Amines and their Derivatives | Organic Chemistry 3

The Amines and their Derivatives are studied in this chapter: the naming and properties of amines, their synthesis, the Hofmann elimination, the Mannich reaction.

Naming the Amines

Amines = derivatives of ammonia NH3, in which one, two or three of the H have been replaced by alkyl or aryl groups.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. Same rules as alcohols.
For secondary and tertiary amines:
- largest alkyl group = main chain
- other alkyl groups = substituents named by using the letter N-
Amine function has the lowest order of precedence of all functional groups (except alkene and alkyne).
We use prefixe amino- when the amine is a substituent.


Properties of Amines

 Alkanamine is tetrahedral

Properties similar to alcohols and ethers.
Amines can:
- serve as nucleophile
- participate in hydrogen bonding (high boiling point + soluble in water)
- be both basic and acidic


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

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:



Step 1: Nucleophilic Substitution

Step 2: Deprotonation

And then, subsequent alkylation.


Amines from azides:


Amines by reductive amination:



Step 1: Condensation


Step 2: Reduction


Amines from carboxylic amides:


Amines from nitriles:

Hofmann Elimination



Mannich Reaction

Mannich reaction can be considered a variation of the aldol condensation:




Step 1: Iminium ion formation

Step 2: Carbon-carbon bond formation

Step 3: Deprotonation