I work on the synthesis of Schiff base. I am trying to synthesize a schiff base from salicylaldehyde & para amino benzoic acid. But I face a challenge to purification of this product. I can't separate p-amino benzoic acid from the synthesized product.
I used to recystallizaion techicque but after recrystallizaiton amine was not reduce which check by TLC under UV-light. That means, I can't reduce p-amino benzoic acid.
So I can't purify the synthesized product.
The synthesized schiff base and primary reactant p-amino benzoic acid solubility are follwings, methanol, ethanol, DCM, DMF, Ethyl acetate,DMSO, acetone, N-hexane(insoluble), chloroform (slight soluble), distled water(insoluble).
Md. Eanur Rahman, you can use methanol/ethanol for re-crystallization of your product.
Hi, concerning the purification of your derivatives I would like to know if your compounds precipitate at high temperature during the reaction and in which solvent? If you do it in ethanol, for example, and the product precipitates, do a hot filtration and wash several times with the solvent. You could also try recrystallization or precipitation. You've probably tried column chromatography, but failed.
Dear Md. Eanur Rahman, I share with you the procedure that I use to prepare this derivative:
1. Dissolve 4-aminobenzoic acid (1.37 g, 10.0 mmol) in 50.0 mL of ethanol (EtOH) in a 100 mL round bottom flask.
2. Add 2 drops of glacial acetic acid followed by salicylaldehyde (1.06 mL, 10.0 mmol).
3. Heat the reaction solution at 50°C for 3 hours.
4. Filter the reaction mixture by suction to isolate the precipitate from the solvent.
5. Wash the product with ethanol (2x30 mL) and dry under vacuum.
Aayushi Joshi Thank you for your response. Already i recrystallized my product. In recrystallization proccess i used methanol and ethanol solvent separately, but i can't reduce p-amino benzoic acid.
Francesco Kouassi Adingra Thanks to your reply. My compound is total disolve in high tempareture. In this criteria i use two solvent (Methanol, Ethanol) separately. Other technique you mention i have already tried and not found any result to separate p-amino benzoic acid.
Juan Antonio Rivas Loaiza Thank you for your cooperation. I follwed your instruction. This time p-amino benzoic acid reduce but not some amount of p-aminobenzoic acid showed in TLC. That means p-aminobenzoic acid was not totaly remove from the product. What should i do now?
Md. Eanur Rahman,try to use para toluene salphonic acid instead of acetic acid and let the reaction for 24hrs.
The product precipitates less, which may be due to the good solubility of methanol. You can try a solvent with a small polarity. If the solubility of the raw material is poor, you can add a certain proportion of a solvent with a large polarity such as methanol.
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