Author Topic: O2 Wacker  (Read 1474 times)

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pooky

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O2 Wacker
« on: July 12, 2003, 10:29:00 AM »
Pooky was thinking of the wacker a little last night.Shaking worked for P,and stirring seems to work for some but not others.Anyways, there are rotary vane high volume/low pressure air pumps on the market.Hook one of these up to a sparkless motor,and another sparkless on a stirring apparatus as well.One would have 2 pp resevoirs,interconnected with an appropiately sized (2"?)pipe;one with the Pd/safrole,alcohol mix being stirred from above,and the other acting as an oxygen resevoir.
The rotary vane pump would reside in the oxygen resevoir, and pump through high volumes via a line, through the connecting pipe, and down through a laser drilled circular aerator, residing at the bottom of the liquid resevoir.Pressurise to 40 psi and hope to hell there are no sparks(!)P imagines a disgustingly foamy red broth stirring around and taking up oxygen like crazy.Any ideas or critiques?? Thanks..

pooky

  • Guest
Addendum
« Reply #1 on: July 12, 2003, 12:52:00 PM »
With more thought,P thinks it would be best to have it all in one resevoir-simpler,less chance for leaks,etc. The overhead stirrer would be mounted,well,overhead.And the rotary vane air pump(s) would be mounted on the uppermost sides or on the top of the resevoir.Found relatively small pump and it cranks out 30 cfm at a few psi,so no laser drilled stuff would be required.Possibly feed the vane's output to a manifold (plastic)which would in turn feed several hydroponics 1/2 inch tubes ,and then several 1/4 inch inside diameter hydroponic emitter tubes coming from each 1/2 incher.The 1/4 inchers may stick straight down into the mix,to almost touch the bottom.Possibly arranged in a circle,who knows?

OcoteaCymbarum

  • Guest
Question about sparks
« Reply #2 on: July 12, 2003, 04:37:00 PM »
I just have a question. Since oxygen is a nonflammable gas, what would a spark do?

Rhodium

  • Guest
anything burns in an oxygen atmosphere
« Reply #3 on: July 12, 2003, 04:42:00 PM »
It would ignite anything else which is flammable, because in an oxygen atmosphere anything which can burn at all will burn violently, including some metals.

Osmium

  • Guest
Don't make it so complicated.
« Reply #4 on: July 13, 2003, 06:12:00 AM »
Don't make it so complicated.
Either spray the reaction solution into an oxygen atmosphere, or bubble the O2 through a long vertical tubular reactor. Shaking might still work best.


LaBTop

  • Guest
Diesel motor injectors.
« Reply #5 on: July 13, 2003, 02:31:00 PM »
Take out the whole diesel injector system from an old diesel car.
Screw the injectors in a homebuild SS pressure vessel filled with O2, and re-pressurized when the O2 pressure drops under a certain value.
Use a collector vessel build under it connected to it with a small diameter SS-line, with a sampling mechanism (rubber thingy you stick a needle through) build in the collecting vessel (which has the same pressure as the reaction vessel by design), to collect samples, until your returning reaction fluid (which is pumped/send back to the diesel pump) matches the maximum conversion.
Is called an endless loop thingy where I live. LT/


Osmium

  • Guest
> Screw the injectors in a homebuild SS...
« Reply #6 on: July 14, 2003, 06:21:00 AM »
> Screw the injectors in a homebuild SS pressure vessel filled with O2

The Cu/Pd catalysts will unfortunately attack the SS. It needs to be painted, or the reaction needs to happen in a plastic or glass container inside a SS enclosure.


OcoteaCymbarum

  • Guest
Have it teflon covered
« Reply #7 on: July 14, 2003, 08:13:00 AM »
A teflon cover can be applied to most SS pressure vessel.
You can find tons of coaters on the net.
It's worth it if youre going to build such a setup

pooky

  • Guest
Replies,etc
« Reply #8 on: July 14, 2003, 11:24:00 AM »
As an oldtime rocket(solid and liquid fuelled) and bomb builder,along with blasting experience- my face and fingers are still intact.
OC,as to the desirabilty of spark control, I believe the methanol vapours (possibly with some help from the catalyst)would be ignited by any spark.Thank you Rhodium for the backup.
Was thinking if one were to build a unit,there are custom plastics places all over, or have a vessel built from aluminum with seals,etc and powdercoat it with teflon.For kicks,P went to Walmart and bought a cheap air mattress inflator,jammed 4 fish tank air lines into the outlet,and sealed them in there with a glue gun.The lines were put under water in a jar, and she bubbled pretty good.Just imagine 35 cfm or more with more hoses!P doesn't think it is too complicated,just a matter of messing around with hoses and mounts.But then P used to build hydroponics set ups to sell.In next month or 2,P will build one and let you all know if and how it works.

