OCR A Jan 2013 Paper 4 Q2

Answers available below

2 A chemist is developing a new azo dye. The structure of this dye is shown below. COONa+ azo dye N(CH3)2 (a) In the first stage of the synthesis of this dye, methyl 3-nitrobenzoate is formed. In this stage, methyl benzoate is nitrated by concentrated nitric acid, in the presence of concentrated sulfuric acid as a catalyst. COOCH3 COOCH3 + HNO3 + H2O NO2 methyl benzoate methyl 3-nitrobenzoate (i) Outline the mechanism for this nitration of methyl benzoate. Show how H2SO4 behaves as a catalyst. (ii) State the name for this type of mechanism. [5][1]OCR 2013 Turn over<br />
 (b) Methyl 3-nitrobenzoate can be converted into the azo dye in a multi-step synthesis. The multi-step synthesis is shown in the flowchart below. COOCH3 reaction 1 NO2 methyl 3-nitrobenzoate reaction 2 N(CH3)2 N,N-dimethylphenylamine COOCH3 N2 reaction 3 diazonium ion N(CH3)2 N(CH3)2 COOCH3 reaction 4 COONa+ azo dyeOCR 2013<br />
 (i) In the flowchart on page 8, draw the structure of the organic product of reaction 1. [1] (ii) Suggest the reagents for reaction 1, and the reagents and conditions for reactions 2 and 4. reaction 1reaction 2reaction 4[4] (iii) The reactions of aromatic amines with bromine and with diazonium ions are similar to those of phenol with bromine and with diazonium ions. In reaction 3, suggest why N,N-dimethylphenylamine reacts with the diazonium ion, but benzene would not react. Explain your answer. In your answer, you should use appropriate technical terms, spelled correctly.[3]OCR 2013 [Total: 14] Turn over<br />

Show answer