Nitrogen compounds

7(a)(i) 2 OR M1: peptide link shown M2: rest of Pro–Gly correct 7(a)(ii) condensation ALLOW substitution / addition–elimination 1 7(a)(iii) there is no H attached to the N 1 7(b)(i) (C H NHCO H +) NaOH → C H NHCO Na + H O 1 4 7 2 4 7 2 2 7(b)(ii) 1 skeletal only © UCLES 2021 Page 11 of 13 7(b)(iii) LiAlH 1 4 7(c)(i) CH (CO C H ) : ● (di)ester 2 2 2 2 5 2 CH =CHCN: ● alkene ● nitrile/cyanide 2 All three correct for two marks 7(c)(ii) addition 1 7(c)(iii) H / Ni OR H / Pt OR H / Pd 1 2 2 2 7(c)(iv) condensation / (nucleophilic) substitution / elimination 1 7(c)(v) ethanol / C H OH / CH CH OH 1 2 5 3 2 7(c)(vi) 3 M1/2: All four correct: • lone pair on NH 2 • curly arrow from N: to C of C—Cl • correct dipole on C—Cl • curly arrow from C—Cl to Cl M3: intermediate = OR 7(c)(vii) Asterisk on *CHCO H 1 2 © UCLES 2021 Page 12 of 13 7(d) 9 1 7(e)(i) M1: 2 M2: proton / H+ transferred from carboxylic acid to amine 7(e)(ii) 4 M1: glutamic acid towards + end (from the diagram) M2: proline and alanine towards – end (from the diagram) M3: Glu moves towards positive (pole) as negatively charged / contains a COO– OR Pro/Ala move towards negative (pole) as positively charged / contains a NH + / contains a NH + 2 3 M4: Ala moves farther than Pro because of lower M / size (with positive charge) ORA r 7(f) M1: initial amount of C H N O SNa = 3.50 / 204.1 OR 0.0171(48) mol 4 4 9 2 4 AND amount of HCl added = 0.200 × 50.0 / 1000 OR 0.0100 mol M2: equilibrium amount of C H N O SNa = 0.0171(48) – 0.0100 OR 0.0071(48) mol 4 9 2 4 AND equilibrium amount of ACES = 0.0100 mol ecf M3: K = 10–6.88 = 1.32 ×10–7 (mol dm–3) a [H+] = (1.32 × 10–7)0.01 / 0.0071(48) = 1.86 × 10–7 OR 1.8465 × 10–7 ecf M4: pH = –log(1.86 × 10–7) = 6.73 3sf min ecf © UCLES 2021 Page 13 of 13

7(a)(i) 2 7(a)(ii) M1: step 1 hot KMnO / MnO – 3 4 4 M2: step 2 conc. H SO and conc. HNO 2 4 3 M3: step 3 Sn and conc. HCl (heat) 7(b)(i) 3 M1 / M2: each structure M3: both displayed linkage 7(b)(ii) 1 molecular formula number of structural isomers formed C H N O 4 9 19 3 4 © UCLES 2021 Page 14 of 17 7(c)(i) 1 7(c)(ii) 2 one mark for two correct two marks for three correct Question Answer Marks

7(a)(i) 2 7(a)(ii) M1: step 1 hot KMnO / MnO – 3 4 4 M2: step 2 conc. H SO and conc. HNO 2 4 3 M3: step 3 Sn and conc. HCl (heat) 7(b)(i) 3 M1 / M2: each structure M3: both displayed linkage 7(b)(ii) 1 molecular formula number of structural isomers formed C H N O 4 9 19 3 4 © UCLES 2021 Page 14 of 17 7(c)(i) 1 7(c)(ii) 2 one mark for two correct two marks for three correct Question Answer Marks

8(a) bromine decolourised OR orange / brown to colourless [1] 2 white precipitate [1] 8(b) no change [1] 1 8(c) 1 [1] 8(d) 2,4,6-tribromophenylamine [1] ECF 8(c) for a bromophenylamine 1 Question Answer Marks

