Author Topic: Rhodium please clarify !  (Read 48479 times)

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  • Guest
Rhodium please clarify !
« on: March 29, 2003, 04:10:00 PM »
Do you remember Osmium's posts regarding analysis of post-wacker ketone ? I believe he found that it was roughly 85% MD-P2P and 15% MD-P1P ....

So what you are saying here , is that by running the reaction hotter , we can move the gradient even more towards the P2P side (perhaps 95% mdp2p , 5% mdp1p) ??

Also to clarify , the benzoquinone is there to provide oxygen , and bees have claimed success using pure O2...

If that is true , then what are your thoughts about running an O2 wacker even hotter ? I have seen some mention an upper limit of 40° , else the vessel will rupture.....

Assuming you had a vessel that could EASILY withstand the heat and pressure , at what level (temp and pressure) would this reaction be most optimized ?

I ask these questions b/c I have no formal chemistry education , and I am not able to talk "chemistry theory"

Please help !

Thanks  8)


  • Guest
Wacker theory
« Reply #1 on: March 30, 2003, 11:23:00 AM »
If that is true , then what are your thoughts about running an O2 wacker even hotter ? I have seen some mention an upper limit of 40° , else the vessel will rupture...

Temp limit: It depends on your vessel. Do not try to heat a vessel not designed for high pressure, or injury will likely result.

Analysis: The O2 wacker of safrole was analyzed by Ritter, not Osmium.

Isomer distribution: The article concerns the wacker oxidations of propenylbenzenes rather than allylbenzenes (as in isosafrole and not safrole itself). To improve the isomer distribution in the case of safrole, perhaps running the reaction cooler is the answer, but to answer that question definitely, someone with a more solid background than myself in physical organic chemistry should probably answer.


  • Guest
Survey Says.....?
« Reply #2 on: August 28, 2003, 06:20:00 AM »
Hiya Bubble - btw.. forgot to thank  you for your much-appreciated detailed reply to my post on Wacker Ox. Anyways.. curious to know if anyones tried this variation, and if so, with what results?

cheers beez


  • Guest
Pd(II)/O2: Terminal Alkenes to Methyl Ketones
« Reply #3 on: February 13, 2004, 07:56:00 AM »
Novel Palladium Catalytic Systems for Organic Transformations
Takahiro Nishimura, Sakae Uemura
Synlett 201-216 (2004)


This article summarizes the results of our recent studies on palladium catalytic systems for the oxidation of alcohols and beta­alkenes using molecular oxygen or air together with several successful attempts to make the system recyclable from the viewpoint of ‘green and sustainable chemistry’.

5.0 Palladium(II)-Catalyzed Oxidation of ­Terminal Alkenes to Methyl Ketones Using Molecular Oxygen

Palladium-catalyzed oxidation of alkenes to methyl ketones has been developed in synthetic organic chemistry as well as in industrial processes using PdCl2 and CuCl2 or Cu2Cl2 as catalysts in acidic water under an oxygen atmosphere.23,24 However, this catalytic system is highly corrosive because of its acidic conditions and may cause the formation of chlorinated by-products in some cases. To overcome such drawbacks, halide-free catalytic systems have also been widely investigated.25

On the other hand, Mimoun and co-workers have reported that a Pd(II)-OOH species undergoes an oxygen transfer to terminal alkenes via peroxypalladation to afford methyl ketones as shown in Scheme 12.26

Scheme 12

An example of the palladium-catalyzed oxidation of cyclopentene to cyclopentanone in ethanol using molecular oxygen as the sole reoxidant was reported by Takehira and co-workers in 1985.9a They also proposed the formation of a Pd(II)-OOH species from palladium, ethanol, and oxygen.9a,27

In the course of our studies on the aerobic oxidation of alcohols described in previous sections, we proposed the in situ formation of a Pd(II)-OOH species as well as H2O2. This assumption prompted us to check whether this Pd(OAc)2/pyridine/O2 catalytic system is applicable to the oxidation of terminal alkenes based on Scheme 12.28 In fact, the treatment of 1-dodecene in toluene (5 mL) and 2-propanol (5 mL) in the presence of 5 mol% Pd(OAc)2 and 20 mol% pyridine at 60°C for 6 hours under an oxygen atmosphere afforded the expected 2-dodecanone (70% GLC yield, Scheme 13). Other simple terminal alkenes were converted to the corresponding methyl ketones in good yields under the same conditions. Interestingly, 10-un­decen-1-ol was mainly transformed to 11-hydroxy-2-undec­anone in 71% yield showing that a terminal double bond was oxidized much faster than a hydroxyl group. It is noteworthy that this oxidation system was applicable only to terminal alkenes, and not to internal ones.

