CIE Nov 2017 v1 Paper 4 Q6

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(a) 4-nitromethylbenzene can be prepared via an electrophilic substitution reaction as shown. 12 PMT CH3 CH3 conc. HNO3 conc. H2SO4 NO2 CH3 NO2 methylbenzene intermediate T 4-nitromethylbenzene (i) This reaction also forms an isomer of 4-nitromethylbenzene as a by-product. Draw the structure of this by-product. [1] (ii) Write an equation for the reaction between HNO3 and H2SO4 that forms the electrophile for this reaction.[1] (iii) Describe how the structure and bonding of the six-membered ring in intermediate T differs from that in methylbenzene.[3]UCLES 2017 9701/41/O/N/17<br /> (b) Benzocaine is used as a local anaesthetic. It can be synthesised from 4-nitromethylbenzene by the route shown. 13 PMT step 1 CH3 NO2 CH3 NH2 step 2 4-nitromethylbenzene CO2CH2CH3 CO2H step 5 step 4 NH2 benzocaine NH2 W (i) Give the systematic name of compound W. CH3 NHCOCH3 step 3 CO2H NHCOCH3[1] (ii) Suggest the reagents and conditions for steps 1 5. step 1step 2step 3step 4step 5[6] (c) Suggest how the basicity of benzocaine would compare to that of ethylamine. Explain your answer.[2]UCLES 2017 9701/41/O/N/17 [Turn over<br /> PMT 14 (d) A sample of benzocaine, shown below, was analysed by proton NMR and carbon-13 NMR spectroscopy. (i) Predict the number of peaks that would be seen in the carbon-13 NMR spectrum.[1] (ii) Benzocaine was dissolved in CDCl 3 and the proton NMR spectrum of this solution was recorded. CO2CH2CH3 NH2 benzocaine/ ppm Suggest why CDCl 3 and not CHCl 3 is used as the solvent when obtaining a proton NMR spectrum.[1] (iii) Use the Data Booklet and the spectrum in (d)(ii) to complete the table for the proton NMR spectrum of benzocaine. The actual chemical shifts, , for the four absorptions have been added./ ppm group responsible for the peak number of 1H atoms responsible for the peak splitting pattern 1.2 3.5 5.5 7.17.4 multiplet [4] (iv) Explain the splitting pattern for the absorption at 1.2 ppm.[1]UCLES 2017 9701/41/O/N/17<br /> PMT 15 (v) The proton NMR spectrum of benzocaine dissolved in D2O was recorded. Suggest how this spectrum would differ from the spectrum in (d)(ii). Explain your answer.[1] (e) Benzocaine can also be used to synthesise the dyestuff S by the following route. CO2CH2CH3 step 1 NH2 benzocaine step 2 NaOH(aq), OH phenol (i) Suggest the reagents used for step 1.[1] (ii) Suggest structures for compounds R and S and draw them in the boxes. [2] [Total: 25]UCLES 2017 9701/41/O/N/17 [Turn over<br />

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