Amines and their Derivatives | Organic Chemistry 3

Amines and their derivatives are studied in this chapter: name, properties and synthesis of amines, Hofmann elimination, Mannich reaction

Nomenclature of Amines


Derivatives of ammonia NH3, in which one, two or three of the H have been replaced by alkyl or aryl groups


The -ane ending of the corresponding alkane is replace by -anamine. The rules for naming alcohols  also apply to amines
For secondary and tertiary amines:
- largest alkyl group = main chain
- other alkyl groups = substituents named as prefixes preceded by N-
The amine functional group has the lowest order of priority of all functional groups (except alkene and alkyne). The prefixe amino- is used when the amine is a substituent


Properties of Amines


Amines have properties similar to alcohols and ethers. They can:

  • serve as nucleophile
  • participate in hydrogen bonding (high boiling point + soluble in water)
  • be both basic and acidic:

 Alkanamine is tetrahedral


Comparison with alcohols:

Oxygen is more electronegative than nitrogen
⇒ amines are less acidic than alcohols
⇒ amines are more basic and nucleophilic than alcohols and ethers
⇒ amines have weaker hydrogen bonding than alcohols

Absorption spectroscopy:

NMR: 1H broad signal and variable δ (1.0-2.5 ppm) 
IR: N-H stretching ⇒ broad band ~ 3250-3500 cm-1

Preparation of Amines

Amines by alkylation:


  1. Nucleophilic substitution:

  2. Deprotonation:

  3. Subsequent alkylations

Amines from azides:


Amines by reductive amination:


  1. Condensation:

  2. Reduction:


Amines from carboxylic amides:


Amines from nitriles:

Hofmann Elimination


Mannich Reaction


The Mannich reaction can be thought of as a variation of the aldol condensation

  1. Iminium ion formation:

  2. Carbon-carbon bond formation:

  3. Deprotonation: