Actually I have tried a lot of experiments for the Schiff base synthesis from amino benzothiazole and various aldehydes using ethanol, methanol, benzene etc. But I didn't get the pure compound I refluxed the mixture at 100 degree Celsius for 5hr. Allowed the reaction mixture to slow evaporation. But I didn't get the solid product. There is no product and sometimes looks as an oil nature. What is the reason of it? Would you please help me to synthesise the pure crystals of compound.
You are getting an oil because your product isnt pure. The crude product needs to be purified first. Also unless you do TLC or some other analytical method how do you know you are even forming your product?
evaporate the solvent then stire the product with crush ice to convert the gum to ppt
try to add the solution of amine in absolute ethanol to an acidefied solution of aldehyde in absolute ethanol then warm the resulting mixture until precipitation of the product , or until TLC showed the completion of reaction.
Please read the tutorial and try to purify your product. Best wishes