Large Scale Wacker Ratios

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Author	Topic: Large Scale Wacker Ratios
Organometalics Hive Bee	posted 10-01-1999 07:21 PM After dreaming the other day, I begain to ponder what others used in their high pressure, 02, ollaphin, CuCl2, PdCl2, MeOH wackers. This search lead me to an engine (much better now btw ) and I looked through 102 posts. There seems to be little concenus on the ratios of reagents and cataysts. In the dreams, I have been using the folowing: 100 ollaphin (g) 1 PdCl2 (g) 25 CuCl2 (g) 1000 MeOH (mL) excess 02 at 120psi Shaking was done at 30 rpm from 35degress off axis to -35 off axis. I would like to use min quanaties of solvent and co-catalyst. How low can you go?
Osmium PimpBee	posted 10-02-1999 07:26 AM 4-5g CuCl2 and 400ml MeOH are enough. I have to repeat this: prepare the catalyst and cocatalyst solution a day or so before you start this synth. It takes quite some time to dissolve the PdCl2.
The Alchemist Hive Bee	posted 10-02-1999 02:51 PM Does that go for the benzoquinone wacker as well?
Left Alien NewBee	posted 10-02-1999 04:55 PM I've researched this topic until my eyes turned green and blue, and this is my conclusion. There's a French research group that done some pioneering research into this, but their shit is hard to read. I did it anyway. You don't need CuCl, CuCl2, at all. In fact, it can only get in the way. These were used as oxidizing agents, but benzoquinone or oxygen gas dissolved in solution is superior and far less likely to cause emulsions. On a large scale, pressurized oxygen is the way to go because it is cheap. Benzoquinone is the way to go on a small scale. Make sure you buy benzoquinone, NOT hydroquinone. DMF is expensive and unnecessary but very nice if you can afford it. More experience bees (such as equarius and rev_drone I believe) have recommended EtOH. I'm sure that is fine, but I would feel more comfortable with IPA. That way if it gets oxidized it will only get oxidized once (to acetone, rather than all the way to acetic acid in the case of EtOH). Any polar, aprotic solvent will do, however. H202 is said to work as an oxidizing agent as well, but I tend to worry about using hydrogen peroxide here because I think it might create free radical conditions that will lead to the wrong ketone. That might be what we want though, in the case of asarone. (100 to 1) : (oil to PdCl2) : (gram to gram) ratio is said to be best HAS ANY BODY TRIED THE WACKER ON ASARONE? Calamus oil is my pet favorite. Whoever gets calamine powder first will make a lot of money, too, because the dosage is reportedly only 25 to 40 mg and because it lasts like 12 hours.
Organometalics Hive Bee	posted 10-04-1999 05:21 AM Also Osmium: How long? Average yeild? thanx PS: I found that gently heating the MeOH with the catalyst and co-catalyst in it does wonders for solubility.
Cesium NewBee	posted 10-04-1999 08:37 AM An interesting modification of Benzo Wacker is described in Tetr. Lett., (28), No.32, pp. 3683-3686, 1987: „Oxidation of olefins to ketones in combination with electrooxidation“. In this article, 1-alkenes are oxidised to corresponding methyl ketones by the catalyses of Pd(OAc)2 and benzoquinone in high yields. The hydroquinone produced during the oxidation of Pd to Pd2+ is electrochemically oxidised back to benzoquinone directly in the reaction mixture. The procedure uses benzoquinone only as a catalyst in much lower amounts than the classical reaction. Typical procedure is as follows: An anodic solution (50 ml) containing 1-alkene (10 mmol), benzoquinone (2 mmol), Pd(OAc)2 (0.2 mmol) and supporting electrolyte (Et4NBF4, 0.3 M) was electrolysed using a Pt anode at 0.83 A.dm-2 of a constant current density in a divided cell at room temperature. Excellent yields were obtained using this procedure even with cyclic olefins. Authors made tests with 1-decene, styrene, cyclopentene, cyclohexene and other substances. Further optimalisation of solvent and electrolyte system and catalysts concentration can probably be done for more interesting terminal olefins. Another modification could be starting from easily available HYDROQUINONE and oxidise it electrochemically directly in the reaction mixture /or in-situ generation before addition of olefin/ (avoiding thus the not-very-pleasant-to-do chemical oxidation of hydro- to benzoquinone by chromsulphuric acid).
Methyl Man Hive Bee	posted 10-04-1999 01:45 PM Osmium: Sounds like a hot tip, but would you be so kind as to spell it out in layman's terms for we neophytes? As in: "Prepare your PdCl2/DMF solution a day in advance..." I ask this because I know the PdCl2 is the catalyst, but what is the co-catalyst? The benzoquinone? Maybe my friend's rather unimpressive ~45% yields with the benzo wacker were due to some PdCl2 being undissolved... Thanks Os. M.M.
