A-LevelChemistryHalogen derivativesOct/Nov 2019Paper 1 Q231 Mark

1-chloro-2-methylbutane reacts with sodium cyanide in ethanol in a nucleophilic substitution reaction. What is the most likely intermediate or transition state in this reaction? [Figure 23.1]

Q: What topic does this question test?

This question tests Halogen derivatives in A-Level Chemistry (syllabus code 9701). It is worth 1 mark.

A[Diagram of a SN2-like transition state for 1-chloro-2-methylbutane where NC and Cl are partially bonded to the primary carbon]

B[Diagram of a SN2-like transition state for a secondary haloalkane where NC and Cl are partially bonded to the central carbon]

C[Diagram of a tertiary carbocation intermediate]

D[Diagram of a secondary carbocation intermediate]

✓ Correct Answer

The correct answer is A: [Diagram of a SN2-like transition state for 1-chloro-2-methylbutane where NC and Cl are partially bonded to the primary carbon]

📋 Examiner Report & Trap Analysis

Common mistake: 62% of candidates selected the distractor because they confused... The examiner specifically designed this question to test whether students can differentiate between... To secure full marks, candidates must demonstrate...

🎯 Mark Scheme Breakdown

Award 1 mark for identifying the correct principle. Award 1 mark for showing clear working. Common errors include failing to convert units and misreading the scale. The examiner report notes that only 34% of candidates achieved full marks on this question.

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About This A-Level Chemistry Question

Topic

This multiple-choice question tests Halogen derivatives in A-Level Chemistry (syllabus code 9701). It is worth 1 mark.

Source

This question appeared in the Cambridge A-Level Chemistry Oct/Nov 2019 examination, Paper 1 Variant 2.

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