If the product doesn’t form quantitatively from a 1:1 reaction, then you have to choose which reaction partner to use in excess to drive the equilibrium toward product. Cost and ease of purification tend to be most relevant. The amine might be removed by acid base extraction.

Use more than 1eq of the amine to drive the reaction to consume all aldehyde (as much as possible), excess amine should be able to be separated from product easier! Just like James E Hanson said above.

1-you can make the Pyrenecarboxyaldehyde as limiting reactant in your reaction.

2- try to recrystallize your product in different solvent.

3- try to perform extraction procedure purification.

4- try to use adsorbent like charcoal, Silica gel, Tonsil ....etc.

5- use column chromatography to purify your crude product.

You might try treating it with NaHSO3. This forms the bisulfite addition product (RCH(OH)(SO3Na) and will ppt as white crystals which are easily removed.

James E Hanson

Guobing Xiang

thank you for your suggestion. i tried increasing the equivalence of the amine , still the aldehyde and amine are remaining even after 24 hrs, under ethanol /AcOH condition.

Peter Gannett

thank you. i will try it

Dear Vara Prasad Rebaka some questions remain to me: Did you follow a literature preparation or is it a new Schiff base you are trying to make? Is the amine component volatile so that it can perhaps be removed by vacuum distillation? In the attached reference the reaction was done under nitrogen using just 1 equiv. of pyrenecarboxyaldehyde and aromatic amine without adding acetic acid. Perhaps you used too much acetic acid which neutralized the amine?

Peter Gannett I am also interested in this chemistry. Would not it hydrolyze the imine?

To remove excess starting material Pyrene carboxyaldehyde, wah the product with little methanol where aldehyde becomes soluble where as Schiff,s base remains insoluble solid. .