Fully_Auto (Hive Bee)
03-18-02 17:57
No 284547
      Little help + Exact Isosafrole way + Oxone way  Bookmark   

Having a problem here. Let me first start by saying SWFAís not a numbskull. SWFA canít believe this failed, SWFA dosent know why this happened.  Chromicís write up was followed to a T with 3 exceptions.

1: The reaction was scaled up x4.

2: A small amount  (29.2 grams) of extra oxone was added to the mix because SWFA called the manufacturer of the product and requested a MSDS for the product in question. They told him that they didnít have the MSDS information available at the time but did say that their product was Ph neutral.

3: All contents were added to an Erlenmeyer flask as opposed to a round bottom flask for stirring reasons.

What SWFA did 
2 liters of DH20 were added to the reaction flask.
65 grams of isosafrole were added to the reaction flask
800 ml Methanol were added to the reaction flask
320 grams of oxone were added ( as opposed to the suggested 290.8)
Added a large 3 inch stir bar
Put a condenser on the flask clod water running just in case
Then cranked the stirrer on full blast (creating a deep vortex in the flask). Aqueous phase temperature was 31.6c. SWFA left this stirring heavily for 5 hours. When SWFA returned and turned the stirrer off the aqueous phase was totally clear no signs of any yellow tint at all. SWFA immediately noticed a problem and decided to stir a little longer. No signs of anything remotely yellow in the flask at the 8-hour mark. It appears the oxone had totally crashed out of solution from the start. The flask looks like a giant snow globe thereís a lot of oxone sitting on the bottom of the reaction flask. When SWFA swirls the flask itís contents it gives off a few small bubbles.
What is the problem here? 
Why is SWFA not seeing the characteristic color changes?
The person who answered SWFA's call at the company didnít appear to familiar of the product other than the fact that his company puts Dupont oxone in their shocking agent. He said the oxone was Ph neutral but did he really mean ph neutral for 10,000 gallons of water?  Did he misinform SWFA? Is the oxone pure?
If the oxone was pure and SWFA didnít add the buffer would the oxone not liberate enough oxygen to epoxidize his
2-Alkene. Is this the problem?
Any help in this matter would be most appreciated.
EDIT It says on the package that the shocking agen will not affect ph levels. Did SWFA get a bad product blend? Is there a flaw in my method above?

The Ultimate Weapon Can't be controlled, banned or confiscated. Your weapon's your mind.
 
 
 
 
    humidbeing
(Can't SWIM)
03-18-02 18:35
No 284569
      Re: Little help with failed reaction please  Bookmark   

Swim's interested in this as well.

No buffer needed, according to V_l, when the oxone content
is the average 85%, and according to chromic the ratios
are in excess anyway, so are you sure that your iso is
good first? And then...
Okay, I missed the first part.
 There does seem to be serious problems with scale up
on this rxn.
 Look for Baal's and noj's probs in this area w/ the
same sucsess/baal, problems/noj.
 Addition/leaving out of MeOh seems to be the disputable
concern here.
 Sorry I could,nt help more.

Did you test ph throughout the rxn?

nipples and buttocks and crotches with wings these are a few
of my favorite things
 
 
 
 
    Vibrating_Lights
(Hive Addict)
03-18-02 19:00
No 284583
      Re: Little help with failed reaction please  Bookmark   

Suspect that your isomerization may have failed. So long as you are doing a H2SO4 rearrangement no extra Bicarb is needed.  The MeOh is needed but the ammounts can be reduced with pratice.  The best way to work it up is to add DCM and pour off the top layer leaving the bottom layer DCM/EPOXIDE/WHITE CRYSTALS. then extraxt the top layer with a little more DCM and add it to the DCM/Crystals.  then just wash with H2O and bicarb solution until all the crystals are gone.*Thanks Chromic
With acid sensetive molocules it is nescesary to use buffer.
VL_
 
 
 
 
    pickler
(Greenhorn)
03-18-02 19:10
No 284591
      Re: Little help with failed reaction please  Bookmark   

It's kinda hard to see the yellow oil in all that liquid especially with the precipitate. Try filtering the oxone,meoh and dh2o before putting it in the flask. Swim has a hard time seeing it even this way, but it's there. 65 grams is a small amount in 2800ml of liquid. It also could have been your isosafrole. Hope this helps.wink

We'll soon find out if I'm a chemist or not!
 
 
 
 
    Fully_Auto
(Hive Bee)
03-18-02 19:51
No 284615
      Re: Little help with failed reaction please  Bookmark   

Thanks for the quick responses guys. You pegged it Isomerzation failed. Truly embarassing. How could the ismerzation have failed? SWFA knows that water in the rxn will kill all isomerzation but the flask was in situated in a sand bath heated to 285įC. Is it possible for water to remain in the flask at that temperature? SWFA knows most bees use vacuum reflux but SWFA thought refluxing at atmospheric pressure would work equally well. madmadmad Guess SWFA will have to wait a few hours. Thanks for the great advice you three. Much appreciated.
 


The Ultimate Weapon Can't be controlled, banned or confiscated. Your weapon's your mind.
 
 
 
 
    pickler
(Greenhorn)
03-18-02 21:03
No 284650
      Re: Little help with failed reaction please  Bookmark   

Swim had the same problems with the iso as you Auto. But some helpful bee(you know who you are-thanks) gave me some pointers on atmospheric. The KOH is hydroscopic and will contain water. Now this helpful bee suggested doing it like this:
set up with a RBF with a condensor with a vacumm distillation adapter at the top with a small flask. begin heating oilbath as soon as it is slightly warm keep heating and turn the vaccume on high. bring it to reflux and start counting there  for 1hr under vaccume. after one hour disconnect the vaccume at the adapter.  dont ever just turn off the vaccume pump if you do the pressure in the vessel will suck oilout of the pump and into your rxn.allow the mix to heat till reflux then count three hours and then cut the heat. re set up to vacume distill. let it cool till it is about 5 .c hotter than your vaccume will boil  iso safrole at.  attach the vacume an ddistill til dryness.yeilds always 99%  just have one dedicated flask to make iso in.  you can reuse the KOH as many times as you want.  just leave the residue in the flask.  the purpose of using the vacumme initialy in the isomerization is to remove water from the KOH.  most KOH will always contain water  the water causes side product in an isomerization and if you remove it before the solution gets to reflux temp then you can eliminate the possibility of side products.  stirr the solution slowly as slow as you can. during the isomerization.


We'll soon find out if I'm a chemist or not!
 
 
 
 
    cheeseboy
(I'm not Cheesie)
03-18-02 21:50
No 284677
      Re: Little help with failed reaction please  Bookmark   

Also, do like the Big G said a few threads up a ways. Before adding your 2-Alkene, make up your dH2O/MeOH/Oxone solution and filter out the excess Oxone/Salt created. This will allow you to SEE your epoxide form as a dark yellow oil lying on the bottom of your beaker when you turn the stirrod off for a minute .Very exciting to see those color changes, makes you feel like doing a little dance eh Greenhorn?!!
  Cheese uses buffer as his Oxone is 100% potassium Monopersulphate.(Oxy-Clear) The buffer can be added after the 2-Alkene. Have fun...

Cheeseboy-a whiteboy with Soul Like a black guy without soul
May The Source Bee With You Always.