CIE A Level Chemistry

Revision Notes

Syllabus Edition

First teaching 2020

Last exams 2024

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3.9.3 Synthetic Routes

Test Yourself

Analysis of Synthetic Routes

  • Students should be able to critically analyse given synthetic routes and determine whether appropriate reagents and reaction conditions are used
  • Students should also be able to predict possible by-product of a synthetic reaction

Worked Example: Two-step synthesis

Organic Synthesis Worked Example - Two-step synthesis, downloadable AS & A Level Chemistry revision notes

Answer

The correct answer is  D

The first step involves a nucleophilic addition of CN- using NaCN as catalyst and heat to form a hydroxynitrile.

In the second step, the nitrile is refluxed with dilute aqueous sulfuric acid causing hydrolysis of the nitrile forming a carboxylic acid and ammonium salt.

Organic Synthesis Answer Worked Example - Two-step synthesis, downloadable AS & A Level Chemistry revision notes

Worked Example: Synthesis of hexanoic acid

 

Organic Synthesis Worked Example - Synthesis of hexanoic acid, downloadable AS & A Level Chemistry revision notes

 

Answer

The correct answer is C

Halogenoalkanes can undergo nucleophilic substitution with ethanolic KCN in which the CN- ion acts as a nucleophile and replaces the chlorine atom in 1-chloropentane to form a nitrile.

The treatment of nitriles with concentrated hydrochloric acid will produce a carboxylic acid and an ammonium salt.

In this case, hexanoic acid and ammonium chloride will be formed.

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Fran studied for a BSc in Chemistry with Forensic Science, and since graduating taught A level Chemistry in the UK for over 11 years. She studied for an MBA in Senior Leadership, and has held a number of roles during her time in Education, including Head of Chemistry, Head of Science and most recently as an Assistant Headteacher. In this role, she used her passion for education to drive improvement and success for staff and students across a number of subjects in addition to Science, supporting them to achieve their full potential. Fran has co-written Science textbooks, delivered CPD for teachers, and worked as an examiner for a number of UK exam boards.