Author Topic: scalling-up the benzoquinone wacker oxidation  (Read 1576 times)

RoidRage

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Re: scalling-up the benzoquinone wacker oxidation
« Reply #20 on: May 28, 2011, 07:05:34 PM »


i was about to order that shit from america for this reaction... did you know that mr methyl???
 
LOL

1 inch by .75?? jeezus man


ROFL ;D...When I started, I was also taking Methyl Man's write-ups as gospel...Like you Shake, I almost ordered some Reynolds Heavy Duty Foil online too since it's not available in Canada hahaha...Then I checked Reynolds website to know how thick their heavy duty product was, and decided to substitute it for something available in Canada...

I remember how nervous I was the first time I ran the reductive amination haha...I though the reaction had failed since I didn't really find it violent  :D ;D

Anyway, without those write-ups, I wouldn't be around ;)

RoidRage

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Re: scalling-up the benzoquinone wacker oxidation
« Reply #21 on: May 28, 2011, 08:58:28 PM »
Lol...No actually I studied all the reactions for a fucking while ;)  I didn't print the instructions one-day deciding to follow that in blind faith ::) I read, read, re-read, re-read and re-read all the write-ups related to the reactions I was going to carry... I started from zero not knowing through what reaction I should proceed...Re-calculated everything many many many times too  ;) I understood everything I was going to do before proceeding as every chemist should do.

In the end, everything worked on the first try  ;) (Alright, alright...I fucked up at the very very end with the gassing because I didn't dry the toluene long enough  :o  :P  ;) )

Methyl Man

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Re: scalling-up the benzoquinone wacker oxidation
« Reply #22 on: May 30, 2011, 05:57:09 AM »
Sorry you feel that way, but they're part of history now, and they do work if done as written.

Just remember, it's like a radio station that's playing an old song you don't like. Just ignore it and go on to something else if it bothers you. I hate the song "Tainted Love" as much as you hate my writeups, but I don't want to erase it from history.

The funny thing is, there were some awesomely talented chemists on the Hive, and not one of them objected to my writeups the way you are. Either they were being very polite, or the methods weren't nearly as flawed as you're making them out to be. Also, my fictitious alter-ego made roughly $10,000 a month for about two years going by those methods, warts and all. Yep, the dirty sloppy benzo wacker and disgusting nitro/Al-Hg.  Does that sound like something he could have done if there were big problems with them? Sure, with better methods and more skill he could have made double that, but it was enough somehow.

I think you're trying to get a rise out of me now, but I'm going to let it roll off my back. Kerplunk.  :)  I think you like me despite yourself. I should know---I like you despite MYself. It's a crazy world...

One more thing, if you're going to send up my sig phrase, please spell that last word correctly. It will have more impact. :)

@ Sassa: Sorry we're mucking up your thread. I hope it's entertaining.
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Sedit

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Re: scalling-up the benzoquinone wacker oxidation
« Reply #23 on: May 30, 2011, 07:35:50 AM »
Shake you do not understand the wacker oxidation or the role of the benzoquinone. Its there as an oxidant, as such it does not need to donate any oxygen at all since this is not what an oxidant does. The oxygen itself comes from O2 where it is mediated to the substate thru a catalytic cycle between Pd, PdII, benzoquinone and hydroquinone.

I am no expert here nor do I pretend to be but if I hear anymore ego stroking in this thread it will be deleted, we are wasting bandwidth talking about balls of aluminum foil in a thread about a reaction that uses none. This excessive off topic rambling that has been taking place at The vespiary lately is getting on my nerves and many other members so I ask everyone to please be precise, too the point with a general overtone of niceness.
There once were some bees and you took all there stuff!
You pissed off the wasp now enough is enough!!!

RoidRage

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Re: scalling-up the benzoquinone wacker oxidation
« Reply #24 on: May 30, 2011, 08:09:33 AM »
First of all Shake, thanks for the compliment...It's really appreciiated  :)


Starting from ABSOLUTLY nothing is really tedious work for sure...I strongly believes those ‘’Write-ups’’ Are good things (Well-written like Bright Star/Methyl Man )..They are far from optimized and they do contains errors + Useless stuff in the procedure, BUT  they are written  with the best intentions and according to the author’s chemical knowledge at the time of publication.  And as far as I’m concerned (Only used METHYL MAN's Work :D) those procedures works EXACTLY AS ADVERTISED...

