Author Topic: isomerisation success (x2)  (Read 5317 times)

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firecracker

  • Guest
Re: some extra notes
« Reply #20 on: May 10, 2001, 06:42:00 PM »
wacko,

So "straight from the bottle" isomerization worked?

1) 100g KOH was ground w/ mortar n pestle.
2) 1600mL of chinese sass oil mixed w/ KOH in a flask.
3) Mixture was heated and stirred for 12 hours at 140C.
4) Post reaction mix was washed once w/ dH20. (and possibly filter because of "chunkiness")
5) Vacuum distill to get 1400ml iso.

2 questions:

1) Wouldn't a 5% NaOH wash at the beginning be useful as well? It would get rid of some of the solids.
2) Why 140C?  Why not hotter/faster?

Thanks for the input,
fc


Snap, Crackle, Pop

wacko_reaco

  • Guest
Re: some extra notes
« Reply #21 on: May 11, 2001, 07:49:00 AM »
Yes that is all true, i wanted to leave it overnight so i didn't want to subject it to conditions too severe, so I only programmed it to 140C, the post washing iso is very murky when the distill begins, alot of water comes off and the mix clears right up, there seemed to be practically no safrole forerun but sometimes it's hard to see (good vac source).
I dunno, try running it hotter and shorter and see how you go, maybe plasma phase at 3600C for 8msec, ha ha ha, a scientist joke.
Anyway, i do suggest to all those with the means to buy some RuCl3, i ran it at lower than the patent  concentrations but hotter and for longer, it was so easy.
bye now


wacka wacka wacka

Osmium

  • Guest
Re: some extra notes
« Reply #22 on: May 11, 2001, 10:58:00 AM »
You used quite a lot of KOH. It will work with much less, and you can skip filtrations and washings etc.
Grinding in a mortar is not necessary either. It will only pick up more H2O from the air, at those temps the KOH flakes will disintegrate on their own anyway.

It's good to see that things like RuCl3 work, but at that cost I doubt I'd consider that reaction. The KOH way gives almost quantitative yields (only limited by your distilling abilities) when starting with pure safrole.

Osmium

  • Guest
Re: some extra notes
« Reply #23 on: May 11, 2001, 02:38:00 PM »
A shy lurker bee asked me to post the following:

> Ruthenium(III)chloride hemihydrate (1.68g, 7.75 mmol) was ground to a
> fine powder and added to safrole (450g, 2.75 mol) in a 1000ml RB flask
> fitted with a reflux condenser and the solution, which soon turned a
> greenish black, was stirred at 150°C for 4h. The resulting black oil was
> distilled at the water pump to give 45g of safrole at 110-117°C, and the
> bulk of the oil distilled at 118-121°C yielding 360g of crystal clear isosafrole
> (90% yield based on the reacted safrole).

Some of that supposed safrole forerun will be cis-isosafrole, so I suggest you save it for the next isomerisation and not use it for a reaction requiring real safrole.

> I just wanted you to know that I tried the RuCl3 isomerization method, and
> it worked better than expected. The yield was 90%, higher than I've ever
> gotten from any other method (I've tried your vacuum reflux thingy, the
> KOH/CaO method and KOH/Aliquat 336). The safrole wasn't distilled, only
> crystallized, half-melted and sucked dry on the buchner, followed by complete
> melting, which may contribute to the fact that 10% of the oil never distilled
> in the desired temperature range, and formed a black tar in the flask (but it
> was soluble in acetone, while the crud left from KOH isomerizations is not).

Alcohol and water washes will dissolve that residue. Also distilling to dryness is not recommended (but can be done without ruining the flask), but since you can use it for at least another isomerisation the mechanical losses aren't that big.

> Perhaps you could post it in the "Safrole Isomerization success (x2)" thread
> for me?

Sure honey  :)   ;)

improv_chem

  • Guest
Re: some extra notes
« Reply #24 on: May 11, 2001, 07:34:00 PM »
SWIM tried to make isosafrole with only washed safrole and using ipa as the solvent at atmospheric.  Distillation was done at atmospheric and got 80% yeild of isosafrole after 3hours.  The key was to make sure that the KOH in ipa and the Safrole in ipa were dried with MgSO4 and everything was anhydrous.  No CaO was used. 
Short rxn times are possible (did it in under 3hours) if the ipa is slowly allowed to evaporate by periodically removing the reflux condenser to concentrate the solution and raise the temperature.  Distillation of Safrole and vaccume are not necessary to do this process.
Have Fun!!!
-improv :)


--Preventing odors from escaping to nearby noses is essential.....

Rhodium

  • Guest
Re: some extra notes
« Reply #25 on: May 11, 2001, 09:19:00 PM »
How much safrole was used? How  much KOH and in how much IPA? Was there any safrole forerun collected, or did the other 20% become tar?


http://rhodium.lycaeum.org


goiterjoe

  • Guest
Re: some extra notes
« Reply #26 on: May 11, 2001, 10:50:00 PM »
here's one for you Rhodium:

240g distilled safrole
3.5g KOH flakes
refluxed for 18 hours with a high vacuum oil pump
initially started refluxing at 88C; at end of reflux temperature was around 83C.  end product was distilled directly out of the boiling flask to yeild 236g of a clear oil with a sweeter smell than the starting safrole and a boiling point about 5C above the boiling point of the starting safrole using the same vacuum(with the oil changed before each run.)




If pacman influenced us, we'd glide around dark rooms eating pills and listen to repetitive music.

PoohBear4Ever

  • Guest
Re: isomerisation success (x2)
« Reply #27 on: September 26, 2001, 05:06:00 AM »
So, it has been said that NaOH may bee used for isomerization, though at least 2% of safrole weight.

If one simply took their sass, boiled at 120C to get rid of the aqua, cool down, then heat back up to boil and use the 99.999% NaOH without allowing any water to enter.  Then, why not just go ahead and use the CaO or MgO for better aqua insurance, and distill on over the isosafrole without filtering, using HCL to clean all glassware of crud.

Better chance at success, or has anyone tried anything similar? How clean should the iso bee if using peracetic?  Distilled 2x?

PB

Chromic

  • Guest
Re: isomerisation success (x2)
« Reply #28 on: September 26, 2001, 05:30:00 PM »
Single distilled iso is fine, it doesn't have to be very clean to go into the peracetic. If I had to isomerize again, I'd add 1% KOH in alcohol (just enough to dissolve it), then add the safrole... distill off the alcohol, reflux with no vacuum, and fractionally distill. Other methods work, but this appears to be the easiest/most OTC.

PoohBear4Ever

  • Guest
Re: isomerisation success (x2)
« Reply #29 on: September 26, 2001, 10:54:00 PM »
Ya'll keep scaring me with that 'fractional distill' shit.  Can one kinda ghetto such without a proper column (vigreux) by boiling off the alcohol (anhydrous isopropyl, or MeOH?) without vacuum, and then collect the second run (unreacted safrole) by slowly turning up the heat?  Change out receiving flask once more, and then shoot for the stars (i.e. higher temp)?

Has anyone had repeatable success by drying out reagents, and if so, how long should the reflux bee maintained?

Thanks,

PB

zooligan

  • Guest
Re: isomerisation success (x2)
« Reply #30 on: September 27, 2001, 03:59:00 PM »

Has anyone had repeatable success by drying out reagents




Had questionable results drying KOH.  Stick with the hydrated form and boil openly until steam is gone, then attach condenser and vac or atm reflux.

z


"And if we don't get some cool rules ourselves, pronto, then we'll just be bogus too!"