Author Topic: "Mn(III)-Catalyzed Aromatic Acetonylation" (Read 324 times)

timecube · « **on:** February 06, 2010, 12:12:39 PM »

http://www.erowid.org/archive/rhodium/chemistry/p2p.manganese.html

This reaction has always seemed to have a lot of potential to me, despite the relatively low yields. Particularly interesting is that it works on 1,4-dimethoxybenzene to give the corresponding 2,5-di-MeO-P2P.

My questions are on practicality. Does anyone here have any actual experience with it? The only suggestion of clandestine attempts I've been able to locate at all is Antoncho's Manganese(III) Acetate workup. He may still be at hyperlab now, so I may try to track him down.

What purpose does the inert atmosphere serve? I assume it's to let the Mn3+ do its radical makin' business rather than promoting full oxidation. Is there a practical way to accomplish this for those of us without argon tanks sitting around our labs? I was thinking about the continuous addition of a volatile solvent in the reaction mix that could then displace the air in the reaction flask. I'm not sure how effective that would be though, or if there would be problems with bumping.

It seems interesting, but I have to imagine there's some reason why it doesn't get brought up very often.

coincoin · « **Reply #1 on:** June 09, 2010, 11:02:08 AM »

Inert atmosphere seems to be useless in that reaction...well according to some russian articles

2bfrank · « **Reply #2 on:** June 10, 2010, 08:26:30 AM »

@coincoin, could you attach those russian articles, or cite the name of the articles, so that someone could look them up. Merely stating what you have stated, without backing it up with literature, especially in light of the reaction itself having links to articles etc, is somewhat frustrating.

coincoin · « **Reply #3 on:** December 24, 2010, 07:40:50 AM »

Well the articles has been translated from russian to english by the guys at Wetdreams (Evils lurker, post
"Our russian Komrads have been busy... ")... it's a 2005 post but i'm wondering if there's been any advances since then. (pm me if you can't find it)

Indeed the yields are really poor even with permanganate in situ regeneration. IS there a way one can be posted with the last outcomes from this method ...or just any new method / development. I intend to post a resume of the many methods but I wonder if that's worth the effort. I'm afraid this is the kind of post that would be lost in the mess... just too many post you gotta take a look at when you want to get the latest news. And few of them a really relevant.

Any idea ?

atara · « **Reply #4 on:** December 25, 2010, 06:07:35 PM »

Does excess manganese acetate improve yield with respect to the arene? I can't imagine manganese acetate is too hard to obtain.

Also, I'm very surprised the reaction has never been tried with O-methylsesamol or benzodioxole.

coincoin · « **Reply #5 on:** December 28, 2010, 05:44:30 PM »

No manganese acetate has to remain at low concentration in the solution as higher concentration are favorising side reactions... and waht would be the products of such a reaction (with methylsesamol or benzodioxole) ?

akcom · « **Reply #6 on:** December 28, 2010, 09:23:36 PM »

Not sure about methylsesamol but with benzodioxole you would get (among other things) MDP2P

jon · « **Reply #7 on:** December 28, 2010, 10:18:36 PM »

hey what are the stated yeilds anyway?

atara · « **Reply #8 on:** December 30, 2010, 03:47:48 AM »

Methylsesamol would give 3,4-methylenedioxy-6-methoxyphenyl-2-propanone, the immediate precursor to MMDA-2, along with the positional isomer 2,3-methylenedioxy-6-methoxyphenyl-2-propanone, which may prove difficult to separate.

Quote from: jon on December 28, 2010, 10:18:36 PM

hey what are the stated yeilds anyway?

Around 39% for 2,5-dmp2p, higher for some other benzenes.

jon · « **Reply #9 on:** December 30, 2010, 04:07:05 AM »

that's pretty good for a simple process like that.

coincoin · « **Reply #10 on:** January 02, 2011, 01:38:52 PM »

Yields based on what ? if on MnAcetate concentration that means low yield...

Sedit · « **Reply #11 on:** January 02, 2011, 06:38:18 PM »

I can't help but wounder about many other single electron oxidizers out there and if they would work here. Iron persulfate seems like one of the simplest to test over the counter while other materials such as Lead tetraacetate may work as well. I have made a thread over at Wet Dreams sometime back detailing a few different single electron oxidizers in an attempt at performing a radical ring closure on Vanillin. What really makes me think is the idea of using a modification of the Kolbe electrolysis to affect this reaction since that in itself is nothing more then a single electron transfer forming a radical just like this reaction.

atara · « **Reply #12 on:** January 02, 2011, 10:21:31 PM »

Silver (II) or Cerium (IV) might work. Neither is as easy to obtain as Manganese (III), though.

timecube · « **Reply #13 on:** January 10, 2011, 05:20:02 AM »

The yields are based on the reacted manganese(III) acetate, so that isn't particularly great.

There is a curious line on the page that reads: "As this almost five-fold increase in concentration only gave a 4% reduction in yield, there is reason to believe that the very large excesses of reactants are necessary for a successful reaction."

I can only assume he meant very large excesses of reactants are NOT necessary.

He is referring to:

39g benzene, 58g acetone, 100ml GAA, 26.8g Mn(III)AcO -> 36% yield P2P
Vinogradov, M. G., Verenchikov, S.P., Nikishin, G. I., Izv. Akad. Nauk. SSSR, Ser. Khim. (7) 1674 (1972)

vs

150ml benzene, 150ml acetone, 250ml GAA, 13.4g Mn(III)AcO -> 40% yield P2P
M. E. Kurz, V. Baru, and P-N. Nguyen, Journal of Organic Chemistry 49, 1603-1607 (1984)

That's actually a 10% decrease in yield (4 percentage points) which is still marginally promising but nothing to get too worked up over as far as P2P is concerned. The reactants are recoverable and accessible, but it's all going to take a while (or lots of huge glassware.)

That's why I was primarily interested in its usage for 2,5-Meo-P2P since a couple grams of it is a decent bit. The more I look at it, though, the more sense just synthing nitroethane makes.

akcom · « **Reply #14 on:** January 10, 2011, 06:15:50 AM »

When you mention synthesizing EtNO2, are you refering to the benzaldehyde route?

jon · « **Reply #15 on:** January 10, 2011, 08:04:15 AM »

2,5 meo p2p would be the shizz for sure.

timecube · « **Reply #16 on:** January 11, 2011, 08:04:59 AM »

@akcom: yes, which is of course considerably simpler for P2P and 2,5-Meo-P2P, although I'm still convinced there is some way to get from the chloromethylation of benzodioxole [1] to piperonal without having to need 2-nitropropane by hydrolyzing to piperonol and then using any of a number of ways to get to the aldehyde.

[1]: http://www.erowid.org/archive/rhodium/chemistry/piperonal.nitronate.html

Author Topic: "Mn(III)-Catalyzed Aromatic Acetonylation" (Read 324 times)

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