Isomers and tartaric acid

[btcboss2022]

I think something wrong with graph.
If you use L+-tartaric acid(cheaper and easier to find)the D enantiomer(amph,Meth) will be in the solution not in the solid as there appears.
If you use D-tartaric acid(more expensive and difficult to find) the D enantiomer(amph,Meth) will be in the solid.
Thanks.

 

[G.Patton]

His scheme is correct. Salt is precipitated into the solid state. No difference, d-amphetamine l-tartaric acid salt or l-amphetamine d-tartaric salt. You can change acid and get difference isomer in the solid state with following procedures.

P.S. same for methamphetamine.

 

[Ihml]

I’m not Patton, but: it’d produce only D-meth of the ephedrine that was used was derived from a plant, since plants naturally only produce L-ephedrine (which turns into the opposite enantiomer after reaction - D-meth in this case). If chemically synthesized ephedrine was used, than you’d get racemic meth, because ephedrine synthesis isn’t stereospecific.

 

[Osmosis Vanderwaal]

I stayed up all night combing through scholar and patents and here is my findings

L(+) tartaric acid (2R,3R) is the naturally occuring isomer.Since it's chiraliity ir R,R, it bends light and is optically active. D(-)(2S,3S) is also optically active. These 2 compounds are enantiomers. They share the same boiling, freezing, temperature, mol.wt. ect.
The diastereomer of both is meso tartaric acid. (2R,3S or 2S,3R) the 2 mesos are enantiomers.
What makes a compound optically active is bending light. What make it bend light? Having an uneven plane of carbon substituants. For instance L(+)tartaric acid is active. It bends light right and right ( I say right but I am just using right as a reference). Same with D(-) tartaric acid, it bends light " left left". Meso tartaric acid is chiral but not optically active. Because (for instance) 2R,3s bends light right the left again for a net gain of 0°.
The reason we are talking about optically active compounds is because active compounds have a higher melting point and a higher boiling point. Another way to look at it is they solidify(crystallize) at a higher temperature. Yes an optically active compound crystallizes before an inactive one. Now we get to the point.
If you use D(ss) tartaric acid the D-(S) Methamphetamine is optically active (S,S,S) and the L(R) Methamphetamine is not, (R,R,S)
The opposite is also true. If you use the natural isomer of tartaric acid, the levo-methamphetamine crystallizes first, so if you use natural tartaric acid, the crystals are the trash. The rework. The mother liquor contains the Dextro-meth.
If you use racemic D,L-tartaric acid on racemic meth, you crystallize racemic Methamphetamine tartrate. Wasted your time.
Summary of the invention; use one tartaric acid isomer and if you want the D-crystals, use the D tartaric acid. Otherwise use the L and filter the crystals out.
Bring your references when you come to debate these facts.

 

[Labchef]

What you are saying is that D tartaric with salt out “L amph d tartrate” while L tartaric will salt out “D amph L tartrate”. Is that right

 

[Acab1312]

Very nicely explained, and I can agree with you 100%. I would like to add: Levo-methamphetamine tratrate is not soluble in cold methanol (Very low). Use it to flush the L-methamphetamine tratrate. After I started flushing, my final yield of d-methamphetamine increased by about 5%. What is also highly recommended is a polarimeter to measure chirality. If necessary, it can be built by yourself.

 

[Labchef]

A member with an expert status suggests using DL tartaric acid to separate both isomers I.e DL tartaric acid will salt out D amph/meth tartrate & dissolve the L amph/meth tartrate in the alcohol mother liquor. Do you think it’s possible to obtain D amph/meth using DL tartaric acid. For now I can only get the L tartaric acid. I hope to perform the resolution soon & obtain pure D meth.

 

[Acab1312]

For me, d,L tartaric acid did not work, L-tartaric acid is the most effective and cheapest to work.
There is also the possibility: via dibenzoyl tartaric acid, the chiral separation is highest in one pass, but also the highest in terms of price. But I have posted a synthesis for dibenzoyl tartaric acid

 

[Osmosis Vanderwaal]

Since then I learned that L tartaric won't bind to D meth because of steric hinderance and vice versa. I'm not sureif it's the same for amphetamine or not. If it is, then it's L-amp-L-tartrate od D-amp-D-tartrate because these are the optically active isomers. If you have 1L,2D or 1D,2L the net rotation is 0. Both chiral carbons have to turn the same way to be optically active .

 

[Labchef]

So I can’t use L tartaric to separate D & L and obtain pure D amph/meth is that what you are saying? Can DL tartaric acid be used for the same purpose.

 

[Osmosis Vanderwaal]

No, I didn't say that. You can L or D tartaric acid if you use L,you have L-meth L-tartrate, an acid salt ( and D-meth base. The salt will precipitate from non polar solvent and you filter it off and the reaction mixture still holds the D, that you can hcl ( hcl isn't chiral, so it obviously attaches to either). If you use D yartaric though A) it's a lot more expensive, 2) it's watched, VI) YOU'LL have to strip the tartrate of and hcl it

 

[Labchef]

Ok, that’s what I actually thought. The video seems to confuse people because DL was used for the resolution. Thanks for the clarification