Preparation of aminesAQA A-Level Chemistry: Mind map

Exam questions on Preparation of amines

1. A student prepares butylamine, CH₃CH₂CH₂CH₂NH₂, from 1-bromobutane, CH₃CH₂CH₂CH₂Br. The 1-bromobutane is added to a large excess of ammonia dissolved in ethanol, and the mixture is heated in a sealed tube.
   Write an equation for the formation of butylamine and explain why two moles of ammonia are needed for each mole of 1-bromobutane.2 marks
2. Propylamine, CH₃CH₂CH₂NH₂, is prepared in industry from propanenitrile, CH₃CH₂CN. The propanenitrile is itself made by heating bromoethane with potassium cyanide in ethanol. The nitrile is then reduced to the primary amine.
   Write an equation for the reduction of propanenitrile using [H] to represent the reducing agent, and suggest one advantage of making a primary amine by this route rather than from a halogenoalkane and ammonia.2 marks
3. A student reduces nitrobenzene, C₆H₅NO₂ (Mr = 123.0), to phenylamine, C₆H₅NH₂ (Mr = 93.0), by heating it under reflux with tin and concentrated hydrochloric acid. After the reaction the student adds excess sodium hydroxide solution and extracts the phenylamine. From 12.3 g of nitrobenzene the student isolates 6.51 g of phenylamine.
   Write an equation for the reduction of nitrobenzene using [H], and explain why sodium hydroxide is added at the end of the reaction.3 marks