OCR A Jan 2010 Paper 4 Q1

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Answer all the questions. 1 A chemist was investigating the reactions of benzene, phenol and cyclohexene with bromine. She found that they all reacted with bromine but under different conditions. (a) The chemist found that when benzene reacts with bromine, a halogen carrier is required as a catalyst. Write an equation for this reaction. You do not need to show the halogen carrier in your equation. (b) The chemist also found that when phenol or cyclohexene reacts with bromine, a halogen carrier is not required. (i) The chemist observed that bromine decolourises when it reacts with phenol. [1] What other observation would she have made? Draw the structure of the organic product formed. ObservationOrganic product: (ii) Cyclohexene also decolourises bromine. Name the organic product formed.[1]OCR 2010 [2]<br />
 (iii) Explain the relative resistance to bromination of benzene compared to phenol and compared to cyclohexene. (cid:4) In your answer, you should use appropriate technical terms, spelt correctly.[5]OCR 2010 Turn over<br />
 (c) Compound A, shown below, is being considered as an azo dye by a chemical company. A chemist planned a two-stage synthesis of compound A starting from an aromatic amine. H3C compound A OH The aromatic amine is first converted into a diazonium ion.Draw the displayed formula of the aromatic amine and of the diazonium ion. State the reagents and conditions for each stage in the synthesis of compound A from an aromatic amine.[5] [Total: 14]OCR 2010<br />

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