Amine
Amines are compounds and functional groups that contain a basic nitrogen atom with a lone pair. They are formally derivatives of ammonia, where one or more hydrogen atoms have been replaced by a substituent such as an alkyl or aryl group. Important amines include amino acids, biogenic amines, trimethylamine, and aniline. Inorganic derivatives of ammonia are also called amines.0 Adam Aminé Daniel is an American rapper, singer, and songwriter who gained notability for his commercial debut single, "Caroline," which peaked at number 11 on the US Billboard Hot 100 chart. He released his debut studio album, Good for You, on July 28, 2017, and his second studio album, Limbo, on August 7, 2020.1
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Structure
Inversion of an amine spatial configuration: Amine "flip-flop" like an umbrella turned over by the wind. The pair of dots represents the lone electron pair on the nitrogen atom.
Alkyl amines characteristically feature tetrahedral nitrogen centers. C-N-C and C-N-H angles approach the idealized angle of 109°. C-N distances are slightly shorter than C-C distances. The energy barrier for the nitrogen inversion of the stereocenter is about 7 kcal/mol for a trialkylamine. The interconversion has been compared to the inversion of an open umbrella into a strong wind.
Amines of the type NHRR' and NRR′R″ are chiral: the nitrogen center bears four substituents counting the lone pair. Because of the low barrier to inversion, amines of the type NHRR' cannot be obtained in optical purity. For chiral tertiary amines, NRR′R″ can only be resolved when the R, R', and R″ groups are constrained in cyclic structures such as N-substituted aziridines (quaternary ammonium salts are resolvable).
Aromatic amines
In aromatic amines ("anilines"), nitrogen is often nearly planar owing to conjugation of the lone pair with the aryl substituent. The C-N distance is correspondingly shorter. In aniline, the C-N distance is the same as the C-C distances.[8]