05-12-04 18:59
No 506756
Okay. Swim has done a good bit of reading and just want's to get the seal of approval from the Bee's who are all knowing! ;-) Swim's dream is nearing, however their a few questions on the Benzo Wacker reaction. Swim is going from the MM write up on this.
Swim gets slightly confused around step 6. When the mixture is flooded with the HCl it should seperate to an aqueous layer (top) and oil layer (bottom). The top layer is removed and then extracted (3x) with the DCM. These colletive extractions are then returned to the oil layer that was created when the HCl was flooded to the mixture.
Hope Swim is on track so far! Now Swim has come across lots of different ideas on the Washes. Swim has read on many posts that the NaCl wash (gentle or violent shaking?) can be left out, and can increase yields. Please keep in mind that this would be Swim's first dream, so Swim would appreciate some Bee's input to help a newbee.
Next wash with saturated NaCl (3x) (400-500ml each wash) (gentle or violent shaking?)
And finally wash with 500ml %5 NaOH (3x)
(gentle or violent shaking?)
The rest of this reaction gives Swim NO nightmares, so hopefully some clarification on the above will lead to a sweet dream!
Bee's are the GR8test!!
(Hive Bee)
05-13-04 06:07
No 506851
Swim gets slightly confused around step 6. When the mixture is flooded with the HCl it should seperate to an aqueous layer (top) and oil layer (bottom). The top layer is removed and then extracted (3x) with the DCM. These colletive extractions are then returned to the oil layer that was created when the HCl was flooded to the mixture.
This is a simple acid base extraction.
Look under ../rhodium /equipme
The Ketone isnīt an amine so it canīt form a freebase. No salt will be formed if HCL dumped in.
This means it isnīt soluble in water.
The writeup says to extract the whole flooded mixture to be on the save side. But I think there shouldn`t be
any Ketone in the water layer. But better ask a more
experienced bee- maybe Iīm wrong.
Keep only the bottom layer(DCM with Ketone) of each wash
and combine them.
Hope Swim is on track so far! Now Swim has come across lots of different ideas on the Washes. Swim has read on many posts that the NaCl wash (gentle or violent shaking?) can be left out, and can increase yields. Please keep in mind that this would be Swim's first dream, so Swim would appreciate some Bee's input to help a newbee.
Normally the NaCl (Brine) wash is the last one because
it pre dries your solution before MgSO4 dumped in.
After the NaOH wash you need to dry with water to
eliminate any traces of NaOH in your DCM.
So as said before itīs better to wash with NaCl after
the lye wash.
(Hive Bee)
05-20-04 13:08
No 508478
Anyways, there IS a whole hell of a lot of ketone in the water...possibly 20 % or so.Hydrolyze it with a 'la methylman with the HCl/water.P did bigger scales so needed help..has a cordless drill with one of those paint mixers on it,not the dinky plastic ones but the steel spiral thingy used for mixing 20 l pails of paint..stir the hell out of it and let it sit 10 minutes.Then decant off as much water as you can, if a little black red raw ketone goes over,dont worry.Take the raw thick ketone(and small layer of water emulsion) and put in your sep funnel(pop bottle,car boy,what have you) and let this sit till it looks ok.Seperate, and put the water emulsion in with the other water.Now extract with DCM,using your mixer(agitate the hell out of it)..seperate, and the first will be almost as dark as the raw ketone and dump this in with your raw ketone.Do it again,seperate and the DCM will be lighter red and the water will be lighter as well.P does it untill the DCM is almost clear..dont be cheap on the DCM, it just takes an extra 10 minutes to distill it off for reuse (with aihlins condensor).
Water and DCM are slightly miscible,and doing the wacker takes all day, so put the final DCM/ketone/water mix in the freezer.In the morning you will have a layer of ice to pull off.Distill off the DCM, small bit of water then vac distill the ketone.Then redistill this.You will have very pure ketone to play with.
Put plastic down everywhere as it is messy,and the ketone will melt your freezer plastic and wreck your My Weigh top.
Don't stand over the DCM/water mix,as the DCM is boiling off.Easy
(Stranger)
05-26-04 08:20
No 509745
Thanks for the input/help. I have been PM'ing a very helpfull bee who has enlightened me on (one of many) a working methods for this wacker.
Stir PdCl2 & MeOH (min 7hours)
Add H2O & P-benzo (stir min 1hour)
Add 178g Safrole w/smiggen MeOH (addition 1+hour)
Add heat if needed to start reflux near end of addition
Stir & Reflux (min 8hours)
*Try to envision the outcome after all this waiting ;-) *
Filter out solids through a couple MeOH saturated coffee filters, VIA gravity filtration.
2L Sep funnel is available, so the reaction is seperated into 2 equal amounts.
1.6L 10% HCl mixture is also seperated into 2 equal amounts.
Each equal seperation is flooded with (one) seperated HCl mixture.
*Bottom Layer (oil) can be seperated off from 2L sep funnel, or extracted with DCM along with Top Layer (aqueous) if a large enough sep funnel is available*
Extract both flooded seperation with DCM.
Collect DCM extractions & add to (oil) if originally seperated.
WASH TIME !!!
----------------------------------------
3 x 500ml Saturated brine (SEP OFF GOODS FROM BOTTOM)
3 x %5 NaOH (???SEP OFF GOODS FROM BOTTOM???)
1-2 500ml DH2O to ensure no NaOH left (SEP OFF GOODS FROM BOTTOM)
DRY KETONE/OIL W/MgSO4, FILTER OFF MgSO4.
DISTILLING TIME !!!
----------------------------------------
Distill off DCM over water bath. DCM (bp)38C
SAVE DCM FOR ANOTHER DREAM!!!
LET WACKER COOL DOWN
Distill Ketone over Oil w/vacuum. (temp dependent on vacuum)
Store in COLD COLD place.
----------------------------------------
This is what SWIM has accumulated so far. Any Errors or tips on the method above is openly accepted!!!
I have TWO questions that would help out GREATLY.
-> CAN 125g of P-Benzo be used instead of 150g ?
-> What is the highest temp Ketone can be kept at, without going bad?
(Hive Bee)
05-26-04 14:35
No 509785
125g benzo instead of 150?
i would scale the safrole amount down:
178g safrole....150g benzo
x g safrole....125g benzo
125*178/150 = 148.34g i would use 150g safrole in this case.
highest temp?
with water aspirator it should never reach 180C, i've heard that this could polymerize the ketone. in my case i pull it between 155 - 165 C with water aspirator vacuum.
greetings
(Stranger)
05-26-04 20:35
No 509860
I should have clarified my question a little better. After the ketone has been obtained, what is the highest temp that it can be stored at without it decomposing. My best guess would be 0 degrees C. But I was just wondering. Thanks for the safrole adjustment idea though! Swim has a water aspirator vacuum that pulls 28.5in so the bp of the ketone should not go anywhere near 180C.
Thanks!
Laterz!!
(Hive Bee)
05-28-04 06:50
No 510047
Once distilled ketone should be kept at freezer temps. Just stuff it in your freezer, and it will be good.
Pure ketone can be kept at room temp.
Never go above 180 degrees, try to stay under 170. At 180, the ketone polymerizes, I know by experience. And its a pain to clean the RBF after.