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Harmala.HCl not precipitating

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blue.magic

blue.magic

Rising Star
I did harmala extractions earlier without problems but now I ran into an issue...

The first Manske does not work at all. I used to dissolve freebase in a "minimal amount of hot vinegar", then adding 10 g salt per 100 ml solution. The crystals took all the space and had nowehere to grow so I used more liquid this time.

I dissolved few grams of alkaloids (from 80 g rue) in 680 ml water and added few ml of acetic acid (pure) - the pH went down to 4.5. The alkaloids have dissolved and I slowly added 68 grams of salt.

Everything dissolved and cooled down but even after several hours in fridge, nothing precipitates and I have somewhat dark brown liquid (with a thin foamy film on top).

Should I freebase+filter the alkaoids and repeat Manske with a smaller amount of water?

How much is "minimal amount of hot vinegar" before Manske step? And how concentrated? What is the targer pH of the acidic solution?

Thanks for clarification.
 
Have you tried to increase the salt ratio to see if anything crashes out. What i’d do in the case of unprecipitating manske, is increase the salt ratio little by little until the alks start crashing out on sight, retrieve, then purify some more. Vinegar is not an issue here imo. That would be an issue in the case of freebasing. I think the main issue here is not reaching proper echilibrium of H2O/NaCl.
 
Before resorting to freebasing give it a full 24 hours in the fridge.
The last bits of alkaloid take more than a few hours to crystallize, and with it that dilute all you have is the 'last bits'.
 
What Auxin said! If you aim for purity, then sure, patience is key. If you aim for retrieval at all costs, the only way i can see it working around that amount of water is heating your supernatant and either go up to 120g/l for somewhat purer precip, or saturate the solution with salt for imediate crash out.

Either way, 680ml water to work with rue alks of 80g worth of seed is a little overboard on the water ime. Precipitation can and will most likely occur but during longer waiting times and i’d think that your precipitate will crash out as very short needles on the bottom, making it a pain to collect or even see if the soln is murky.

I think that the thin foamy film on top is caused by the reaction between acid and base, if your starting material was a base to begin with.

Ime freebasing now would eat a big amonut of base due to the acid content. Better to proceed as manske.

When dissolving the freebase, i always use plenty acid, i’d say maybe i aim for a ph of 3 usually. Can’t comment on what the exact value is.
 
It seems the crystals formed at the bottom, they were only hardly visible until next day (24 hrs after).

Maybe I will filter them and add more salt to the leftover liquid to see if more will precipitate.

Thanks for the ideas and support!
 
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