of table salt fix that issue and generetate two phases which could be separated, and then
proceed with basification of the water phase followed by extraction with non-polar solvent?
Am I just too tired to see the obvious here? 
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bio2
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If based with enough 20% NaOH the density goes high enough and there is enough water to hold the IPA and allow a non-polar extraction.
You will get a much cleaner product by adding the base solution, distilling off the IPA, adding more water as needed and steaming out the product into
some of the gassing solvent and plenty of salt in the receiver.
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KidCurry
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It would probably take a shitload of water to hold the IPA, and after a 10g reduction the volume is already pretty large.
Wouldn't a reasonable work-up be:
1) Boil off most IPA.
2) Dissolve in non-polar (xylene/toluene etc).
3) Wash with multiple portions of water to get rid of the last IPA.
The question is how big waterwashed would be needed to remove the water?
And thanks!
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FriendlyFinger
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Dude, swim deceided to froget IPA and use methanol instead. There were no problems. 86% freebase after acid base.
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bio2
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.........Scenario: Amine (from Al/Hg reduction) solved in IPA. Will the addition of dilute hydrochloric acid form two phases, one containing the
amine+HCl(aq) and the other IPA?...............
No, how could this happen if they are miscible in all proportions?
.........And would water washes of a basic solution of amine freebase solved in IPA/xylene get rid of the IPA?............
Yes, what is the basic solution if not the amine? Better to wash with 5% NaOH instead plain water. Two or three times with half volume is enough. Then
wash with 2X half volume brine to clear it up.
.........The easiest way would be to just strip off the IPA, leaving you with the freebase as an oil which could be dissolved in xylene. But then
someone wrote that this is bad since the IPA is basic and it would leave some nasty solid hydroxides............
How can an alcohol be basic and leave hydroxide residue? You need to clarify what you actually did.
.........If dilute HCl is soluble in IPA, wouldn't the addition of table salt fix that issue and generetate two phases which could be separated,
and then proceed. with basification of the water phase followed by extraction with non-polar solvent?..............
Not IF, both HCl (g) and water are soluble. Why mess around with salt when only water needs to be added. I realize that IPA can be salted out from
water but why go to all this trouble. Are you following a proven procedure or just making it up as you go?
In general the three lower alcohols can be removed by diluting with 2-3 volumes of water. Use salt in the form of brine at the end to clear
water/alcohol traces seen as cloudiness in the extraction solvent. Do it as many times as it takes to clear it up or you will end up with nasty
residues.
Taking shortcuts like trying to crystallize with only an A/B is just asking for trouble IMHO. Skip the A/B if you have to take a shortcut and distill
it. The results will be far superior.
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KidCurry
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The procedure leaves two phases:
1) IPA with freebase amine.
2) Water with Al-slurry
I did not state that separation and stripping of the IPA would lead to hydroxide residues and troubles, it was simply a question since someone else
(On synthetikal I think) said that this "work-up" would lead to OH/Hg contaminants and problems.
I was just terribly confused and tired and irritated.
But then, just separate phases, strip of 90% of the IPA, dissolve everything in xylene and wash this with NaOH(aq) to get rid of the last IPA, dry the
xylene with NaOH pellets and finally gas with hydrochloric acid would work fine.
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bio2
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............The procedure leaves two phases:
1) IPA with freebase amine.
2) Water with Al-slurry ...........
Have you done this particular procedure before? Not mentioning adding hydroxide solution I assume that none is used.
Following a similar procedure using MeOH where 2 phases were supposed to separate, it did only one of three times after a long wait (overnight).
Everything being the same I never have been able to figure this out. IPA however should separate easier but don't count on it, from what
I've heard.
I've since gone to a better method and don't forget that there is a LOT of product tied up (trapped) in the Al sludge.
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KidCurry
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It's been done more than one time, and it always formed two layers after basification. Once the IPA was separated and stripped of, leaving orange
freebase oil. The other two times work up failed due to stress and general fucking up.
But if a lot of product is in the al sludge the best workup might be:
1) Separate IPA, strip it off, solve freebase in xylene and wash the xylene with NaOH(aq).
2) Extract Remaining al sludge with 3x50ml xylene.
And then proceed to gas it. This should get everything (most of it anyway) out of it, right?
[Edited on 29-8-2005 by KidCurry]
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flyingbanana
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looks like you've figured it out already, but Shulgin's workup for Al/Hg with IPA is a good procedure (pihkal #109).
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