blue.magic
Esteemed member
I am trying to find good parameters for initial Manske precipitation, but it never seems to work right.
I wash the free base alkaloids several times, re-acidify (with acetic acid), re-filter, re-basify and wash again several times.
I then try to find good parameters for Manske, e.g.
- harmala concentration: 1.5% (15 g/L)
- acetic acid concentration: 7% (70 g/L)
- salt concentration: 10% (100 g/L)
Once the solution is made, I heat it above 70 °C and let cool down slowly.
Unfortunately, I usually get only small amount of dark brown/red crystals and most stay in the solution.
The problem is of course there are still too many impurities and it is hard to guess the good concentration for harmalas.
I am also thinking about using HCl instead of acetic acid, since the hydrochlorides are less soluble in water, thus might crystallize more easily.
I wash the free base alkaloids several times, re-acidify (with acetic acid), re-filter, re-basify and wash again several times.
I then try to find good parameters for Manske, e.g.
- harmala concentration: 1.5% (15 g/L)
- acetic acid concentration: 7% (70 g/L)
- salt concentration: 10% (100 g/L)
Once the solution is made, I heat it above 70 °C and let cool down slowly.
Unfortunately, I usually get only small amount of dark brown/red crystals and most stay in the solution.
The problem is of course there are still too many impurities and it is hard to guess the good concentration for harmalas.
I am also thinking about using HCl instead of acetic acid, since the hydrochlorides are less soluble in water, thus might crystallize more easily.
However, this is just my preference and each person may enjoy a different approach.