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Experiment - Soxhlet extractor for recrystallising harmala alkaloids

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alchemizt

Rising Star
Crude harmala alkaloids

https://i.postimg.cc/mtf0fSJk/20231214-173036.jpg

https://i.postimg.cc/0rJLB4th/20231214-191425.jpg

Crystallized harmala alkaloids


First pictures shows crude harmala extract from banisteriopsis caapi vine. The solvent used in this case is 96% alcohol. Pure methanol is the most effective solvent and it can be used relatively safely in a soxhlet because the vapours are contained inside but still, ethanol was chosen because the space doesn't have good ventilation. You need to remove the condenser every bow and again and use a long spoon or something to stir the alkaloids inside the thimble for this to work properly. With methanol it dissolves much quicker so stirring is less necessary.

The idea is that the hot solvent will bit by bit dissolve all of the alkaloids, leaving behind any impurities in the thimble. You will end up with a supersaturated solution of harmala alkaloids in the flask. Letting this cool, crystals will form. In these pictures, the thimble is very small. It would be much better to have a bigger thimble to fit more crude alkaloids. With this small thimble its necessary to remove the condenser and drop more crude alkaloids in periodically.

Its very slow with 96% ethanol. It works but takes hours to get the same results as doing it manually. Next experiment will be methanol.
 
Nice experiments - I'm looking forward to seeing how the crystallization from methanol goes since the higher solubility will affect the outcome. Doesn't the red colour of the methanol solution suggest more/a higher concentration of impurities? What colour does the ethanol-crystallized product display when dissolved in methanol?
 
downwardsfromzero said:
Nice experiments - I'm looking forward to seeing how the crystallization from methanol goes since the higher solubility will affect the outcome. Doesn't the red colour of the methanol solution suggest more/a higher concentration of impurities? What colour does the ethanol-crystallized product display when dissolved in methanol?
Click to expand...
The red colour is definitely a sign of concentration, when its more dilute, its yellow. But witth ethanol, it never goes red. It goes straight from yellow to brown. I believe methanol ectracts a coloured impurity better than EtOH does. When you filter boiling EtOH harmala solution, over time a chromatography happens on the filter paper and a big blood red ring forms.
 
That red ring you mention can't help but remind one of harmala red. Have you tried some actual chromatography (tlc) on the crude alkaloid mix yet? It would be nice to see where the red stuff sits.

How are the methanol crystals looking now?
 
Yield from methanol soxhlet run

Here yielded 2.9g of sparkling crystals. You can see the red ring in this photo. If I evaprated the methanol, the crystals be red. Not a very big difference between yields.

The manual method, boiling in ethanol and filtering through filter paper, then recrystallising, its more practical, and the product appears more pure:

Normal crystallisation product

but Im sure the soxhlet method can be adapted to work much better. To improve it, the crude harmala alkaloids shouldn't be placed in a thimble, instead cotton should be placed at the bottom of the soxhlet and the harmalas should powderised and dispersed into a matrix, like a sponge so that the solvent can easily reach every part of the sample.
 
Looks like I was too slow off the mark and missed your video :( The photo still depicts the sparkliness very nicely though. Great that you can get this result for the harmala freebase - getting sparkly hydrochloride is fairly straightforward with a Manske precipitation, of course.

I wonder if you've seen Brennendes Wasser's pictures of freebase harmala crystallised from DMSO? [second link gives shortcut to pics, first link is for the whole post] Those are transparent and almost colourless - food for inspiration, perhaps?
 
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