03-03-03 16:26
No 413330
I have used TFSE, to no avail on these questions.
Peracetic acid formation requires 35% H2O2 - will 31% bee enough? Will I have to adjust the other reagents to compensate?
I have read conflicting reports concerning the H2SO4 rearrangement. Different amounts of 15% H2SO4, different temps, and different lengths of reflux (2-5 hours). It seems as though most people reflux at around 80C for 2 to 3 hours. Is there a definitive answer to these questions, or am I going to have to hit it with trial and error?
Thank you bees.
(Chief Bee)
03-04-03 03:10
No 413508
Peracetic acid formation requires 35% H2O2 - will 31% bee enough?
Yes.
Will I have to adjust the other reagents to compensate?
Yes. To make it simpler, you can adjust only the amount of H2O2 instead (use 1.13x as much, weight-wise).
For the H2SO4 rearrangement, dissolve your crude glycol in twice the amount of methanol before adding it to the H2SO4 - the layers will mix a lot easier and when you are refluxing the solution lightly, the temperature will stay at a moderate 65°C throughout the reaction, which is just fine.
(Hive Bee)
03-04-03 22:56
No 413793
i believe the origional ref for the performic that ritter worked with specified 180g 15% h2so4 and 60ml MeOH per 16.2g isosafrole reacted.
labtop and many bees specify 90g h2so4, 30ml MeOH which works for them, using strong enough stirring.
swim has been getting glycol contamination in his ketone up the wazoo though, even using about 30mm of steel wool in a fractionating column, so he's going back to the amounts in the origional ref.
be sure to follow chromic's peracetic writeup that says to keep the peracid mix at room temp for 5days, shaking occasionally. that's the shit that works.
(Hive Addict)
03-06-03 15:05
No 414293
It works without methanol too,somebees say it's even better without methanol,must have good stirring though...
For those about to synth,we salute you
(Stranger)
03-06-03 17:24
No 414319
the peracetic preparation - Rhodium's formulation is different from Chromic's. One has an excess of GAA, while the other has an excess of H2O2. Will both work?
(Chief Bee)
03-06-03 23:10
No 414400
Yes, both will work. The important thing is to have an excess of either, to drive the equilibrium towards formation of the peracid.
(Synaptic Self-Mutilator)
03-07-03 06:08
No 414493
I and others never had success with the other peracetic. Perhaps it works, perhaps not. I personally vouch that the peracetic in DCM does work beyond a doubt. Pursue the other one for academic interest only...
(Hive Elder)
04-26-03 09:54
No 429500
I can vouch that the original one works as written, but I would go the DCM route if I were you. The reason for this is simple, the amount of acid needed is greatly reduced, and the yeilds are much better. SWIM tried to get the DCM/peracetic route to work prior to Chromic's work on it, SWIM wasn't lucky with the modified(DCM) version. But remember that SWIM hasn't personally tried it out since Chromic's writeup. So to recap, they both work but use Chromic's writeup, the other one was more of a proof of concept type of thing...
Mean People Suck
(Hive Bee)
04-28-03 07:04
No 429909
Swim followed Chromic's Peracetic, to the letter, and even with poor equipment and technique still achieved a 50% isosafrole to ketone ratio.
P.S. Thanks Chromic!
when we forget to pray for the angels, the angels forget to pray for us!
(Synaptic Self-Mutilator)
04-28-03 18:19
No 430008
I personally think it's the one of the most OTC methods, next to the Oxone method, for newbees. Fortunately it provides better yields (in my experience) and is more encouraging. Good luck with your endeavours.
(Hive Addict)
04-29-03 08:40
No 430157
sadly, SWIM's performics performed to the letter at varying scales with lab grade reagents seem to always end up with at most 50% yield. although the forerun should still be isosafrole, and reusable in the next.
Now with 12% more Bottom!
Nymphomania is not a disease, its a goal! (Methadist)
(Hive Bee)
04-30-03 06:16
No 430334
Bees, please take note!!!!
and even with poor equipment and technique still achieved a 50% isosafrole to ketone ratio.
If done with better equipment and technique (there was some spillage) Swim believes this method could yield 65 - 70 % Isosafrole/ketone w/w ratio.
when we forget to pray for the angels, the angels forget to pray for us!