10(a) 1 [1] © UCLES 2021 Page 14 of 16 10(b) A and B 3 any two from: [all net single positive charge] [1] × 2 C at pH 1.0 [2+ positive charge] [1] © UCLES 2021 Page 15 of 16 10(c) M1: peptide link correct and displayed unit including C=O 2 M2: everything else correct OR [2] © UCLES 2021 Page 16 of 16

9(a) 6 organic starting material reagent and conditions 1-butyl halide, e.g. NH under pressure or [1] + [1] 3 CH CH CH CH Br heated in sealed tube 3 2 2 2 butanenitrile H and Ni or Pt / LiAlH / [1] + [1] 2 4 CH CH CH CN Na + ethanol 3 2 2 butanamide LiAlH / Na + ethanol [1] + [1] 4 CH CH CH CONH 3 2 2 2 9(b) M1 butylamine > ammonia > phenylamine [1] 4 M2 basicity related to ability of lp to accept proton / H+ [1] M3 butylamine is stronger because of positive inductive effect of alkyl group / C H [1] 4 9 M4 phenylamine is weaker because lp on N is delocalised into ring [1]

8(a) bromine decolourised OR orange / brown to colourless [1] 2 white precipitate [1] 8(b) no change [1] 1 8(c) 1 [1] 8(d) 2,4,6-tribromophenylamine [1] ECF 8(c) for a bromophenylamine 1 Question Answer Marks

10(a) 1 [1] © UCLES 2021 Page 14 of 16 10(b) A and B 3 any two from: [all net single positive charge] [1] × 2 C at pH 1.0 [2+ positive charge] [1] © UCLES 2021 Page 15 of 16 10(c) M1: peptide link correct and displayed unit including C=O 2 M2: everything else correct OR [2] © UCLES 2021 Page 16 of 16

6(a) a mixture containing equal amounts of each optical isomer 1 6(b) 1 carbon‑13 NMR proton NMR number of peaks in CDCl 4 5 3 6(c)(i) the pH at which an amino acid exists as a zwitterion 1 OR the pH at which an amino acid has no overall charge © UCLES 2022 Page 12 of 15 6(c)(ii) 1 6(d) 2 M1 peptide bond displayed M2 rest of the structure correct + continuation bonds 6(e) 3 spot identity E Asn F Lys-Asn G Lys M1 table correctly completed M2 Lys and Lys-Asn are positively charged OR Asn is (nearly) uncharged M3 Lys-Asn has the highest M r 6(f)(i) aluminum oxide / silica (on solid support) AND inert gas / named inert gas e.g. N 1 2 6(f)(ii) S AND R is the same as the unknown amino acid in both solvents 1 f © UCLES 2022 Page 13 of 15 6(g) mass of L = 58 / 44 * 5.52  10–2 = 7.28  10–2 g 1 conc. of L = 7.28  10–2 / 116 = 6.27  10–4 (mol dm–3) min 2sf Question Answer Marks

9(a) cyclohexylamine > ammonia > phenylamine 3  (order of basicity) linked to ability of N to accept a proton / donate its lone pair (to a proton)  alkyl / cyclo / hexyl group is electron donating group / positive inductive group (and increases electron density on N)  lone pair / p-orbital from N in phenylamine delocalised / overlaps with ring (and decreases electron density on N) two for one mark, three for two marks 9(b)(i) (nucleophilic) addition-elimination 1 9(b)(ii) 4 M1 / M2  lone pair on N  correct arrow from (lone pair) N to C (of C=O)  dipole on C=O  correct arrow on C=O two for one mark, four for two marks M3 correct intermediate M4 arrow from lone pair on O– to C-O bond AND arrow from C-Cl to Cl © UCLES 2022 Page 15 of 16 9(b)(iii) O O 1 C C H C N CH 3 3 © UCLES 2022 Page 16 of 16

