Question Answer Mark Guidance 1 (a) (i) M1 p-orbitals overlap (to form pi/π-bonds) 4 ANNOTATE ANSWER WITH TICKS AND CROSSES ETC

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1 Question Answer Mark Guidance (a) (i) M p-orbitals overlap (to form pi/π-bonds) 4 ANNOTATE ANSWER WIT TICKS AND CROSSES ETC IGNORE p-orbitals overlap to form sigma bonds M2 π-bond(s) are delocalised in structure B ALLOW electrons are delocalised in structure B IGNORE B has delocalised structure or ring (must be electrons or π-bonds) M3 π-bonds are localised/between two carbons in structure A M4 ALLOW π-electrons/p-orbital overlap localised/between two carbons in structure A ALLOW p-orbitals overlap with one other carbon IGNORE electrons are localised OR structure A has localised structure (must be π-bonds/π-electrons/p-orbital overlap) ALLOW labelled diagram showing overlap of p-orbitals between two carbon atoms DO NOT ALLOW C=C in this diagram Diagram for structure A must show the full ring for M4 IGNORE C=C in M4 diagram AND Diagrams show correct position of delocalised and localised π-bonds/π-electrons OR correct position of p-orbital overlap QWC requires delocalised/delocalized spelled correctly and used in correct context IGNORE charge density DO NOT ALLOW electronegativity Structures do not need to be labelled A and B if the description matches the structure

2 Question Answer Mark Guidance (ii) structure B/delocalised structure is (more) stable 2 ALLOW structure B is low in energy IGNORE structure B is less reactive structure B is a better because (enthalpy change of hydrogenation for benzene is) less (exothermic) than (-) 357 (kj mol - ) ALLOW enthalpy change/hydrogenation for benzene is less (negative) than 3 ( )9 IGNORE more positive than (-)357 kj mol - ALLOW enthalpy change is less than 3x enthalpy change for cyclohexene ALLOW structure B is more stable by 49 kj mol - (2 marks) DO NOT ALLOW more/less energy needed for the reaction Answer must refer to data given in the question and must be a comparison IGNORE 360 kj mol - No marks can be awarded if structure A is selected (b) N N 2 curly arrow from C N bond to N + curly arrow from lone pair on fluoride ion to positive charge on benzene ring F First curly arrow must come from bond not from C atom ALLOW first curly arrow to nitrogen atom OR to positive charge on nitrogen atom ALLOW second curly arrow from negative charge on fluoride ion ALLOW second curly arrow to carbon atom with positive charge

3 Question Answer Mark Guidance (c) (C 3 ) 2 CBr + FeBr 3 (C 3 ) 2 C + + FeBr 4 ALLOW correct structural OR displayed OR skeletal formulae OR a combination of above as long as unambiguous ALLOW positive charge anywhere on the electrophile IGNORE AlCl 3 OR AlBr 3 (d) (i) First reactant = NO 2 3 ALLOW NaNO 2 + Cl OR NO 2 + Cl IGNORE conditions/concentration Second reactant = ALLOW correct structural OR displayed OR skeletal formulae OR a combination of above as long as unambiguous Third reactant = ALLOW

4 Question Answer Mark Guidance (ii) FIRST CECK TE ANSWER ON TE ANSWER LINE IF answer =.35 (g) award 3 marks IF answer = 0.54 (g) award 2 marks (no scale-up) IF answer = 0.26 (g) award 2 marks (incorrect scale-up) n(compound D) =.73/346 = mol n(,3-diaminobenzene) required = 00/40 x = mol Molar mass of,3-diaminobenzene = 08 (g mol ) AND Mass of,3-diaminobenzene = (08)(0.025) =.35 g 3 ANNOTATE ANSWER WIT TICKS AND CROSSES ETC If there is an alternative answer, check to see if there is any ECF credit possible ALLOW ECF from incorrect amount, scale-up or molar mass Alternative n(compound D) =.73/346 = mol Molar mass of,3-diaminobenzene = 08 (g mol ) AND Mass of,3-diaminobenzene = ( )(08) = g Mass of,3-diaminobenzene required = (0.540)(00/40) =.35 g Alternative g gives 08 g.73 g gives 08/364 x.73 = 0.54 g 0.54/40 x00 =.35 g (iii) (compound D has) two chiral centres 3 ALLOW (Compound D) has two asymmetric carbons OR has two stereocentres Four optical isomers exist ALLOW four enantiomers OR two pairs of enantiomers (Synthesis could) use enzymes OR bacteria OR use (chemical) chiral synthesis OR chiral catalysts OR use natural chiral molecules OR single isomers (as starting materials) INDEPENDENT MARK ALLOW biological catalysts ALLOW chiral transition metal complex/catalyst OR stereoselective transition metal complex/catalyst ALLOW 'chiral pool'/chiral auxiliary Total 8

