Hi. I am final year student doing my researh project in synthesis of schiff base by using phenylalanine and terephthaldehyde. Since, i did not get the precipitate even after i'm using reflux method so, i'm confius either there are specific condition reaction that amino acid schiff base required or is it same with the common schiff base? And is that compulsory to add KOH or NaOH for the synthesis?
My recommendation would be to reflux phenylalanine and terephthaldehyde in dichloromethane and add molecular sieves to absorb water byproduct.
You dont need to add base in this method.
You can try using few drops of acetic acid instead of KOH o NaOH which will prevent the salt formation of amino acid during Schiff,s base formation.
Dear Fatin,
thanks for sharing this very interesting chemical question with the RG community. Apparently, adding catalytic amounts of NaOH or KOH is common in the synthesis of Schiff bases derived from amino acids. For example, please see the following useful article in which Schiff bases derived from phenlalanine are reported:
Synthesis and characterization of amino acid (phenylalanine) schiff bases and their metal complexes
Article Synthesis and characterization of amino acid (phenylalanine)...
Fortunately this article has been posted as public full text on RG so that it can be downloaded as pdf file. The authors use an ethanolic solution of NaOH and obtain the Schiff base as precipitate which is easily isolated by filtration and drying.
Good luck with your work and best wishes!
The ethanolic KOH or NaOH can be used for the synthesis of Schiff bases from amino acids are precipitated and obtained by filtration and drying.
Owh i see. Thank you for the recommendation. I will try it later. Btw, is it ok if i'm not using any of the catalyst but just let it stir for overnight to see either the reaction occur or not?
Dear Fatin,
thanks for your kind response and new question. Of course you are absoluely fee to run the reaction without any catalyst. It's prefectly OK to try it out. However, don't be disappointed if nothing happens and after stirring overnight only the starting materials are present. My personal guess is that without a catalyst no reaction will occur. Please remember that amino acids are present in a zwitterionic forms in which the –NH2 group becomes –NH3+. Thus it also becomes less nucleophilic and less reactive towards carbonyl functional groups.
In any case, good luck with your experiment and best wishes!
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