element109 (Hive Bee / Eraser)
07-11-01 02:21
No 189968
      Decarboxylation (sigh..)  Bookmark   

I was feeling good with the good spring weather so i decided that barium hydroxide must be the way to go for decarboxylating an alpha-amino acid, following the equation:

  R-CH(NH2)-COOH + Ba(OH)2 --> R-CH2-NH2 + BaCO3 + H2O

Works great for glycine to get methylamine, but unfortunately not for L-tryptophan:
5 gr L-tryptophan was dissolved in 200ml H2O containing 8 gr Ba(OH)2 and refluxed for 10 hours.
Dil. H2SO4 was added, BaSO4 filtered off (3 coffeefilters), and the yellow mother liquor basified with NaOH, a lousy hundred milligrams off grey material fell out of solution.

During reaction, BaCO3 should fall out of solution, and allows one to monitor the reaction to completeness.
But why wasn't there a rxn ? temperatures too low ?

Sigh.. Will buy myself another 50gr of L-tryptophan

(Hive Addict)
07-12-01 13:54
No 190200
      Re: Decarboxylation (sigh..)  Bookmark   

Do you have a reference for that reaction?
It would be a nice method for ethylamine from the corresponding amino acid

Do Your Part To Win The War
(Master Searcher)
07-12-01 17:53
No 190236
      Re: Decarboxylation (sigh..)  Bookmark   

Check out the part on tryptamine here.  Post 108611 (dormouse: "methylamine via glycine(Amino acid) (Page 1) -hellman", Novel Discourse)  It looks like a good thread on glycine decarboxylation, too.
Here's a reference I found.  Post 181072 (PolytheneSam: "Re: synthesis of ethylamine/isopropylamine", Stimulants)