Organic 2 Section 3 - Unit 28: Amines

Question 1

Give the reagent and conditions used to ensure that a primary amine is formed from the reaction of a halogenoalkane and ammonia (2 marks)

Answer 1

• NH₃

- In excess

Question 2

Explain why butylamine is a stronger base than ammonia (2 marks)

Answer 2

• Lone pair (on N)

- R group increases electron density / donates electrons

Question 3

State and explain the difference in base strength between phenylamine and ammonia (3 marks)

Answer 3

• Phenylamine weaker
• Lone pair on N (less available)
• Delocalised into ring

Question 4

Explain why ethylamine is a Brønsted-Lowry base (2 marks)

Answer 4

• Lone pair on N

- Accepts a proton

Question 5

Why is phenylamine a weaker base than ethylamine (2 marks)

Answer 5

• Lone pair less available

- Due to delocalisation

Question 6

Explain why 2-aminopentane is a stronger base than ammonia (2 marks)

Answer 6

In 2-aminopentane:

• Lone pair on N more available or Lone pair on N accepts H+ better
• Because of alkyl electron pushing /inductive effect