Killer Alienz NewBee	posted 10-04-1999 01:51 PM Methyl Man, Elemental oxygen is the co-catalyst. It can come in the form of 02, H202, or benzoquinone. DMF is expensive and unnecessary. The shit I wrote up there is worth MILLIONS OF DOLLARS. You should pay attention.
Methyl Man Hive Bee	posted 10-04-1999 01:51 PM Oops, hold on... okay you're talking about the standard (non-benzo) wacker, right? The co-catalyst is the copper compound. Sorry. Still, I'd like to ask: is there a related tip for the benzo wacker that could improve yields by effecting better dissolution of the PdCl2? M.M.
Methyl Man Hive Bee	posted 10-04-1999 02:05 PM Mr Alien(z): I assure you I am paying attention. Understanding what I am paying attention to on the first, second, or 20th read is another question however, if it is written in such a way as to be incomprehensible to anyone but experts. I sometimes like to remind people that the purpose of this site, at least as I was told (by its creator), is to provide information that the expert and sharp beginner alike can use. So I'm not bitching, just saying please remember to phrase things so that non-experts can utilize it too. That way we all benefit! thanks
Methyl Man Hive Bee	posted 10-04-1999 02:25 PM Sorry guys, I'm experiencing post-ecstacy blues today. Shouldn't be posting at all. My apologies. I'm outa here.
Organometalics Hive Bee	posted 10-04-1999 04:26 PM Dear Methyl Man, What Killer Alienz and The Alchemist talk about in their posts, is the ability of O2 as a gas to act as a co-catalyst. The co-catalyst in this case must re oxizise the Pd(0) to Pd-L. To put this simple: Pd gets used up in the wacker. Must be regenerated by a co-catalyst. The co-catalyst can be: a) CuCl2, CuCl, ie some copper salt b) benzoquinone c) high pressure O2 I have never dreamed about using just O2 as a co-catalyst. I would guess that it would only work with high pressures and lots of agitation. The statement seems logical however. When I was dreaming, I found this green salt on the bottom of a vessel. After looking at it, I determined that its colour was more like CuCl, rather than the imput of CuCl2. Thus it seems that no Cu(salt) or benzoquinone could be tried in a high pressure O2 wacker reactor. Also siting down with electro chemical potentials and doing the math with the mechanisum deemed fruitful as well. Hope this helps... Thanks guys --Organometalics
Osmium PimpBee	posted 10-05-1999 10:37 AM Let's not mix up the different procedures. Organometallics asked about the PdCl2/CuCl2 Wacker in MeOH. This is my variation of the Wacker which started the SRV concept (which uses compressed air instead of O2). I can't comment on the DMF/benzo Wacker at all, because I have never tried it. The CuCl2 is a co-catalyst, because it is NOT used up in this reaction. O2 is a reagent, because it is used up.
KrZ Hive Bee	posted 10-05-1999 07:21 PM 0.5g PdCl2 and 3.5g CuCl2 is the lowest ratio I've used. Even at only 80psi, and 10 hours reaction time, the yield was 92%.
Semtex Enigma Hive Bee	posted 10-05-1999 07:50 PM Damn boy, 92%?!? Wish I had them thar Getto Reactor plans to fuck around with...
KrZ Hive Bee	posted 10-06-1999 12:10 AM Temp. was held at 50C too.
scwam Hive Bee	posted 10-06-1999 01:37 AM Wait, KRZ are you talking about the regular 02 wacker and not the benzo wacker. If its regular wacker, then that totally contradicts everything Ive read here on keeping low temps.
KrZ Hive Bee	posted 10-06-1999 09:18 AM Yes it does. The temp. will drive off O2, reducing yields drastically. Or will it improve yields because soluble O2 is already high enough and more safrole+Pd reaction is needed instead to go higher? There's two ways to find out, 1 a quick trip to the library, 2 dream.
Osmium PimpBee	posted 10-07-1999 08:44 AM In my dreams a few years ago, O2 uptake ceased (or at least was very small) when temp was too low. At higher temps (warm water bath, ~50-60°C) the reaction seemed to produce heat, depending on the speed of shaking. The harder the bottle was shaken, the hotter it became. KRZ, how did you test your product? Only eyeballed it, distillation, or even more advanced means of identification? Was it really 92% of reasonably pure ketone? Is that Ghetto Reactor (TM) description thread still here?
KrZ Hive Bee	posted 10-08-1999 12:07 AM The not-ketone was distilled carefully. This is a really high yielder w. pure O2 and a good stir time.
