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
