3.11 Amines

Amines are compounds based on ammonia where hydrogen atoms have been replaced by alkyl or aryl groups. This section includes their reactions as nucleophiles.

Lessons 3.11.2014 and 4.11.2014 (download pdf Amines Organic A2)

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Nucleophilic properties of amines - Amines are nucleophiles The nucleophilic substitution reactions (including mechanisms) of ammonia and amines with haloalkanes to form primary, secondary, tertiary amines and quaternary ammonium salts. The use of quaternary ammonium salts as cationic surfactants. The nucleophilic addition–elimination reactions of ammonia and primary amines with acyl chlorides and acid anhydrides [in new syllabus from 2015]. Students should be able to outline the mechanisms of: • these nucleophilic

Base properties of amines - The strength of a Brønsted-Lowry base depends on how readily it will accept a proton (H+). Both ammonia and amines have a lone pair of electrons that attracts a proton. In primary aliphatic amines, the alkyl groups tend to release electrons and have an inductive effect on the electron density of the nitrogen atom making the lone pair on N

Amine preparation - Primary aliphatic amines can be prepared by the reaction of ammonia with haloalkanes The mechanism is nucleophilic substitution R-Br + 2NH3 → R-NH2 + NH4+ Br− Otherwise, there is a tendency for the primary amine product to act as a nucleophile and react with the haloalkane, generating a secondary amine, R2NH. R-Br + R-NH2 → R2NH + HBr Furthermore, the secondary amine will react