Scheme 13

A plausible reaction pathway for this oxidation using Pd(OAc)2/pyridine/2-propanol/O2 catalytic system is shown in Scheme 14, where two catalytic cycles operate. One cycle is the oxidation of 2-propanol (cycle A) to give acetone and a Pd(II)-H species, the latter of which is transformed to a Pd(II)-OOH species by the reaction with oxygen. The Pd(II)-OOH species reacts with an alcohol to give an alkoxypalladium(II) species as well as H2O2.9 This Pd(II)-OOH species also reacts with alkenes via peroxypalladation (Scheme 12) in another catalytic cycle (cycle B) to produce methyl ketones and a Pd(II)-OH species which reacts with H2O2 to reproduce the Pd(II)-OOH species.

Scheme 14


[9a] Strucul G. Ros R. Michelin RA. Inorg. Chem. 21, 495 (1982) (See Below)
[9b] Takehira K. Hayakawa T. Orita H. Chem. Lett. 1835 (1985)
[9c] Hosokawa T. Murahashi S.-I. Acc. Chem. Res.  23, 49 (1990) (See Below)

For recent reviews see:
[23a] Tsuji J. Palladium Reagents and Catalysis  Wiley; New York: 1995.  p.19-30 
[23b] Jira R. In Applied Homogeneous Catalysis with Organometallic Compounds   Cornils B. Herrmann WA. VCH; New York: 1996.  p.374-393 
[23c] Monflier E. Mortreux A. In Aqueous-Phase Organometallic Catalysis   Cornils B. Herrmann WA. Wiley-VCH; New York: 1998.  p.513-518 
[23d] Takacs JM. Jiang XT. Curr. Org. Chem. 2003, 7: 369

Recent examples of Wacker oxidation of higher alkenes see:
[24a] Smith AB. Cho YS. Friestad GK. Tetrahedron Lett. 39, 8765 (1998) (See Below)
[24b] Mohammedi O. Chemat F. Brégeault J.-M. Eur. J. Org. Chem. 1998, 1901
[24c] Karakhanov E. Maximov A. Kirillov AJ. Mol. Catal. A: Chem. 2000, 157: 25
[24d] Yokota T. Sakakura A. Tani M. Sakaguchi S. Ishii Y. Tetrahedron Lett. 2002, 43: 8887
[24e] Choi K.-M. Mizugaki T. Ebitani K. Kaneda K. Chem. Lett. 2003, 32: 180

[25a] Bäckvall J.-E. Hopkins RB. Tetrahedron Lett. 1988, 29: 2885
[25b] Bäckvall J.-E. Hopkins RB. Grennberg H. Mader MM. Awasthi AK. J. Am. Chem. Soc. 1990, 112: 5160
[25c] Yokota T. Fujibayashi S. Nishiyama Y. Sakaguchi S. Ishii Y. J. Mol. Catal. A: Chem. 1996, 114: 113
[25d] Kishi A. Higashino T. Sakaguchi S. Ishii Y. Tetrahedron Lett. 2000, 41: 99
[25e] Monflier E. Blouet E. Barbaux Y. Mortreux A. Angew. Chem. Int. Ed., Engl. 1994, 33: 2100
[25f] Monflier E. Tilloy S. Fremy G. Barbaux Y. Mortreux A. Tetrahedron Lett. 1995, 36: 387
[25g] Monflier E. Tilloy S. Blouet E. Barbaux Y. Mortreux A. J. Mol. Catal. A: Chem. 1996, 109: 27
[25h] Hirao T. Higuchi M. Hatano B. Ikeda I. Tetrahedron Lett. 1995, 36: 5925
[25i] Higuchi M. Yamaguchi S. Hirao T. Synlett 1996, 1213
[25j] ten Brink G.-J. Arends IW. Papadogianakis G. Sheldon RA. Chem. Commun. 1998, 2359
[25k] ten Brink G.-J. Arends IW. Papadogianakis G. Sheldon RA. Appl. Catal. A 2000, 194-195: 435
[25l] Ito H. Kusukawa T. Fujita M. Chem. Lett. 2000, 598

