dormouse (Member)
04-23-00 05:25
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      MDP2P by electrochemical oxidation -Osmium  Bookmark   


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Author  Topic:   MDP2P by electrochemical oxidation 
Osmium
PimpBee   posted 07-23-99 11:24 AM          
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I think Rhodium has some electrochemical oxidations on his site, and Fester mentioned them in his LSD book, too. Here's another one, oxidation of safrole in H2O/acetonitrile at ambient temp, with PdCl2 and tri(4-bromophenyl)amine catalysts.
Chem. Lett. 1994, 121-124

These procedures all look pretty good on paper. Why isn't anybody using them?
Oh yes, yield 85%.


gyrogearloose
Worker Bee   posted 07-24-99 02:10 AM          
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post a proceedure that I can read and I will try it and post results, how about that?


Osmium
PimpBee   posted 07-26-99 05:27 AM          
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Is that all you bees have to say about it after one weekend? Shame on you!
gyro:
Sorry, can't get that ref right now. Maybe somebody else was interested and got that ref?

Check out Rhodium's site, there are a few high-yielding electro-epoxidations.


sunlight
Worker Bee   posted 07-26-99 06:16 AM          
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I guess that most of us use to spend the weekends to taste our favorites cakes, specially in summer
 
Slappy
PimpBee   posted 07-26-99 06:54 AM          
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Os: Hey, as soon as I can get to the library, I'll take a look at it. After all, it IS summer, and most libraries (mine) has cutback their hours. However, until then, I can't say anything about it besides it looks real nice! (Unless you want to change that by posting it <wink> )
 
Osmium
PimpBee   posted 07-26-99 07:06 AM          
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No honey and cake for this bee but the daily GHB.
Anybody has some empty vials and baggies left where O. can scrape the last milligrams out?
 
sunlight
Worker Bee   posted 07-27-99 05:24 AM          
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Are you kidding Osmium ? Seriously, it would be a pleasure to help you.
 
rev drone
Worker Bee   posted 07-27-99 11:43 AM          
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Os,
My guess is two things: that organic chemists generally don't like electrolytic chemistry, for the most part, and that among chemhacks, those terminal epoxides can be a little intimidating in their percieved fussiness. As organic chemists, we're not trained extensively in electrocemistry (as far as I know, I'm the only one among my peers with any lab experience with this stuff), and even most well-funded organic research labs don't have the equipment. Most other chemists I know are a little suspicious of it; yes, these feeling aren't rational, but that's how most organic chemists I know are "brought up".

Yes, by eliminating the need for more expensive oxidizing reagents, electrolytic reactions can be both more economical and environmentally friendly. Yes, the chemistry is straight-forward, and yes electrolytic processes give chemists a unique control over the reactin conditions. But still, there is s distrust for it. Wierd, huh?

So, without the suport of a few well-placed eggheads to push this method, it sits there looking sad and negected. However, with the right attemtion and promotion from a few prominent bees, a method with this much "potential" (nerd joke) could really become a hit.

And one last thing: what method of isomerization would you suggest? There is a lot of mentioning of using LiI as a catalyst, but certainly a less exotic solution must be out there (yes, LiI isn't that strange, but its a damn far cry from being OTC as well.)

------------------
-the good reverend drone


 
Osmium
PimpBee   posted 07-27-99 02:58 PM          
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LiBr is cheaper and will work, too. I think I remember that all iodides catalyse the rearrangement. Not 100% sure though.
The epoxide can be rearranged by distilling under a bad vacuum (heat will rearrange it). BF3 should work, too. But it's not quite otc either.

Sunlight: do I smell bacon?


anonymous
Worker Bee   posted 07-27-99 08:55 PM          
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I got the article today. I'll try to post it in full in the next 24 hours or so. Untill then the article actualy uses the conversion of safrole to MDP-2-P as an example. The yeilds were 57% using a "divided cell" and 85% using a "undevided cell".
anonymous


Osmium
PimpBee   posted 07-28-99 03:35 AM          
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sunlight: if I only had your email...
 
sunlight
Worker Bee   posted 07-28-99 03:37 AM          
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Osmium, I e-mailed you to your old lycaeum account, but it does not work, just e-mail me and I'll try to make you happy.
 
Osmium
PimpBee   posted 07-28-99 05:42 AM          
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Really smells like bacon here...
What's your email?


rev drone
Worker Bee   posted 07-28-99 12:53 PM          
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Os,
You wouldn't catalyze the rearrangement with BF3 or any other strong Lewis acid if you were sentimental about keeing that methylenedioxy bridge intact.
How exactly would you explain the mechanism of the LiBr-catalyzed isomerization?


