blaztoff (Hive Bee)
12-23-01 05:57
No 250060
      Wacker Guidelines  Bookmark   

Was wondering if anybody has guidelines on how to judge the DMF O2 wacker. What are the main things to look for and such. The reaction mechanism and how it progresses. 
Swim just finished a wacker but isnt sure how to judge it. Did not get much O2 eaten up at first. So started to turn up the pressure first to 45psi then 55 psi then 65 then 80psi. Was not getting much O2 uptake and after 150 minutes probally only had 45 psi used. So decided to shake it like spiceboy method.Whoah big uptake of 02. Running at 80 psi in the next 20 minutes tool up 14 psi. Pressurized again shook boom 20 minutes 20 psi taken shook a little more another 5 psi and decided to shut down since didntr want to go over 1mole 02 and time limit. Hit with Hcl and a nice reddish orange layer but with a coupkle of drops on bottom of that that looked to be a darkish oil.
So does anybody have any insight to a failed reaction versus a good reation here. A lot of touchy posts regarding this method. Some people hate it some love it.
Please anybody some suggestions here. Dont mind R@D but want to know what to look out for.
(Commodore "Mole Bouncer")
12-24-01 09:16
No 250271
      Re: Wacker Guidelines  Bookmark   

react 1ml of yourketone with 15-20mls of ice cold saturated aqueous sodium metabisulfite, in a test tube. shake like hell for 2minutes, return to freezer for a couple then repeat a couple more times, at end all of(or some) the yellow ketone that floated on top will have reacted and become a white suspension; your ketone/bisulfite adduct, proof that you ineed have created ketone.

this technioque can also be used on a preparative scale instead of distilling (for the lazy) and then the ketone is released by reacting you bisulfite adduct with an excess of Na2HCO3 solution.