Author Topic: Benzo Wacker in 1L Flask?  (Read 2980 times)

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opposite2eve

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Benzo Wacker in 1L Flask?
« on: July 27, 2004, 10:42:00 AM »
SWIM has used TFSE multiple times and hasn't been able to figure out if using a 1L 2 Neck Flask is doable performing a MM Wacker using 2.5g PdCl2.  He also wants to use his 200mm Liebig for the Reflux.  Any ideas if this rxn will be too much for this flask?

OcoteaCymbarum

  • Guest
You probably can
« Reply #1 on: July 27, 2004, 06:47:00 PM »
It doesnt run that hot anyway so breathing space is not so important. A 1L should work, altough i've always run that scale in a 2l.

400 ml plus about 200 of iso with the benzo will get close to 1L but a little under.

As for the column, same answer, it doesnt run so hot, its doable.

Of course neither are the 1L flask and the column perfect for that scale. I think everybody needs a 2L flask. Maybe you have one but without 3 necks. As for the column, you will need IMHO a longer one someday. If you go trhough MM nitro route it wont be sufficient. A alihin at least 400mm would be needed(i prefer the 600mm one I have)
OC

opposite2eve

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Update for anyone thats interested
« Reply #2 on: July 28, 2004, 05:42:00 PM »
Currently SWIM decided to perform the wacker at MM scale with his current gear.

He charged a 1L FBF with 2.3g PdCl2 and 400mL tech grade MeOH and let it prestir for ~ 3 hours.

Then he added 50mL dH2O and 120g p-Benzo (yellowish/green stuff).  The pBenzo was added to the flask while it was stirring at ~22g increments.  That much pBenzo will fuck up your stirring so watch it closely.  SWIM eventually had his stirring cranked up twice as much as it took to stir the PdCL and MeOH.

SWIM let the PdCL2 + MeOH + dH2O + pBenzo stir for another 60 minutes.

Around the 60 minute mark SWIM began to drop 178g Safrole about 1-2 drops per second.  After all the Safrole was added over a 75 minute period he gradually increased the temp on his hotplate to bring the rxn to a reflux at ~65C.

He is currently mid rxn and will post any further comments here.

The jist of this post was to amend his question which was "can he use a 1L 2 neck flask?"

So far SWIM assumes everything is ok because the rxn is not out of control and everything seems to be going as planned.

opposite2eve

  • Guest
Follow up.
« Reply #3 on: July 29, 2004, 07:30:00 AM »
After the rxn neared the 4 hour mark SWIM dreamt of removing the rxn flask from the hotplate and let it cool a bit.  He then gravity filtered off the PdCl and Benzo.  Mixture was flooded with 1.7 10% Hcl solution.  This flooded mixture was then extracted with 3 DCM amounts 500mL 250mL and 100mL these three DCM extractions were combined. 

The DCM/Oil layer (ketone here?) washed 3x with Bicarb washes.  After the bicarb washes were done SWIM decided to skip the NaCl washes and proceed directly to the NaOH washes.  The first NaOH wash was very dark reddish and the DCM layer was a lighter orange.  The next two NaOH washes got much lighter almost clear with a little emulsion forming in the NaOH water.  The DCM/organic layer is now a light orangish color with tiny hints of green.  SWIM is wondering if something is going wrong because other wackers claim the DCM to be almost greenish and SWIM isnt seeing much green.

After NaOH washes were completed SWIM set up to distill off the DCM and set it over night.  Bad idea he woke up 4 hours later and the DCM was still only half distilled off.  He turned up the heat again and let it continue distilling at ~39C.  Went back to sleep.  Woke up another 3 hours later and DCM is only about 60% distilled.  Now SWIM has to leave for a few hours and is going to let the rest of the DCM distill off slowly.

It has now been almost 10 hours after the washes were performed.  Is SWIMs Ketone going to be ok?  Is it going to mess up?  Did SWIM even do the wacker properly?  He thinks he messed up somewhere because the DCM/Organic solution is very orangish.

Any ideas from some other experienced bees?

homeslice

  • Guest
It sounds just fine to me.
« Reply #4 on: July 29, 2004, 08:48:00 AM »
It sounds just fine to me. DCM takes a while to distill. Ya cant rush it bc of the low bp.


OcoteaCymbarum

  • Guest
Drastic change in dcm layer upon NAOH wash?
« Reply #5 on: July 29, 2004, 10:52:00 AM »
When u trow in the NaOH washes, you should see a clear change. The bottom layer becomes more tick-like and is usually reddish-brown.
But everything should be fine since a wacker is hard to fuck up. All that can really change is the yield which can vary I would say from 50 to 65-70 percent max

opposite2eve

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Post Wacker Solution Color
« Reply #6 on: July 29, 2004, 11:30:00 AM »
The Post wacker solution in SWIMs dream was similar to the color of green tea.  It's not as thick/dark orangish like SWIM sees in some pictures.  It's almost transparent..  Maybe its all the DCM?  He extracted with 500mL 250mL 100mL then another 100mL using the MM scale.  Is it supposed to be darker/thicker?

opposite2eve

  • Guest
Nothing
« Reply #7 on: July 29, 2004, 02:06:00 PM »
SWIM brought the temp up slowly after all the DCM was distilled off and it went to about 90C which is where SWIMs pump pulls saf at and then some saf came over but it was bluish.  After ~6mL of the bluish stuff came the temp dropped to 40C and its been there for 45 mins.  No Ketone ver came over.  What possibly went wrong?

Snakebyte

  • Guest
temp prolly too low
« Reply #8 on: July 29, 2004, 03:27:00 PM »
You will need to turn up your hotplate higher than you have it when you distil your safrol.  Swim's ketone comes over roughly 40C higher than his safrol so his hotplate is set at least that much higher.  Swim's ketone is a pale yellow when it comes over but after being in the freezer overnight it turns orangish.