5 Question Answer Marks Guidance 2 (a) Nitrogen lone pair accepts a proton/ + Requires position of lone pair on N DO NOT ALLOW Nitrogen/N lone pair accepts hydrogen Proton/ + is required ALLOW nitrogen donates a lone pair IGNORE N 2 group donates a lone pair (b) ALLOW correct structural OR displayed OR skeletal formulae OR combination of above as long as unambiguous + 6 [ + 2 2O DO NOT ALLOW O (c) curly arrow correct intermediate correct products from ring curly arrow from MUST AVE Br + to + NO 2 C Br to reform ring 4 ALLOW + + NO 2 OR NO 2 ALLOW first curly arrow from the ring OR from within the ring to any part of the NO + 2 including the + charge DO NOT ALLOW intermediate with broken ring covering less than half the ring or incorrect orientation of broken ring + must be within the br ken ring ALLOW non-delocalized (Kekulé) structures with carbocation on either side of Br/NO 2 substituents DO NOT ALLOW M if a second arrow used on the diagram DO NOT ALLOW M3 ecf if arrow does not come from C-Br bond If O missing on intermediate do not award M2. If O missing on final product do not award M4 (d) (i) hydrochloric acid/cl ALLOW conc / dilute Cl

6 Question Answer Marks Guidance (ii) 4-amino-3,5-dibromophenol ALLOW 3,5-dibromo-4-aminophenol ALLOW 2,6-dibromo-4-hydroxyphenylamine ALLOW 2,6-dibromo-4-hydroxy(--)aminobenzene OR (-)amino-2,6-dibromo-4-hydroxybenzene ALLOW absence of hyphens numbers must be clearly separated ALLOW full stops OR spaces (iii) ALLOW correct structural OR displayed OR skeletal formulae OR combination of above as long as unambiguous B (iv) ALLOW correct structural OR displayed OR skeletal formulae OR combination of above as long as unambiguous ALLOW O Na + OR O DO NOT ALLOW O-Na (e) (i) dyes/dyestuffs/pigments/food colourings ALLOW indicators / biological stains DO NOT ALLOW unqualified paint or food

7 Question Answer Marks Guidance (ii) 5 ALLOW correct structural OR displayed OR skeletal formulae OR combination of above as long as unambiguous No alternative pathway possible reaction NO 2 (with or without Cl) OR NaNO 2 + Cl ALLOW dilute 2 SO 4 but NOT conc 2 SO 4 ALLOW conc Cl temp <0 C compound B = reaction 2 CuI reaction 3 alkali(ne) ALLOW KO(aq)/NaO(aq)/O - (aq) IGNORE temp < 0 o C DO NOT ALLOW heat/boil/warm DO NOT ALLOW use of phenol in M5 Total 6

8 Question Answer Mark Guidance 3 (a) (i) donates a lone pair (on N) OR IGNORE forms a dative covalent bond (no direction of lone pair) accepts a proton/ + ALLOW forms a dative covalent bond with/to + ALLOW mark for N: + (can be from correct equation) (ii) (C 2 5 N 3 + ) 2 SO 4 2 C 2 5 N 3 + C 3 COO 2 ALLOW (C 2 5 N 3 ) 2 SO 4 DO NOT ALLOW (C 2 5 N 3 ) SO 4 OR (C 2 5 N 3 + ) SO 4 brackets not required ALLOW (C 2 5 N 3 ) (C 3 COO) OR (C 2 5 N 3 + ) (C 3 COO ) brackets not required ALLOW separate ions with or without a + sign between them, e.g. C 2 5 N C 3 COO (b) (i) O In diazonium ion, IGNORE Cl ALLOW + sign up to halfway along triple bond from left-hand N + N diazonium ion N COO compound B 2 In compound B, ALLOW O ionised as O ALLOW COO ionised as COO (ii) BOT responses required for one mark conditions = alkaline /O AND use = dye/pigment/colouring ALLOW named alkali, e.g. NaO/KO ALLOW base IGNORE references to temperature ALLOW use = indicator

