P2P to (d)-Phenyl-2-propanol Possible?

[Acab1312]

Hello I have in the search for the racemization of L-meth, on what interesting and namely, it was about p2p = > with yeast redzuieren =>bromination of the alcohol to (d)-phenyl-2-bromopropane. To my question would that be possible? Since I have no real chemistry background but if that is possible we would save much worse. If there is interest I could share link

 

[Acab1312]

Hello I have seen a P2NP synthesis that mainly produces the d isomer. Wouldn't it then be during the conversion to P2P to take over the D product?

 

[OrgUnikum]

Thats an interesting one, I have not known this, cool! It is of course not P2NP what is made but it has a alcohol group added on the first carbon, it is the direct precursor to Norphedrine as P2NP is the direct precursor to Amphetamine.

This means you need some heavier guns then NaBH4/CuSO4 to get d-Amphetamine, of course RP/H3PO3/H3PO2 + I or the Birch will do the trick, some other methods come to mind.

But I have not the slightest idea why the condensation of benzaldehyde with Nitroethane with triethylamine as catalyst results in the nitroalcohol and not the nitro-only-compound as known. Also why it is selectiv not only for cis or trans configuration, thats also a surprise. Strange.

 

[StarWars]

Look the video on forum

 

[Acab1312]

Hello
thanks you, I already know the general synthesis for p2np. What I'm looking for is a sterospecific synthesis for P2P to increase yields. At the same time, avoid the separation of isomers. The picture I posted I understood that the p2np synthesis has a higher (d-isomer) content. My question is whether the conversion to P2P then takes over the isomer ratio, or again the same 50/50 ratio comes as regular.I have no chemist training, so I don't know my way around. I also don't know if I understood the picture correctly.

 

[G.Patton]

Hi, You will get racemic (50/50) methamphetamine/amph product in any case. The most simplest way is separate isomers from racemate.

 

[HerrHaber]

first thing you should know is that neither p2p nor p2np are chiral, the secondary alcohol indeed has two stereoisomers, the stereospeciffic reduction with yeast is pretty messy and I kindly reccomend carrot slices (sounds funny but did a lot of experiments with this even if not exactly p2p), having the phenyl-2-propanol in an optically pure form does not mean that you will not racemize it in the halogenation reaction (you need stereoselective bromination to make sure), substituting the halogen with amino or methylamino may also lead to racemic mixture, my advice is use L-tartaric acid to resolve the final amine then racemise the less desired isomer (L) from the remaining solution

 

[Acab1312]

That's exactly what I was looking for Thank you. I've been researching the racemisirung for quite some time, but I can't really get any further. Do you have experimental experience with the process?

 

[G.Patton]

There are several topic about this issue. Look around the forum.

Isomers and tartaric acid

I have never split isomers. Can anyone who has done this process clear this up for me. There is L+ tartaric acid {which is the dexto isomer, what is easy to buy ) And D-tartaric acid(which is Levo, what is hard to buy besides from china) I am a little bit confused reading threads and articles...

bbgate.com

Dextroamphetamine synthesis (Nabenhower, 1942)

Introduction At the moment, there are many ways to synthesize dextroamphetamine. They can be divided into 3 types: biosynthesis (using biomass), direct synthesis, and synthesis of racemic (the sum of l- and d-isomers) amphetamine followed by separation of optical isomers. In our case, a...

bbgate.com

 

[Acab1312]

Thank you G. Patton I have successfully separated the isomers. But I have problems with the unwanted L(-) isomer to racmesize again to dl-isomer

Question - Racemisation

Hello, I stumbled across an interesting article where the topic of racemisation of l-methamphetamine back to the racemic product is mentioned. Does anyone have experience in this regard?

bbgate.com

 

[HerrHaber]

racemisation is a thing of equilibrium that is normally the chemists job to avoid... it usually occurs when mixture is left stirring for too long and/or heated for too long... while doing research I was focused on resolution or stereoselective methods not synthesis of LSD so it was not my goal to racemise anything (it was rather oops)... i promise you will fully understand all this if you do not stop learning them molecules by a good strategy and in a clear stepwise manner going deeper and deeper... you well see people here are responsive to help you