------------------
-the good reverend drone


 
Osmium
PimpBee   posted 07-29-99 02:08 PM          
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Good question, I have no idea right now. I remember I found something about it in Houben-Weyl several years ago, maybe when I find some free time soon I'll check that again.
 
sunlight
Worker Bee   posted 07-30-99 08:09 AM          
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Osmium, please confirm that I've received a mail from you, and everything will happen.
 
Osmium
PimpBee   posted 07-30-99 01:03 PM          
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Yes you did. I will generate a new key soon and confirm it here, too.
My old keys which some bees might still have is no longer valid. In my innumerable OS "improvements" from Win95 to Win98, back to Win95, then Linux, BSD, another version of Linux and finally Win98 with Linux, both on one HD, my old keys got somehow lost. Properly running fdisk is not one of my god-given abilities, especially at 4.00am. It might still exist somewhere in that big mess of backup disks, but I guess I don't remember the passphrase either.  (It was about 20 random characters long and didn't resemble any real language)

So in case I'll post a fingerprint soon and some bees can't confirm it, don't freak out.

The other bees I emailed recently, please take note of this, too. My personal security measures don't allow me to work with mcaffeemail, hushmail etc. and I don't plan to change that, since IMHO they don't offer more security. If you insist we can use PGP, too, but my answers will be delayed since I don't post from home. I only use public computers which do not have PGP installed.


CHEM GUY
Worker Bee   posted 07-30-99 03:52 PM          
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How nice this is,...
It seems now you can oxidize a safrole like compound into a MDP2P-like compound. Then you can switch compartments of the electrocell and reduce the MDP2P to an amine compound, in just over the course of hours.

ARE THERE ANY OTHER REFERENCES LURKING OUT THERE FOR THIS?

What other conditions could one employ? Ones that are perhaps more viable and cheap.


rev drone
Worker Bee   posted 08-01-99 05:08 AM          
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Hm,
If one used a super-clean Wacker electrolytic oxidation, tossed in some dehydrating agent, then ammonia or methylamine, then switched the poles on the cell, you really could do it in one step.

The problem is that electrolytic reactors aren't all that clean, and if you got a bunch of crud in there, you're really going to foul things up.

------------------
-the good reverend drone


 
CHEM GUY
Worker Bee   posted 08-08-99 04:45 PM          
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Rev drone,
Are you saying that you CAN put in a wacker oxidation reagent and electrolyticly produce the ketone without having to reflux the exopide intermidiate?
 
CHEM GUY
Worker Bee   posted 08-08-99 04:48 PM          
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To make this clearer,
Have you done it?
Also, can you aminate without an isolation step?


rev drone
Worker Bee   posted 08-09-99 12:24 PM          
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CHEM GUY,
The Wacker doesn't go through an epoxide intermediate (or at least, not much. It is one of several mechanistic pathways that've been found, but I'm trying not to confuse you, so forget I even mentioned it), and yes, you can do it electrolyticly -- that's one variation of this multi-purpose WunderReaktion. The very definition of the Wacker oxidation is that it makes ketone, spoecifically alpha-methyl ketones from terminal olefins, as the final product. Epoxides aren't really a concern.

I've never said that amination without isolation was a metaphysical reality, though I certainly wish it were, and I can see the potential for it to be feasible. It *may* be possible, but I know of no written procedure for it -- no matter what you do, it seems the Wacker makes a lot of byproducts, and these will interfere.


------------------
-the good reverend drone


 
CHEM GUY
Worker Bee   posted 12-29-1999 10:22 PM          
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From "Chemistry Letters", page 121-124, yr 1994
"Table 2 Electrochemical Wacker Process with a Combination of Pd(OAc)2 or PdCl2 and (4-BrC6H4)3N in a Divided or an Undivided Cell a)

Substrate / Products / Yeilds- divided / Yeild undivided

[Safrole] / MDP2P / 57 / 85
...
a) Reaction carried out by useing substrates 1 (1 mmol) and Pd(OAc)2 (divided) or PdCl2 (Undivided) (0.05 mmol) in an MeCN-H2O (7:1)-0.5 M Et4NOTs-(Pt)-(Pt) system at room tempapture for 2.0-3.0 F/mol of electricity.
"
"Table 1. Electrochemical Wacker Oxidation of 1-Undecene (1a) with Organic Mediators a)
Organic Mediator / Products Yeild [ of methyl ketone]
(Br-C6H4)3N / 39
...
HO-C6H4-OH / 27

a) Reaction carried out in a CH3CN/H2O (9:1 V/V, 10 mL)-Et4NOTs-(Pt)-(Pt) system in the presence of Pd(OAc)2 (5 mol %) and an organic mediator (20 mol%) at room tempature (20 C) in a divided cell. Conditions: 3.0 V (0.4-5.5 mA); Electricity charged: 2.5 -3.0 F/mol."

