Edexcel Jun 2017 Paper 5 Q20

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SECTION B Answer ALL the questions. Write your answers in the spaces provided. 20 Benzenediazonium chloride, C6H5N2 +Cl, can be prepared from benzene in a series of steps. Step 1 Step 2 Step 3 C6H6 C6H5NO2 Compound X C6H5N2 +Cl (a) (i) Identify the substances that are used to convert benzene into C6H5NO2 in Step 1. (1)(ii) Give the mechanism of the reaction taking place in Step 1, including one or more equations for the formation of the electrophile. (4) 10 *P48070A01028* D O N O T W R I T E I N T H I S A R E A D O N O T W R I T E I N T H I S A R E A D O N O T W R I T E I N T H I S A R E A<br /> (iii) Identify compound X and state the reagents needed to prepare it in Step 2. (2) Compound XReagents(iv) State the reagents and condition needed to convert compound X into benzenediazonium chloride in Step 3. (2) ReagentsCondition(b) Benzenediazonium chloride is used to prepare dyes. Write an equation for a reaction of benzenediazonium chloride with a compound of your choice in which the product is a dye. Show the structure of the dye in your equation. (c) Benzenediazonium chloride can be converted into benzoic acid, C6H5COOH, in two steps. The first step is a substitution reaction to produce the nitrile, C6H5CN. State the reagent needed for the second step. (2) (1)A E R A S I H T N I E T I R W T O N O D A E R A S I H T N I E T I R W T O N O D A E R A S I H T N I E T I R W T O N O D *P48070A01128* 11 Turn over<br /> (d) An aqueous solution of benzenediazonium chloride decomposes when it is warmed. The products of decomposition are a colourless unreactive gas, hydrochloric acid and an aryl (aromatic) compound. A white precipitate forms when bromine water is added to this aryl compound. (i) Write a balanced equation showing the decomposition of an aqueous solution of benzenediazonium chloride. State symbols are not required. (ii) Give the formula of the white precipitate. (2) (1) (Total for Question 20 = 15 marks) 12 *P48070A01228* D O N O T W R I T E I N T H I S A R E A D O N O T W R I T E I N T H I S A R E A D O N O T W R I T E I N T H I S A R E A<br /> A E R A S I H T N I E T I R W T O N O D A E R A S I H T N I E T I R W T O N O D BLANK PAGE A E R A S I H T N I E T I R W T O N O D *P48070A01328* 13 Turn over<br />

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