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Pyridine, the parent compound of the pyridine alkaloids. Pyridine alkaloids are a class of alkaloids , nitrogen-containing chemical compounds widely found in plants, that contain a pyridine ring. Examples include nicotine and anabasine which are found in plants of the genus Nicotiana including tobacco .
Pyridine is colorless, but older or impure samples can appear yellow, due to the formation of extended, unsaturated polymeric chains, which show significant electrical conductivity. [page needed] [17] The pyridine ring occurs in many important compounds, including agrochemicals, pharmaceuticals, and vitamins.
Isoquinoline and quinoline are benzopyridines, which are composed of a benzene ring fused to a pyridine ring. In a broader sense, the term isoquinoline is used to make reference to isoquinoline derivatives. 1-Benzylisoquinoline is the structural backbone in many naturally occurring alkaloids such as papaverine.
The structure of pyridine is similar to that of benzene except that a nitrogen atom replaces one carbon atom. Pyridine is used as a flavoring agent. The pyridine ring is part of two B vitamins: niacin and pyridoxine. Niacin, also called nicotinic acid, is found in most organisms.
Simple aromatic rings can be heterocyclic if they contain non-carbon ring atoms, for example, oxygen, nitrogen, or sulfur. They can be monocyclic as in benzene, bicyclic as in naphthalene, or polycyclic as in anthracene. Simple monocyclic aromatic rings are usually five-membered rings like pyrrole or six-membered rings like pyridine.
A heterocyclic compound or ring structure is a cyclic compound that has atoms of at least two different elements as members of its ring(s). [1] Heterocyclic organic chemistry is the branch of organic chemistry dealing with the synthesis, properties, and applications of organic heterocycles .
With secondary amines and not primary amines the Zincke reaction takes on a different shape forming so-called Zincke aldehydes in which the pyridine ring is ring-opened with the terminal iminium group hydrolyzed to an aldehyde: [4] Zincke aldehydes. This variation has been applied in the synthesis of novel indoles: [11] Zincke aldehydes Kearney ...
First, the nucleophilic NH 2 − group adds to the δ+ ring carbon atom, pushing electrons onto the ring nitrogen atom and forming the anionic σ-adduct, which is stabilized by sodium. Electrons from the N atom are then pushed towards the ring to regain aromaticity , forming a C=N bond and ejecting a hydride ion in the process.