 

[HerrHaber]

btw, your chemistry appears to be on the upper side since you posted a problem that prooves complex thinking but also shows that you skipped some basic stuff so keep up the good work (in chemistry concepts are built upon one another so it is natural to skip lessons without completely understanding them, if say you are self educated in the topic, therefore you must read again stuff that you thought never to be helpful)

 

[Acab1312]

Ok thanks to everyone for the help and advice. In any case, I will continue to learn, they are also right in their statement.

 

[K-Cyanide]

The topic is also of great interest for me, though from a different point of view. The resolution of racemic methamphetamine free base can be done without solvent through my favorite compound (grin):
O,O`(+)-dibenzoyl-d-tartaric acid in good yields. (80-85% ).

However, i wanted to ask if anybody has expierence with the so called RRR-process. RRR stands for resolution-racemisation-recycling, to re-racemise the unwanted l-isomer back to a 50:50 racemic mixture. This is conducted using small amount of a radical initiator like AIBN and a source of thiyl radicals (ie methyl thioglycolate). This way one can drive up yields from theoretical 50% to over 90% by running the process several times. I couldn´t find any reasonable procedure write down so far.

 

[花谢花开]

Which dibenzoyl tartaric acid do you use to split cas? Is it the liquid part or the crystal part? Can you explain it in detail? I agree with this method. I think it's better than tartaric acid. Thank you.

 

[OrgUnikum]

This is what you need to know....

Optical Resolution of N-methylamphetamine Via Diastereoisomeric Salt Formation With 2R,3R-O,O´-Di-p-toluoyltartaric Acid
DÁVID KOZMA, ZOLTÁN MADARÁSZ, CSABA KASSAI, AND ELEMÉR FOGASSY
Department of Organic Chemical Technology, Technical University of Budapest, Budapest, Hungary
CHIRALITY 11:373–375 (1999)

 

[OrgUnikum]

Dutch resolution and a lot of other stuff regarding all this good explained:

RIJKSUNIVERSITEIT GRONINGEN

Resolutions of Racemates by Crystallization
Additives and Attrition
Proefschrift

 

[Acab1312]

Maybe this will help you further I have not tested it personally yet. I could look in my folders maybe I can find the original PDF still

General Procedure for the Racemization Experiments. A
0.06 M solution of amine (100 mg) and thiol (1.2 or 0.2 equiv)
in benzene was refluxed for 2 h (stoichiometric condition) or 7
h (catalytic condition) in the presence of AIBN (an overall
quantity of 20 mol % of AIBN was divided into three equal
portions (when reaction time > 2 h) that were added succes￾sively each 2 h). After concentration, the residue was diluted
with HCl (1 M), and the solution was washed with Et2O. The
aqueous phase was basified with saturated sodium carbonate
and extracted with Et2O. The pure amine was isolated after
drying on MgSO4 and concentration

 

[HerrHaber]

like a true chemist!

 

[Sciencenutz]

I have access to aibn and thiol but would appreciate some help with the proper ratios converted to say per kg of L-meth freebase? I'll post my results

 

[Sciencenutz]

Awesome excited to hear results!!

 

[Sciencenutz]

Any updates on this?

 

[Acab1312]

There is the pdf

 

[K-Cyanide]

Great, thank you Acab1312, you have already more than my research has shown. I will definitely give this procedure a try, only issue is where to obtain AIBN, any hints, aside of the big extended arms of LE.

 

[HerrHaber]

my parents threw it away (along with other stuff that would make both of us cry if I were to mention them)

 

[Acab1312]

For AIBN I only found something from China

 

[HerrHaber]

there is a listing on this forum somewhere and an email address of constantilyos or something like this.... users give him good review as the guy will send over just about any chemical with great discretion at his price (which is just above the sigmaaldrich price)