9 Question Answer Mark Guidance (b) (iii) Organic product: IGNORE phenoxide: O OR O Na + (c) Other products: CO 2 AND 2 O 2 N + N + 2 O ALLOW COO OR COONa ALLOW 2 CO 3 Note: must be formulae and not names (in question) ALLOW N 2 + on structural formula ALLOW C 6 5 N O C 6 5 O + N ALLOW C 6 5 N 2 Cl + 2 O C 6 5 O + N 2 + Cl O + N Total 9 If + charge shown, IGNORE its position

10 Question Expected Answers Marks Additional Guidance 4 a O O N ALLOW * in place of circle ALLOW if circle extends to include O O ii Mark production of a single isomer is more expensive/difficult OR separation of the single isomer is expensive/difficult 4 Mark 2 one of the isomers is more (pharmacologically) active or one of the isomers might have adverse/harmful/nasty side effects IGNORE any reference to dosage ALLOW one is more effective/works (better) Marks 3 and 4 problems are overcome by using: Enzymes/bacteria/biological catalyst Chiral synthesis Chiral catalyst or transition metal complex Start with a natural chiral molecule or chiral pool any DO NOT ALLOW use naturally occurring isomer unless stated that it is a chiral compound DO NOT ALLOW transition metal ion DO NOT ALLOW pool synthesis Chiral pool synthesis scores (not 2) marks b i O 2 C C + N 3 O C 2 C 2 N 2 2 ALLOW O N 2 ALLOW epoxy ethane as C 2 4 O, (C 2 ) 2 O, C 2 OC 2 ALLOW product as O(C 2 ) 2 N 2 DO NOT ALLOW product as C 2 7 NO ii O C 2 C 2 N C 2 C 2 O ALLOW (C 2 ) 2 ALLOW displayed/skeletal formula DO NOT ALLOW molecular formula

11 Question Expected Answers Marks Additional Guidance c i O C 2 C 2 N 3 + Cl - Must show Cl ion ALLOW OC 2 C 2 N 3 Cl if formula is correct and both charges not shown ALLOW (C 2 ) 2 / any correct unambiguous structure DO NOT ALLOW ions joined by covalent bonds ii O C 2 C 2 N 3 + S - Must show S ion ALLOW if formula is correct and both charges not shown ALLOW (C 2 ) 2 / any correct unambiguous structure ALLOW + O C 2 C 2 N 3 S 2-2 d i Both N 2 and COO are joined to the same C ALLOW 2 N C CO 2 or RC(N 2 )CO 2 R The 4 groups/atoms attached to the C can be in any order but C must be adjacent. ( ) not essential ii O C 2 C 2 N 2 + 2[O] O O C C 2 N O ALLOW (C 2 ) 2 DO NOT ALLOW molecular formula e i Question 5e is followed by two blank lined pages (5 and 6) which candidates can use instead of requesting additional paper. Please check to see whether or not pages 5 or 6 have been used

12 Question Expected Answers Marks Additional Guidance e i Isomer F O C C N 2 2 ALLOW O(C 2 ) 4 N 2 / ALLOW any correct unambiguous structure of -aminobutan-4-ol Isomer G O * C C * C C ALLOW C 3 C(O)C(N 2 )C 3 ALLOW any correct unambiguous structure of 2-aminobutan-3-o N 2 * not required Total 3

ANNOTATIONS MUST BE USED

ANNOTATIONS MUST BE USED 1 (a) ATATIS MUST BE USED ALLW skeletal ALLW R ALLW 1st curly arrow from the ring R from within the ring to any part of the 2 including the charge H D T ALLW intermediate with broken ring less than halfway