6(a) a mixture containing equal amounts of each optical isomer 1 6(b) 1 carbon‑13 NMR proton NMR number of peaks in CDCl 4 5 3 6(c)(i) the pH at which an amino acid exists as a zwitterion 1 OR the pH at which an amino acid has no overall charge © UCLES 2022 Page 12 of 15 6(c)(ii) 1 6(d) 2 M1 peptide bond displayed M2 rest of the structure correct + continuation bonds 6(e) 3 spot identity E Asn F Lys-Asn G Lys M1 table correctly completed M2 Lys and Lys-Asn are positively charged OR Asn is (nearly) uncharged M3 Lys-Asn has the highest M r 6(f)(i) aluminum oxide / silica (on solid support) AND inert gas / named inert gas e.g. N 1 2 6(f)(ii) S AND R is the same as the unknown amino acid in both solvents 1 f © UCLES 2022 Page 13 of 15 6(g) mass of L = 58 / 44 * 5.52  10–2 = 7.28  10–2 g 1 conc. of L = 7.28  10–2 / 116 = 6.27  10–4 (mol dm–3) min 2sf Question Answer Marks

7(a)(i) 1 7(a)(ii) plane of polarised light will be rotated (in both isomers) [1] 2 by same angle / equal amounts in opposite directions [1] 7(b)(i) CH COCl AND HCl 1 3 © UCLES 2022 Page 11 of 16 7(b)(ii) 3 methanol [1] ester bond → primary alcohol OR amide → 2° amine AND benzene ring unchanged [1] rest of the structure of second compound is correct [1] 7(b)(iii) Q < phenylamine < P [1] 3 any three from: ability of N to accept a proton OR donate its lone pair to a proton phenylamine lone pair of N delocalised into ring OR p-orbital on N overlaps with  cloud of ring (and decreases electron density on N) compound P (2° amine) alkyl group has a positive inductive effect (and increases electron density on N) compound Q (amide) lone pair of N (in amide) delocalised by C=O OR overlap of lone pair of N with C=O (and decreases electron density on N) 7(c)(i) conc. HNO and H SO (25 °C < T ⩽ 60 °C) [1] 2 3 2 4 Sn and conc. HCl and reflux (followed by NaOH(aq)) [1] © UCLES 2022 Page 12 of 16 7(c)(ii) 2 NH on ring gives diazonium ion [1] 2 dibromo compound with Br atoms 2,6 to amine group [1] 7(d)(i) pH where the species is a zwitterion is the dominant form 1 OR pH where the species is electrically neutral © UCLES 2022 Page 13 of 16 7(d)(ii) 2 repeat unit identified by label / brackets / circle [1] three monomers complete all amide/peptide bonds correct all CHCH C H / CHR groups correct 2 6 5 trailing bonds or other convention(everything else correct) [1] Question Answer Marks

9(a) pH 7 +H N(CH ) CHNH COOH 2 3 2 4 2 pH 9.47 +H N(CH ) CHNH COO– [1] 3 2 4 2 pH 12 H N(CH ) CHNH COO– [1] 2 2 4 2 9(b) D ethanoyl chloride [1] 3 E correct phenyl ester [1] F correct amide [1] 9(c) Br substitutes at both 2 and 6 positions [1] 3 both phenol and COOH groups deprotonated [1] NO substitutes at one or both of 2 and 6 positions [1] 2 9(d)(i) distance travelled by amino acid divided by distance travelled by solvent [1] 1 9(d)(ii) tyr is more soluble in the solvent used 1 or lys is more attracted to the stationary phase used © UCLES 2022 Page 11 of 11

7(a)(i) 1 7(a)(ii) plane of polarised light will be rotated (in both isomers) [1] 2 by same angle / equal amounts in opposite directions [1] 7(b)(i) CH COCl AND HCl 1 3 © UCLES 2022 Page 11 of 16 7(b)(ii) 3 methanol [1] ester bond → primary alcohol OR amide → 2° amine AND benzene ring unchanged [1] rest of the structure of second compound is correct [1] 7(b)(iii) Q < phenylamine < P [1] 3 any three from: ability of N to accept a proton OR donate its lone pair to a proton phenylamine lone pair of N delocalised into ring OR p-orbital on N overlaps with  cloud of ring (and decreases electron density on N) compound P (2° amine) alkyl group has a positive inductive effect (and increases electron density on N) compound Q (amide) lone pair of N (in amide) delocalised by C=O OR overlap of lone pair of N with C=O (and decreases electron density on N) 7(c)(i) conc. HNO and H SO (25 °C < T ⩽ 60 °C) [1] 2 3 2 4 Sn and conc. HCl and reflux (followed by NaOH(aq)) [1] © UCLES 2022 Page 12 of 16 7(c)(ii) 2 NH on ring gives diazonium ion [1] 2 dibromo compound with Br atoms 2,6 to amine group [1] 7(d)(i) pH where the species is a zwitterion is the dominant form 1 OR pH where the species is electrically neutral © UCLES 2022 Page 13 of 16 7(d)(ii) 2 repeat unit identified by label / brackets / circle [1] three monomers complete all amide/peptide bonds correct all CHCH C H / CHR groups correct 2 6 5 trailing bonds or other convention(everything else correct) [1] Question Answer Marks

