Schiff base

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A Schiff base (or azomethine), named after Hugo Schiff, is a functional group that contains a carbon-nitrogen double bond with the nitrogen atom connected to an aryl or alkyl group—but not hydrogen [1]. Schiff bases are of the general formula R1R2C=N-R3, where R3 is an aryl or alkyl group that makes the Schiff base a stable imine. A Schiff base derived from an aniline, where R3 is a phenyl or substituted phenyl, can be called an anil.[2]

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:[3]

File:Schiff base.gif
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 Schiff base 3 (2.27 g, 97.00%)


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

References

  1. International Union of Pure and Applied Chemistry. "Schiff base". Compendium of Chemical Terminology Internet edition.
  2. International Union of Pure and Applied Chemistry. "anils". Compendium of Chemical Terminology Internet edition.
  3. 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.

de:Schiffsche Base it:Immine he:אימין mk:Имин mk:Шифова база sv:Imin



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