Interestingly enough, the reaction, at 1/10 methyl man's scale, is complete in 3 hours as pointed out in this paper where they followed the reaction by TLC I wonder if it's also complete in that timeframe when ran at full scale ?

Bit Off-topic: Too funny there are ACTUALLY referencing to Methyl Man in the scientific litterature hahahaha

The purpose of the CuCl/CuCl2 is to provide Cl- ions to regenerate the [PdCl4]2- which does the work.

Both the CuCl/CuCl2 and the PdCl2 are regenerated catalysts. Neither is consumed to exhaustion. The necessity of the copper (I,II) chloride catalyst comes from the requirements of the palladium cycle, not any concern arising from the presence of a balloon.

The system itself is efficient. The limiting rate in an O2 Wacker is the available oxygen. Balloon Wackers run at low pressure with no agitation, which makes for terrible O2 uptake from the gaseous phase. A pressurized SRV is a bit better at causing O2(g) to be taken up into solution where it can react. Mechanical agitation of the SRV further quickens this update.

Wackers with benzoquinone run so much quicker due to the full quantity of needed oxygen already being carried in solution. This reaction rate is not limited by an equilibrium between gaseous O2 and dissolved O2.

An unpressurized all-liquid Wacker could also be run with H2O2.

An all-liquid Wacker can be run under heat to shorten the duration.

O2 balloon Wackers don't "require" an entire gram of PdCl2. The proper way to view this is that the reaction has a heavy loading of catalyst due to the poor O2 uptake at balloon pressures. Any amount of catalyst will get the job done. Quantity selection of the precious catalyst is balanced by the also-precious chemist's time.

If you came across the KRV reference at Rhodium, that is an excellent example of Wacker equipment done right. Forget about balloons. Go with pressure and agitation or all-liquid.

prestirring catalyst, annd pre saturation of the solution with o2 prior to adding safrole is good protocol

thankyou for all of your help those who spoke up to help me out.

Are we ready for this?? OH yeah

Selective synthesis of carbonyl compounds from internal olefins by Wacker–Tsuji oxidation remains a major challenge. Combination of a PdCl2 catalyst system with N,N-dimethylacetamide (DMA) allows direct O2-coupled Wacker-type oxidation of various internal olefins to the corresponding ketones under copper-free conditions. It is revealed that the lack of a requirement for copper is fundamental to overcome the problem of low activity for internal olefins, from which traditional Wacker–Tsuji oxidation has suffered.

Coming soon.


 

ps. this uses molar 1% pdcl2 calalyst and runs for 45 minutes.

the ketone will more than likely be clean enough to not need distillation other than to strip off the dma, not only this but this is a monute amount of pdcl2, talking 10grams per kilo olefin. the old dmf tsuji crapper oxidation used a 1gram pdcl2 per 10mills olefin stated in ts2 which was taken from the original ref and often yeilds upto 50 percent aldehyde. oh and it takes 2 days.

yileds of ketone for the new 02 pdcl2 DMA wacker reported 85 percent ketone. i think we have a winner!

and finally, here it is, the best ref ive read so far..

we are looking at table 2 8b

http://ebooks.unair.ac.id/data/jurnal/kimia/pdf/Recent%20Progress%20in%20Wacker%20Oxidations%20Moving%20toward%20Molecular.pdf

Im guessing you mean the peracid route using GAA h202 H2so4 and KOH in the isomerisation. Correct me if i am wrong here, From what I have heard it it not very scalable, you yield 70-80% alone just making iso safrole, and then yield 70 at best in the next rxn.  As for the performic, using formic  acid, that is a watched chem now..

The wacker ox I mention above requires 1%pdcl2, pure o2 80psi in DMA and h20, it goes for 45 minutes. Just need a vessel under heat.

And to be honest this does not surprise me that such a small amount of pdcl2 is needed, the point of the thread was because I am noticing a gram of palladium absorb 50psi of 02 wondering why the hell we need cucl2 at all since it is the factor that makes the tsuji suck rxn time wise and with un predictable by products. Turns out the problem was the DMF not being the ideal solvent as the DMA keeps the pd from deactivating, just like the cucl2 used to.

With 1 gram of pdcl2 used for every 100ml olefin  plus the co solvents in there, the clean up looks like it would be fairly easy with the DMA 02 PdCl2 wacker. What would be impurities in the ketone here? After you do the work up washes, filter the pd salts out I think you could skip distillation of the ketone with this one.

