Chichibabin pyridine synthesis
The Tschitschibabin pyridine synthesis is a name reaction in organic chemistry and was first published in 1906 by the Russian chemist Alexei Evgenjewitsch Tschitschibabin . The reaction allows the synthesis of pyridine from aldehydes and ammonia .
Overview reaction
In a cyclic condensation reaction , aldehyde reacts with ammonia over an aluminum catalyst to form a pyridine:
Reaction mechanism
The reaction mechanism is described in the literature and is illustrated using the example of acetaldehyde with ammonia:
Acetaldehyde ( 1 ) reacts with ammonia ( 2 ) with elimination of water and further vinylamine generated by imine-enamine isomerization ( imine-enamine tautomerism ) to form intermediate 3 . Repeated reaction with vinylamine (an enamine ) yields intermediate 4 . Subsequent electron rearrangement with charge equalization creates a ring closure with the formation of intermediate 5 . The pyridine derivative 6 ( 2-picoline ) is obtained by splitting off ammonia and hydrogen .
application
The Tschitschibabin pyridine synthesis is a key reaction for the synthesis of complex pyridines. Benzaldehyde reacts with acetophenone with the addition of ammonium acetate and acetic acid to form 2,4,6-triphenylpyridine:
Individual evidence
- ↑ Chichibabin, AEJ In: Russ. Phys. Chem. Soc. 37 , 1906, p. 1229.
- ↑ Tschitschibabin, AE and Oparina, MP (1927), On the condensation of crotonaldehyde with ammonia in the presence of aluminum oxide. Ber. German Chem. Ges. A / B, 60: 1877-1879, doi: 10.1002 / cber.19270600830 .
- ↑ a b Z. Wang: Comprehensive organic name reactions and reagents Volume 1 . John Wiley, Hoboken (NJ) 2009, ISBN 978-0-470-28662-3 , pp. 635-638 .
- ↑ Marvin Weiss: Acetic Acid Ammonium Acetate Reactions. An Improved Chichibabin Pyridine Synthesis In: J. Am. Chem. Soc. 74 (1), 1952, pp. 200-202, doi: 10.1021 / ja01121a051 .