CIE Jun 2017 v3 Paper 2 Q4

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A, B and C all have the formula C4H8. They all decolourise bromine and are structural isomers of each other. 10 PMT (a) State the name of the process by which A, B and C could be obtained from C10H22.[1] (b) Draw the structures of these three structural isomers. [1] (c) Only A shows geometrical isomerism. (i) Explain the meaning of the term geometrical isomerism.[2] (ii) Draw the displayed formula of A and use it to show the mechanism of the reaction of A with HBr. Include all necessary charges, dipoles, lone pairs and curly arrows. [4]UCLES 2017 9701/23/M/J/17<br /> PMT (d) B does not show geometrical isomerism. 11 B reacts with HBr to form a mixture of two structural isomers, X and Y. X (has a chiral centre and is produced in higher yield than Y) B + HBr Y (does not have a chiral centre) (i) State the meaning of the term chiral centre.[1] (ii) Name B.[1] (iii) X exists as a pair of optical isomers. Draw these isomers using the conventional three-dimensional representation. [2] (iv) Explain why X is produced in higher yield than Y.[2]UCLES 2017 9701/23/M/J/17 [Turn over<br /> PMT (e) C does not show geometrical isomerism. 12 C reacts with HBr to form a mixture of two structural isomers, neither of which has a chiral centre. (i) Name C.[1] (ii) Draw the displayed formula of each of the structural isomers produced by the reaction of C with HBr. [2] [Total: 17] Permission to reproduce items where third-party owned material protected by copyright is included has been sought and cleared where possible. Every reasonable effort has been made by the publisher (UCLES) to trace copyright holders, but if any items requiring clearance have unwittingly been included, the publisher will be pleased to make amends at the earliest possible opportunity. To avoid the issue of disclosure of answer-related information to candidates, all copyright acknowledgements are reproduced online in the Cambridge International Examinations Copyright Acknowledgements Booklet. This is produced for each series of examinations and is freely available to download at www.cie.org.uk after the live examination series. Cambridge International Examinations is part of the Cambridge Assessment Group. Cambridge Assessment is the brand name of University of Cambridge Local Examinations Syndicate (UCLES), which is itself a department of the University of Cambridge.UCLES 2017 9701/23/M/J/17<br />

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