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Author: Subject: REDUCTIVE AMINATION
azo
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[*] posted on 5-5-2010 at 03:54
REDUCTIVE AMINATION


I have recently looked at the direct reductive amination of aldehydes and ketones using potassium formate as the reductant and palladium acetate as the catylist and DMF as the solvent . It appeares to me this could be a viable method due to the lower cost of reagents as well as the less toxic bi products left after reaction contents being
decomposed .As well as the low temperatures needed and lower reduction times.This method also gives high yields and can be done on a large scale .Unlike the leuckart reaction or the wallach no n formyl products are formed and is suitable for both primary, secondary aliphatic and aromatic amines .Has anyone used this method that could add to this and provide further information.



REGARDS azo :cool:

[Edited on 5-5-2010 by azo]
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hissingnoise
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[*] posted on 5-5-2010 at 04:29


Use lower case letters if you want your posts read. . .

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mr.crow
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[*] posted on 5-5-2010 at 06:51


Usually Azo's posts are intelligent, I don't know what happened



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Arrhenius
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[*] posted on 5-5-2010 at 23:31


Can you draw a mechanism for this reaction? I don't have any experience with this, but I presume a palladium hydride species is formed in situ with concomitant evolution of CO2. I don't know what the fate of the potassium ion is, but realistically this reaction needs to be air-free in order to effectively form Pd(0). Honestly, if a method isn't commonly used, it probably doesn't work that great. Not knowing what you intend to reductively aminate, I would strongly suggest using a known procedure such as imine formation followed by reduction with sodium borohydride or hydrogenation, or in situ reductive amination with sodium triacetoxyborohydride (can prepare it yourself from NaBH4 + 3AcOH). I'm presuming you don't really care about scalability. Anyway... imine formation is favorable, and they're hydrogenated easily with Pd/C, perhaps urushibara catalyst if you have faith in that stuff..
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JohnWW
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[*] posted on 6-5-2010 at 06:26


Where does the N for the -NH2 groups (or substituted -NH2 groups) for the amination come from? There is no N in aldehydes, ketones, HCOOK, Pd(CH3COO)2; while the DMF (dimethyl formamide) is supposed to be only a solvent, not an actual reagent. Azo must have omitted a reagent in his above post.
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azo
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[*] posted on 7-5-2010 at 16:09


http://superkuh.ath.cx/users/superkuh/Library/000-Chem/



johnwww here is the site where you can find this protocol


regards azo

[Edited on 8-5-2010 by azo]

[Edited on 8-5-2010 by azo]
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Barium
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[*] posted on 18-5-2010 at 08:15


Quote: Originally posted by Arrhenius  
I presume a palladium hydride species is formed in situ with concomitant evolution of CO2. I don't know what the fate of the potassium ion is, but realistically this reaction needs to be air-free in order to effectively form Pd(0).



It is the same mechanism behind this reductive alkylation as if a, more commonly used, pressurised catalytic hydrogenation with in situ imine formation is used. Potassium usually precipitates as potassium bicarbonate as end product and no, the system can very well be open to the atmosphere.
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