I found this article: Journal of Applied Electrochemistry, 14, yr 1984, page 779-790
It uses iron chloride as the recycler of PdCl and uses an aqueous medium, with no organic co-solvent. Really quickly the article states that the reaction works well with an FeCl3 concentration at and below .5 mol per liter at 35 C, and with .3 mol HClO4- (510 mA per gram Pd and above). It states later, "Presumably, dilute sulfuric acid could replace the perchloroc acid used in this study."
Also the oil and the electrolyte solution are not miscilble nor is the ketone in this study, so they study the dispersing methods and their efficiencies as well. In short the finer the emulsion the better the effeciency and reaction rate.
Higher the tempature the higher the oxidation rate as well.'

In short the wacker oxidation of a safrole like compound could take place in a dilute sulfuric acid electro-cell, with PdCl2

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Everything in this post is for informational purposes only, and is not intended to facilitate illegal activity. I've done nothing illegal and nor should you.


 
Catechol
Worker Bee   posted 12-30-1999 04:39 AM          
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alpha-methyl ketones from terminal olefins, as the final product. Epoxides aren't really a concern
If the xdroid thinks it works and due to similiarties in the poster I am gona go w/ silver dollar, I think maybe a nickel would work also I have red the information is all ove th place
Please what is a terminal oilifin?


Niels Bohr
Worker Bee   posted 12-30-1999 09:25 PM          
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This looks like quite a novel process.
But what the hell is: Et4NOTs-(Pt)-(Pt) ??? tetraethyl tosylate platinum electrode?

What??? Did you make a typo here?


Stonium
Worker Bee   posted 12-31-1999 01:49 PM          
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Gawd! You guys with all your chemie talk. It's such a sexual turn-on!
Sorry for letting that slip out there. Just lost control for a moment...

Stonium


CHEM GUY
Worker Bee   posted 12-31-1999 03:14 PM          
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Not a typo. It refers to the electrode material and whatnot, but it full meaning is unapperant to me, a self-taught chemist. I only included it because I was quoting.
I will quote the paper some more to illumianate the subject.

From "Chemistry Letters", page 121-124, yr 1994

" The electrolyses were carried out either in a divided or undivided cell under a constant applied voltage. Typically, the electroysis in an undivided cell was performed by useing the substrate ( 1 mmol), PdCl2 (5 mol%), and (4-BrC6H4)3-N (5 mol%) in an MeCN-H2O (7:1)-(Pt)-(Pt) system at an applied voltage of 3 V, current 2-3 mA for 2-3F/mol, giving the desired methyl ketones. The results of the electrochemical Wacker oxidations are given in Table 2."


psychokitty
Worker Bee   posted 01-02-2000 06:17 PM          
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On Rhodium's page under the segment describing the wacker oxidation of asarone, I listed several Tetrahedron Letters articles that specifically focus on the electro-oxidation of safrole and its 1,2-halohydrin to MD-P2P.
I don't have the actual articles on hand so someone else will have to look them up.

--PK


psychokitty
Worker Bee   posted 01-02-2000 06:33 PM          
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Catechol: Safrole is an olefin and more specifically, it has an allylbenzene structure. The reason that it is referred to as being "terminal" is due to the fact that its double bond is located at the far end of the side chain.
If instead the side chain were conjugated to the benzene ring (in other words if it was as close to benzene ring as it possibly could be) then the olefin in this case would be "internal" making it a propenylbenzene (specifically named isosafrole).

Olefins:

Allylbenzene = safrole.

Propenylbenzene = isosafrole

To understand all of this better I recommend you look up safrole and isosafrole in the Merck index in order to more specifically identify their structures.

Hope this has been of some help.

--PK


Osmium
PimpBee   posted 01-03-2000 06:44 AM          
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NB and others who are wondering:
Et4NOTs-(Pt)-(Pt) ??? tetraethyl tosylate platinum electrode?

No, it's an electrolysis performed with two Pt electrodes (both cathode and anode are made from Pt), and the electrolyte is tetraethylammonium tosylate.

Stoni: SMOOCH. I love it when you talk like that. But not when the others are around.


Niels Bohr
Worker Bee   posted 01-03-2000 09:47 PM          
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Thanks Osmium - I know little to nothing about electrolytic reactions :O
I went to the library the other day to get the full text of the paper, and I found a most interesting claim in the citation:

[QUOTE] Up to 50 turnover of the palladium catalyst could be achieved without noticeable loss of activity of the electrolysis system [QUOTE]

Beat that!!

The Tri(4-bromophenyl)amine or the tetraethylammonium tosylate electrolyte solution are hardly OTC and would be inconvenient to obtain for the average bee, but would be worth the trouble of acquiring for the fact that one could save so much money on palladium catalyst - the platinum electrodes notwithstanding. Maybe something other than platinum could be used here. Any expert opinions out there? Rev Drone?

