Author Topic: Akk! NaOH instead of Bicarb! on Mdp2p  (Read 627 times)

0 Members and 1 Guest are viewing this topic.

ClearLight

  • Guest
Akk! NaOH instead of Bicarb! on Mdp2p
« on: January 13, 2004, 03:30:00 AM »
I can't BELIEVE this.. I copied the data into the working notes w/ 5% NaoH rather than 5% sodium bicarbonate to neutralize the acid after the DH20 washes on a performic reaction. Everything was perfect until then.  Immediately the aqueous layer went reddish brown and the bottom dcm looked like coffe w/ milk in it.  I immediately dumped in some 15% H2SO4 to reverse the pH and now I have some OJ colored layer on top of the dcm and yellow/coffe underneath.  After about 10 min the top oj layer is yellowish brown and the bottom dcm layer is still milky but more brownish green.


The NaoH was 4 gms in 150 mls DH20. H2S04 was 20 ml conc in 220 mls DH20

  Have I screwed everything up, or can I still recover from this??  Please help asap! ( side reactions are looming!)


Antibody2

  • Guest
don't sweat it
« Reply #1 on: January 13, 2004, 06:20:00 PM »
nothing is fucked up, at all. An NaOH wash will simply extract different impurities than a mildler alkali, it will not hurt your ketone, just wash w/ H2O a couple times before you distill and you are good to go


ClearLight

  • Guest
THX!
« Reply #2 on: January 13, 2004, 07:01:00 PM »
Thanks antibody... I ran a tlc plate ( posts coming when I get done) of the MeOH/H2SO4 completion stage product, one of the NaOH aqueous layer, and one of the DCM layer after I added the 15% H2SO4 to recover from the NaOH addition.

  The plate showed exactly the same spot sequence before/after and nothing in the Water/alkali layer.  Based on that info, I took a deep breath and appreciate your time posting a reply! Thx for the confirmation!


Rhodium

  • Guest
NaOH as option
« Reply #3 on: January 13, 2004, 07:20:00 PM »
NaOH is actually an option, but with a bit lower yield:

https://www.thevespiary.org/rhodium/Rhodium/chemistry/peracid.html#performic2