Edexcel Jan 2010 Paper 4 Q26 (with explained solutions) |

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Edexcel Jan 2010 Paper 4 Q26

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PMT 26 This question is about compounds X, C4H10O, and Y, C4H8O. (a) Compound X, C4H10O, can be oxidized to compound Y, C4H8O. The infrared spectrum of X is given below. Infrared Spectrum of X Transmittance /% 100 50 0 4000 3000 2000 1500 1000 500 Wavenumber/cm1 What can be deduced about the structures of X and Y using all this information and the data booklet? Justify your answer. (4)*N36289A02328* 23 Turn over<br />
PMT (b) Below are the nmr spectra of X and Y. nmr spectrum of X Chemical shift/ppm nmr spectrum of Y Chemical shift/ppm 24 *N36289A02428*<br />
PMT *Use these nmr spectra and your answer to (a) to deduce the structural formulae of X and Y. Justify your answer and explain why both nmr spectra are consistent with these structures. (6)(Total for Question 26 = 10 marks) TOTAL FOR SECTION C = 20 MARKS TOTAL FOR PAPER = 90 MARKS *N36289A02528* 25<br />

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Mark Acceptable Answers Reject X is a phenol (0) (IR spectrum of X) peak at 3400 (cm1) (1) MAY BE ANNOTATED ON SPECTRUM ALLOW anything in the Data Booklet range which is 3200 to 3750 (cm-1) X has an O-H (group) OR X is an alcohol (1) (From the chemical information) X is primary or secondary (alcohol) OR X is not tertiary (alcohol) OR X is any two from: butan-1-ol, butan-2-ol, (2)-methylpropan-1-ol (1) Y is an aldehyde or a ketone ALLOWY is a carbonyl (1) NOTE RE THIRD/FOURTH SCORING POINTS: If just state that X is butan-1-ol with no justification (0) but then go on to state Y is butanal, give (1) CQ mark OR If just state that X is butan-2-ol with no justification (0) but then go on to state Y is butanone, give (1) CQ mark OR If just state that X is (2)-methylpropan-1-ol with no justification (0) but then go on to state Y is (2)-methylpropanal, give CQ mark (1) NOTE: These Part (a) marks may be awarded from answers to either Part (a) or Part (b) Question Number 26 (a)<br />
26 (b) QWC First two marks: X is CH3CH(OH)CH2CH3 (1) Y is CH3COCH2CH3 (1) These marks are stand alone NOTE: Two correct names, but no structural formulae for both scores (1) out of (2) If X identified as CH3CH2CH2CH2OH and and Y identified as CH3CH2CH2CHO award (1) unless previously credited in (a) (NMR spectrum of X) Third mark:- hydrogen OR H in five (different) environments (IGNORE reference to butan-1-ol here) OR (so must be butan-1-ol or butan-2-ol and) not 2-methylpropan-1-ol which has four peaks/hydrogen environments (1) NOTE: Candidates may annotate a structural or displayed formula to show that there are five environments. (For this mark, no details of splitting or chemical shifts are needed.) sextuplet at 3.7 triplet at 0.9 quintuplet at 1.5 doublet at 1.3 singlet at 2.4 splitting pattern (2,6,1,5,3) consistent with butan-2-ol OR splitting pattern inconsistent with butan-1-ol (which is 3,6,5,3,1) (1)<br />
Fourth mark:- splitting pattern (2,6,1,5,3) consistent with butan-2-ol OR splitting pattern inconsistent with butan-1-ol (which is 3,6,5,3,1) OR assign peaks correctly quoting chemical shifts from the spectrum (1) (NMR spectrum of Y) Fifth mark:- hydrogen OR H in three (different) environments (1) NOTE: Candidates may annotate a structural or displayed formula to show that there are three environments. (For this mark, no details of splitting or chemical shifts are needed.) quadruplet at 2.4 singlet at 2.1 triplet at 1.0 Sixth mark:- splitting pattern (1,4,3) is consistent with butanone OR splitting pattern is inconsistent with butanal (which is 3,6,4,3) OR splitting pattern inconsistent with 2-methylpropanal (which is 2,8,2) OR assign peaks correctly quoting chemical shifts from the spectrum (1)<br />

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