witchbaby (Stranger)
11-11-02 02:51
No 378535
      Peroxide and Formic reacting pre drip  Bookmark   

Simply put my friend is running 750g iso baalchemist style... so whats up is that the performic is bubbling/heating reacting almost right away... it has to be taken off the retort else it blows all over mum...

thought it could be a filthy sep funnel, washed and cleaned 3x no avail... 86% formic, heard maybe there is methanol in it?  h2o2 should be good but he says he is going to try running with some new h2o2 and see what happens...

what about running the performic 2x except a bit smaller on the second run, before hydrolysis just to make sure all that iso gets reacted?

peace
wb
 
 
 
 
    baalchemist
(Chef d'Equippe)
11-11-02 05:33
No 378586
      Slow drip over a few hours time is the key.  Bookmark   

Slow drip over a few hours time is the key. Rushing the addition process is #1 cause when it goes runaway/exothermic. The bicarb will cause it to bubble alot in the beginning as co2 is released. Larger glassware is a definite plus.

    GODISNOWHERE
Shoot Narcs, Not Drugs
 
 
 
 
    GC_MS
(Hive Bee)
11-11-02 09:36
No 378631
      oxirane  Bookmark   

Formation of the oxirane occurs rather quickly, and the reaction is exothermic. The golden rule of "don't let the temperature go higher than 40C" also applies here. Adding the performic by slow dripping, or by adding X mL every Y minutes after checking the reaction mixture temperature are the ways to follow. Made experience makes the difference between a cook and a chef d'equippe wink

Ave Hive, synthetisandi te salutant!
 
 
 
 
    noj
(Hive Addict)
11-13-02 06:46
No 379180
      Odd  Bookmark   

By your message title, are you saying that the formic acid and H2O2 are reacting violently before you drip it into the iso mix? That shouldn't happen.

There is no need to perform 2 oxidations 'just to make sure'. If you have a significant amount of isosafrole left after the oxidation, either you didn't allow enough time to react (16-24 hrs) or your H2O2 has degraded and you need to adjust accordingly.

there's a big difference between criticizing your government and criticizing your country
 
 
 
 
    Ritter
(Master Whacker)
11-13-02 09:33
No 379211
      here's your fix....  Bookmark   

You guys didn't understand his query properly.  What he is saying is that the pre-reaction mixture of formic acid and H2O2  is being catalyzed by something causing an exotherm of effervescence of O2 gas.  The problem is a simple one; it can be one of only two possibilities.  Either the formic acid is contaminated or the addition funnel is dirty or has a piece of a foreign substance in it that can catalyze decomposition of peroxides/peracids.  Even though you cleaned the additional funnel out thoroughly, it may be the culprit because metal oxides from the stopcock clip may have worked themselves up into the funnel or stopcock joint.  The way to determine if the funnel is the guilty party is to fill it with plain 30% peroxide and watch it for a few hours to see if it starts to decompose(bubbles- not a few bubbles as thats normal, we're talking about vigorous effervescence).  Make sure you twist the stopcock around a few times so the peroxide is exposed to any catalytic materials possibly stuck in the joint.  If the plain peroxide does not bubble, than the problem is obviously contaminated formic acid.  Chances are the mystery catalyzing substance dissolved in the formic is not an organic chemical, rather a transition element salt from a previous storage container.  You have no way of knowing what the formic was stored in before it was rebottled and sold to you, neither do you know what kind of equipment was used to transfer the bulk liquid into the smaller bottles for retail sale, therefore metal salts could have easily been deposited/dissolved into the acid resulting in your conundrum.  The easy solution is to distill the formic acid at STP using scrupulously cleaned glassware.  Report back and let us know which of my guesses correct!
 
 
 
 
    witchbaby
(Stranger)
11-24-02 08:33
No 382744
      Problem is the h2o2  Bookmark   

According to your reply, my friend has decided that it must be the h2o2.  stop cocks were clean and bubbling is occuring. heating up. apparently they tried new h2o2 and it worked fine.  but they tried doing the drip in 2 half parts and it seems to be okay also and it doesnt get to crazy before it has all dripped in.  did mention that the drip was a bit slower since the misture was heating up a bit more than usual. thx again ritter ;)