4(a)(i) CH CONH + 4[H] → CH CH NH + H O 1 3 2 3 2 2 2 4(a)(ii) nucleophilic substitution 1 (ammonia with) ethanol AND heat under pressure 1 OR ethanol AND heat in a sealed tube 4(a)(iii) (CH CH ) NH OR (CH CH ) N 1 3 2 2 3 2 3 © UCLES 2023 Page 9 of 17 4(b) (least) phenylamine < ammonia < ethylamine (most) 1 explanation 3 • (order of basicity) ability of base AND to accept a proton OR donate its lone pair (to a proton) phenylamine • lone pair / p-orbital from N delocalised / overlaps with (-)ring / benzene ethylamine • alkyl / ethyl group is electron donating group / +I group • increases electron density on N (ethylamine) ORA any two [1] any three [2] all four [3] 4(c) 1 concentrated HNO and H SO (and 25–60 °C) 1 3 2 4 (reduction with) Sn and concentrated HCl (heat) 1 4(d)(i) 1 4(d)(ii) nitrous acid / HNO 1 2 OR NaNO AND dilute HCl 2 © UCLES 2023 Page 10 of 17 4(d)(iii) phenol 1 4(d)(iv) NaOH / alkali 1 4(d)(v) dyestuffs / dyes 1 4(e)(i) species that uses one lone pair of electrons 1 that forms a single dative covalent bond to a central metal atom / ion 1 4(e)(ii) correct 3D cis isomer 1 correct 3D trans isomer 1 4(e)(iii) 6 1 4(f)(i) units = mol–4 dm12 1 4(f)(ii) CdCl 2− 1  4  (K =) stab 4 Cd2+Cl−    4(f)(iii) [CdCl 2–] = K  0.043  0.0724 = 7.28 / 7.3  10–4 (mol dm–3) min 2sf 1 4 stab © UCLES 2023 Page 11 of 17 4(f)(iv) CH NH (is basic so) reacts with water to produce OH– that reacts with Cd2+ 1 3 2 OR CH NH acts as a base and accepts a proton from Cd[H O) ]2+ / water 3 2 2 6 OR [Cd(H O) ]2+ + 4CH NH → [Cd(OH) (H O) ]2– + 4CH NH + OWTTE 2 6 3 2 4 2 2 3 3 4(f)(v) Cd(OH) 2– = most stable (2nd box) AND [Cd(H O) ]2+ = least stable (first box) 1 4 2 6 Cd(OH) 2– has highest K (and all K values given > 1) 1 4 stab stab Question Answer Marks

2(a) geometrical / cis-trans AND optical 1 2(b) square planar 1 © UCLES 2023 Page 7 of 17 2(c) 3 1 2 3 4 Two correct for one mark, three correct for two marks, four correct for three marks. © UCLES 2023 Page 8 of 17 2(d)(i) 3 M1 two correct curly arrows M2 correct dipole M3 correct structure of intermediate 2(d)(ii) use an excess of ammonia OR limiting amount of oxirane 1 2(d)(iii) 2 M1 M2 elimination / dehydration / condensation Question Answer Marks