Like Methyl Man stated in his last post, his methods are working OUT-OF-THE-BOX...I don’t even think  the term ‘’FLAWED’’ applies to any of his awesome contributions.....

 I would actually LOVES seeing the ‘’Rhodium Chemistry Archives’’ being updated and adding new interesting procedures etc. Well, maybe not the actual Rhodium Archive but the Underground Clandestine litterature...  

Haven’t read about it lately so I don’t know where it’S heading (If it’s actually heading anywhere),  but ‘’The Vespiary WIKI’’  would be something extremely interesting  watching evolves, especially considering how intelligent/knowledgeable many members are...I’m actually amazed everyday about this...


EDIT:   Why on earth should those publications be removed?!?!? Completely irrational statement ;)
« Last Edit: May 30, 2011, 08:16:34 AM by RoidRage »

Shake

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Re: scalling-up the benzoquinone wacker oxidation
« Reply #25 on: May 30, 2011, 09:59:49 AM »
I like you methyl man, i dont even remember posting that last post..  :-[

As for the name it wasnt a send up, and it was dumb to spell it wrong lol.

Was irrational roid rage you are right.

Sedit, ill have to look into that a bit more then. I did posts huge thread on Palladium Chloride and 02 and nobody answered any of my questions. and yes ill clean up my posting.

So - please continue

akcom

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Re: scalling-up the benzoquinone wacker oxidation
« Reply #26 on: May 30, 2011, 02:53:04 PM »
Shake you do not understand the wacker oxidation or the role of the benzoquinone. Its there as an oxidant, as such it does not need to donate any oxygen at all since this is not what an oxidant does. The oxygen itself comes from O2 where it is mediated to the substate thru a catalytic cycle between Pd, PdII, benzoquinone and hydroquinone.

I am no expert here nor do I pretend to be but if I hear anymore ego stroking in this thread it will be deleted, we are wasting bandwidth talking about balls of aluminum foil in a thread about a reaction that uses none. This excessive off topic rambling that has been taking place at The vespiary lately is getting on my nerves and many other members so I ask everyone to please be precise, too the point with a general overtone of niceness.
The oxygen on your product does not come from O2, it comes from water. The O2 serves to regenerate the copper II which in turn regenerates the palladium II species.  Benzoquinone regenerates the Pd(II) directly.
http://www.organic-chemistry.org/namedreactions/wacker-tsuji-oxidation.shtm
Shows the complete catalytic cycle.

Sedit

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Re: scalling-up the benzoquinone wacker oxidation
« Reply #27 on: May 30, 2011, 03:10:25 PM »
Thanks for that Akcom, so looking at that, am I correct to assume the Benzoquinone is taking the place of the CuCl2 in the oxidant cycle?

I was thinking about this a lot last night and I have a question. If an oxygen source such as H2O was not present in this or a similar reaction what would we be left with?  A charged carbon?
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akcom

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Re: scalling-up the benzoquinone wacker oxidation
« Reply #28 on: May 30, 2011, 05:27:15 PM »
Thats correct, it takes the place of CuCl2.

If no nucleophile is present the reaction simply will not go forward.  All the steps in the cycle are equilibriums, with the active species usually only present in very minute quantities.  It is the cycle itself that it is the driving force pushing the reaction to completion.  Thus if there is no H2O present the first step will just be in a rapid equilibrium (along with numerous other reactions)

Shake

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Re: scalling-up the benzoquinone wacker oxidation
« Reply #29 on: May 30, 2011, 11:54:55 PM »
So i was right, sedit h20. So it seems i understand this to a degree after all.

I would like to add some more points about CuCl2 and its efect on this reaction. becasue, i was right with the points i made, and i didnt make clear points about benz other than to say, i dont know how it is an "Oxygen Source" as it is consistantly refered to in refs.

I will attatch a ref outlining the effects of CuCl2 on this reaction. But i would like to quote a few things out of it.


