Nucleophilic properties of aminesAQA A-Level Chemistry: Flashcards

What these 13 flashcards ask

Why is ammonia a nucleophile?
What type of reaction is ammonia with a halogenoalkane?
Why is the carbon in a C–Br bond δ+?
What are the conditions for ammonia with a halogenoalkane?
Describe the second step of the mechanism of ammonia with bromoethane.
Why can a primary amine react further with a halogenoalkane?
What are the products of repeated substitution, in order?
Why does substitution stop at the quaternary ammonium salt?
How can you make mainly the primary amine?
How can you make mainly the quaternary ammonium salt?
What is a quaternary ammonium salt?
What are quaternary ammonium salts with long chains used for?
Why is a long-chain quaternary ammonium ion a surfactant?

Exam questions on Nucleophilic properties of amines

A chemist heats bromoethane, CH₃CH₂Br, with a large excess of ammonia dissolved in ethanol. The reaction is carried out in a sealed tube and ethylamine is formed.
Explain why ammonia can act as a nucleophile in this reaction.2 marks
A student heats an excess of 1-bromopropane, CH₃CH₂CH₂Br, with a small amount of ethanolic ammonia in a sealed tube. Analysis shows a mixture of amines and an ionic compound.
Write an equation for the reaction of propylamine with 1-bromopropane to form a secondary amine, and explain why propylamine can react in this way.2 marks
Hexadecyltrimethylammonium bromide, [CH₃(CH₂)₁₅N(CH₃)₃]⁺ Br⁻, is a cationic surfactant used in hair conditioners. It is manufactured from the tertiary amine hexadecyldimethylamine, CH₃(CH₂)₁₅N(CH₃)₂.
Suggest how this surfactant is formed from the tertiary amine, giving the reagent, an equation and the type of mechanism.3 marks

Written by the Exaim team, led by Shaun Daswani (Head of Upper Secondary, Improve ME Institute; MSc Financial Mathematics, Imperial College London; BSc, UCL) and Jason Daswani (operational lead, Improve ME Institute; LSE).