dormouse (Member)
04-19-00 11:38
No 122749
      Benzoquinone in the Wacker Oxidation -Strike  Bookmark   

Author Topic:   Benzoquinone in the Wacker Oxidation
Administrator posted 09-04-98 07:22 PM          
With people throwing around remedies and new twists on the Wacker Oxidation, Strike would like to ask those interested to comment on the use of benzoquinone as the oxygen source. There seems to be a great reduction in rxn time and simplicity of equipment.

From JOC, 29, p241 (1964):

"2-Decanone Using, p-Benzoquinone. - Palladium chloride (0.020mol), p-benzoquinone (0.10mol), 1-dodecene [safrole] (0.01mol), and 50mL of DMF were placed in a 250mL roundbottomed flask fitted with a stirrer, condenser, thermometer and dropping funnel, and 1mL of water was added from the dropping funnel. The solution temperature rose to 70C. After 0.25hr an additional 1mL of water was added and heat was applied to maintain a 70C temperature. A third milliliter of water was introduced at 0.75hr and a milliliter at 2.5hr. The mixture was cooled and flooded with water after a total reaction time of 3hr and the product was extracted with pentane. The pentane solution was washed several times with water and then dried. Removal of the solvent etc. etc. gave 13.5g 2-decanone (77%)."

Strike knows all of ya'll know that article and then Spiceboy (Strike believes) gave this account below:

‘Holy Ketone! What a dream.....
Dream setup; 100 ml of DMF stirring in a flask equipped w/ a sidearm 34 g of safrole was added in 4 portions of about 8 g each. Mixed intimately. Next, 11g of p-benzoquinone was added. Stir rate was upped. Finally, 7 g of pdcl2 was added. A dry addition funnel was coupled to the flask, and 5ml of dh2o was measured into it. Thermometer was attached to side tube. At midnite, one ml of h2o was added, temp went to 70c.Brisk stir rate.15 min et and another ml of h2o added. External heat, if needed is used. At 1:00 another ml was added, and temp held at 2:30 the final ml was added, and there should be a trace left, but ok if it aint.....held at 70 c for 30 more minutes, allowed to cool to room temp, flooded w/ chilled h2o, and extracted w/ starting fluid(nod to Q)....BOOOOOM! yield; over 70% “

So Spiceboy's story checks out ok. She followed the JOC article except she doubled the amounts of PdCl2 and Safrole (the ratio between them the same though), but kept the benzoquinone amount the same (didn't double it). Yet things look good.

In studying for TSII Strike came across another article by Tsuji (The doctor that wrote the wacker article that Strike first used to work out this thing). Anyway, this came much later after the first article he published so he should be all-the -more wiser. Here is his benzoquinone recipe from Synthesis, p369 (1984):

“ In a 100mL round-bottomed flask fitted with a magnetic stirrer is placed a mixture of palladium (II) chloride (89mg, 0.5mmol), p-benzoquinone (5.94g, 55mmol) and 7:1 dimethylformamide/water (20mL). To the solution, 1-decene [substitute safrole for this compound] (7.0g, 50mmol) is added in 10 min and the mixture is stirred at room temperature for 7h. The solution is poured into cold 3 normal hydrochloric acid (100mL) and extracted with 5 portions of ether. The extracts are combined and washed with three por-tions of 10% aqueous sodium hydroxide solution and a portion of brine, and then dried After removal of the solvent, the residue is distilled to give 2-decanone [P2P]; yield 6.1g (78%).

This one looks pretty good to. The reaction time is a little longer but it goes at room-temperature. But the really interesting thing is that that the extrapolated ratio of PdCl2/safrole is about 22 times less than the other method.

It would be around 0.16g PdCl2 for ~16g(~1M) safrole. That's pretty nice.

Does anyone have any comment about this?

If not, Strike would like to take this time to discuss the dynamics of having sex with Sporty Spice. You all know that she is the only one of them that is 'keepin' it real'. She is getting some bad-ass body art, all the while the other dim-witted girls are getting knocked up, discrediting their "girl power" stance. And then theres...

drone 342
Member posted 09-05-98 06:04 PM          
This is quite a lovely addition to the Wacker reagent pantheon. As I had mentioned in a previous article, I think we could profit greatly from the use of less exotic reagents. While benzoquinone isn't too strange, I was wondering about the use of something as simple as calcium hypochlorite. Any thoughts on this?

-drone #342

Administrator posted 09-12-98 10:56 PM          
Testing this board

Administrator posted 09-13-98 03:08 PM          
Strike found this account written on the back of a chewing gum wrapper:

"Don't get me wrong, but you just can't believe everything you see on this site. Take that shit Strike wrote above. Looks ok. But what does Strike know. Anyway, I jotted it down, went to my Lab at the University, applied for a grant, got the money and was about to try a representative run when I fell asleep. Had an interesting dream though. Here's how it went:

"Decided to see if the Tsuji method above would work. Wouldn't try it on an illegal ketone like safrole, but decided to use it an a ketone called not-safrole:

In a flask was the following:

DMF = 700mL
Water = 100mL
p-Benzoquinone = 216g (2M)
PdCl2 = 3.6g

In dropping funnel was 320g not-safrole. Dripped into the solution at room temp (30C) over 30min time. After addition the solution was dark reddish orange. Almost black. Throughout the addition, and for a few minutes after, the temperature stayed at room temp so it was left alone unattended. After 41/2 hours the solution had progressed on its own to 48C. Who knows how hot it got during the 4hrs. Obvious exothermic reaction. After 7 hours solution was back to 30C.

The reaction mix was flooded with water (3L). The oil fell out of solution to the bottom. It was black in color. The upper aqueous layer was a dark blood red. The upper layer was decanted from the oil. The aq. Layer washed with 2X 200mL DCM. The DCM added back to the oil. The oil/DCM was washed twice with clean water. Each time an emulsion formed which eventually separated out after 15min. Vacuum filtering helped a lot (next time am gonna skip the water washes and go straight to distillation).

Dried oil/solvent thru sodium sulfate and distilled. With high vacuum at 100-140C ~35g not- safrole came over. At 166C came over ~250g ketone. A tiny amount of white precipitate accompanied the the distillate towards the very end of the run.

Hmm, what to do with all this stupid ketone? Could reduce it. Could add a hydrocarbon. Naw! Might as well try an amination.

Wow! Amination successful. Have to go now. 70 monkeys working on typewriters just appeared in my living room!"

Member posted 11-03-98 10:08 AM          
Does anyone know why some Wackers need copper chloride and some don't?