L-Ephedrine synthesis from L-phenylacetylcarbinol (L-PAC)

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The problem with l-PAC is that it racemizes quick to d/l-PAC what yields not the wanted l-Ephedrine but d/l-ephedrine what in consequence leads to racemic Meth as made from P2P.
We want d-Meth or at least predominantly d-Meth.
Two factors drive racemisation of l-PAC: First alkaline environment, say the presence of bases of any kind and transition metal ions, say any salts of iron etc. present even in minuscule amounts as they work catalytically.

Now many reduction systems are alkaline as is NaBH4, so its clear what would happen. Therefor besides storing and handling the l-PAC properly and adding something like oxalic acid and/or stannic acid or EDDA to take care of any metal salts around one chooses an acidic reduction system or one which works in slightly acidic conditions at least. I would recommend to use STAB whats an acidic derivative of NaBH4 and works especially well in reductive aminations. Methylamine is then used as the acetate, say the acetic acid salt of methylamine and all together as one pot one go Imine formation/Imine reduction whats called reductive amination.
Information on how to make STAB from NaBH4 and GAA is all over the net and also on how to use it. Yields are excellent.
Zinc-Borohydride would be another easily prepared possibility if one has anhydrous ZnCl2.
Al/Hg is also possible bust it must be done in THF or diethylether.
But a native acidic system as STAB or Zinc-Boro is best.

l-PAC production from Benzaldehyde by biosynthesis is not necessarily difficult but it is more of a technical challenge for the large volumes to handle. And first of all one has to find a good strain of yeast for the purpose. With this at hand it is mainly a problem of extracting the l-PAC at the end, a continuous extraction system is a must have here and ether is the solvent of choice.

good luck!
 

rampage

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when the fermentation or condensation is finished is there a need to make the broth nuetral or slightly alkaline for the ether to pick up the l-pac
 

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Once the yeast has been removed from the brew mixture, the phenylpropanol-l-one-2 can be extracted out of the solution. The original references used ether to do the extraction. I would suggest substituting
hardware store toluene. Several extractions with a few hundred ml portions of toluene should be enough
to completely remove the product.
 

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ive used toluene in the past didnt work out so good, ethers my go too. ive read enough references but none of them qoute whether the wash needs to be slightly alkaline to extract the l-pac, i'll trial without doing this and see what happens
 

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my first trial run of making l-pac, here is my recipe not sure if it's all correct but i'll give it a go anyway.

2.5 ltrs of h2o
87.50 gms of molasses
yeast and nutrient
20ml of benzaldehyde
75ml of ether

in to a 5ltr demijohn goes 2.5ltrs of h2o and 87.50 gms of molasses,
saturate wash with pure oxygen,
add yeast and nutrient and allow to ferment for 8hrs or so,
once wash is rapidly fermenting add 10ml of benzaldehyde ,
after 4hrs or so add another 10ml of benzaldehyde and allow to ferment for another 12hrs or more,
once finished remove yeast,
extract l-pac with 50ml of ether and then 25ml of ether,
combine ether and distill
collect l-pac?
theoretical yield 10ml is 50% conversion.

feedback is appreciated and i'll post my results once done.
 

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sorry guys this evaluation was not correct, there is a need to incorporate sodium pyruvate and a yeast strain that can handle slightly acidic conditions, ph 5 - 5.5, and possibly a greating temperature range. its still a work in progress, albite very slow progress lol
 

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l-PAC threads are always instantly overrun by bullshitters, so I say good-bye.

You got the most important information: Acetaldehyde or Pyruvate, a suited yeast and ph <5.

Nobody asked the big and obvious question: How can I find out if a strain of yeast is good or not?
And as nobody asked, there will be no answer but the mention that rather easy methods exist.
Happy searching don't PM me.

bye
 

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How can I find out if a strain of yeast is good or not?
 
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Do several small batches see witch ones best
 

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Please my super heros, please give us summary of the procedure , your mentorship is highly appreciated
 

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Go the 4mmc to epher route there’s a video on it save time and money
 

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so i'm running it at ph 5.5-6, and just wanted to know when the condensation finish's should i make it nuetral or slightly alkaline to extract the l-pac with ether?
 

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had a go at this, the fermentation seemed to go okay, seperated wash from yeast. then added ether to the wash but it did not form a seperate layer it just became 1 with the wash, i left it for a few days but the ether still hadnt seperated from the wash. but the wash seemed to have layered itself into 3 different colours, top yellow, middle orange, bottom pink. so i seperated them, i took a few samples and made 1 acidic and 1 alkaline and 1 nuetral then allowed them to evaporate on a heat pad, the alkaline solution of the bottom layer produced a pink waxy product, which i have no idea what it is? it doesnt smell, is there a way i can test it to see if its cooked itself into psuedo? or could it be the pyruvate? the yellow and orange layers didnt seem to amount to anything other than i very miniscule amount of an orange oily substance that was no more than a millilitre in volume, i dont know whether that was unreacted benzaldehyde or pac? the pink waxy substance weighs 9 gms
 

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The yeast/ Benzaldehyde reaction aims to produce L-Pac then a reductive alkylation of L-pac (L-phenylacetylcarbinol) with methylamine to produce ephedrine
 

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yeah thats what i was aiming to get, hopefully someone can identify what i did get, it was a mission to get anything lol
 
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