Author Topic: Modified vs old formic amounts?  (Read 482 times)

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guyincognito

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Modified vs old formic amounts?
« on: August 10, 2002, 10:48:00 PM »
In the modified performic - the amount of formic acid is approx 1100 grams per 750 iso, yet in the old (classic)performic it is like 3500 grams formic plus per(like 3 times more) for 750 grams iso.

The amount of hydrogen peroxide is about the same in both.

why when the only difference is acetone instead of DCM does it need so much more formic acid??

Has anyone done the old (classic)performic with with less formic (closer to modified ratios)

Rhodium

  • Guest
The modified performic uses a LOT of DCM, which ...
« Reply #1 on: August 10, 2002, 11:42:00 PM »
The modified performic uses a LOT of DCM, which is immiscible with the aqueous phase, and the "original" uses just a tiny bit of acetone, which is miscible with the aqueous phase.

If there wasn't so much formic acid as solvent in the original procedure, the isosafrole and/or ketone would just oil out from the solution, killing the yield. In the modified procedure with DCM, the isosafrole/ketone is always dissolved in the organic phase, and when the performic acid is added, it too will dissolve in the DCM, but not the water the solution contains.