07-27-04 14:46
No 521976
I decided to run my first buffered performic yesterday.
Post 208821 (LaBTop: "The ONE and ONLY buffered Performic", Methods Discourse) following this post and ratios
Everythins was setup, and the performic was prepared by mixing 384g of 88%formic into about 232g H2O2. Left to stir, I left the room.
One hour later when i came back, the performic wasnt stirring anymore, my stirrer had decided to die on me at that exact time. I was bubblinb a little bit already.
About 15 minutes into addition it got real hot and started to boil over!!!Nasty smell and a little freaking later Im trying to understand what happened.
My first guess would be contamination of the formic. But the formic is ACS grade. The peroxyde is from a hydroponic store and it was stable initially.
I am hopping to rule out that possibility and replace it with the fact that the mixture didnt stir previously.
I really dont hope that the formic I have is useless.
Could the fact that not stirring the solution for an hour accelerated the decomposition of the peroxyde???
I dont want to stop this dream there, any clues?
(The Archetypical "Good Guy")
07-27-04 15:39
No 521981
Your details are somewhat vague, so the answer will unfortunately reflect this.
Did you add the isosafrole without stirring, or did you replace the mag stirrer?
If you did add it without stirring, the problem is pretty obvious...
The mixture forms two layers, and when mixed enough from the dripping, you will get an exothermic reaction. With a big layer of peracid floating on top, the exothermic reaction will turn into a run away reaction, once things get hot enough to boil an really stirr up things. Simply stirr the next time.But if you did stirr I'd guess that you simply added the performic acid too fast. It is a highly exothermic reaction and DCM boils if you simply look at it. So add very slowly or you'll get a volcano reaction in no time!
I would say that you'r reagents are dandy, but the actual problem is located in you patience
Enjoy, regards
Bandil
Cocaine blows!
(Hive Bee)
07-27-04 15:46
No 521984
I meant the performic mixture in the sep funnel.
But i just answered my own question. Made some performic in an erlenmeyer with constant stirring on an ice bath.
No bubbling at all.
The reason is then that my mag stirrer broke and if not preoperly stirred the peracid formation wont go well, it gets exothermic like crazy.
With aother stirrer that works, the performic was prepared real easy. Thanks anyway
(arrogant bee of the day)
07-28-04 12:34
No 522228
I had this problem too, (the performic acid boiling uncontrollably before addition had completed, once before it even started.
Solution: Don't mix them for 1 hours and then store in freezer for an hour, just mix the two and start addition.
Cause: Impurities in either that accelerate degradation.
Thank Osmium.
I'm not fat, I'm just too short for my weight.
http://www.whatreallyhappened.com
(Quasiquerumodo)
07-28-04 12:38
No 522231
i hope it did only decompose into O2 and water, not heat to 100°C?
He always lied while on the earth and now he's lying in it
(Hive Bee)
07-28-04 14:12
No 522236
Believe me it made a mess!!!
My stirrer broke so the peracid wasnt properly mixed nor cooled. After an hour, it was already bubbling real hard when i started the addition. While the addition was going on, it got more and more hot until it boiled over. I wish it had only been 02 but it did spit out the formic, burning lungs and eyes when i had to move from the sep.
It was a scary experience but I know why, because it didnt stir.
So I did the addition again, on a 250 grams iso, this time preparing one half an hour before, under stirring and cooling. The other half was prepared once the first portion was started to add. You can still see some little decomposition 2 hours after preparing the peracid, but by preparing smaller portions at intervals, no problem occured whatsoever during the addition.
Now I have a nice solution that turned from yellow to orange, the glycol!
So definitely the not-stirring caused that boil over, so I guess its mandatory to do so!!!