Sciencemadness Discussion Board

Ideas needed - Decarboxylation of Amino Acids

un0me2 - 19-6-2010 at 17:20

I've been looking around for a while now and despite there being a lot on the decarboxylation of carboxylic acids to the alkane with one less carbon (or other strategies), or the decarboxylation of amino acids to nitriles/aldehydes...

I cannot find anything on the decarboxylation of amino acids to the relevant amine that don't use fairly high-end reducing agents (eg like so).

What I'd like to know, is if anyone here has any good ideas for the decarboxylation of y-aminobutyric acid or B-alanine to give n-propylamine or ethylamine respectively?

Best kudos going to simplest routes as usual, personally I think a thermal route using a ketone, but I may be wrong, it might be that the destructive distillation of the copper salt of the amino acid might be the better option...

I'm just looking to see if anyone else has considered it:cool:

Mildronate - 19-6-2010 at 23:51

To my mind its not cheap method. Some info http://www.erowid.org/archive/rhodium/chemistry/trp.decarbox...

gardenvariety - 20-6-2010 at 10:24

GABA isn't an alpha-amino, which might prevent the alpha-amino decarbox reactions from working the same way. I have some alanine that I will get around to turning into ethylamine, but haven't bothered yet. I had fairly good results on tryptophan with different enones, a bit better results from carvone than from pulegone.

The major problem with the ketone decarbox is the solubility of the amino acid. I haven't looked into it, but a PTC of some kind would be ideal.

Mildronate - 20-6-2010 at 12:42

But amino acids are expensive

gardenvariety - 20-6-2010 at 13:10

Amino acids are dirt-cheap and readily available in most any biomass on the planet.

Nicodem - 20-6-2010 at 13:29

Quote: Originally posted by un0me2  
What I'd like to know, is if anyone here has any good ideas for the decarboxylation of y-aminobutyric acid or B-alanine to give n-propylamine or ethylamine respectively?

Best kudos going to simplest routes as usual, personally I think a thermal route using a ketone, but I may be wrong, it might be that the destructive distillation of the copper salt of the amino acid might be the better option...

You can not use any such thermal route, with a ketone catalyst or without it, because gamma-aminobutyric acid and beta-alanine are not alpha-amino acids (obviously, their names already say so!). So the imines they form with the ketones can not lead to decarboxylation. Though, in principle at least, due to a particular tautomerization property of imines (C=N-CH <=> CH-N=C), the imines of beta-amino acids might decarboxylate via the beta-imino carboxylic acid intermediates, but I have never seen this mentioned in the literature (but neither have I searched).
The only decarboxylation reaction that is general for many types of carboxylic acids (provided the other functional groups are properly protected for the steps involved) is the Barton decarboxylation. The primary amino groups needs to be protected.

solo - 20-6-2010 at 13:55

...this might help,...solo
--------------------------------------------------------
One-pot Sequence for the Decarboxylation of a-Amino Acids
Bernard T. Golding
Synlett
2003, No. 4, 542–546




Abstract:
Treatment of an α-amino acid with N-bromosuccinimide
in water at pH 5 or in an alcoholic-aqueous ammonium chloride
mixture, followed by addition of nickel(II) chloride and sodium
borohydride, effected an overall decarboxylation via an intermediate
nitrile to afford the corresponding amine in good yield.

Key words: α-amino acid, nitrile, amine, decarboxylation

Attachment: aminoacid.decarboxylation.pdf (66kB)
This file has been downloaded 756 times

Nicodem - 20-6-2010 at 14:00

Solo, that is the paper linked in the original first post by un0me2, but unfortunately it has no relevance for his question (decarboxylation of beta- and gamma-amino acids), because it is a procedure that can only work on some alpha-amino acids (see the mechanism).

zed - 20-6-2010 at 20:54

So, there....Decarboxylation of Beta- Aminoacids, isn't very likely. However, if you wish to produce Ethylamine from ordinary Alanine, you probably can. Also, to my recollection, B-Alanine is spendy, and Alanine itself is quite inexpensive.

B-Alanine is sometimes offered for sale as a bodybuilding supplement, which may in some locales, make it more easily accessible than ordinary Alanine.....