Kindly take one trial by converting amino acid into pure amine form (primary) using decarboxylation process than allow the reaction with aldehydes .

Amino acid and aldehyde both dissolve in warm methanol then mix them and allow to stir for an hour at ambient temperature.

Дорогой исследователь вы сперва аминокислоту переведите в соответствующий эфир и далее согласно методике!

Are you sure your product is insoluble? You're making a potassium salt with KOH, so if original amino acid salt is soluble, product also may be. If it's insoluble, are you sure amino acid salt participates in this reaction? You can use tertiary amines as catalysts for this reaction too.

Ни в коем случае не используйте КОН, так как происходит образование сахаров! Присоединяюсь М.Некрасову

If mino acid donot dissolve then add few drops of strong base like triethylamine (TEA) into your amino acid and solvent(ethanol/metha nol).

Agree with Тургунов Эрхан and Mikhail Nekrasov Aby Jimson , . what about your conversion ? unreacted reagent interference for crystallization. kindly check

Synthesizing Schiff bases involves the reaction between an amine and an aldehyde or ketone. In the case of amino acids, which contain both an amino group (-NH2) and a carboxylic acid group (-COOH), you can selectively react the amino group with an aldehyde to form a Schiff base. Here's a general procedure:

Materials:

Amino acid (containing an amino group), Aldehyde, Solvent (commonly ethanol or methanol), Acid catalyst (commonly acetic acid or hydrochloric acid), Reaction vessel and equipment

It's important to note that the reaction conditions, such as temperature and reaction time, may need to be optimized depending on the specific amino acid and aldehyde chosen. Additionally, the choice of solvent and acid catalyst can also influence the reaction outcome. Always consult the literature or experimental protocols for specific details related to your chosen reactants.

Procedure:

1. Preparation of Reactants:

- Choose an amino acid with a free amino group. Common amino acids include glycine, lysine, or arginine.

- Choose an aldehyde as the other reactant. Formaldehyde is often used, but other aldehydes can be employed.

2. Reaction Setup:

Mix the amino acid and aldehyde in a molar ratio of 1:1. The molar ratio may vary depending on the specific amino acid and aldehyde used.

3. Solvent Selection:

Dissolve the reactants in a suitable solvent. Common solvents include ethanol or methanol.

4. Acid Catalysis:

- Add a small amount of acid catalyst to the reaction mixture. Acetic acid or hydrochloric acid can be used for this purpose.

- The acid catalyst helps in the imine formation by protonating the amino group of the amino acid, making it more reactive towards the aldehyde.

5. Reaction Conditions:

Heat the reaction mixture under reflux (boiling and condensing) for a specific duration. The refluxing helps in driving the reaction to completion.

6. Workup:

- After the reaction, cool the mixture and neutralize any excess acid with a base (e.g., sodium bicarbonate).

- Extract the Schiff base product from the reaction mixture using an appropriate solvent.

7. Purification:

Purify the Schiff base product using techniques such as recrystallization or column chromatography.

8. Characterization:

Analyze the purified product using spectroscopic techniques like NMR, IR, or mass spectrometry to confirm the formation of the Schiff base.