Furthermore (as stated above), there was an 85% yield of the desired ketone.

The authors also don't mention any undesirable side products for the safrole, like some of the other olefins that they oxidized under similiar reaction conditions.


Niels Bohr
Worker Bee   posted 01-03-2000 11:11 PM          
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shit - how can I get an undivided electrolytic cell to work when I can't even use UBB codes correctly!?! o:


Semtex Enigma
Worker Bee   posted 01-04-2000 01:27 AM          
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Would Pt plated electrodes work? Would save a lot of cash...
 
Osmium
PimpBee   posted 01-04-2000 05:17 AM          
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Niels: check those European patents Rhod has on his site. They use NaBr as the electrolyte, and aq. MeCN or DMF as the solvent. Apparently you don't need Pt electrodes either. Look at those yields! http://rhodium.lycaeum.org/chemistry/guest.phenylacetone.txt 
 
Osmium
PimpBee   posted 01-04-2000 05:20 AM          
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Graphite anodes, and stainless cathodes. It doesn't get any cheaper than that.


CHEM GUY
Worker Bee   posted 01-04-2000 12:25 PM          
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In the Chem Lett. paper they list another mediator other than (BrC6H4)3N; they also used HO-C6H4-OH, which is easily made or obtained. It's yields aren't as good, but still respectable.
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Everything in this post is for informational purposes only, and is not intended to facilitate illegal activity. I've done nothing illegal and nor should you.


 
Niels Bohr
Worker Bee   posted 01-04-2000 05:58 PM          
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Os: I am assuming that that proposed oxidation in the patent that you refrenced would be friendly to the methylenedioxy bridge in safrole. They were dealing with dimethoxyphenylacetone in the patent.
It probably is since the oxidation has a similiar mechanism as the one in the Chemistry Letters citation.

I'm assuming that the oxygen in these electrolytic reactions is comming from water (i.e. 7:1 MeCN/H2O). Am I right?


Osmium
PimpBee   posted 01-05-2000 06:08 AM          
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IMHO the methylenedioxy is fully compatible with this kind of reaction.
Yes, the oxygen is supplied by the water. I'm totally clueless how this reaction works, one possibility could be a direct epoxidation, although I guess that's unlikely. Another possibility would be the formation of bromine by the electrolysis which produces a bromohydrin intermediate, which cyclizises to produce the epoxide. Does anybody have an explanation for the reaction mechanism?


CHEM GUY
Worker Bee   posted 01-05-2000 07:44 PM          
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Reaction mechanism for which electrolysis?
The one from the Chem Lett paper IS a Wacker process. The electrolysis only recycles the Pd(0) back into Pd(+2).

The patent on the other hand could be anything. I have found very little in hand research about electrolytic epoxidation. But you are probably correct about the Br thing because Br is seems to be the necessary ingredient.

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Everything in this post is for informational purposes only, and is not intended to facilitate illegal activity. I've done nothing illegal and nor should you.


 
CHEM GUY
Worker Bee   posted 01-05-2000 10:14 PM          
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A little quote from Journal of Applied Electrochemistry, 14, yr 1984,
page 779-790. It concerns the electro-Wacker oxidation with FeCl2/FeCl3.
"4. Conclusion

This electrochemical chloropalladate process looks promising for small
plants converting C4 and higher linear olefins to the corresponding
ketones, cases where the corresponding air oxidation process has not
been commercialized. The advantage of the electrochemical process lies
in its avoidance of excess chloride, which leads to slow rates and
chlorinated by-products. The process has been demonstrated in a
continous labatory unit with good current selectivities and
maintainance of high catalytic activity. The cost remains to be
investigated. It is known that the palladium inventory can be very
low, the electrode cost and material of construction have not been
determined. The details of product recovery via extraction or
stripping would have to be worked out for each olefin one desires to
oxidize. Further studies would also have to be carried out to choose
the optimium acid type and concentration based on considerations of
safety and total cell voltage drop. Presumably, dilute sulphuric acid
could replace the perchloric acid used in this study. Cells would
have to be designed to optimize the current densities for the ferrous
oxidation, to reduce the cathodic reduction of ferric ion and to
minimize the voltage drop. None of these problems appear to present
any great difficulties."

------------------
Everything in this post is for informational purposes only, and is not intended to facilitate illegal activity. I've done nothing illegal and nor should you.


 
Semtex Enigma
Worker Bee   posted 01-07-2000 01:03 AM          
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Anyone know how to get ahold of Fester? I remember hearing something about this kind of thing(I think it was from Boz) before the advanced book of his came out. Being in the electro-chem industry he might be able to offer some help in any means...
 
psychokitty
Worker Bee   posted 01-08-2000 11:55 AM          
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His e-mail address is located under the George magazine article thread.


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