As Strike already outlined in TSII, page 33, Brazilian Sassafras or Brown Camphor contains normally no Eugenol.
Thus a 3-5% NaOH solution wash before freezing the oil is redundant in most cases.
Let's look at what he had to say about purifying by freezing of Sassafras oil, page 34 :
It will be a little tricky, but one can also try to purify by freezing!
The sassafras oil is thrown into the freezer to chill. Safrole itself freezes at -14C, so anything that starts to freeze before that can be cold filtered in a prechilled vacuum setup. Thefiltrate goes back in the freezer until -14C is reached and the motherload of safrole freezes up. This again is filtered cold but this time the frozen mass of safrole crystals are washed with some icecold methanol or ethanol (preferably beeing -14C also), to wash away the unfrozen high-boiling constituents.As you can see in the above posts, there are much better procedures described now, to purify by freezing.
= = = = =
LT/: Editted 08May2002.
Proceed with your now mainly pure 1-alkene (safrole) to a:
5% weight/weight (99%pure) KOH + Safrole overnight vacuum reflux:
Setup: 1.---Highly adviced: (when you have one!) an air cooled 20 or 40 cm vigreux column vertically set on your distillationflask,
2.---(flask placed in an aluminum oilbath, [filled with peanut oil or silicone oil and a STIRBAR], which stands on a stirrer/hotplate, flask for 3/4 or nearly totally submerged in the oil, just the neck free),
this will keep the refluxtemp of the MANY constantly condensing and falling back safrole/isosafrole drops much higher than by using just simply a watercooled condenser, thus avoiding a too fast cooling down of the main safrole/isosafrole/KOH body in your distillationflask at full vacuum reflux all those hours overnight and perhaps slow down the reflux rate and lower flask-temperature,
3.--- PLUS on top of that a vertical set watercooled-condenser setup,
(which will trap and forcefully cool all eventual vapours which eventually still escaped the vigreux column).
4.---On top of the condenser you place a vacuum adapter and vacuum tubing to your vacuum pump.
This gives conversion from 1-alkene (safrole) to 2-alkene (isosafrole), under full vacuum, OVERNIGHT, while first removing all traces of water which would wreck your isomerization results.A.---
To remove all water traces FIRST, you begin the procedure with a different simple setup, with the vacuum adapter connected directly to the distillation flask, put on the full vacuum for 30 minutes, while the hotplate is switched on for the first time. In that time the mix will not heat up very much, thus avoiding sucking off too much volatile oils, but the high vacuum will remove all water traces at that temperature.
After those 30 minutes you put the vigreux column + watercooled condenser back on the distillation flask, put the vacuum adapter back on top of the watercooled condenser, and switch the vacuum on again.
(Already in the first 15 minutes after switching on the vacuum pump and the stirrer/hotplate and adding a egg-shaped stirrbar to the contents of your distillation flask, before your safrole/KOH even reaches near its boiling point
under your specific vacuum, depending on what pump you use, you will -perhaps, when traces of water are present- see some light boiling in your flask, that is the eventual water boiling and evaporating to your pump, after that time all that water will be gone into your pump; leave the GAS BALLAST of your pump full open!, in case of an oil-filled vacuumpump, this will allow the watertraces to be washed out of the pump by the air washed through the vacuum oil when that gasballast is full open. You should leave that one always fully screwed open, it will influence your maximum vacuum very minimal, no more than half a mbar, but will keep your vacuumoil as clean as possible).
B.---After those first 30 minutes, you replace the whole setup as in 1-2-3-4 above, and continue the heating and stirring under full vacuum again.
Then when your safrole + KOH starts
steadily boiling and full refluxing back from the vigreux column, fix your temperature setting at that specific temperature scale point of your hotplate,
(I can't give a precise temperature, because it will differ for everyones specific vacuum obtained by different pumps and setups),
and leave it OVERNIGHT
full refluxing. No need to crank up the heat further, don't do it.
C.---The next morning you switch off the vacuum temporarily, to insert a T-piece with thermometer sticked in, on top of the (ev., but highly adviced) vigreux column, attach your watercooled condenser now on the T-piece's sidearm under a ~30° downward angle, put a vacuum alonge on the other end of the condenser, and hang a receiving flask on the vacuum alonge, put the vacuumtube on the alonge outlet, switch the vacuumpump and mixer on again, and just increase the heating untill the vapours of your boiling --now 95-98% isosafrole/3-5% safrole mix-- reaches the top of the (ev.) vigreux and the sidearm of the still head (it still refluxes back partially, that's good, you now have the purests vapours at that temp reaching the top of your vigreux and still head side arm) and starts condensing in the condenser and drips in the receiving flask.
C2.---The first small portion coming over will be the 5 to 2% safrole+?impurities? -left after the isomerization process.
When at that temp setting and vacuum nothing more comes over, remove the receiving flask and discard this portion in a "Fore-run Safrole" labeled glass bottle for use in the next isomerization batch again! Check its DENSITY (and total weight of this fraction compared to the starting weight of your safrole!) and compare it to my density data in
Post 294426
(LaBTop: "Sassafras components data", Methods Discourse) in this thread.
Note this fore-run temp setting and density and total fraction weight in your labnotes (handy for your next batch).
C3.---Hang your receiving flask on the alonge again, switch the vacuum on again, and proceed to heat further untill you reach a new higher temp where as good as all fluid (isosafrole) at that temperature will come over. Inbetween you will have to check at intervals your (now) isosafrole vapour temperature in the still head (T-piece), if that goes up suddenly FAST more than 5-10°C, your done, all what comes next is not isosafrole and should be thrown away. Better don't use the leftovers from your distilling flask (KOH + Whatever carbonized shit?) in a next batch, just use then fresh KOH in your distilled and freezed-out safrole again!
Check the density of your obtained isosafrole against the density data in my
Post 294426
(LaBTop: "Sassafras components data", Methods Discourse) in this thread.
If not sufficient precise, repeat the whole procedure again, until you got it RIGHT.
A PURE isosafrole will give you the highests REAL KETONE yields in a performic, peracetic or other method, ALWAYS! LT/
WISDOMwillWIN