[26a] Mimoun H. Charpentier R. Mitschler A. Fischer J. Weiss R. J. Am. Chem. Soc. 102, 1047 (1980) (See Below)
[26b] Roussel M. Mimoun H. J. Org. Chem. 45, 5387 (1980) (See Below)
[26c] Mimoun H. Angew. Chem. Int. Ed. Engl.  21, 734 (1982)

[27] Takehira K. Hayakawa T. Orita H. Shimizu M. J. Mol. Catal. 53, 15 (1989)

[28] Nishimura T. Kakiuchi N. Onoue T. Ohe K. Uemura S. J. Chem. Soc., Perkin Trans. 1, 1915-18 (2000) DOI:



[9a]Preparation and oxygen-transfer properties of novel palladium(II) and platinum(II) hydroperoxo and alkylperoxo complexes
Strukul, Giorgio; Ros, Renzo; Michelin, Rino A.

Inorganic Chemistry (1982), 21(2), 495-500 (1982)


Mononuclear hydroperoxo and tert-butylperoxo complexes RML2OOR1 (L = 1/2 diphosphine or monophosphine; M = Pd, Pt; R = H, Me3C; R1 = activated alkyl) were prepared by condensation reactions of RML2OH with R1OOH. Whereas Me3COOH reacts in all the cases tested, with H2O2 the preparation reaction is sensitive to the nature of R. These compds. behave as typical O-transfer agents, reacting with PPh3, CO, NO, and PhCHO. trans-CF3Pt(PPh2Me)OOCMe3 oxidized terminal olefins to the corresponding Me ketones.
____ ___ __ _

[9c]New aspects of oxypalladation of alkenes
Hosokawa, Takahiro; Murahashi, Shunichi

Accounts of Chemical Research 23(2), 49-54 (1990)


Summary: A review with 54 refs. dealing with mechanistic and synthetic aspects of intramol. oxypalladation and acetalization of alkenes.
____ ___ __ _

[24a]Convenient Wacker oxidations with substoichiometric cupric acetate
Amos B. Smith, III, Young Shin Cho and Gregory K. Friestad

Tetrahedron Letters 39(48), 8765-8768 (1998)



A modification of the Wacker oxidation of terminal olefins to methyl ketones using substoichiometric amounts of Cu(OAc)2 as a redox shuttle reagent is described. The modified procedure is generally high yielding despite reduced levels of copper salt and convenient. Importantly, in a problematic case, the conditions suppressed acidic hydrolysis during oxidation of substrate (+)-5 containing an acetonide. Has been mentioned in

Post 108566 (missing)

(dormouse: "improvements in wacker rxn.  -neocelsis", Novel Discourse)

____ ___ __ _

[26a]Palladium(II) tert-butyl peroxide carboxylates. New reagents for the selective oxidation of terminal olefins to methyl ketones.
Mimoun, Hubert; Charpentier, Robert; Mitschler, Andre; Fischer, Jean; Weiss, Raymond

Journal of the American Chemical Society 102(3), 1047-54 (1980)


The synthesis and characterization of new Pd(II) tert-Bu peroxide carboxylates with the general formula [RCO2PdOO-tert-Bu]4 (R = Me, CCl3, CF3, C5F11) are described. X-ray data gave the crystal and mol. structures of [Cl3CCO2PdOO-tert-Bu]4 (I). The 4 Pd atoms of I are coplanar and are located approx. at the corners of a square. Four trichloroacetate bridging anions are alternatively above and below this square. I are highly efficient reagents for the selective stoichiometric oxidation of terminal olefins to Me ketones at ambient temperature, and catalysts for the ketonization of terminal olefins by tert-Bu hydroperoxide. A mechanism involving a 5-membered pseudocyclic peroxymetalation of the coordinated olefin was suggested.
____ ___ __ _

[26b]Palladium-catalyzed oxidation of terminal olefins to methyl ketones by hydrogen peroxide
Roussel, Michel; Mimoun, Hubert

Journal of Organic Chemistry (1980), 45(26), 5387-90 (1980)


Pd(II) complexes are very efficient catalysts or the selective oxidation of terminal olefins RCH:CH2 (R = n-hexyl, n-octyl, n-decyl, AcOCH2) to RCOMe by H2O2. HOCH2CH:CH2 gave a mixture of HCO2H, AcOH, and EtCO2H. This reaction is best carried out in solvents such as tert-BuOH or AcOH, and requires a large excess of H2O2 with respect to the olefin in order to achieve a nearly complete conversion of the substrate without precipitation of metallic Pd. The general trend of this reaction suggested a mechanism very similar to that previously shown for the oxidation of terminal olefins by Pd(II) tert-Bu peroxide carboxylates, and involving a pseudocyclic hydroperoxypalladation of the coordinated olefin.


