Dude, where's my freebase!!

bio · Working Bee

Aromatics work fine for the amine extraction and using say 10-15ml/g expected helps.

Experience has shown that the sludge can hold as much as 20%+ of the product especially if a lot of extra Al is used (>3:1 moles) This was when using no base to dissolve. Filtering is useless, even cellite doesn't work so well. DE is available as pool filter fill (25# $7) and is pure enough to use right out of the bag.

All these troubles go away by adding lot's of aqueous base, distilling off the alcohol then adding water and steaming out the amine into some crystalization solvent with salt in the receiver. The entire procedure can be done in the reaction pot without ever f....g with any sludge.

Bushroot · Sat Aug 27, 2005 3:39 pm

bio, please reply -

icecool · Insistent Chemist

The IPA will float on top of the salt solution.
IPA isn't miscible with salt solutions neither NaOH-solution.
So there'll be an orangy organic upper layer as you describe it, most of the time with SWIM it is brown/red.
But that'll probably be because not all the nitrostyrene has been reduced...
Can anyone explain SWIM(or give a nice pdf or link) on how to do an proper Al/Hg reduction since he is fed up getting shitty yields.
Preferably just Al/Hg not the pre-amalgamated method.
SWIM now does it like this:
10g nitrostyrene
21g Al foil, but in the grinder for 5-10 seconds to make shreds of it like 2cm long and 0,5cm width.
The half of this is but in a 1 liter RBF and MeOH is added(next time will use EtOH).
Then 50mg of HgCl2 is added and waited until the mixture turns blue/grey and starts bubbling a bit.
Then the hot nitrostyrene is added (nitrostyrene dissolved in 80ml IPA and 100ml GAA), all at once.
Stirring put on full blast, and then wait until all the aluminium dissolved or almost everything and then add the rest (before no more aluminium reacted after this first 10g was dissolved even with addition of more HgCl2 no more aluminium would dissolve.
Most of the time there was used in total around 80ml of water for the whole reduction.
And enough MeOH to cover the Al.

Bushroot · Sat Aug 27, 2005 6:32 pm

Big thanks for the answer, icecool!

My most sucessive Al/Hg run with unsubstituted P2NP was 78% yield of freebase.
In 3l FB flask were placed:
275 mls of GAA
275 mls of IPA
25 g foil (it was folded several times and cut into 2x2 cm pieces)
and a common pharmacy thermometer's bulb, crushed into 3 mls of nitric acid (there was about 1g of elemental mercury).
Solution was heated a bit, until bubbling was clearly visible
and a suspension of 10g P2NP in 50 mls IPA and 50 mls GAA was added
This caused a volcanic eruption, and flask was immidiatelly cooled in the flow of cold water. No foam had escaped the flask's neck. Rm was kept under water stream for 15 minutes and then heated atreflux for 1 hour.
Then I basified rm with 400g of NaOH, cooled, upper layer was decanted and -that was a mistake- extracted it with dichloromethane. Almost all DCM was lost, as it reacted with NaOH and heating caused even more evaporation. Adding DCM into reaction mix makes white clouds, as basifying does. Ethanolic solution of phosphoric acid was added dropwise until pH=6.5 (used pocket pH meter, I'm daltonic so litmus paper is useless to me) The yield of amphetamine phosphate after drying was 11 g (6,5g freebase).

icecool · Insistent Chemist

So do you think you would have gotten an even bigger yield when extracting properly with toluene or so?
Or did you finally extract it good anyway.
Well much much big thanks for the answer, I'm going to tell SWIM and tell him to do it this way, and he'll do this on a 10g 2,5-DMNS.
Anyway How do you think you can prevent that volcanic eruption (I think by not heating the reaction mixture before).
How was the rm stirred?

Has anyone else idea's to modify this method to optimise it or would you like to post your method.

Bushroot · Sun Aug 28, 2005 6:10 pm

Well I lost the solvent that time... but after DCM washes rm did not smell amine base. So I think all good stuff was extracted.

icecool · Insistent Chemist

Well the reaction mixture will start bubbling out of itself without heating...
It will heat up a little bit and a lot when adding P2NP.
But I guess if you just let it stirr for 10-15minutes it will start to bubble out of it's own.
Is all the aluminium eaten up at the end of the reaction (and how long does that take).

Friendlycat · Sun Sep 25, 2005 12:09 pm

Swim found the problem. according to notes, looks like 3 x 5%NaHCO3 was used for the washes. Repeated the synth with 3 X 10% NaOH washes and got 86% yield clean freebase after acid/base + distillation.

Why does the freebase migrate from toluene to the 5% NaHCO3 layer?

Friendlycat · Sun Sep 25, 2005 12:11 pm

Swim found the problem. according to notes, looks like 3 x 5%NaHCO3 was used for the washes. Repeated the synth with 3 X 10% NaOH washes and got 86% yield clean freebase after acid/base + distillation.

Why does the freebase migrate from toluene to the 5% NaHCO3 layer?

joe_aldehyde · huxleys associate

are you sure it wasn't supposed to be a Na2CO3 wash? i dunno about sodium bicarbonate, but the plain carbonate salt is supposed to make a basic solution. could be that the bicarbonate just dissociated into an equilibrium of H2CO3 and CO3(2-).

bio · Working Bee

.........Why does the freebase migrate from toluene to the 5% NaHCO3 layer?..........

Bicarb is not a strong enough base to disassociate the amine. IIRC the pH must be at least 12.8 or something near that. Carbonate also won't make a solution much more than pH 11.7

Friendlycat · Thu Sep 29, 2005 10:10 am

This is the advice I was given from another thread;