I used L-Histidine and L-Tyrosine as coupling agent for azo coupling reaction and sodium hydroxide solution to adjust pH. Although color change was observed during the coupling, no precipitate occurred after saturating with water.
Dear Baris Sezgin
I coincide with Frank T. Edelmann and Corentin Lefebvre . I work on the preparation of different azo compounds. Please, you need to optimize your procedure.
All the best
Dear Baris Sezgin,
Your coupling seems very difficult to carry out... Addition of NaOH may allow for deprotonation of hydroxyl group of tyrosine molecule (maybe the colour change you see in your reaction) and without protecting group on selected amino groups and previous formation of diazo desired compounds it might your reaction not occurs... If I think it's right, converting an amino-acid like histidine to diazo compound must not be straightforward with conventionnal method. As Prof. Frank T. Edelmann asked you, litterature on your reaction would be helpful for helping you solving this problem.
Dear Baris Sezgin
I coincide with Frank T. Edelmann and Corentin Lefebvre . I work on the preparation of different azo compounds. Please, you need to optimize your procedure.
All the best
Dear Baris Sezgin
I think you need to protect the NH2 group of the amino acid to avoide nucleophilic attack to the diazonium salt.
Dear Baris Sezgin, did you solve the problem in the meantime? If not, it would be very helpful if you could provide a schematic formula drawing of your reaction sequence. Chances are that you will then get more helpful and more specific answers from other RG members.
Dear Baris Sezgin thank you again for your very interesting question. I did a Scifinder search for the compound derived from diazotized aniline and tyrosine.
The search revealed only two papers:
1. The anatomy of an antigen molecule: Functional subregions of l-tyrosine-p-azobenzenearsonate
Article The anatomy of an antigen molecule: Functional subregions of...
Unfortunately this article doesn't have an experimental section.
2. SYNTHESIS, CHARACTERIZATION AND ANTIBACTERIAL SCREENING OF AZO COMPOUNDS CONTAINING TYROSINE MOIETY
https://www.wjpps.com/Wjpps_controller/abstract_id/5249
Unfortunately I was unable to download the full text. Here is at least the Abstract:
ABSTRACT
Synthesis of most azo compounds involves diazotization of a primary aromatic amine, followed by coupling with one or more nucleophiles. Thus, benzoic, phenolic, salicylic and naphtholic compounds acts as nucleophiles and undergoes coupling reactions. In this study, a series of azo compounds were synthesized with excellent yields via the diazotization of different aromatic amines followed by coupling with Tyrosine, which is a phenol as well as amino acid. These compounds were characterized by elemental analysis, IR, 1HNMR and MASS spectroscopic techniques. The synthesized compounds have been tested in vitro against human pathogens in order to assess their antibacterial properties using disk diffusion method. The compounds analysed for its antibacterial action showed moderate to extraordinary inhibitory effect at most of the concentrations against all the tested pathogens.
Please note that this article has appeared in a somewhat obscure journal. Thus there is no guarantee that these compounds are real. Apparently the synthesis of amino acid-derived azo compounds is not a trivial task.
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