OCR A-Level Chemistry Synthesis and analytical techniques (02), June 2024: Question 9

1 mark · Easy difficulty · Multiple Choice

Identify which given chemical structure represents a secondary amide.

Practise this question

Question

Multiple-choice question 9 asking which compound is a secondary amide, with four options labeled A, B, C, and D showing different organic structures containing functional groups like alcohol, amine, and amide groups.
Question text

9 Which compound is a secondary amide?

N

A

OH O

N C

B H

O

O

C

N

H

OH

NH2

D HO C

O

Your answer

[1]

Mark scheme

Show the mark scheme Mark scheme showing the correct answer as C for question 9, worth 1 mark.

9 C 1

How to answer it

Identifying a Secondary Amide

What this question tests

This question assesses your ability to recognise functional groups in organic molecules, specifically the classification of amides as primary, secondary, or tertiary based on nitrogen substitution, while distinguishing them from other functional groups like amines and alcohols.

Question 9

Full Worked Solution & Breakdown

✅ Correct Answer: C

Compound C contains a carbonyl group ( C=O ) bonded directly to a nitrogen atom ( -NH-CH₃ ), making it an amide. Because the nitrogen atom is bonded to one carbon chain (and one hydrogen atom), it is classified as a secondary amide.

💡 Key Knowledge: Classifying Amides

  • Primary Amide: Nitrogen is bonded to zero alkyl groups ( -CONH₂ ).
  • Secondary Amide: Nitrogen is bonded to one alkyl group ( -CONHR ).
  • Tertiary Amide: Nitrogen is bonded to two alkyl groups ( -CONR₂ ).

🧠 Exam Technique

Scan the structures systematically for the amide functional group ( -C(=O)-N- ). Once found, look exclusively at the nitrogen atom and count how many carbon-containing groups (alkyl chains) are attached directly to it, ignoring any other functional groups present elsewhere in the molecule (such as alcohol -OH groups).

❌ Common Errors & Distractor Analysis

  • Compound A: Features a tertiary amide because the nitrogen atom is bonded to two methyl groups ( -CON(CH₃)₂ ).
  • Compound B: This is an amino ketone / secondary amine, not an amide. The -NH- is separated from the carbonyl carbon by a -CH₂- group.
  • Compound D: Features a primary amide ( -CONH₂ ) with an alcohol group on the other end.
Exam Mark Scheme Allocation: 1 mark available for selecting option C.

Topics

Module 6: Organic chemistry and analysis · 6.2 Nitrogen compounds, polymers and synthesis

Question and mark scheme from the OCR A-Level Chemistry examination, Synthesis and analytical techniques (02), June 2024. QuestionVault is an independent revision resource; questions remain the copyright of the awarding body.