Amines

Question 1

Explain the production method for aliphatic amines

Answer 1

Aliphatic amines are formed via nucleophilic substitution of a halogenoalkane and an excess of ammonia;
Reagent: ethanolic ammonia
Conditions: heated in a sealed tube

RCl + 2NH3 —> RNH2 + NH4Cl

Question 2

Explain the production method for aromatic amines

Answer 2

Aromatic amines are formed by the reduction of nitroarenes.
Nitro arenes are formed by the electrophilic substitution of benzene.
Reducing agents: Sn & conc HCl
Conditions: Reflux
Then add a strong alkali to neutralise the remaining acid and the protonated amine

Question 3

Explain the basically of amines in terms of proton acceptance by the nitrogen lone pair

Answer 3

Amines have a lone pair of electrons on the nitrogen and so can act as a proton acceptor by donating the lone pair to a H+

Question 4

Explain the limitations within the method for producing aliphatic amines and propose a new method

Answer 4

Due to the nucleophilic substitution; forming a primary amine can lead to the formation of a secondary amine. This is because amines also have a lone pair and get progressively stronger as nucleophiles and so can cause multi substitution. This can be limited by adding XS ammonia as this favours the monosubstitution

Question 5

Explain the reactions of amines with dilute acids

Answer 5

Amines react readily with dilute acids to form ionic salts (e.g HCl) which are fully soluble in water