How to stabilise the Schiff base product and avoid it from reverse back to the aldehyde and primary amine.
Recrystallization is a best choice for purification of such imines. However, you may also opt for column chromatography, but it is advisable to use neutral alumina instead of silica gel, as silica is acidic in nature. These are my personal views though.
Schiff bases are imines that come from amines, ketones, or aldehydes. They can be used as optoelectronic agents, antimalarial, antibacterial, antifungal, and for a variety of biological and industrial purposes. The product of Schiff base purified by recrystallization, filtration followed by washing with water and drying processes, sublimation etc.
To be honest,
First always try to avoid long storage of mines. And use them for next step.
We can further reduce the imine into amine and can store. We can resume the amine fori mine by using Pd/C but it is costly.
Best: What I have optimise is that try to precipitate Schiff base using diethyl ether. (Monitor Schiff base reaction by interval based NMR, after no carbonyl residue, dry it and precipitate in diethyl ether
Schiff's bases can be purified by recrystallization from solvents like EtOH, dry benzene, dry benzene-pet. ether mixture, anhydrous dichloromethane-pet ether mixture (depending on its solubility) or by column chromatography over neutral alumina or silica gel. Purified compounds can be stored at low temperature protecting from moisture. Schiff's bases derived from aliphatic aldehydes specially having alpha hydrogen are unstable and decomposes rapidly because of it's tautomerization to enamine derivatives. Imino-enamino tautomerization is very common for Schiff's bases of aliphatic aldehydes with alpha hydrogens. Traces of moisture, acids catalyze such tautomerization.
It depend upon the solubility of Schiff base. First check solubility. Use EtOH, CHCl3, CH2Cl2.
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