CIE Jun 2016 v3 Paper 4 Q6

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Nitrobenzene, C6H5NO2, can be reduced to phenylamine, C6H5NH2, in acid solution in a two step process. PMT (a) (i) Balance the half-equation for this reaction to work out how many moles of electrons are needed to reduce one mole of nitrobenzene. C6H5NO2 + e + H+C6H5NH2 + H2O [1] (ii) The reducing agent normally used is granulated tin and concentrated hydrochloric acid. In the first step, the reduction of nitrobenzene to phenylammonium chloride can be represented by the equation shown. Use oxidation numbers or electrons transferred to balance this equation. You might find your answer to (i) useful. C6H5NO2 + HCl + SnC6H5NH3Cl + SnCl 4 + H2O [2] (b) When 5.0 g of nitrobenzene was reduced in this reaction, 4.2 g of phenylammonium chloride, C6H5NH3Cl, was produced. Calculate the percentage yield. percentage yield of phenylammonium chloride =% [2] (c) Following the reaction in (b), an excess of NaOH(aq) was added to liberate phenylamine from phenylammonium chloride. (i) Calculate the mass of phenylamine, C6H5NH2, produced when 4.20 g of phenylammonium chloride reacts with an excess of NaOH(aq). mass of phenylamine =g [1] The final volume of the alkaline solution of phenylamine in (i) was 25.0 cm3. The phenylamine was extracted by addition of 50 cm3 of dichloromethane. After the extraction, the dichloromethane layer contained 2.68 g of phenylamine. (ii) Use the data to calculate the partition coefficient, K partition, of phenylamine between dichloromethane and water.UCLES 2016 9701/43/M/J/16 K partition =[2]<br /> PMT (d) How does the basicity of phenylamine compare to that of ethylamine? Explain your answer.[2] (e) Phenol can be synthesised from phenylamine in two steps. NH2 step 1 OH step 2 + N2 (i) State the reagents and conditions for steps 1 and 2. step 1step 2[2] (ii) Draw the structure of the intermediate compound E in the box above. [1] [Total: 13]UCLES 2016 9701/43/M/J/16 [Turn over<br />

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