The surprisingly strong stabilization by the oxidant CuCl2 could also explain the observed formation of chlorohydrin products at
higher [CuCl2]. It is not clear exactly how this occurs, but our preliminary results indicate that forming a C-Cl bond from either
reductive elimination or nucleophilic attack (SN2) directly from 9-H has a barrier >50 kcal/mol.

Furthermore, since the ratio of chlorohydrin to aldehyde products increases with increasing [CuCl2],5c this implies a second- (or higher) order dependence of chlorohydrin formation on CuCl2. Consequently, eq 6, which only describes loss of starting material, should be replaced by the sum of two different terms, that is, eq 7, where k1 and k2 are the rate constants associated with the formation of aldehyde and chlorohydrin products, respectively

In summary, using theoretical methods, we have identified the two main mechanisms for the Wacker process, both of which are
in full agreement with experimental observations and rate laws.
At low [Cl-] and low [CuCl2], the rate determining step is not hydroxypalladation as typically believed, but isomerization from 10 f 6, a step that is necessary for subsequent hydride transfer processes.

At high [Cl-] and high [CuCl2], the rate-determining step is an external nucleophilic attack by water, which is only low energy in the presence of [CuCl2]. Consequently, the rate law athigh [Cl-] and [CuCl2] should include a [CuCl2] term.

Quote
Shake you do not understand the wacker oxidation or the role of the benzoquinone

not to be a smartass but it seems i was exactly right with my first post about the wacker and the effect of CuCl salts.

As for benzoquinone, i said the oxygen source was water did i not? so i was right there too. Ill give it to you that i am not an expert here either, but this has been an area i have been studying the last couple months


« Last Edit: May 31, 2011, 12:11:20 AM by Shake »

Sedit

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Re: scalling-up the benzoquinone wacker oxidation
« Reply #30 on: May 31, 2011, 12:13:24 AM »
I don't know why a reference would state that benzoquinone is the oxygen source, it is an oxidizing agent more powerful then molecular oxygen hence the reason it is used to mediate the transfer of electrons. I made the statement i did because it seemed as though you where under the assumption that an oxidizing agent means that it delivers oxygen to a substrate and this is not the case.
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jon

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Re: scalling-up the benzoquinone wacker oxidation
« Reply #31 on: May 31, 2011, 01:17:46 AM »
benzoquinone makes free rad oxygen between the water present in the system and the palldium(0)
oxidizing the HCl and regenerating pd(II).
there are other oxidants that could be used in it's place.
Manganese divalent for example.
as in MnO
also using palladium chloride the chloride ion interferes with the palladium complexation to the alkene.
so using strong acids like (perchloric acid for example) would accelerate the turnover rate of the catalytic cycle.
by displacing the chloride anion from palladium in equilibrium.
there are many ways to do this reaction.

Methyl Man

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Re: scalling-up the benzoquinone wacker oxidation
« Reply #32 on: May 31, 2011, 02:34:40 AM »
Jumping back for a moment to the original subject of scaling up the benzo wacker, I just had a thought for sassa, about that: I don't know how you'll do the separations for washes and extractions at 3X or 4X the original MM scale. I recall that I was using a 4000 mL sep funnel and that was a nice little workout at that scale as it was a big funnel and was quite full. Unless you did it without a sep funnel, but that seems like it would be very difficult.

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akcom

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Re: scalling-up the benzoquinone wacker oxidation
« Reply #33 on: May 31, 2011, 02:47:53 AM »
At that scale you definitely have to use an improv sep funnel.  Solvent volumes are definitely one of the biggests issues with the wacker in my humble opinion. 

