CIE Nov 2016 v2 Paper 4 Q8

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Compound F is a carboxylic acid. 16 PMT (a) Compound F contains 31.4% oxygen by mass and its mass spectrum has a molecular ion peak at m / e = 102. Use all of this information to show that the molecular formula of compound F is C5H10O2. Show all your working. (b) There are four possible structural isomers of C5H10O2 that are carboxylic acids. (i) Therst isomer has been drawn. Draw the skeletal formulae of the three other structural isomers. OH isomer 1 isomer 2 isomer 3 isomer 4 [1] [2] (ii) State the systematic name of isomer 1.[1]UCLES 2016 9701/42/O/N/16<br /> (c) F is one of the four structural isomers in (b)(i). A carbon-13 NMR spectrum of F is shown. 17 PMT 180 160 140 120 80 100/ ppm 60 40 20 (i) Use the spectrum to identify isomer F. Draw its structure in the box below. [1] (ii) Use the Data Booklet and your knowledge of carbon-13 NMR spectroscopy to identify the environments and hybridisations of the carbon atoms responsible for each of the three absorptions. environment of the carbon atom hybridisation of the carbon atom/ ppm 27 41 179 [2]UCLES 2016 9701/42/O/N/16 [Turn over<br /> (d) G is another of the four structural isomers in (b)(i). The proton NMR spectrum of G is shown. 18 PMT 12 11 10 6/ ppm (i) Use the Data Booklet and the spectrum to complete the table below. The actual chemical shifts for the four absorptions in G and the splitting pattern at= 1.6 ppm have been added for you./ ppm type of proton number of protons splitting pattern 0.9 1.6 2.4 11.5 multiplet (ii) Deduce which isomer is G and draw its structure in the box. [4] [1]UCLES 2016 9701/42/O/N/16<br /> 19 PMT (e) Name or give the formula of a suitable solvent for obtaining a proton NMR spectrum.[1] [Total: 13]UCLES 2016 9701/42/O/N/16 [Turn over<br />

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