Author Topic: Cleaning-Up Isosafrole  (Read 2592 times)

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LaBTop

  • Guest
Rhodium,
« Reply #20 on: May 04, 2002, 07:01:00 PM »
You still have this hanging in your Chemicals section of the Peracetic :
Distillation:
100ml of Cooking oil to prevent scorching

And YES, it must be clear now for all beginners that use of any additive in the form of another high boiling oil like peanut oil or damm whatever is totally nonsense.
It gives way to that fine possibility of carbonizing a futher perfect batch. LT/

WISDOMwillWIN

Rhodium

  • Guest
Error fix
« Reply #21 on: May 04, 2002, 09:00:00 PM »
LT: Thanks - I missed that. Now it is all corrected.

dr_ruthenium

  • Guest
Rh: Can I blame all of my failures on you- having ...
« Reply #22 on: May 04, 2002, 11:14:00 PM »
Rh: Can I blame all of my failures on you- having used a buffer oil while distilling safrole, iso, and ketone (trifecta)?!  Guess that I would have to give you credit for all future success too... Dr. Ru

LaBTop

  • Guest
No, you can't.
« Reply #23 on: May 05, 2002, 04:46:00 AM »
Rhodium collects all these goodies as some sort of super librarian for underground chemists, because no one else seems to do it at this level and scale. That means that he gathers all really interesting posts or threads in our forums, and can't be held responsible for small typo's, mistakes or even sometimes blatently wrong pieces of postings. You have to address that to the poster.
And those will do this also not willingly, they just follow a slowly introduced hoax or mistakenly copied piece of info from the web or whatever other kind of bad info.

That's why you need to dig deep on the Web or better in the libraries, when you follow a posted method and engage strange anomalies which can't be explained by your own mishaps.

In your case I don't think that that bit of peanut oil is the culprit, you will probably have encountered the chem fairy, that nasty little bitch, who influenced your thoughts and let you make the same mistake multiple times.
Only time will tell, and a lot of repeated batches, as usual.
Please don't be shy to report the real mishap, so everyone can learn from that.
The bravest scientists are the ones who can admit a mistake, and correct it publicly. LT/

WISDOMwillWIN

Bwiti

  • Guest
$$
« Reply #24 on: May 05, 2002, 07:07:00 AM »
"Only time will tell, and a lot of repeated batches, as usual."

  Lots of ideas/desires, but little money is my problem.
:(

Love my country, fear my government.

metwurst

  • Guest
More on tan oil, maybe even the answer
« Reply #25 on: May 06, 2002, 04:35:00 PM »

As part of an isomerization experiment, 100.6 g of safrole (fractionally distilled at STP) was placed in a 250 mL flask. 1.2g of 90% KOH was added.
The flask was heated to 100°C at 60kpa (~450 mmHg) to drive off water, then a condensor was fitted for reflux.
Temp was brought up to 110°C, and the setup was left to react overnight at 60 kpa.

Approx 14 hours of heating later (reflux did not occur, and this was deliberate) the flask was left to cool.

A small quantity of the resultant oil was removed. The oil was a nice light tan color. A boiling point test was performed with the thermometer 5 mm above the surface of the liquid. (A beautiful condensation/thermal inversion effect was noted. Very pretty, if inconsequential) Boiling point was established to be 235°C. Boiling point of the distilled safrole using the same setup was previously established at 232°C

It is apparent from this that very little isomerization - if any - did occur. metwurst could have perhaps looked this up, but felt inclined to try it anyway: Practice makes fairly good.
In any case, if the oil is light tan, then metwurst would suggest no isomerization occurred.

The flask was then vacuum refluxed for 4 hours at ~130°C at 95 kpa, which resulted in 92.4 grams of isosafrole after distillation. metwurst supposes some of the safrole decomposed during the long slow heating.

Rhodium

  • Guest
bp measurement
« Reply #26 on: May 06, 2002, 06:19:00 PM »
A boiling point test was performed with the thermometer 5 mm above the surface of the liquid.  Boiling point was established to be 235°C.

You cannot measure boiling points like that, your reading would still be ~232°C or slightly above even if you had 95% isosafrole and 5% safrole, as the safrole boils first of the two and is thus the only compound to reach the thermometer.

Chromic

  • Guest
More on isomerization
« Reply #27 on: May 07, 2002, 01:27:00 AM »
You must fractionally distill the isomerized sassafras to get a good idea of the BP.

You should be making laboratory notes that look like this:

May 6, 2002: safrole (100.0g, frac of sassafras oil, BP 230-234C) was refluxed with flake potassium hydroxide (1.5g) for 12 hours at 160C reflux. The color of the reaction turned from an light yellow to black, as per usual. Fractionally distilled contents of flask at atmospheric pressure:

(100C-230C) 1.0g brokedown safrole
(230-250C) 2.0g unconverted safrole
(250-254C) 94.0g isosafrole
(>254C) 3.0g undistilled crap in flask / losses

Then you discard the brokedown safrole, store the unconverted safrole (to add it to future isomerizations), then use the isosafrole for making ketone, and throw out the rest... you also get a good idea of where you went wrong etc, and if you post information like that to the hive, everyone will be more than happy to help you out!!

metwurst

  • Guest
bp measurement?
« Reply #28 on: May 07, 2002, 07:36:00 AM »
You cannot measure boiling points like that, your reading would still be ~232°C or slightly above even if you had 95% isosafrole and 5% safrole, as the safrole boils first of the two and is thus the only compound to reach the thermometer.

Interesting, and thanks for the clarification.
Have you any ideas on how I reached 235°C then?
Further detail:
The thermometer was suspeneded 4.5 - 5 mm above the surface of the oil in a duran test tube.
The impatient metwurst carefully brought the soil to boiling point using a butane torch.
A very gentle simmer was maintained with the butane torch in a stationary position.
The thermometer temperature rose from about 12°C above ambient to 228°C over the course of 75-80 seconds. This rapid rise began several seconds to the first bubbling of the oil.
3.5 - 4 minutes after boiling began, the temperature began ro rise. It fluctuated between 234°C and 236°C. I chose the approximate temperature of 235°C to report.
When the temperature failed to climb above 236°C, metwurst presumed insignificant isomerization had taken place, and that an azeotrope of safrole and isosafrole was the cause of the slightly elevated temperature.

Is this thinking incorrect?

I think this might be the point where I'm chastised for a) not using an oil bath to ensure temperature regulation and b) being presumptuous.
If so, I humbly shoulder the mantle of blame.