Amphetamine purification by acid-base extraction

[ACAB]

The ratio is freely selectable whether 1:1 1:4 or 1:10, the thinner the sulfuric acid the more solution is needed to neutralize. Some also use 2 different solutions, at the beginning 1:1 and when nearing pH6 take a thinner solution, because it is easier to adjust the pH6 without overacidification. Keep in mind that the thicker the H2SO4 solution, the greater the risk of temporary acidification, you must add the solution very slowly to avoid this.

 

[deeperdive36]

I keep over acidifying... I thought the precipitation would be immediate so I kept adding acid and when I checked it was 1, red. I tried walking it back by adding more acetone but then it started making crystals. At this point in nsonr know what to do start over or filter it. What are the consequences of over acidifying and what can you do to fix it.

 

[Mr Good Cat]

if there is excess of acid probably there is only one way resolve this issue: to do ABE again. simple washing in acetone will not help.

 

[HerrHaber]

also be minful of the fact that acids and alcohols form esters in an equilibrium reaction kinetics, therefore do not store solutions of especially strong acids in alcohols (primary alcohols especially methanol is a no no; IPA is better but acetone is best)

 

[DavidNichols]

One correction: any strong acid will start catalytic self-condensation of acetone with results of colorful tars and various unsaturated ketones.

 

[HerrHaber]

can get deep red when forgotten about it but I advise throwing it away as soon as job is done, I am most mindful that vitriol is a strong oxidiser by tradition and I had a solution made of it in a compound that can yield triacetoneper...kaboom if by chance the oxidant was 50%+ a.q. peroxide

 

[ACAB]

The following observation, which synthesis route to amphetamine does not matter.
After the A-freebase is released with the addition of NaOH and collects oilily on the surface, I perform an extraction with petroleum ether.
First I transfer the solution to a cylinder and wait for the layers to form. With a syringe I collect the upper layer in an Erlenmeyer flask. Then the solution comes into the separating funnel and is shaken with 10% of the volume of the solution 3 times with petrol ether and also collected in the Erlenmeyer.

Here it is noticed that the amphetamine base does not mix completely with the petroleum ether and two layers are formed here as well.
The Erlenmeyer is dried with 1-2 teaspoons of MgSO₄ and now something strange happens.
The solution becomes thicker and thicker even shaking does not help, it becomes a mush. Two hours in the freezer and then vacuum filtered and I now have much more salt than I added.

What happens here?
Does the A-freebase react with the SO₄ from the MgSO₄ and form amphetamine sulfate?

When I partially dissolve the salt in a beaker with water, an oily layer forms again. After adding NaOH, the upper layer can be extracted and placed together with the petroleum ether on a dish to evaporate the ether.

Who can tell me what happens there with the MgSO₄ during drying, is another desiccant to choose?
Use something else like petroleum ether?
Am grateful for any help. thanks

 

[diogenes]

ACAB, I have re-read your post and I think the key to the problem is in this sentence:
`Here it is noticed that the amphetamine base does not mix completely with the petroleum ether and two layers are formed here as well.` This means that the layer what you extract as `oily base` is not pure oily base. Why don`t you use some petroleum ether (or other non-polar solvent) here too? I mean from the point your solutions reaches pH12 and a layer forms, it is ok, to separate the oily layer, but put this in the separating funnel and add equal amount of petroleum ether, then save the petroleum ether layer in the Ehrlenmeyer if two layers are formed. The not petroleum ether layer (if it forms) you can add to the original water and then extract with the rest of the water. Using only 10% of the water volume 3 times is probably too little, use 30% then 20% then 20%.

I know it is quite a lot of ether, you can use the water as indicator: the water becomes almost clear when most of the oil has been extracted.

Combine the petrol ether fractions add them to the separating funnel and wash at least 2-3X with distilled water, then 1X with brine (saturated NaCl solution). Then start drying it, but only add `enough` MgSO4, not `more is better`. When the MgSO4 is showing snowball effect after 15-20 minutes, then you are good. If you have mol sieve then you can use that too instead of MgSO4/Na2SO4. GRAVITY filter the MgSO4. I don`t really like it as it has quite small molecular size and might come through some filters and need filtering more than one time.

When you have your clear and dry petrol ether then distill it, so that using more before won`t matter, you get it back. You should do this anyway with most of your solvents.

Also, as a general rule, when cooling or just leaving outside any dry solutions, never forget to cover it with kitchen kling film and a rubber band so that it is airtight.

Let us know if the problem still persists if you follow this way.

 

[ACAB]

I assume that the formed layer can be separated (for me this is A-oil, because something else cannot be in there, except impurities, after I have released the freebase) and I only have to extract the rest of the solution with petroleum ether. Is this assumption not correct?
Because if I try to extract the two layers with petroleum ether, I always have 3 layers and I do not get everything extracted, or I would have to make many extractions until the middle layer is completely dissolved. If that is possible at all.