sassa

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Re: scalling-up the benzoquinone wacker oxidation
« Reply #34 on: May 31, 2011, 09:09:10 PM »
well,not problem at all if thread goes by other ways than expected,because all you are talking about it´s probably most interresting than strictly scalling up the benzo wacker.
   About that controversy related to Methyl Man,have to say y didn´t know until days ago,that Methyl man that´s writing with us this days it´s the same who wrote so usefull write-up on the nitromethane Al/hg.I supossed was a member that wanted to homage him ,but of course to me it´s really a honor talk in the same place he talks.Can´t believe someone can criticize one of the most important write-ups about this matter.Obviusly ,we can argue little more notes on some phases will be great,but never question if the autor it´s totally chemistry formated or directly ther is something wrong.
   Both Bright Star´s  and Methyl Man´s write-ups  are of an unquestionable value, for my, and I suppose for the majority,overcoat, because behind of his publication there can no be economic interest, only that interest  can be a philanthropic interest....What is the only thing that these men could obtain it publishing for all? The answer it´s make things more easy for all of us, escaping of the scientific academicysm  and centring more on the practical   seeing of chemistry.
   Of course,Bright Stars have big erros,more exactly,inexplicable lacks of information,...like why not tell us that after flooding the benzoquinone wacker reaction,the result it´s an incredible mess of scum,if we not filter it previously?.
   And like said,both,have lack of information about emulsions on extractions and how to proceed if something goes wrong,if i have to say something bad about it.
  But this is enough to say those articles are not as usefull as people think?Not without doubt.
   I talked time ago that Methylman´s Al/hg with nitro not worked for me,because i didn´t know i was fucking it  with the HCL Gas,but neve said(i think so),that wondefull write-up it´s wrong.Only could say it didn´t worked for me.
  Anyway,information will be allways wellcome to me,and if it´s from people tha talks more practical than theorically,more if it´s posible.
    Thank´s Methyl Man ;)   and all others are working on that.

sassa

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Re: scalling-up the benzoquinone wacker oxidation
« Reply #35 on: May 31, 2011, 09:28:23 PM »
About big extractions and funnel,i was one day on the supermaket looking at that big 5 litre PTE water transparent bottles with faucet and said....man you have to check it out,....well ,that bottles works extremly well like big separation funells,....but your are thinking of course ....how you vent it while liquid exits by the faucet?....nothing as simple as make like 4-5 holes with a needle on top,and cover it with chemical resitant tape(i use aluminium tape?) when you are going to shake,since contact with liquid it´s mininal,.....that thing didn´t eliminate the use of separation funell,because little portions are imposible to separate,but reduce work time extremly.
    Only it´s very important to test the faucet with all your solvents first ,....because i had little accident one day with DCM, literally disolving the faucet conection and resulting on 2 litres acid solution/DCM running along my arms.....first time i introduced dressed on shower ;D

Methyl Man

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Re: scalling-up the benzoquinone wacker oxidation
« Reply #36 on: June 01, 2011, 02:12:02 AM »
Thanks for your kind words in the post #39 sassa.  :D Indeed, this type of thing

Quote
Of course,Bright Stars have big erros,more exactly,inexplicable lacks of information,...like why not tell us that after flooding the benzoquinone wacker reaction,the result it´s an incredible mess of scum,if we not filter it previously?.

...is precisely the reason I did the writeups in the first place: so I could have something to follow that included "little" details like that and prepared me for them. I didn't realize so many other people would appreciate them.

Back to your scale-up dilemma... yeah, I'm pretty sure you can't use that kind of plastic with DCM. I think even if it doesn't melt it outright, it will leach plastic into your product... yuck.

Any other ideas? I'd say you are not in fact ready to scale it up 3 or 4X this week. That is a pretty major aspect, how to do the separations. Critical, even...
« Last Edit: June 01, 2011, 02:20:45 AM by Methyl Man »
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jon

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Re: scalling-up the benzoquinone wacker oxidation
« Reply #37 on: June 01, 2011, 06:23:58 AM »
yeah that's why i like the h2o2 wacker in t-butanol with palladium acetate.
i've never done it myself because iodosafrole is the tits.
but it's clean fast requires little catalyst and the workup is easy easy
just extract it.

here:

http://www.oocities.org/methamphetamine_x/wacker.h2o2.txt

http://www.oocities.org/methamphetamine_x/wacker.peroxotungstate.txt

here is a good explanation of mechanisms
http://alexandria.tue.nl/extra2/9900308.pdf
« Last Edit: June 01, 2011, 06:43:29 AM by jon »

