Meth Racemic Methamphetamine Recrystallization Questions

[truur]

Hello, I have 93g of Racemic Methamphetamine hydrochloride that was synthesized by NaBH4 reduction.

How do I now recrystallize it to a clean product with preferably big crystals. I read about a lot of different Methods (Isomer seperation, recrystallizing by Ethanol) but I am not sure about any of them and I dont want to waste the product.

If someone with knowledge would like to help me I would be very thankful

 

[Docta]

How do I now recrystallize it to a clean product with preferably big crystals.

The racemic mixture will need to be resolved if you want to grow sizable crystals, that would result in a yield of ruffly half of what you have now. It involves mixing the racemic methamphetamine with d-tartaric acid and refluxing in alcohol. Filtered and refrigerated, you will end up with an isomerically pure methamphetamine to be recrystallized.

If you’re asking these questions I not sure you’re up to the task but if you are, search the net for: Racmic Resolution via D-Tartaric Acid.

If small crystals are ok (about the size of a grain of sand) and you don’t want to lose half the product to resolution just skip it and go straight to recrystallization.

For recrystallization go with the Two Solvent Recentralization method. It’s simple and effective. Only use new solvents preferably from unopened containers. Always do a small run of a gram or so first to ensure there are no issues.

After filtering wash in ice-cold Acetone and you’re done.

That’s probably an appropriate level of detail for Bluelight, don’t be surprised if the tread gets locked or deleted.

 

[truur]

Thanks , I learnt a lot about the general theory of recrystalization and I understand it, the problem is just I dont want to to all the effort of getting the reagents etc. and in the end something is wrong in my specific case. So i just wanna go a 100% sure.
So if I understand you right you recommend:

1. Isomers Seperation by Tartaric Acid to get d-methamphetamine
2. And then recrystalize it

So if you dont mind, what solvents would you recommend for recrystalization?
And how long should it be in the freezer when recrystalizing?

Thanks for your help

 

[Docta]

1. Isomers Seperation by Tartaric Acid to get d-methamphetamine
2. And then recrystalize it

Correct.

So if you dont mind, what solvents would you recommend for recrystalization?

Dried: Methanol + Acetone

If drying with 3Å molecular sieves it’s fine to use and reuse for both but don’t leave the Acetone stirring as its prone to reacting with its self in an aldol condensation. A good alternative drying agent is Calcium Sulfate.

And how long should it be in the freezer when recrystalizing?

24 hours should be plenty of time.

You’ll actually get better results in the refrigerator than the freezer but the prosses is somewhat photosensitive so freezer is often the way to go. Smaller beakers work best, score the sidewall to create a nucleation site or hang a seed crystal to help kick things off.