 

[Mr Good Cat]

Thanks for the interesting method. I'm trying to purify quite dirty MDMA HCL. The product itself has'nt been purified at all. PH at the beginning was 7.


So the crystals after first crystallization are almost black. I tried to finish some small quantity around 18 gr + 20 ml of water.

I did step 2 and reached PH=12. It took approximately 6 ml of 50% NaOH solution. But instead of forming on the top, the freebase forms on the bottom. There is also third layer, very thin barely visible, on the top. I'm pretty sure the freebase is on the bottom, as this part has specific smell of pussy.

Is it normal and I can begin step 3, or I did something wrong?

 

[Mr Good Cat]

After the night in the separating funnel the layers changed their positions.
Here are three layers - water, freebase, ether.
It looks this black layer is the freebase. Separate it and checked weight - it fits.

 

[Mr Good Cat]

After all the efforts I got approx 10 ml of the pure freebase. I don't now, either I did the mistake or the volume of pollutants was huge. I think both. Any way, not bad for the first time. At least the sequence is clear for me now.
Did wash it 3 times with ether until all the emulsion was dissolved. Dried with MgSO4, evaporated it under the hood and acidified it in the cold acetone with 36% HCl. The result looks quite pure.
As I understand the emulsion was formed by the high level of pollutants, and the target was to wash the freebase from all this black shit.

 

[Mr Good Cat]

9 gr in total of the pure product - exactly as I was thinking in one of the the previous messages.
Little upset with PH=7.5 - is it the disaster for the oral intake?

 

[G.Patton]

I think so. Your mixture looked too dirty.

 

[G.Patton]

pH in your mucous membranes is 7, it is good pH.

 

[diogenes]

Actually, a higher pH increases the absorption rate and amount of amphetamines. I once licked some freshly made base off my fingertip, it burnt, but then I got an almost psychedelic rush from a tiny amount.

 

[Mr Good Cat]

Tried to work with DCM. In my opinion, ether is much easier to work with.

It was also noted that at the end of evaporation at the bottom of the beaker, salt crystals appeared in a barely noticeable amount. This means that DCM easily degradates to HCl + CH2O in the presence of water. Probably drying with MgSO4 was't perfect((( or some water was caught from the air.

 

[Mr Good Cat]

Another stupid question about ether washing.
Does it worth to use any distillation system to separate pure FB from ether instead of evaporation in case petroleum ether 40/60 is used?
Main goal is to do it faster than regular vaporation in a beaker, and probably save some ether in the receiving flask.

 

[ACAB]

low heat in water bath or only vacuum distillation, i heard best to use is a rotovap at low Boiling points...but I never used one

 

[Mr Good Cat]

Rotavap is the best, that's for sure. Vevor sales for 1140 EUR, may be I would even buy, but simply don't have place to store it)))))))))

 

[deeperdive36]

I was under the impression that diethly ether was the nonpolar to use. I thought pet ether was totally diff...Pet ether is far easier to obtain so if that works so much the better... What is the difference between the two ethers? Is one better than the other to use

 

[UWe9o12jkied91d]

It dosen't matter here

 

[deeperdive36]

Ive seen a heroin purification and it mentions other solvents I believe methanol or diethly ether.... Can you use Petro ether instead here as well. Also why does it not matter... I thought they were vastly different.

 

[deeperdive36]

So I'm struggling with step 8. Seems like a lot of waste and loss for me here. I transferred extract from sep funnel added magnesium put in freezer. Now here I did the filter with vacuum. I think Buchner is way better than the setup I got as it leaked and volume is too large. So 1st when pouring into setup are you suppose to dump the whole thing in... I don't understand how to properly pour off the ether extraction without getting magnesium with it unless I don't pour all of the extract then at that point I have a lot of extract left with the magnesium what do I do with that remaining part to separate. Also I've attached pics of the leak. What do I do with this. Is this all waste . If there is magnesium that got through the filter what should I do? Basically stuck and waiting at this step

 

[ACAB]

What kind of filter is this?
I would get the solution out of the freezer, stir it well and then pour it quite evenly into the filter, towards the end rinse the filter with solvent to reduce the losses.

 

[deeperdive36]

It's joanlab vacuum filter... It was cheap but the design is all wrong it allows stuff to leak on the outside... Ya I will try pours differently I read the sticky Patton wrote helpful in clarifying things a bit

 

[ACAB]

@deeperdive36 It looks like it is a ball joint which is held together with a clamp.
Have you tried greasing the ball joint with grinding grease beforehand and turning the ball until the grinding becomes clear?
That should solve your problem.

 

[deeperdive36]

Ahhh I do remember reading somewhere about greasing it. I will try it today hopefully will fix the problem. Thanks.

 

[Mr Good Cat]

Come on, man: you can do it. If me with my arms growing from my ass can, then you can too.
And yes! Nothing is more pleasing to my eyes than MDMA after ether washing.