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CIE Jun 2015 v2 Paper 2 Q4
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![There are seven structural isomers with the molecular formula C5H10O that are carbonyl compounds. Four of these are aldehydes. These four aldehydes, A, B, C and D, have the following properties. Aldehyde A has a straight chain while B, C and D are branched. Aldehyde B is the only one of the four isomers with a chiral centre and it exists as a pair of optical isomers. Aldehyde C has two methyl groups in its structure but D has three. (a) (i) Give the structure of each of the four isomers. (ii) Draw the three-dimensional structures of the two optical isomers of B.UCLES 2015 9701/22/M/J/15 [4] [2] [Turn over<br />
(b) (i) Describe a chemical test that would allow you to distinguish between any of the four isomers A to D and any of the other three structural isomers of C5H10O, that are carbonyl compounds. In your answer you should describe any necessary reagents and conditions as well as explaining what you would see in each case.[3] (ii) Describe a test that would give the same result with all seven carbonyl isomers of C5H10O.[2] [Total: 11] 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 unwit ingly 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 2015 9701/22/M/J/15<br />](https://learnah.org/wp-content/uploads/2018/08/June_2015_v2_QP_-_Paper_2_CIE_Chemistry_A-level_4-0.jpg)
![Page 4 Question (iii) Cambridge International AS/A LevelMay/June 2015 9701 22 Mark Scheme Syllabus Paper Mark Scheme Mark Total [1] [1] [1] [1] [1] [1] [1] [1] [1] [5] [1] [2] [1] [13] [1] [1] [1] [1] [4] [1+1] [2] [1] [1] [1] [1] [1] [3] [2] [11] Initiation Cl2 2Cl(cid:127) Propagation C2H6 + Cl(cid:127) (cid:127)C2H5 + HCl (cid:127)C2H5 + Cl2 C2H5Cl + Cl(cid:127) Termination (cid:127)C2H5 + (cid:127)C2H5 C4H10 All three names correctly assigned (b) (i) ethene (ii) KOH / NaOH ethanolic AND heat / reflux (iii) H2 AND Pt or Ni (catalyst) (a) (i) A = CH3CH2CH2CH2CHO B = CH3CH2CH(CH3)CHO C = (CH3)2CHCH2CHO D = (CH3)3CCHO (ii) CH3 CH3 CH3 CH2 H CH H H CH2 CH3 (b) (i) Fehlings / Benedicts OR Tollens OR dichromate OR manganate Warm / heat Fehlings / Benedicts =(Brick)-red ppt Tollens = silver / mirror OR grey/black precipitate Dichromate = orange to green with the aldehyde / A-D Manganate = purple to colourless (ii) (2,4-)DNP(H) / Bradys reagent Orange / yellow / red-orange / yellow-orange pptCambridge International Examinations 2015<br />](https://learnah.org/wp-content/uploads/2018/08/June_2015_v2_MS_-_Paper_2_CIE_Chemistry_A-level_4.jpg)