Actinium - 3-9-2014 at 15:32
Hello to all, this is my first post here but have been reading thru the forum for some time now.
I've been practicing my analytical chemistry skills, but have come to a point of being stumped.
My problem is trying to identify the contents/ Fractions of this particular oil?
I do not have a Fancy pump and hate wasting water with an Aspirator, so have used good old fashioned steam distillation with a packed Claisen to
separate fractions.
The oil is a dark yellow/ red,brown oil. there is smell of camphor and anise. the oil was placed in the freezer where a few clear crystals in thin
plates formed, upon removal more crystals formed. the crystals are incredibly hard to extract and examine, as they melt quickly as soon as they are
exposed to the temp outside the freezer. I did notice that there where a few long needle like crystals as well. I put 3ml of this oil in 3 test tubes.
one of the tubes was dyed with MgSO4. all formed crystals with the exeption of the dyed sample which produced thin needles?
Ive used various reagents to attempt at identifying the contents including, Conc. H2SO4 Which produced very red/purple on the crystals, dark
red/purple on a clear fraction and red slightly lighter orange on a light yellow fraction.
The only noted difference was with the chilled oil, where dark dark rd/purple with almost blue,black, violet was observed.
I apologies for the lengthy post, i'm just really stumped and there seems to be so much information out there concerning reagent use and so many
variables for alkaloid makeup/content that its hard to pinpoint exact definition of color.
Thanks Ac
forgottenpassword - 4-9-2014 at 02:07
Your crystals sound like water. The sample dried with MgSO4 had crystals of hydrated magnesium sulphate.
If possible, I would suggest that you do a TLC of the mixture. There are solvent systems and Rf values available for most natural products, which will
help you to identify the constituents. Simple colour tests will enable you to further confirm the identity. Again, this information is available.
Failing that -- even if you could separate the fractions using steam distillation, how would you identify them? It would be better to distill them
straight from the oil, and record the boiling points of the fractions. At least that would give you some data with which to make an identification.
Actinium - 4-9-2014 at 12:48
thank you for the reply.
Im using a corning hotplate/stirrer with oil bath so temps can only go so far as opposed to a heating mantle. ive been wondering as well if the
aspirator isn't holding a proper vacuum or if I'm doing something incorrectly?
Ive had considerable trouble getting my oil bath 200c and even with full vaccum the temp never rises on the thermometer as whatever i'm trying to
distille is sitting in reflux and never comes over, this has been an issue and hence why I used the steam distillation.
How big of a temperature difference in the oil bath do you need to reach internal temps within the flask? I know this is an ambiguous question..
Ac
forgottenpassword - 5-9-2014 at 12:13
Did you put petroleum jelly on the joints of the glassware?
If I understand you correctly, you are trying to determine what you have in your mixture, rather than necessarily trying to separate them. Vacuum
distillation at an unknown pressure will not help you to get any useful data. You can record the boiling point, but you will not be able to correct it
to atmospheric boiling point unless you know the pressure.
If you have a small enough flask, perhaps you could try distilling a portion of your oil over a free flame. An alcohol burner, for instance. You can
watch the thermometer and record the boiling points of any substances that distill over. That would at least give you a starting point for further
identification.
Actinium - 6-9-2014 at 15:38
thanks for taking the time to reply.
Yes I put grease on the ground glass joints. I actually now use, "diode teflon grease". what I dont have are keck clips, so used teflon tape to wrap
the joints.
The reason I was using vacuum distillation was,
A) Practice
B) establishing efficiency of my vacuum
C) trying to isolate compounds without distruction.
Yes I want to find out whats in this liquid, figured thought that separating them out would give me possibly an easier time identifying them.
As i mentioned in the previous post I was having trouble getting my oil bath over about 170c hence why I was trying to use a vacuum, although the
suspected allylbenzene is pretty tolerant to heat I'm assuming that it like anything else though has its limit and especially at the elevated temps of
<200c?
Polymerization of the oil was taking place.
I took your advice and did a boiling point test.
">3ml of the oil was placed in a test tube and secured to a clamp with the" oil portion submerged in a peanut oil bath.
>The temp was quickly brought up, with a thermometer measuring the bath as well as one in the tube.
>crackling occurred around 150c-175c where water was coming off.
>Once internal temp reached 225c-228c noticeable reflux was occurring.
>At 230c-232c boiling was observed and vapor was coming off the surface of the liquid.
> Boiling was continued for approx 10 min bath temp increased another 5 degrees and internal temp of the tube stayed at a constant.
>Hotplate was turned off and test tube was removed, with strong smell of Anise permeating the air, oil had darkened slightly.
>The oil was quickly chilled and several drops where placed on a spot plate.
>Reagents used where Conc. H2SO4, Marquis, Meckie, Mandelin.
>The Conc.H2SO4 produced deep reddish/purple/violet
The Marquis produced deep purple/violet with red hues and blue black edges inward.
The Meckie produced what started as reddish/violet and produced dark bluish green.
the Mandelin produced a very dark purple/violet.
>There is alot of conflicting information on the internet going thru different journals of flavor and chemical engineering.
Here is a reference that seems pretty complete with pictures and all.
http://www.unodc.org/documents/scientific/SCITEC21_07fin.pdf
So One would assume that this could be Safrole in question? After all it boiled within the range. reagent testing seems to line up.
only thing that makes me think otherwise is, that Anethol has almost the same B.P. and smells of Anise as well. the oil floats on the water which
would mean it has a lesser density than the water which according to
has Density: 998.00 kg/m³ = 0.998 g/cm³ vs. Safrole with a Density: 1.10 g/cm³
safrole wiki
So I guess at this point just try and do a simple distillation and maybe try again a vacuum, and invest in TLC plates when I get more money.
Should I pack the Claisen and do a short path fractional?
Should I maybe use foil and cover the the oil bath/flask to try and hold the heat in better?
-Ac-