Comment by cyounkins
5 years ago
Can anyone comment on how producers could be isolating the the 'd' enantiomer? Are they using enzymes?
Steve Mould has a great video [1] on homochirality in nature and says, "Why are all the sugar molecules that you buy from the shops right-handed? ... If you were to make some sugar for yourself in a chemistry lab by mixing some chemicals together, you would get a 50/50 mix of left-handed sugar and right-handed sugar." He goes on to describe how enzymes in nature exclusively make homochiral molecules, and since all our sugar is made by enzymes, all our sugar is homochiral.
Later in the video he describes how you can filter enantiomers by finding an enzyme in nature that 'eats' the undesired enantiomer, finding the DNA for it, and coercing bacteria into producing that enzyme. This seems quite complicated and potentially out of reach for a clandestine drug-making operation. Is there another way?
They are most likely using resolution via the Pope–Peachey Method. There was supporting evidence found in a laboratory in Guadalajara[0].
It is possible to do asymmetric reductive amination using enzymes but this is out of the scope of clandestine producers. Likewise a chemical and not enzymatic asymmetric reductive amination would be easy in a bench lab, probably to expensive and impractical in a clandestine setting.
[0] Joseph S. Bozenko, "Clandestine Enantiomeric Enrichment of d–Methamphetamine via Tartaric Acid Resolution", JCLIC, 2008, vol.3 (not publicly accessible but you can find this if you know where to look)
I did not know it had a name. TIL.
I will back the Tartaric Acid hypothesis. If it's being done, this is the only way it makes sense. It requires nearly nothing but the D-Tartaric Acid and Ethanol/Methanol + basic glassware.
Disclaimer: Am not a chemist.
Methamphetamine synthesized from pseudoephedrine gives enantiomerically pure Dextro-methamphetamine.
Phenylacetone synthesis yields racemic methamphetamine.
You can actually use a laptop screen, and polarized sunglass lenses to check the optical rotation at home, cheap polarimeter.
As far as purifying enantiomer with amphetamine and methamphetamine goes:
It can be done relatively easily with just D-tartaric Acid.
Look up "Procedures for the Resolution of Racemic Amphetamines"
https://erowid.org/archive/rhodium/chemistry/amphetamine.res...
I do not believe this practice is in use in illicit drug manufacture. There's no economic incentive and it requires some braincells.
From "Selective Crystallization of Methamphetamine with d-Tartaric Acid:"