Dear bees, this is my first real contribution. Hope you like it.
In short: It's much easier to get good asarone crystals from your Indian calamus oil if you add a little ethanol!
The long version: after I tried my first freezing experiment, I scooped a spoonful out of the container, after decanting the low-boiling stuff as much as possible, after melting a bit. Then I cleaned the crystals in a coffee filter with ice-cold 100% ethanol. It's important to note that the entire contents of the beaker were frozen, even though there were color-differences in the mass.
This is what it looked like before the thawing and scooping:
(note: the paper underneath is not pure white but a very light beige/yellow)
At the time I wasn't convinced that what I got was actually pure, so I let the the now cleaned crystals melt and put the beaker back in the fridge. Only now there was a bit of ethanol mixed in of course, from the washing, which I intend to distill off later.
The crystals formed again, only much slower (two days before they started to form), and this time a fraction of the beaker's contents stayed liquid, like this:
Important: the crystal mass formed in about two days, and the liquid on top has not decreased further in the two days after that. It's stable.
I hypothesised that the EtOH is preventing the non-Asarone from crystallizing, while the Asarone itself is not affected because it is relatively apolar (I think. Please note: I'm much more a cook than a chemist at this time).
So I tried mixing in a dash (a few milliliters) of EtOH with a larger volume of the oil, and this is what it looks like right now (after two days in the fridge):
Beautiful huge crystals! And they're still growing! In fact, it looks like a mono-crystal of about an inch across.
I have not taken the experiment further yet, so I am not sure (and have no other way to confirm than boiling point and density) if this is in fact the asarone fraction, but since it is by far the largest fraction, I'm pretty sure that it is.
If you recognize the color, shape or other attributes to confirm or deny this, please let me know!
Since it's pretty hot right now where I live, it's not really an option to start fiddling with the fridge temperature. I think this new way might make things a bit easier for the bees among us working with asarone. Let me know if you can repeat this finding, hopefully it works with other batches of oil as well.
Hope this helps!
nautilus
EDIT: PS: Before this I tried the freezing and thawing procedure as described elsewhere on this forum, waiting for a layer to form, but that didn't work for me.