A few years ago I purchased some essential oil and separated it into its component parts through vacuum distillation. The main component was a
clear colorless [edit: such a freshman mistake. I need to hit the books again] oily substance which was highly aromatic (no surprise
since it came from an essential oil I guess). After a bit of (successful) experimentation I stored the substance in a ground glass stoppered flask.
Now, 3 years later, I'm again ready to broaden my knowledge of chemistry, using experiments I find on the internet as a learning aide. I dug out the
flask which still contained roughly 100ml of the aromatic compound and found it was no longer clear colorless but instead had a
orange tint to it, closely resembling the color of the original essential oil, although it still smells, to the best of my recollection, as strongly
as it did when I first distilled it.
My question is this: Can I safely assume whatever is coloring the substance is a component of the original essential oil and simply run it through
another vacuum distillation to clear everything up? I guess my main concern is, could some type of slow reaction have occurred over the last 3 years
and what I now have in the flask is no longer the original substance? I can use distillation to separate components of a mixture, but not to undo the
effects of a reaction. My current plan is to run it through and see at what temperature the distillate comes over. The problem with this is I had to
use a somewhat homemade vacuum regulator on my vacuum pump (a ball valve regulator purchased at a local hardware store instead of a better pin valve
one like I intend to purchase soon) since the pump pulled so hard it boiled the essential oil at room temperature, so I cannot guarantee I'll have the
same pressure as the original distillation and therefore could not have an accurate comparison to the temperature the distillate came across the first
time (which I recorded in my lab notes like any good science student).
[Edited on 4-21-2007 by Z-Row]
[Edited on 4-21-2007 by Z-Row]bio2 - 20-4-2007 at 20:30
The color is almost surely polymerization products which
will remain in the flask when fractionated.
Use a nomograph to convert temperatures for different
pressures. Its within a few degrees accuracy but is
suficient for most purposes.
A tiny syringe needle makes a good vacuum regulator
if used as bleeder in a vacuum system.Z-Row - 20-4-2007 at 22:37
Quote:
Originally posted by bio2
The color is almost surely polymerization products which
will remain in the flask when fractionated.
Thanks for the reply and the syringe tip bio2. If you'll forgive a freshman follow-up question. Polymerization is the process used to create polymers,
long strands of molecules, aka plastic, correct? Are you sure you didn't mean isomerization?Nicodem - 20-4-2007 at 23:51
I'm sure he meant polymerization, since isomerization is a term that would make no sense in the context. Many terpenes and other components of
essencial oils are alkenes and these do not isomerize spontaneously at room temperature, while they rather happily polymerize in the presence of O2.
But nobody knows if that is the cause of deterioration in your case since you did not explain which compound you talk about.vulture - 21-4-2007 at 11:54
Nitpicking mode on: One can have a colorless liquid which isn't clear, for example because a colorless solid is suspended in it.UnintentionalChaos - 21-4-2007 at 12:10
If you're playing with essential oils, this site: www.newdirectionsaromatics.com has fairly thorough MSDS for a broad range of oils. Here's one for sweet orange
oil:http://www.newdirectionsaromatics.com/msds/orangesweetmsds.htm,
the major component being (over 90%) d-limonene (a terpene).oxybate - 29-4-2007 at 12:35
Sounds like this "orangish" essential oil seems to be quite a sassy one, eh?