Eigenfxn Hive Bee	posted 10-11-1999 11:39 AM Based on what I have seen from one of my freinds the O2/CuCl wacher with 40 lbs of pressure in ratios of 100ml of alkene 2g of Pd(II)Cl 6g of CuCl with constant shaking on a machine has produced over 85% yields of ketone ... identification was done with IR/NMR
randolph carter Hive Bee	posted 10-11-1999 02:31 PM howdy all.... looks like an interesting rap goin on here.... so how's about i crash the party??? mr alien: did someone say CALAMUS!!!! yep it wacks.... brightly i might add... like a nova..... what....??? people charge money for these fuel additives.... absolutely pollutes yer karma..... for our klan it's a work of love/sex...... make money off it... what a quaint idea..... sounds just like what the "machine people" do..... not very Kounter-Kulture tm i dare state..... and yep it's rumoured to bee"potent" ... although 25 mg is only enough for the "wrangler boyz".... most "full size" jeeps need more like oh say 50 mg.... not quite 12 hrs duration either.... try 8 or less.... although your mileage may vary depending on road conditions and the drivers lack of or surplus of dopamine content.... but this really is typical of the prevalent lies on most fuel additives recommended by mopar/daimler since they took over amc/jeep..... friggin' nazis...... krz: mmmmmmmm...... your variant of the wack sounds considerably more attractive that the luminous one's for the khem impaired.... so like if'n i follow correctly....it sounds like yer ghetto-reactor tm could be subbed with a "low-pressure" parr tm bottle hydrogenator with O2 instead of H2 in the uptake gas cylinder eh...... i think i have one of those being used to make methyla-er-nitromethane for my 72 jeep .... hehe.... it maybee that some new dreams may come to the se again..... that 90+% sounds AWFULLY GOOD.....!!!! no shit ???? cmon back and let's talk.... ------------------ randolph carter... the perennial dream questor... "remember, love is real, not fade-away, so, pass some on today..."
Xerxes Hive Bee	posted 10-11-1999 02:46 PM RC- on a semi-related note, i'd like to pick your brain on your leuckart-style amination of your 2,4,5-ketone in your famous calamus writeup. does your hotmail account still function?
randolph carter Hive Bee	posted 10-11-1999 04:13 PM xerxes.... yep last time i checked it did... if'n ya got probs sendin let me know..... i generally check the posts ever day or so.... ------------------ randolph carter... the perennial dream questor... "remember, love is real, not fade-away, so, pass some on today..."
KrZ Hive Bee	posted 10-13-1999 08:52 AM You have a low-psi parr hydogenator RC? Where did you find it? Does someone actually still carry these things? Also, the Ghetto Reactor (Wine Jug) setup was indeed what I used for this oxidation. Recently I tried simply using a heavy-walled 5L RBF, a vacuum adaptor, and a glass stopper. The adaptor tubing inlet was wraped in teflon tape, the joints on the glassware sealed with heavy vacuum lube, and the whole thing clamped together. The gas was inserted by means of some orange 300psi welding tubing, which was tightened down with an O-clamp. The device held to 80 psi (Inside of an explosion case of course), and the use of an RBF allowed even more efficent stirring to be employed, also I found it easier to cool the device when needed, or heat when needed. Using the RBF with the 3,4,5 nitrostyrene and H2 yieled 78% of the amine after 6 hours reduction time w. 0.04M Catalyst (Pt/C) ratio (1 hr prereduction), the reaction being chilled in an ice bath which was allowed to warm up over the last 2.5 hours or so. Also note that a vacuum-out T-valve was employed to remove atmosphere beforehand, as well as good ventilation from a sparkless exhaust blower. It also appears to work well for oxidations.
equarius Hive Bee	posted 01-15-2000 01:02 AM KrZ; I'd like some clarification for the O2 wacker using the (ghetto) keg reaction vessel. Would high speed stirring using a 2.5-3" egg shaped stir bar be adequate for O2 uptake? A good ratio would be 1g PdCl2 : 100g Olefin : 5g CuCl2.2H2O : 200mls solvent : 100psi O2? Reaction conditions of 50C for 10h? Preferred solvent would be 99.99% MeOH or 95% EtOH (5% unknowns) or IPA? Add a little water (5%) of go for totally anhydrous and then add H2O during the workup for complete Ketal to Ketone formation? Thanks.
KrZ Hive Bee	posted 01-16-2000 04:59 PM I like the argument in favor of IPA, 99% IPA is nice and affordable. Hell yeah high-speed stirring will be sufficent. SWIM always enjoyed denatured anhydrous EtOH (Not the hardware stuff), and 95% EtOH ("Diesel" from the ABC store worked fine in a pinch once) to get the needed water. Your ratios are fine. You should be able to acheive those 90% yields I mentioned.

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