In my schiff base there is a impurities, which is n,n-dimethylaminobenzaldeyde. I want to seperate the compounds by column chromatography. Now which solvents, and what ratio I should use? The other precursor is p-anisidine. The schiff base is soluble in water, ethanol, methanol but insoluble is n-hexane, diethyl ether.
Did you try to use DCM to dissolve the product?,
Do TLC with 10% or 20% MeOH in DCM to see the product move or not. If the product moved, even the product is not very solube in DCM, you can adsorb the product onto silica gel (product is stable on silica gel or not?) by dissolving in MeOH first, add silica gel, dry, load on the top of silica gel colum prepacked with DCM, elute with gradient of MeOH(5-20%, higher than 20% is not good) in DCM maybe the solution!
Recrystallize in a suitable mixed solvent system as most Schiff bases are labile to silica and can't be purified via silica gel column chromatography.
Find your solvents and ratio using TLC. Really it will be in "borders" from DCM, to MeOH... But the main (!!). Your solvents and SiO2 have NOT to content any traces of acid. Else - your Shiff base will be hydrolised
You can try to focus on crystallization. Schiff base crystallization is generally achieved using acetonitrile, acetic acid, ethanol water, DMF water, and acetone
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