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Edexcel Jun 2012 Paper 4 Q15
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![Reject Mark Reject Mark C9H18O KMnO4 (0) for last 2 marks HCl (0) for 3rd mark Reject Mark Acceptable Answers 2,6-dimethylhept-5-enal (2) Either part scores (1) e.g. 2,6-dimethyl (1) hept-5-enal (1) IGNORE missing/misplaced/misused hyphens or commas ALLOW ene for en ALLOW methy or methly for methyl Question Number 15(b)(i) CH3C(CH3)=CHCH2CH2CH(CH3)CH2OH (1) Acceptable Answers OR CH3C(CH3)CHCH2CH2CH(CH3)CH2OH OR CH3C(CH3)=CHCH2CH2C (CH3) HCH2OH ALLOW displayed or skeletal formulae K2Cr2O7/Na2Cr2O7/name (oxidation state must be correct if given (VI)) (1) This is a stand alone mark H2SO4/name (ignore any references to concentration) (1) ALLOW H+ and Cr2O7 Acidified dichromate (1) 2- (2) Acceptable Answers Question Number 15(b)(ii) (Steam) distil off melonal (as it forms) Allow add a limited amount of oxidizing agent/excess alcohol/excess X (1) To prevent further oxidation/To prevent carboxylic acid forming (1) Stand alone marks Question Number 15(a)<br />
Question Number 15(c) Question Number 15(d) Question Number 15(e)(i) Acceptable Answers Reject Mark Wavenumber range / cm-1 Bond Functional group present in melonal 17401720 C=O (saturated) OR 29002820 27752700 16691645 OR C-H C=C 3095 - 3010 C-H Aldehyde/CHO (1) (1) Alkene ALLOW carbon to carbon double bond ALLOW any single value or range within the ranges above ALLOW one mark if both wavenumber ranges and bond columns are correct but neither bond identified Just carbonyl Just C=C in 3rd column Acceptable Answers C3H5O+/CH3CHCHO+ (1) + (1) C6H11 [ALLOW Structural, skeletal or displayed formulae] Penalise omission of + charge once only ALLOW any order of atoms if correct totals. Reject Mark C4H9 C5H7O+ Acceptable Answers Reject Mark Circle around any other additional atoms<br />
Acceptable Answers Reject Mark Circle around any other additional atoms Acceptable Answers Reject Mark Arrow from anywhere on the cyanide ion to the carbon of the carbonyl. Arrow to the O must come from the carbonyl bond (1) Formula of intermediate (1) Arrow from oxygen to H and from H-CN bond to CN (1) ALLOW arrow from O to H+ or to H2O Starting from HCN/ CN- Single headed arrows Question Number 15(e)(ii) Question Number 15(f)(i)<br />
Reject Mark attack on a (planar) carbocation OR attack on a (planar) intermediate OR SN1 OR SN2 OR planar product Any/either direction or any/either angle Question Number 15(f)(ii) These marks are stand alone Acceptable Answers EITHER No First mark: Reaction site/carbonyl/aldehyde/molecule is planar (1) Second mark: Attack (equally likely) from both sides OR Attack (equally likely) from above and below (1) Third mark: (gives) racemic mixture/(gives) equal amounts of each isomer/(gives) equal amounts of each enantiomer (1) OR Yes Melonal has a chiral carbon atom (1) Correct identification of chiral centre (1) This chiral centre unaffected by reaction (1)<br />](https://learnah.org/wp-content/uploads/2018/08/June_2012_MS_-_Unit_4_Edexcel_Chemistry_A-level_15-0.jpg)
