Schiff base

A Schiff base, named after Hugo Schiff, is a compound with a functional group that contains a carbon-nitrogen double bond with the nitrogen atom connected to an aryl or alkyl group, not hydrogen.[1] Schiff bases in a broad sense have the general formula R1R2C=NR3, where R is an organic side chain. In this definition, Schiff base is synonymous with azomethine. Some restrict the term to the secondary aldimines (azomethines where the carbon is connected to a hydrogen atom), thus with the general formula RCH=NR'.[2]

The chain on the nitrogen makes the Schiff base a stable imine. A Schiff base derived from an aniline, where R3 is a phenyl or a substituted phenyl, can be called an anil.[3]

Synthesis

Schiff bases can be synthesized from an aromatic amine and a carbonyl compound by nucleophilic addition forming a hemiaminal, followed by a dehydration to generate an imine. In a typical reaction, 4,4'-diaminodiphenyl ether reacts with o-vanillin:[4]


There is a Schiff base intermediate in the fructose 1,6-bisphosphate aldolase catalyzed reaction during glycolysis and in the metabolism of amino acids.

References

  1. ^ IUPAC, Compendium of Chemical Terminology, 2nd ed. (the "Gold Book") (1997). Online corrected version:  (2006–) "Schiff base".
  2. ^ IUPAC, Compendium of Chemical Terminology, 2nd ed. (the "Gold Book") (1997). Online corrected version:  (2006–) "azomethines".
  3. ^ IUPAC, Compendium of Chemical Terminology, 2nd ed. (the "Gold Book") (1997). Online corrected version:  (2006–) "anils".
  4. ^ Jarrahpour, A. A.; M. Zarei (February 24, 2004). "Synthesis of 2-({[4-(4-{[(E)-1-(2-hydroxy-3-methoxyphenyl)methylidene amino}phenoxy)phenyl imino}methyl)- 6 -methoxy phenol". Molbank M352. ISSN 1422-8599. http://www.mdpi.net/molbank/molbank2004/m0352.htm. Retrieved February 22, 2010.