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Optical isomerism (A-level only)

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Question 3

The aldehyde CH3CH2CHO\text{CH}_3\text{CH}_2\text{CHO}CH3​CH2​CHO reacts with KCN\text{KCN}KCN followed by dilute acid to form a racemic mixture of the two stereoisomers of CH3CH2CH(OH)CN\text{CH}_3\text{CH}_2\text{CH(OH)CN}CH3​CH2​CH(OH)CN.

1.

Give the IUPAC name of CH3CH2CH(OH)CN\text{CH}_3\text{CH}_2\text{CH(OH)CN}CH3​CH2​CH(OH)CN.

[1]
2.

Describe how you would distinguish between separate samples of the two stereoisomers of CH3CH2CH(OH)CN\text{CH}_3\text{CH}_2\text{CH(OH)CN}CH3​CH2​CH(OH)CN.

[2]
3.

Explain why the reaction produces a racemic mixture.

[3]
4.

An isomer of CH3CH2CHO\text{CH}_3\text{CH}_2\text{CHO}CH3​CH2​CHO reacts with KCN\text{KCN}KCN followed by dilute acid to form a compound that does not show stereoisomerism. Draw the structure of the compound formed and justify why it does not show stereoisomerism.

[2]
Markscheme

Optical isomerism (A-level only) Questions

  1. A Level
  2. /Chemistry
  3. /Optical isomerism (A-level only)

9 exam-style questions on AQA A Level Chemistry Optical isomerism (A-level only), covering Optical isomerism (A-level only). Each one has a worked solution and a mark scheme showing where the marks go.

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