recrystallization problem

[Acab1312]

Hi can anyone help me with the recrystallization of methamphetamines, after separating the isomers as well as acetone washing. Every time I have the problem that no real crystals form. It was recrystallized with dcm/acetone also with h20 (7 days) . But I always get flat papers. Can anyone tell me what the problem is? The quality is good - after reagent test, it is also the right product. Thank you for your help

 

[Frit Buchner]

The crystals shape is determined by the solvent. Perhaps try a few different mixtures? Are you evaporating it down until you start to see snowflakes? With iso/acetone I get iridescent flakes and with iso/h2o I get spiky blobs Like a sea urchin. I'd love to see some weird crystals and what the solvent was

 

[Acab1312]

The crystals shape is determined by the solvent. Perhaps try a few different mixtures? Are you evaporating it down until you start to see snowflakes? With iso/acetone I get iridescent flakes and with iso/h2o I get spiky blobs Like a sea urchin. I'd love to see some weird crystals and what the solvent was

Frit BuchnerWhich solvent would you recommend to get crystals such as btcboss2022? I dissolve the product in a solvent and let it evaporate until a skin forms on the surface, then it is slowly cooled 24 room temperature, then 48 hours, refrigerator, if not with h2o, then another 72 hours then I continuously get this result. At first I thought it was due to the isomeric separation that the ee value is too low, but now I have separated it 2 times in a row with the similar end result

 

[Acab1312]

The crystals shape is determined by the solvent. Perhaps try a few different mixtures? Are you evaporating it down until you start to see snowflakes? With iso/acetone I get iridescent flakes and with iso/h2o I get spiky blobs Like a sea urchin. I'd love to see some weird crystals and what the solvent was

Frit BuchnerDCM/acetone

 

[Frit Buchner]

Uh, that is exactly L-meth to my eye, racemic at best

 

[Acab1312]

Uh, that is exactly L-meth to my eye, racemic at best

Frit BuchnerThank you very much my friend you were right that was the L isomer. Have all my precipitate of isomeric separation, acidified, acetone crash and recrystallized now looks like the desired product. I can confirm that L(+) tartaric acid has the desired isomer in the precipitate not in the h20 solution. What fascinates me is that people found the L-meth very good and active. Thank you sincerely

 

[Frit Buchner]

Thank you very much my friend you were right that was the L isomer. Have all my precipitate of isomeric separation, acidified, acetone crash and recrystallized now looks like the desired product. I can confirm that L(+) tartaric acid has the desired isomer in the precipitate not in the h20 solution. What fascinates me is that people found the L-meth very good and active. Thank you sincerely

Acab1312It just so happens that I spent hours hunting down literature that showed the difference. At the microscopic level, D- meth is "rays ", long and slim,and L- meth is square shaped and has the appearance of a 4-leaf clover. Racemic meth can't produce the stellagtite shaped shards and when you look closely you can see the 2 different crystal structures

 

[Acab1312]

Sorry I don't quite understand their answer, judging by the effect it is the d-meth or L-meth when they refer to it. Unfortunately, the racmic product is not so desired, I would also prefer. Or do you think that the crystals are still racmic?

 

[Acab1312]

Do you think this is the undesirable isomer? That would be fascinating

 

[Zan444]

You need the d meth not the l meth you can throw the l meth away it is useless

 

[Frit Buchner]

You need the d meth not the l meth you can throw the l meth away it is useless

Zan444You can resolve it into D-methamphetamine via a couple of pathways an sn2 reaction (an inversion, a backside attack) is one way

 

[Acab1312]

You can resolve it into D-methamphetamine via a couple of pathways an sn2 reaction (an inversion, a backside attack) is one way

Frit BuchnerYes, I have already informed myself about this, which way would you recommend for the racemization of L-meth?

 

[Zan444]

You can resolve it into D-methamphetamine via a couple of pathways an sn2 reaction (an inversion, a backside attack) is one way

Frit BuchnerYes but the user asked why his crystals look like that and i answeared. And it is better to crystallize the d meth right away then making the l meth or does i missunderstood something? The user made l meth instead of d meth right?

 

[Acab1312]

Yes but the user asked why his crystals look like that and i answeared. And it is better to crystallize the d meth right away then making the l meth or does i missunderstood something? The user made l meth instead of d meth right?

Zan444Yes, that's right, that was L-meth, not the desired d-meth.

 

[Acab1312]

So sehen die heute aus mit danke nochmal

 

[Zan444]

So sehen die heute aus mit danke nochmal

Acab1312You made it with the d-meth now?

 

[Acab1312]

Yes, the attributions for the isomeric separation with L-tartaric acid were wrong. There it was said that d-meth is in the mother solution, but unfortunately that was wrong the desired isomer was in the precipitate. Luckily I kept all my precipitate and was able to extract it now.

 

[Zan444]

Yes, the attributions for the isomeric separation with L-tartaric acid were wrong. There it was said that d-meth is in the mother solution, but unfortunately that was wrong the desired isomer was in the precipitate. Luckily I kept all my precipitate and was able to extract it now.

Acab1312So i was right and the l-meth was white and the d-meth transparent right?

 

[Acab1312]

So i was right and the l-meth was white and the d-meth transparent right?

Zan444It would have less to do with the color of L-meth as well as d-meth clear and white. I think it was more related to the type of crystal or shape, the L-meth forms more square crystals. And the d-meth forms elongated crystals.

 

[UWe9o12jkied91d]

Grats

 

[Acab1312]

Grats

UWe9o12jkied91dUnfortunately I don't understand, soon I will give a more detailed update about the division of the isomers. As soon as my polarimeter is available.

 

[UWe9o12jkied91d]

Unfortunately I don't understand, soon I will give a more detailed update about the division of the isomers. As soon as my polarimeter is available.

Acab1312I just said congrats.