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CIE Nov 2014 v3 Paper 4 Q5
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![PMT L-DOPA is used in the treatment of Parkinson's disease. It can be prepared from vanillin. 10 HO HO NH2 HO CO2H CH3O L-DOPA vanillin (a) L-DOPA and vanillin each contain an aromatic benzene ring. Describe, with the aid of a diagram, the bonding and shape of a molecule of benzene, C6H6.[5]UCLES 2014 9701/43/O/N/14<br />
PMT (b) A student carried out some reactions with samples of L-DOPA and vanillin using reagents X, Y and Z. 11Reagent X reacted with L-DOPA and with vanillin.Reagent Y reacted with L-DOPA but not with vanillin.Reagent Z reacted with vanillin but not with L-DOPA. Assume that the CH3O group in vanillin does not react. Suggest possible identities of reagents X, Y and Z and give the structures of the organic products that were formed. Reagent Xproduct with L-DOPA product with vanillin Reagent Yproduct with L-DOPA Reagent Zproduct with vanillinUCLES 2014 9701/43/O/N/14 [7] [Total: 12] [Turn over<br />](https://learnah.org/wp-content/uploads/2018/08/November_2014_v3_QP_-_Paper_4_CIE_Chemistry_A-level_5-0.jpg)
![Page 5 Mark Scheme Syllabus Paper Cambridge International A LevelOctober/November 2014 9701 43 (d) (i) OH OH pKa 2.99 OH OH OH + H+ OH OH OH OH pKa 4.40 OH -O + H+ OH OH (ii) OH HOOC COOH OH OH HOOC COOH OH (S,R) (R,S) OH HOOC (R,R) COOH OH any two of the above (a) any five of these seven points.-bonds are between C-C OR C-Hcarbons are sp rings of charge above and below the ring must be in diagrampresence of -bondselectrons/bonds are delocalisedplanar molecule/bond angles 120 PMT [4]all C-C are the same length/have intermediate bond length between C-C & C=C [5]Cambridge International Examinations 2014<br />
Page 6 Mark Scheme Syllabus Paper Cambridge International A LevelOctober/November 2014 9701 43 (b) Reagent X e.g. Br2, HNO3, Na, NaOH, benzenediazonium salt / ion; RCOCl ; Fe 3+ ; H2+Ni substituted product for L-DOPA & vanillin (examples given are for X = Br2 and NaOH) Br Br OH OH OH or NH COOH CO NH OH CO Reagent Y e.g. HCl; Na2CO3, Mg, SOCl 2, PCl 5, ROH + c.H2SO4; HCl+NaNO2 / HNO2; CH3Cl Correct substituted product for L-DOPA OH OH NH COOH Reagent Z e.g. acidified Cr2O7 ; 2,4-DNPH, hydrazine ; Fehlings, Tollens; HCN; HCN + NaCN; 2 NaBH4 ; correct substituted product for vanillin OH OH OH PMT [7] (a) (i) C15H21NO2Cambridge International Examinations 2014<br />](https://learnah.org/wp-content/uploads/2018/08/November_2014_v3_MS_-_Paper_4_CIE_Chemistry_A-level_5-0.jpg)
