The imine that I synthesised using a hydrazine and an aldehyde is extremely polar and cannot be eluted on a TLC plate, hence I cannot purify it using column chromatography. Is there another way to isolate my extremely polar product?
More details on the reaction: it was performed in room temperature with ethanol as the solvent. The product did NOT precipitated out of the reaction mixture (unlike what is expected based on literature survey) and I was unsuccessful in trying to precipitate the product by adding the reaction mixture to ice cold water.
Is it soluble in acetone or acetonitrile? If not, try HILIC. The weak solvent is an organic solvent such as acetonitrile or acetone, the strong solvent is water.
for examples, see:
https://www.teledyneisco.com/en-us/liquidChromatography/Chromatography%20Documents/Application%20Notes/RediSep%20Rf%20Gold%20Silica%20and%20Highly%20Polar%20Solvents%20App%20Note.pdf
https://www.teledyneisco.com/en-us/liquidChromatography/Chromatography%20Documents/Application%20Notes/HILIC%20Purification%20Strategies%20App%20Note.pdf
Since the compound is extremely polar as you said, I think isolating it as precipitate would be good choice. Non-polar solvents might give precipitate such as diethyl ether or hexane. Try other solvents also.
I would like to add some recent developments to the above question. I don't think the bottom dark spot that I observed in my TLC was actually the product. Here's why: when I tried a different procedure I got a product that matches the description of what imine should look like (a coloured solid within the reaction mixture). When I tried eluting it with 20% ethyl acetate and 80% petroleum ether the product was rising substantially.
Imines can be separated by column chromatography on an alkaline alumina column, and the eluent is petroleum ether and ethyl acetate.
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