As for why people prefer benz wackers in meoh, well, I don’t know but as soon as I learned how much pbenz is actually needed (almost gram for gram pbenz to olefin),  it really is not practical for me nor do I want all that tarry emusional ketone to have to clean up and distill, yields in the benzo wacker in reality are 50% to 75% at best anyway

psychexplorer, what is SSL?  If you mean it's on that special supervisory list you're right.  Along with sodium acetate, hexane, tryptophan, and lactose.  All completely innocuous chemicals.  Buying a SSL chemical like the above in and of itself is not suspicious.  I assure you that buying PdCl2 off ebay is going to flag you a lot quicker than formic acid.  Or buying 20gr of it from your friendly photography supply shop.  Not only that, but you can just as easily use acetic acid in place of formic acid which is completely unwatched.

It's not just the cost thats an issue IMHO.  The benzoquinone wacker work up is a fucking mess.  I did it twice, did the peracetic and never looked back.

Shake: safrole -> isosafrole yields are essentially quantitative.  I've gotten 95%+ every time doing atmospheric reflux.

Just my personal opinion though, whatever floats your boat I suppose.

OK more confusion.

Please, big dogs, feel free to correct the amature, i need it

A by product of the methanol/pbenzo wacker is hydroquinone. this is a benzene ring with 2 OH groups attached on either side. Now p-benzoquinone is supposed to be the oxygen source for this reaction! BUT from where i am standing hydroquinone and p-benzoquinone both have the same oxygen content! am i wrong??

So first of all, how it is an oxidant, or 'oxygen source' i cannot see. More likely it is acting as a 'ligand' for the pdcl2 to keep active in its cycle of being oxidised by the h20 present then oxidising the alkene and so on. I would say the pdcl2 is getting the oxygen from the h20, which would in turn give off hydrogen gas - which reacts with the double bonded oxygens hanging on p benzoquinones rings to make hydroquinone

SO here are some facts about wackers which i have come to learn thus far.

Pdcl2 is a weak oxidant on its own only because it deactivates very quickly. I roughly understand why but i have alot to fit in here without going to deep into 1 thing

In the tsuji PdCl2 + CuCl 02 wacker the reaction mech is STILL NOT FULLY UNDERSTOOD the papers that are only now getting to the bottom of this are seeing CuCl and CuCl2, although they work, they are the cause of every downside to this reaction.. they only act as a ligand to reactivate the pdcl2, and as a downside, the excess Cl ions slow the reaction rate dramatically, increase the need for pdcl2 salts, and also contribute to the aldehyde being formed.

PdCl2 is a powerfull oxidant if the rxn takes place in the presence of a ligand which keeps the pdcl2 taking up 02, and oxidising the alkene, and stops it from precipitating out of solution forming Pd black, there is plenty of proof of this, as shown in the benz wacker pdcl2 is the sole oxidant at something like molar 1%. There are also 02 wackers yeilding 85% ketone, with mol 1%pdcl2 in DMA as reaction media with no CuCl and no pbenz.. ALSO NOTED was under the same CuCl free conditions, DMF yielded NOTHING.

OK so why is DMA so much better than DMF? difference between DMF and DMA is a methyl group on DMA where the hydrogen is on DMF. For some reason the methyl group on DMA makes this solvent act as a ligand which helps PdCl2 come close to its full potential, which i believe is a hell of alot more than what we have seen so far..

why does 1 methygroup do so much to keep the pdcl2 in the system?

Interestingly recent refs have show many 02 wackers with 80 - 90 yields in toluene! - a benzene ring (just like pbenzo) and a methyl group (just like DMA) See where i am going here?

The methanol 02 wacker has been put aside as being to finniky, and unpredictable, so many mixed results here people stopped trying. Even i have run several 02 wackers in meoh with pd and cucl2.. aka SRV now i will say that most people say that it is due to meoh weak ability to dissolve pdcl2 salts. if this is the case then how are you benz wackers out there dissolving them? and furthermore, i have seen first hand meoh and palladim salts draw in alot of air with mild heating.

The benz wacker runs for 6 - 8 hours the salts are disolved in meoh for how long? 60 minutes!! SRV meoh wackers STRESS that the salts be dissolved for 24 hours?? Methanol SRV wackers using 1% mol pdcl2 and 6x that cucl2, with heating in pure 02 atmoshpere has been reported upto 80 percent yields of ketone, which i suspect 20% was actually aldehyde which is always the case when you have cucl2 involved.

This tells me, pdcl2 salts are, although not so soluble in meoh they are sufficiently soluble. in fact i would say you could use a 1/4 pdcl2 catalyst stated in the methylman write up in a benz wacker if you dissolve it in methanol for 24 hours with stirring

1g pdcl2 in meoh solution 200mills, was put in a glass bottle on a heater. for the next 2 hours every time it was opened it drew in massive amounts of air, that amount of molecular 02(only 15 percent or so in normal atm) would be enough to oxidize a significant qty of our alkene.

