OCR A-Level Chemistry Synthesis and analytical techniques (02), June 2018: Question 15

1 mark · Medium difficulty · Multiple Choice

Identify which of the given reactions with 2-bromo-2-phenylacetic acid form a carbon-carbon bond

Practise this question

Question

Multiple choice question 15 asking which of three reagents or conditions could react with a given chemical structure containing a benzene ring attached to a CH(Br)COOH group to form a carbon-carbon bond. Reagent 1 is CH3Cl and AlCl3 (Friedel-Crafts alkylation on the aromatic ring), Reagent 2 is KCN in ethanol (nucleophilic substitution forming a nitrile), and Reagent 3 is CH3OH and H2SO4 (esterification forming an ester). Four multiple-choice options A, B, C, and D are provided, with an answer box.
Question text

15 Which of the following could react with the compound below to form a carbon–carbon bond?

H O

C C

Br OH

1 CH3Cl and AlCl3

2 KCN in ethanol

3 CH3OH and H2SO4

A 1, 2 and 3

B Only 1 and 2

C Only 2 and 3

D Only 1

Your answer

[1]

Mark scheme

Show the mark scheme The mark scheme table shows question number 15 with the correct answer B, worth 1 mark in total.

15 B 1

Total 15

How to answer it

Forming Carbon-Carbon Bonds in Organic Synthesis

What this question tests

This question assesses your ability to identify synthetic routes that result in carbon-carbon (C-C) bond formation—a crucial concept in A-Level organic synthesis. You need to analyse functional groups and evaluate three distinct named reactions: Friedel-Crafts alkylation, nucleophilic substitution with cyanide ions, and esterification.

Question Analysis (Multiple Choice)

Exam Breakdown: Part 15

Evaluating statements 1, 2, and 3 for C-C bond formation

✅ Correct Answer: Option B (Only 1 and 2)

Statements 1 and 2 both form new C-C bonds, whereas statement 3 forms a carbon-oxygen (C-O) ester bond.

Mark Awarded: 1 / 1

💡 Key Knowledge: Identifying C-C Bond Formers

  • Friedel-Crafts Alkylation (Statement 1): Reacting an aromatic ring with a haloalkane and a halogen carrier (e.g., CH₃Cl and AlCl₃ ) attaches an alkyl group directly to the benzene ring, forming a C-C bond.
  • Cyanide Substitution (Statement 2): Reacting a halo acid with KCN in ethanol introduces a nitrile group ( -CN ), increasing the carbon chain length and forming a new C-C bond.

🧠 Exam Technique

Do not evaluate the reagents in isolation. Always look at both the starting organic molecule (here, 2-bromo-2-phenylethanoic acid) and the incoming reagent to trace exactly which atoms bond together.

❌ Common Errors

Students frequently mistake esterification ( CH₃OH and H₂SO₄ ) as a method for lengthening carbon chains. Remember that esterification forms an ester link ( -COO- ), which contains a carbon-oxygen bond, not a direct carbon-carbon bond.

Topics

Module 6: Organic chemistry and analysis · 6.1 Aromatic compounds, carbonyls and acids · 6.2 Nitrogen compounds, polymers and synthesis

Question and mark scheme from the OCR A-Level Chemistry examination, Synthesis and analytical techniques (02), June 2018. QuestionVault is an independent revision resource; questions remain the copyright of the awarding body.