Amines

Question 1

State why the the amine formed from nucleophilic sub is contaminated with other amines. Suggest how the reaction conditions could be modified to minimise contamination (other products)

Answer 1

1 Further substitution occurs 2 Use excess nucleophile e.g NH₃

Question 2

Why can’t bromobenze undergo nucleophilic sub?

Answer 2

Delocalised system of benzene repels nucleophiles

Question 3

Why is methylamine a stronger base than ammonia

Answer 3

• CH₃ pushes electrons to N
• So the electron density on N increases
• Lone pair on N more available so can attracts and accept H+

Question 4

Why is a 1• the major product when ammonia is in excess for the reaction with haloalkane

Answer 4

• Further substitution prevented so 2• or 3• amine not made
• Because ammonia is more likely to react with the haloalkane rather than the amine product
• All the haloalkane is used up

Question 5

Explain why the melting point of aminoethanoic acid is much higher than that of hydroxyethanoic acid, HOCH₂COOH

Answer 5

• ionic bonding in aminoethanoic acid
• stronger attractions than Hydrogen bonding in hydroxyethanoic