  • Guest
GC's of standard benzo DMF wacker showed the...
« Reply #4 on: February 15, 2004, 11:15:00 PM »
GC's of standard benzo DMF wacker showed the reaction to be finished around 3.5 hour mark. There was no yield increase with the extra time. On saying that, it really also depends on what your starting temp is, and how large the reaction. (The larger may be a little quicker due to the higher heat generated by the reaction.)


  • Guest
Chloride-Free Aerobic Wacker Oxidation
« Reply #5 on: August 13, 2004, 10:06:00 AM »
Wacker oxidation of cyclohexene in the presence of Pd(NO3)2/CuSO4/H3PMo12O40
Marisa S. Melgo, Alexandra Lindner and Ulf Schuchardt, Applied Catalysis A: General, Vol. 27x, p. xxx (2004) - Article in Press


The Wacker oxidation of cyclohexene to cyclohexanone, using the chloride ion-free catalytic system Pd(NO3)2/CuSO4/H3PMo12O40, was investigated at different air pressures, temperatures, and catalyst concentrations. The results show that this system is very efficient and highly selective. After 1 h of reaction at 80°C and an air pressure of 50 bar, a conversion of 80%, with a turnover frequency of 260 h?1, and a selectivity of more than 99% for cyclohexanone was obtained. Using aqueous hydrogen peroxide and no external pressure, the oxidation was more rapid, giving 80% conversion already after 30 min and 95% conversion after 60 min without the formation of any byproducts.


  • Guest
Perchloric tallyWACKER
« Reply #6 on: October 20, 2004, 02:05:00 AM »
Hi Y'all!  Someone is willing to do research.

Perchloric Wacker

     The improved wack was done by my favorite harry primate: Max the bonobo, and no joke, he seriously went ape-shit over the results.  Not only was the molar % of Pd greatly reduced from previous times, but the amount of benzoquinone too was reduced which makes life a lot easier.   As many familiar with the benzo-wack know, the work-up is equally as important as the rxn for a pleasant outcome, so please take note of those details below or Max will throw some poop at you.

Based on the improved wacker article on Rhod's page:

 120 g safrole (.74 moles)
 1.66 g Pd(OAc)2 (1 molar %)
 72 g benzoquinone (90 molar %)
 19 g 70% perchloric acid
 440 mL acetonitrile
 60 mL water

     Pd(OAc)2 was stirred for 30 minutes (to ensure good dissolution) w/350 mL AcCN in a 3 neck 2 L rb.  Benzoquinone was added (endothermic), the funnel washed with 50 mL AcCN, and the solution was allowed to stir until temp climbed back up to ambient (~1 hr).  Perchloric acid was then gently poured in (.24 M at midpoint of saf. addition).  Flask was fitted with a condenser (not really necessary) and an addition funnel with 120 g safrole dissloved in 40 mL AcCN.  Addition was started at a healthy drip rate.  The flask heated up within minutes, but no condensate was ever noted in the condenser.  The flask was allowed to stir until it returned to room temperature (~2 hours).


