MadHatter

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Sorry for spamming, but I found the key. The image you post is from the wikipedia article on stereochemistry. It's faulty. That article is pretty heavily critizised in the Talk-section.

The picture I post is the correct one.

The prefixes l and d are just short for dextrorotary or levorotary: which way the molecule rotates polarized light. "l" = levo = to the left, "d" = dextro = to the right. But these prefixes are old and not used anymore.
In the modern nomenclature these have been replaced by the (+) for dextro and the (-) for levo.

The prefixes L and D (uppercase letters) refer to the Fischer projections of the molecules and have nothing to do with how they rotate light, but in what direction key parts of the molecule is drawn. They are in this case actually REVERSED in relation to the d and l prefixes: d is L and l is D.

So L-(+)-tartaric acid means: "a tartaric acid molecule that's drawn with the highest priority group at the top on the Fischer projection and the relevant group pointed to the Left, and rotates polarized light to the right", a.k.a dextrorotary, a.k.a dextro, a.k.a d-tartaric acid. This is the natural form of tartaric acid.

And, of course, vice versa for D-(-)-tartaric acid.

Now, as far as I understand, both isomers of tartaric acid can be used to resolve enantiomers of amphetamines. If you use D-(-)-tartaric acid you will get crystals of d-amph/D-tartrate crashing out, and if you use L-(+)-tartaric acid you will get crystals of l-amph/L-tartrate crashing out.
Using DL-tartaric acid would be absolutely useless, since it wouldn't separate anything: both enantiomers would crash out.

Phew.
I have spoken.
 

BrownRiceSyrup

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Sorry for spamming, but I found the key. The image you post is from the wikipedia article on stereochemistry. It's faulty. That article is pretty heavily critizised in the Talk-section.

The picture I post is the correct one.

The prefixes l and d are just short for dextrorotary or levorotary: which way the molecule rotates polarized light. "l" = levo = to the left, "d" = dextro = to the right. But these prefixes are old and not used anymore.
In the modern nomenclature these have been replaced by the (+) for dextro and the (-) for levo.

The prefixes L and D (uppercase letters) refer to the Fischer projections of the molecules and have nothing to do with how they rotate light, but in what direction key parts of the molecule is drawn. They are in this case actually REVERSED in relation to the d and l prefixes: d is L and l is D.

So L-(+)-tartaric acid means: "a tartaric acid molecule that's drawn with the highest priority group at the top on the Fischer projection and the relevant group pointed to the Left, and rotates polarized light to the right", a.k.a dextrorotary, a.k.a dextro, a.k.a d-tartaric acid. This is the natural form of tartaric acid.

And, of course, vice versa for D-(-)-tartaric acid.

Now, as far as I understand, both isomers of tartaric acid can be used to resolve enantiomers of amphetamines. If you use D-(-)-tartaric acid you will get crystals of d-amph/D-tartrate crashing out, and if you use L-(+)-tartaric acid you will get crystals of l-amph/L-tartrate crashing out.
Using DL-tartaric acid would be absolutely useless, since it wouldn't separate anything: both enantiomers would crash out.

Phew.
I have spoken.
MadHatteryour clarification here across three comments here has been the most clarifying and absolutely useful thing ive fucken read in a while. thank you. I know you posted this like 8 months ago so im just saying it now in case no one else does, this is what i needed to clear the air about all this shit... for years i didnt get it and was too confused to try and come close to making sense of it.... thank you... seriously
 

Xiao hua

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What can replace of petroleum ether? thanks!!😊
 

xxxx-8888

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Grandmaster. I dissolved 11.8gd-tartaric acid (cas:147-71-7) in 118g methanol, stirred and heated to dissolve. Then pour in 10g of exported Xuan's free base. Continuous stillness. But nothing solid emerged. Is my approach wrong? Can you help me?
 

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G.Patton

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Grandmaster. I dissolved 11.8gd-tartaric acid (cas:147-71-7) in 118g methanol, stirred and heated to dissolve. Then pour in 10g of exported Xuan's free base. Continuous stillness. But nothing solid emerged. Is my approach wrong? Can you help me?
xxxx-8888What is Xuan's free base?
 

cokemuffin

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@G.Patton I'm kinda confused about what enantiomere is what and used for what, so please correct me if i'm wrong.

So the naturally occuring and easy to get enantiomere is: L-(+)-tartaric acid, dextrotartaric acid, d-tartaric acid, (2R,3R)-tartaric acid
The not naturally occuring and hard to get one is: D-(-)-tartaric acid, tartaric acid, (2S,3S)-tartaric acid

So if i use L-(+)-tartaric acid on racemic amphetamine the levoamphetamine salt precipitates out and the dextroamphetamine salt stays in solution?
 

G.Patton

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@G.Patton I'm kinda confused about what enantiomere is what and used for what, so please correct me if i'm wrong.

So the naturally occuring and easy to get enantiomere is: L-(+)-tartaric acid, dextrotartaric acid, d-tartaric acid, (2R,3R)-tartaric acid
The not naturally occuring and hard to get one is: D-(-)-tartaric acid, tartaric acid, (2S,3S)-tartaric acid

So if i use L-(+)-tartaric acid on racemic amphetamine the levoamphetamine salt precipitates out and the dextroamphetamine salt stays in solution?
cokemuffin
The l-amphetamine d-tartaric salt precipitates. The d-amphetamine remains in the solution.
 
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cokemuffin

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Why are you asking? Do you wanna grow it? lol
G.PattonNo xD, D-(-)-tartaric acid is just a pain in the ass to get and i wasn't sure if you can do it with L-(+)-tartaric acid. I always get confused of it because apparently d-tartaric acid is also called L-(+)-tartaric acid and i then don't no which one is which
 

Acab1312

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No xD, D-(-)-tartaric acid is just a pain in the ass to get and i wasn't sure if you can do it with L-(+)-tartaric acid. I always get confused of it because apparently d-tartaric acid is also called L-(+)-tartaric acid and i then don't no which one is which
cokemuffinAlways looking for the "natural" and "cheap", tartaric acid then you are on the safe side.
 

G.Patton

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No xD, D-(-)-tartaric acid is just a pain in the ass to get and i wasn't sure if you can do it with L-(+)-tartaric acid. I always get confused of it because apparently d-tartaric acid is also called L-(+)-tartaric acid and i then don't no which one is which
cokemuffinYou can use racemic mixture also.
 

Acab1312

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Since i know that it works i'm going for it, do you know if it does work for MDMA too?
cokemuffinYes, it should also work for mdma, only that they have to keep precipitation, not the solution. I also prefer the separation with h20/tartaric acid disadvantage at least 2 repeat the separation. But for cost technical reasons, I think it makes more sense.
 

JoshL1221

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hi, excuse me, when you say "We precipitate d-amphetamine with an additional amount of d-tartaric acid.", how much d-tartaric acid is used? thanks.
 
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