chrisbob44
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Oxidation to nitriles...
So recently I ran into these articles, and was wondering if someone could elucidate the mechanism at work here...
http://www.erowid.org/archive/rhodium/pdf/aminoacid.decarbox...
http://www.organic-chemistry.org/abstracts/lit2/979.shtm
I ran into the organic-chemistry article first, and was kinda skeptical (the article came out of Iran...), but then I ran into this erowid rhodium
archive article, and my interest was piqued... I was imagining something that involved the amine being pushed to a higher oxidation state, but quite
frankly I'm pulling that out of my ass, so any help would be appreciated.
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kristofvagyok
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The mechanism is that the NBS brominates the amine what will immediately form an imine while a HBr eliminates from with a hydrogen from the alpha
position, this will cause the decarboxylation of the COOH, what is followed by another bromiation what will go on the imine what will release a HBr
and the nitrile is formed woala.
Same works at the TCCA method.
But, nitriles are usually formed by much easier reactions:
subtitution (halogen and nitrile)
dehydration of an amide with P2O5, SOCl2, POCl3 ect. (just made some trifluroacetonitrile from trifluroacetamide and P2O5, it is an awesome rxn  )
from amides with grignards
from aldehydes with hydroxylamine
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turd
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The Iranian article was posted in the "References" section and IIRC it contains a putative reaction mechanism. My uneducated guess would likewise be
chlorination of the amine and elimination.
Being skeptic is advisable, and the best method would be to try it. Benzyl bromides are easily made (https://www.sciencemadness.org/whisper/viewthread.php?tid=11... ; IIRC the original Monatshefte article is floating around somewhere on this
board) from OTC materials. You would do the community a huge favor
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chrisbob44
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Don't have glassware mate  As a first year chem student, I'm damn broke, but
when I do slop some funds together, I promise this'll be on the top of my beaker list.
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UnintentionalChaos
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See also www.sciencemadness.org/talk/files.php?pid=216672&aid=153...
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chrisbob44
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Quote: Originally posted by kristofvagyok  | The mechanism is that the NBS brominates the amine what will immediately form an imine while a HBr eliminates from with a hydrogen from the alpha
position, this will cause the decarboxylation of the COOH, what is followed by another bromiation what will go on the imine what will release a HBr
and the nitrile is formed woala.
Same works at the TCCA method. |
You explained the NBS method, but the TCCA method also oxidizes alcohols to nitriles... How is the N introduced?
[Edited on 9-12-2012 by chrisbob44]
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oldflattop
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It's a very useful paper. Thanks for bringing it to my attention. The mechanism of nitrile formation is assumed (by the authors) to proceed via imine
formation as shown in 'Scheme 2' (the reaction is conducted in ammonia):
Attachment: s-0029-1218827.pdf (115kB)
This file has been downloaded 2238 times
[Edited on 10-12-2012 by oldflattop]
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