Tishchenko reaction

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The Tishchenko reaction is a chemical reaction that involves disproportionation of an aldehyde lacking a hydrogen atom in the alpha position in the presence of an alkoxide.[1] The reaction product is an ester. Catalysts are aluminium alkoxydes or sodium alkoxides. Benzaldehyde reacts with sodium benzyloxide (generated from sodium and benzyl alcohol) to benzyl benzoate.[2]

The Tishchenko reaction: benzaldehyde reacts to benzyl benzoate, the catalyst is generated in situ from sodium and benzyl alcohol

Paraformaldehyde reacts with boric acid to methyl formate.[3] The key step in the reaction mechanism for this reaction is a 1,3-hydride shift in the hemiacetal intermediate formed from two successive nucleophilic addition reactions, the first one from the catalyst. The hydride shift regenerates the alkoxide catalyst.

The Tishchenko reaction: reaction mechanism

In the related Cannizzaro reaction the base is sodium hydroxide and then the oxidation product is a carboxylic acid and the reduction product is an alcohol.

[edit] Related reactions

[edit] References

  1. ↑  V. Tishchenko, J. Russ. Phys. Chem. Soc. 1906, 38, 355, 482, 540, 547.
  2. ↑  O. Kamm and W. F. Kamm Organic Syntheses, Coll. Vol. 1, p.104; Vol. 2, p.5 Online article
  3. ↑  Boric acid catalyzed Tishchenko reactions. Paul R. Stapp, J. Org. Chem. 1973, 38(7), 1433-1434. Abstract
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