     The reaction mix was filtered through an inch of packed, solvent-wetted celite (makes filtration very easy).  The filtrate was then poured into a 4 L separatory funnel and shaken with (.45 L conc. HCl + 200 mL brine + 800 mL water).  This is then extracted with 600, 300, 200, and 100 mL DCM, taking very great patience to allow a full as possible separation and with light agitation as it drains to knock DCM globs to the bottom.  Care was also taken to not allow the crud at the bottom edge of the water layer into the pooled DCM.  The DCM was then washed once with 500 mL sodium bicarbonate.  This is the main wash where product will be lost if not careful, so patience with the separation is very beneficial as well as maybe the addition of some brine (50-100 mL).  One can check that they got most all of their product by making sure that the total pooled DCM adds up to close to 1200 mL (DCM) + 110 mL ('tone) + ~150 mL more DCM (used to wash the rxn flask, filter funnel, and filter flask) or, alternatively one could back extract with a bit of DCM.  Next, the DCM/'tone is washed once with 500 mL brine and twice with 10% NaOH (again care and patience).  The DCM/'tone is then dried with mag. sulfate and distilled (24/40 regular vac. distill set-up pulls faster and potentially with more theoretical plates than a short path).  There is no noticable forerun of saf/isosaf, just straight bright neon-yellow/clearish 'tone (118 g) and a bit of black crap left in the flask.  Yield: 89.5%  The H'nMR looked very good, very clean. 

If only ya didn't have to do the washes, I think this modified wacker would get up to 95%.  Might asarone do as well or would the perchloric acid cause some issues?  Hmmm.....


  • Guest
It depends on your vac.
« Reply #7 on: October 23, 2004, 04:27:00 AM »
It depends on your vac.  Max's is somewhat crappy right now so it came over at ~130 +/-5 °C 

These questions are kinda more dependant from person to person and since I think you are mostly going to ask q's that only serve you, I think pm is the best way to converse.  Reduce the crap that peope have to filter when going through TFSE ya know. 

Anywayz, typically if you have good 'tone, it is yellow.  Double distilled 'tone is clear.  So, clear-ish/yellow 'tone from the first distillation would bee a good sign.  During distillation, normally with the regular benzo wack, one gets a few mL's of completely clear isosaf b4 the temp climbs a bit and the 'tone comes over.

Not the case with the perchloric version.... :P


  • Guest
please clarify for newbie this statement
« Reply #8 on: November 01, 2004, 08:25:00 PM »
from the workup
"The filtrate was then poured into a 4 L separatory funnel and shaken with (.45 L conc. HCl + 200 mL brine + 800 mL water"

does this mean all at once? or each of those separately? i know this is a stupid question, but .....i am new after all!

i am planning on testing this thursday....since my performics appear to suck on yields

thanks for the awesome research Dope_Amine!


  • Guest
Yea, all at once. One of the biggest problems...
« Reply #9 on: November 01, 2004, 10:00:00 PM »
Yea, all at once. 

One of the biggest problems with the benzo wacker is the work-up.  It can totally fuck your yields.  I absolutely do not recommend trying to scale up the 'tone without scaling up the washings also.  What is stated is barely enough to get it well clean enough for a good distillation- mainly refined by doing extra washes and realizing that they didn't do all that much.  In the future, it might bee decided to get rid of the bicarb wash altogether, cuz that's a real motherfucker on da yield....  Prolly, next time it'll bee dropped and we'll see how it goes.  If you wanna give it a try, then get rid of the bicarb wash and maybee do an extra brine wash or maybee not.  Then let us know.  Otherwize, we'll have to wait a while for the bonobo to do it (he's a busy primate). :P


  • Guest
good work
« Reply #10 on: November 09, 2004, 07:33:00 PM »
Congratulations, fine to read your work. A question about the distillation, in the regular benzo wacker with DMF, the range of temp is wide, about 25 C, and the distillate contains crystalline solids. The yield in the conversion of that ketone to aminee is low, so the real yield of ketone is not really good, 50-60 %. In your experience did you observe this winde range of temp in distillation and solid impurities or the rxn seems more clean ?


  • Guest
Thanks Sunlight! No solid impurities were...
« Reply #11 on: November 11, 2004, 06:28:00 PM »
Thanks Sunlight!

No solid impurities were noted. There wasn't much left in the distilling flask at all.  The temp range that it came over was ~10 °C. Unfortunately, the H-nMR taken was from darker yellow residue on the side of the distilling flask (Max was being a cheap-skate, won't do that again).

Was the DMF 'tone that you speak of that blue kind?  This 'tone was a very especially clear bright yellow.

I'm sure Max the bonobo would have done more tests by now if it weren't for the fact that his benzo supply has run dry...


  • Guest
« Reply #12 on: November 13, 2004, 12:08:00 PM »
It has been said reppeated times that ketone from benzo is fluorescent green, you can see pictures in Rhod's page, but what I saw was a yellow ketone, not specially different in colour from the ketone coming from performic.
Your experience sounds promising.