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.