scram

  • Guest
Why do you want to make it so complicated.
« Reply #9 on: July 15, 2003, 10:05:00 AM »
Why do you want to make it so complicated. Listen: 2" egg-shapped stirbar in a 3 liter pop bottle at 40 psi. 176g oil 1.2g pd 6g cucl2. Mix with 500ml MeOH Psi drop on one of these bottle for complete reaction will be 80 psi over 12 hours. For every 10 psi you have approx 2.8 g 02. So total oxygen at 40 psi is approx 11.9 grams. Personally I would add 5ml water to the beginning of the reaction to slow the peak point down.

pooky

  • Guest
Been there,done that
« Reply #10 on: July 15, 2003, 11:18:00 AM »
Thanks Scram for the O2 drop info. But P isĀ  curious and interested in new and different ideas,and ways to hopefully improve them.When P gets bored of this topic, P will get into something else...:)

Nmethyl

  • Guest
Don't forget the water!
« Reply #11 on: July 15, 2003, 10:14:00 PM »
I've noticed that the emphasis on supplying enough oxygen to the Wacker system has somehow overshadowed the basic neccesity for the Wacker to work.

I'm wondering how any of these failed reactions are due to a lack of water. Water is the molecule that the reaction is co-dependant on! It's water not oxygen that is coordinated to the double bond, the role of oxygen is 'merely' to regenerate the CuCl2. The CuCl2 is there keep the catalytic system homogenous.

It would be much more advantageous to keep the system as aqueous as possible, while keeping the alkene miscible. Wouldn't it also act as a more absorbant phase for the oxygen? I'd be interested to hear yields from increased water content in these reactions.

Osmium

  • Guest
Arrrgh!
« Reply #12 on: July 16, 2003, 03:05:00 AM »
NO WATER DAMMIT!

Water slows the reaction down. The reaction works perfectly without any water.

> I'm wondering how any of these failed reactions are due
> to a lack of water.

Not one!

> Water is the molecule that the reaction is co-dependant
> on! It's water not oxygen that is coordinated to the
> double bond,

In this reaction it is the alcohol that is added to the double bond, producing the ketal R-CH2-C[(OMe)2]-CH3, and which in turn is decomposed forming the desired ketone during workup. The ketal hydrolyses easily under slightly acidic conditions.

> It would be much more advantageous to keep the system as
> aqueous as possible, while keeping the alkene miscible.
> Wouldn't it also act as a more absorbant phase for the
> oxygen? I'd be interested to hear yields from increased
> water content in these reactions.

In the original literature ref. the alcoholic O2 Wacker is based on all these experiments were already made (some 30 years or so ago), the result being that reactions with the lowest water content were the fastest.

Keep the water out. And pre-dissolve your catalysts with stirring overnight!


Nmethyl

  • Guest
Highly *aminated* response!
« Reply #13 on: July 16, 2003, 03:28:00 AM »
Haha you convinced me, I'll keep the water to a minimum when I UTFKRV ;)

scram

  • Guest
I agree that no water will bring you closer to
« Reply #14 on: July 16, 2003, 03:59:00 PM »
I agree that no water will bring you closer to the peak (heat and 02 uptake pinnacle) of the reaction by a few hours. I can only tell you that with the water this peak is more controlable, particularly if the water is added at or around the peak. Without water your peak will occur at the scale mentioned above about 2 to 4 hours from start and with water about 4 to 8 hours after start. Of course this is dependent on the stirring too. Some stirrers will produce minimal bubbling. Something evident with water is that the reaction heats up (lukewarm), & changes colour during the first 10 minutes of stirring, & then cools. Several hours later it gets very hot (peak). Without water this doesn't happen, you just wait for the peak around that 2 to 4 hour mark. It's fast, around 15 to 45 minutes w/o water. With water that peak can be made to last 30 minutes to 1.25 hours as temperature is easier to control. It seems to be either way the reaction is finished taking up 02 at the same time (10-12 hours after beginning). You can actually get the cu/pd to dissolve in MeOH with 3 hours if you heat it up to 60c while stirring. This has also produced a peak that begins closer to the beginning of the wacker.