OK so here is where my head is at, i hope you are with me so far, WHY is pbenzoquinone/ hydroquinone a good ligand for pdcl2?  

Dont tell me pdcl2 is "just the catalyst" and pbenz is "the oxygen source" because pdcl2 is a in efficient oxidant without something to assist it to reoxdise and stay in the system, and that is not pbenzo becasue it is not losing its oxygens, it is only gaining hydrogens. the how can the spent oxygen source come out heavier than it went in, with its oxygens still attached.

I think that once we find a good co catalyst for pdcl2, then meoh reaction media with heating in air atmosphere would be enough  molecular 02 to oxidize our alkene, as the pd draws in alot of air, even in weaker solvents such as methanol.

this leads me to believe also that the rxn might be possible under 02 atmosphere, with shaking, srv style in methanol with molar 1% - 0.5% pdcl2  with 'equimolar' qty of hydroquinone, only enough to sufficiently do the same job as it actually does in the pbenz wacker, which is help the pdcl2 in the cycle, in this case it would be taking molecular o2, then oxidise the alkene. if it must be benzo that is needed then it is not becasue of the 0xygen in pbenzo it is because of the electrons it gives up? who knows where they go

Can start to see why the srv wacker worked, but was clearly stated that no H20 be added as it slowed the reaction down! In DMF 02 wacker, h2o is a necessity. what is methanol? methyl group and a OH group for some reason this looks like good solvent for this system maybe meoh and toluene mix?.

Anyone tried running a 02 wacker in toluene? with no cucl2 catalyst? perhaps the toluene in itself can act as a good solvent + chiral ligand for PdCl2 it has the benzene ring AND the methyl group, (like the benzo and like the dma)

Please forgive my base chem knowledge, and if i am making any dumb errors i am sorry i am also really tired. hopefully you can see im putting in effort here, if no one chips in that that is ok i will continiue my learning on my own either way.. even links or refs are welcome as i will take a look as soon as i can to learn further what is happening here.

I am really only just putting all the pieces together from the many examples and experiences i have seen.

i think the benzo turd wacker is not what it seems, i believe we can get these suckers running super clean, even under probably increased pressure air atmosphere (i have seen recent refs on the wacker siting good yields with just air 1 atm aswell) different reactions but high yeilds from just the 02 from the air was enough o2, and the palladium salts are primo at drawing in air, just need to keep them cycling

100g alkene to be oxidised as an example is not that much 02 uptake, not much at all.

i have about 2 hours sleep now before i go to work fml.

Cheers

well i can tell you that nitrite wacker is real fickle from anectdotal reports.
it was abandoned long ago.

im just going to keep going here as things develop. may aswell pos the full picture.

pressures of O2 (6 atm, 80 ?C) with significantly enhanced
substrate scope (Table 2).50 Of particular note, DMF, the
solvent used in Tsuji’s Wacker oxidations, yields only trace
amounts of the product. The excellent catalyst stability
observed in DMA may be a result of a more negative redox
potential of Pd(0) in DMA compared to other solvents. The
basic, coordinating nature of the solvent may also provide
direct ligation to the Pd catalyst

"Though the Wacker oxidation has been studied for about half a century, a detailed mechanistic understanding of the
process continues to be elusive because of the utilization of added ions and co-oxidants. This lack of understanding may explain the difficulties in developing variants that do not require additives where the interplay of oxidant, solvent, and ligand is clearly complex.

As has been observed within the developments in our laboratory, the change from peroxide mediated to direct-O2-coupled Wacker oxidations required a change in both the ligand and the solvent. This nonobvious modification in the reaction conditions may also be associated with a different mechanistic scenario, highlighting the challenges in developing truly practical and applicable methods for the Wacker oxidation.

The recent developments in this field should allow the community to begin probing the mechanism in detail without the encumbrance of cooxidants and potentially apply these findings to the development of new Pd(II)-catalyzed oxidative olefin functionalization reactions, including asymmetric variants"



To summarise the 30 or so refs i have read on this reaction, the tsuji wacker is completly ineficcient, catalyst, selectivity, time of rxn, and yeild wise and the end of the story right now is basically that the mechenisim of this reaction is still not completly understood. and most idead are just hypothesis and the same is for the benz wacker as far as i can tell.

This might be one of those chemicals you're just better off buying.  $41 bucks for 1L is not bad at all