13616.08RRR 13 Phenylethanone is used as a fragrance in perfumes and soaps. C O H3C phenylethanone It is prepared by the reaction of benzene with ethanoyl chloride in the presence of an aluminium chloride catalyst. (a) (i) Outline a mechanism for the acylation of benzene to form phenylethanone. The mechanism should include equations to show the formation of the electrophile and the regeneration of the catalyst. [5] (ii) Define the term electrophile. [1] 13616.08RRR [Turn over (b) Phenylethanone can be nitrated to form (3-nitrophenyl)ethanone which is a solid at room temperature. (i) State the reagents required for this nitration. [2] (ii) Write an equation for the nitration of phenylethanone to form (3-nitrophenyl)ethanone. [1] (iii) Describe how the melting point of a solid sample of (3-nitrophenyl)ethanone could be determined. State two effects that the presence of impurities would have on the melting point. In this question you will be assessed on your written communication skills including the use of specialist scientific terms. [6] 13616.08RRR (c) Phenylethanone reacts with 2,4-dinitrophenylhydrazine. (i) Write an equation for the reaction of phenylethanone with 2,4-dinitrophenylhydrazine. [2] (ii) Calculate the volume of phenylethanone needed to form 5.00 g of the 2,4-dinitrophenylhydrazone assuming a 90.0% yield. The density of phenylethanone is 1.03 g cm-3. Give your answer to 3 significant figures. Answer                              [4] 13616.08RRR [Turn over (d) Ketones react with hydroxylamine to form an oxime as shown by the general equation below. C O R1 R2 OH H2O NH2OH C N R1 R2 ketone oxime When 0.8764 g of a ketone was treated with excess hydroxylamine it produced 1.103 g of an oxime. Calculate the relative molecular mass of the ketone. Answer                              [2]