sassa

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Re: scalling-up the benzoquinone wacker oxidation
« Reply #38 on: June 03, 2011, 09:03:11 PM »
that new methods jon´s talks about sounds very interesing,and most important,very clean....posibly i will look at it on next batches.
    Well,i was thinking about some improvement on the benzo wacker to follow,...first,...i will use the minimal amount of benzo since mine it´s of very good purity,and on other hand i was dreaming  about what will happens if i flood mix after reaction with more concentrated hcl solution than usual,and too on distill first the DMF or methanol after filtering,thinking for example on the method i´ve followed on the cyanoborohydride to mda,All i can visualize that can make that reaction more easy it´s to limitate the amount of organic crap,and limitate the amount of solution before have to extract.If i can deal with half amount of liquid on that will be a real improvement for me....so....from my almost total incompetence about theorical chemistry....what do you think about:
  1.After filtering the reaction mix,boil with vacum the water and DMF(aprox 150ºC without vacum) or the methanol...if i use dmf,i will finish only with ketone+organic crap...water will boil away too.
  2.add more concentrated hcl than usual(10%) on less volume.Use for example as minimal 37º Hcl to liberate ketone and begin the extractions with as less solution as posible.
    That can result on less toluene/dcm need to make the ketone extraction,and deal with less toluene/dcm when have to make the naoh washes...probably less ketone lost on so big water amount.
    Well,supossed that will be totally wrong and will fuck ketone on some moment,mostly about boil the dmf/water  with the ketone included and add so concentrated hcl,but really be usefull or better discard and go straight like always?....
   Only to prove new things,...

NeilPatrickHarris

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Re: scalling-up the benzoquinone wacker oxidation
« Reply #39 on: June 03, 2011, 09:32:40 PM »
here's a pain in the ass method.  i've used it in the past and it does help somewhat but it's a pain and causes more time on the work-up:

1) after the reaction is complete, let it cool off then stopper the flask and put it in the freezer overnight
2) gravity filter it through #101 filter.  i've even used a #103 filter and the result is a very clean work-up but the #103 just took way too long and that was scaled at only 10% of Methyl Man's write-up, you can imagine how long it would take for a large scale!
3) when you add the HCl, make sure the contents of the reaction flask are freezer-cold and make sure the HCl is refrigerator cold.  make everything as cold as possible without freezing and slowly add the HCl.  doing this i've actually been able to precipitate black crystals before instead of the usual tar

anyway just some ideas of things i've tried since you're thinking some of the same thoughts i was in the past.  i have since given up gravity filtering because even though it makes everything cleaner to work with, it didn't make an impact on my end result of ketone so it didn't prove to me worthwhile IMHO.  what i do recommend doing though is #3.  after the wacker is done, let it cool off, stopper it and put it in the freezer overnight.  keep your HCl in the fridge overnight also.  the next morning, slowly add the HCl to the reaction flask while keeping everything as cold as possible.  the precipitation of the gunk is much cleaner rather than the typical tar-turd that appears at the bottom.  the lower amount of benzo helps a lot too, i'd recommend doing 0.75 molar equivalent of benzo to safrole, so a little less than equal molar.  if you've done the typical 1.265 molar equiv benzo to safrole then you'll notice a big difference - not just in the addition of HCl but also during the reaction itself.  normally there's a point where stirring gets super thick, stops the stirbar, then it thins back out again.  with less benzo as i described, the reaction never gets anywhere near that thick.

i've never tried distilling off MeOH or using higher concentrated HCl because i was working at a very small scale, no worry about solvent volumes so i can't comment there.  i would keep in mind that the HCl solution helps in changing the density of the aqueous (MeOH) layer.  using a lesser volume of HCl solution may make it more difficult to extract with a light-density solvent like toluene.  so you may want to stick with DCM if you plan to change the density of the aqueous layer.  maybe it wouldn't really pose a problem, i don't know, just thinking out loud.  i can only say that using Methyl Man's solvent volumes but substituting toluene for dcm works well.  it's less selective than dcm but i wouldn't say the extracts are any cleaner, the benefit to toluene is that it is less soluble in water than dcm so less of it (and the ketone) is lost due to that reason.  in fact the crude undistilled ketone is dirtier from toluene in comparison to dcm, my toluene-extracted ketone was always black with visible bright yellow trails if you agitate it.  but all that remaining crap stays behind during the vacuum distillation so no worries there.  i've always had better yields using toluene instead of dcm just due to losing less extraction solvent during the work-up.

good luck
« Last Edit: June 03, 2011, 09:35:30 PM by NeilPatrickHarris »