CHICHIBABIN REACTION PDF

Reaction mechanism[ edit ] The elementary contributing steps of the reaction mechanism can be classified as more familiar name reactions, including an imine synthesis , a base-catalyzed aldol condensation , and initiating the ring-synthesis step, a Michael reaction. Fundamental reaction steps[ edit ] Detailed reaction mechanism[ edit ] Synthetic applications[ edit ] Alkyl-substituted pyridines show widespread uses among multiple fields of applied chemistry, including the polymer and pharmaceutical industries. For example, 2-methylpyridine , 4-methylpyridine and 2-ethylmethylpyridine exhibit widespread use in syntheses of latexes , ion-exchange matrixes , and photography materials. Nucleophilic attack of ammonia on the enamine or imine Aldol condensation step 3.

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Reaction mechanism[ edit ] The elementary contributing steps of the reaction mechanism can be classified as more familiar name reactions, including an imine synthesis , a base-catalyzed aldol condensation , and initiating the ring-synthesis step, a Michael reaction. Fundamental reaction steps[ edit ] Detailed reaction mechanism[ edit ] Synthetic applications[ edit ] Alkyl-substituted pyridines show widespread uses among multiple fields of applied chemistry, including the polymer and pharmaceutical industries.

For example, 2-methylpyridine , 4-methylpyridine and 2-ethylmethylpyridine exhibit widespread use in syntheses of latexes , ion-exchange matrixes , and photography materials. Nucleophilic attack of ammonia on the enamine or imine Aldol condensation step 3.

Enolate ion attack of the enamine or imine carbon 5. Enolate ion attack of an unintended aldehyde- or keto-carbonyl Pyridine synthesis step 6. Protection of the carbonyl increases product yields [1] 2. Use of paraldehyde as a source of gradually available acetaldehyde [1] 3. Researchers found that protein-incorporated allysine , deaminated lysine from bovine ligamentum nuchae elastin fibers appeared to be pyridine crosslinked.

The structures of these cross-linked amino acids had 3,4,5- and 2,3,5-trisubstituted pyridine skeletons, specifically pyridinated desmosine DESP and pyridinated isodesmosine IDP.

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Chichibabin pyridine synthesis

Side reaction The Chichibabin reaction is a method for producing 2-aminopyridine derivatives by the reaction of pyridine with sodium amide. It was reported by Aleksei Chichibabin in The following is the overall form of the general reaction: The direct amination of pyridine with sodium amide takes place in liquid ammonia. Ciganek describes an example of an intramolecular Chichibabin reaction in which a nitrile group on a fused ring is the source of nitrogen in amination. The hydride ion abstracts a hydrogen from the positively charged nitrogen, forming hydrogen gas.

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Chichibabin reaction

The hydride ion abstracts a hydrogen from the positively charged nitrogen, forming hydrogen gas. The ring nitrogen then pushes electrons back into the ring, regaining aromaticity, the now negatively charged NH group abstracts a proton from water giving the product. Another competing pathway could be the elimination of hydride by sodium to form sodium hydride. Factors influencing reaction[ edit ] Different aromatic nitrogen heterocyclic compounds proceed through the Chichibabin reaction in a matter of minutes and others can take hours. Factors that influence the reaction rate include: Basicity - The ideal pKa range is and the reaction either does not proceed, or proceeds poorly outside of this range.

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