OCR A Jun 2010 Paper 2 Q3 (with explained solutions) |

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OCR A Jun 2010 Paper 2 Q3

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3 Alcohols are used in the industrial production of many organic compounds. 12 (a) Complete the flowchart below to show the organic product formed in each of the reactions of butan-1-ol. K2Cr2O7(aq) / H2SO4(aq) reflux K2Cr2O7(aq) / H2SO4(aq) distil CH3CH2CH2CH2OH acid / heat CH3COOH / H2SO4 reflux [4]OCR 2010<br />
(b) Butan-1-ol can be prepared by the alkaline hydrolysis of 1-iodobutane. CH3CH2CH2CH2OH + I CH3CH2CH2CH2I + OH 13 The reaction mixture is gently heated for 20 minutes. (i) The curly arrow model is used in reaction mechanisms to show the movement of electron pairs. Use the curly arrow model to outline the mechanism for the alkaline hydrolysis of 1-iodobutane. In your answer, include the name of the mechanism, the type of bond fission and relevant dipoles. name of mechanismtype of bond fission[5] (ii) A student decides to prepare butan-1-ol by the alkaline hydrolysis of 1-chlorobutane. Suggest, with reasons, any change in the conditions from those used in the alkaline hydrolysis of 1-iodobutane.[2] [Total: 11]OCR 2010 Turn over<br />
14 BLANK PAGE PLEASE DO NOT WRITE ON THIS PAGEOCR 2010<br />

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F322 Question Mark Scheme Marks Expected Answers Answers clockwise from top left CH3CH2CH2COOH (cid:57) CH3CH2CHCH2 (cid:57) CH3COOCH2CH2CH2CH3 (cid:57) CH3CH2CH2CHO (cid:57) June 2010 Additional Guidance ALLOW skeletal formula ALLOW butanoic acid ALLOW but-1-ene ALLOW butyl ethanoate ALLOW butanal If name and structure given both must be correct If C3H7 used instead of CH3CH2CH2 penalise once and then apply ECF If wrong carbon skeleton used then penalise once then apply ECF If a hydrogen is missing then penalise once 10<br />
F322 Question i Mark Scheme June 2010 Expected Answers Nucleophilic substitution (cid:57) Heterolytic (cid:57) Dipole shown on CI bond, C+ and I (cid:57) Curly arrow from OH to carbon atom of CI bond (cid:57) Curly arrow from CI bond to the iodine atom (cid:57) Marks Additional Guidance ANNOTATE WITH TICKS AND CROSSES DO NOT ALLOW fish hooks No need to show lone pair on OH or I Curly arrow must come from the negative sign or lone pair on the oxygen of the hydroxide ion ALLOW SN1 mechanism dipole shown on CI bond, C+ and I (cid:57) curly arrow from CI bond to the iodine atom (cid:57) curly arrow from OH to correct carbonium ion (cid:57) ALLOW heat stronger OR heat for longer OR heat at a higher temperature OR more heat Answer must refer to the CCl bond or CI bonds 11 ii Use reflux OR heat for more than 20 minutes (cid:57) CCl stronger bond (than CI bond) OR CCl shorter bond (than CI bond) OR CCl bond is harder to break OR needs more energy to break CCl bond OR ora (cid:57) Total 11<br />

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