RollWitMe (Hive Bee)
01-02-02 19:17
No 252110
      p-Benzo variation  Bookmark   

Has anyone tried any other catalysts other than Palladium Chloride for the p-Benzo Wacker. Would Palladium Acetate work? Or Palladium on Calcium Carbonate or 5% Pd on Carbon?
Would problems with dilution occur? Maybe some tweaking of solvents.

I like to cook! . . . but some dudes in blue vests with yellow letters took my kitchen.
(Stoni's sexual toy)
01-03-02 01:04
No 252185
      Re: p-Benzo variation  Bookmark   

I've seen refs where using other Pd salts (nitrate, acetate)produced different products in Wacker reactions.
I don't remember anyone having used the acetate.
And the other two are hydrogenation catalysts. They will not work in the Wacker reaction.
(Chief Bee)
01-03-02 08:16
No 252250
      Re: p-Benzo variation  Bookmark   

Pd acetate has been tried in conjunction with t-BuOH and H2O2, and while it worked great on the classical 1-octene, it seemed to produce aldehydes instead of MDP2P with safrole. I believe the description can be found at my page.
(Pioneer Researcher)
01-03-02 13:38
No 252306
      Re: p-Benzo variation  Bookmark   

I have a reference that uses Pd acetate with the benzo, and some mineral acid H2SO4, HNO3 or HClO4 what is said to make the rxn 50 times faster. HCl inhibites the rxn and PdCl2 doesn't work too much, best catalysts are Pd(OAc)2, PdSO4 and Pd(NO3)2  and best acid HClO4. The solvent is MeCN/water 7:1 w/w, 1-2 % catalyst, best acid conditions 0.15-0.3 M and time is reduced to a bit more than 10 minutes for total conversion of oleofin.
General procedure :
0.2 mmol Pd(AcO)2, benzo 9 mmol, and the inorganic acid, 0.1 M were dissolved in acetonitrile/water 7:1 50 ml. The solution was deoxygenated by purgin with argon for at least 30 min. and stirred vigorously until the Pd(AcO)2 was dissolved. The oleofin 10 mmol was added to the flask by syringe, and the rxn was stirred for 10 min. The products were separated from the catalyst by extraction into hexane or diethyl ether, washed with 30 % NaOH nad analyzed by a  capillary GC-internal standard method. It produces as well some other ketones and/or aldehydes like all wackers, and yields more 2 ketone at 23 C or so, with more temp ther's more isomerization and other ketones are produced, yield for 1 decene is 81 %.
JOC 1990, 55, 2924-2927
It would be interesting to test it with our favourite oleofin, but as far I know, nobody have checked it. May be 1 % of catalyst could be used, 0.25 H2SO4 or HClO4, rxn time 2 hours or so to get the ketone.
(Hive Bee)
01-03-02 17:06
No 252347
      Re: p-Benzo variation  Bookmark   

Is there a link to this reference?

I like to cook! . . . but some dudes in blue vests with yellow letters took my kitchen.
(Pioneer Researcher)
01-03-02 18:12
No 252359
      Re: p-Benzo variation  Bookmark   

I don't know, better go to the library. Anyway I've posted what I think is the essence of the work, including the experimental section.
Pd/C won't work at all, wacker needs Pd(II) catalyst.