A Schiff base is a functional group or type of chemical compound containing a carbon-nitrogen double bond with the nitrogen atom connected to a aryl group

-HC=N(Ph)-

where Ph stands for a phenyl or aryl group. The phenyl group makes the Schiff base a stable imine. Schiff bases are synthesised from an aromatic amine and a carbonyl compound in a nucleophilic addition to a hemiacetal followed elimination of water to the imine.

In a typical reaction ^[1]

a mixture of 4,4'-diaminodiphenyl ether 1 (1.00 g, 5.00 mmol) and o-vanillin 2 (1.52 g , 10.00 mmol) in methanol (40.00 mL) is stirred at room temperature for one hour to give an orange precipitate and after filtration and washing with methanol to give the pure imine 3 (2.27 g, 97.00 %).

References

• ^[1] Synthesis of 2-({[4-(4-{[(E)-1-(2-hydroxy-3-methoxyphenyl) methylidene]amino}phenoxy)phenyl]imino}methyl)- 6 -methoxy phenol A. A. jarrahpour, M. Zarei Molbank 2004, M352 [1] open access publication