7(a) M1 diethylamine > ethylamine > ethanamide 4 explanation M2 basicity linked to ability of lone pair on N to accept a proton / H+ M3 electron donating ethyl group increases electron density on N / makes lone pair more available for donation M4 lone pair of electrons on N is delocalised into C=O group 7(b)(i) M1 resists change in pH 2 M2 when a small amount of acid or alkali is added 7(b)(ii) M1 H NCH(CH )COOH + H+  H N+CH(CH )COOH 2 2 3 3 3 M2 H NCH(CH )COOH + OH–  H NCH(CH )COO– + H O 2 3 2 3 2 7(c)(i) 1 © UCLES 2023 Page 14 of 17 7(c)(ii) 2 M1 displayed peptide bond (between two amino acids) M2 rest of the structure correct 7(d) 3 M1 relative positions of the spots drawn M2 Ala is a zwitterion / neutral / at its isoelectric point (at pH 6) OR ala-glu AND glu are negatively charged M3 glu has lower M OR ala-glu has higher M r r © UCLES 2023 Page 15 of 17 7(e)(i) 3 number of 1H atoms number of protons chemical splitting responsible for the on the adjacent shift (δ) pattern peak carbon(s) 1.4 doublet 3 1 3.5 singlet 3 0 4.0 quartet 1 3 Three correct for one mark, six correct for two marks, nine correct for three marks. 7(e)(ii) one extra peak for NH group seen in CDCl , AND H exchanged for D in D O 1 2 3 2 Question Answer Marks

2(a) geometrical / cis-trans AND optical 1 2(b) square planar 1 © UCLES 2023 Page 7 of 17 2(c) 3 1 2 3 4 Two correct for one mark, three correct for two marks, four correct for three marks. © UCLES 2023 Page 8 of 17 2(d)(i) 3 M1 two correct curly arrows M2 correct dipole M3 correct structure of intermediate 2(d)(ii) use an excess of ammonia OR limiting amount of oxirane 1 2(d)(iii) 2 M1 M2 elimination / dehydration / condensation Question Answer Marks

7(a) M1 diethylamine > ethylamine > ethanamide 4 explanation M2 basicity linked to ability of lone pair on N to accept a proton / H+ M3 electron donating ethyl group increases electron density on N / makes lone pair more available for donation M4 lone pair of electrons on N is delocalised into C=O group 7(b)(i) M1 resists change in pH 2 M2 when a small amount of acid or alkali is added 7(b)(ii) M1 H NCH(CH )COOH + H+  H N+CH(CH )COOH 2 2 3 3 3 M2 H NCH(CH )COOH + OH–  H NCH(CH )COO– + H O 2 3 2 3 2 7(c)(i) 1 © UCLES 2023 Page 14 of 17 7(c)(ii) 2 M1 displayed peptide bond (between two amino acids) M2 rest of the structure correct 7(d) 3 M1 relative positions of the spots drawn M2 Ala is a zwitterion / neutral / at its isoelectric point (at pH 6) OR ala-glu AND glu are negatively charged M3 glu has lower M OR ala-glu has higher M r r © UCLES 2023 Page 15 of 17 7(e)(i) 3 number of 1H atoms number of protons chemical splitting responsible for the on the adjacent shift (δ) pattern peak carbon(s) 1.4 doublet 3 1 3.5 singlet 3 0 4.0 quartet 1 3 Three correct for one mark, six correct for two marks, nine correct for three marks. 7(e)(ii) one extra peak for NH group seen in CDCl , AND H exchanged for D in D O 1 2 3 2 Question Answer Marks

7(a) C H N O S 2– OR C H N O S [1] 1 16 10 2 7 2 16 10 2 7 2 © UCLES 2023 Page 12 of 18 7(b) 3 [1] [1] ECF from E [1] 7(c) M1 step 1: HNO OR NaNO + HCl [1] 3 2 2 M2 step 1: T ⩽ 10 °C [1] M3 step 2: NaOH(aq) / alkaline conditions [1] 7(d) 14 / fourteen [1] 1 © UCLES 2023 Page 13 of 18

9(a) chloroethane and ethylamine [1] 4 heat, pressure, ethanol [1] N-ethyl ethanamide CH CONHC H [1] 3 2 5 LiAlH [1] 4 Other syntheses that work also got credit / 9(b) phenylamine, ammonia, diethylamine [1] 3 • Availability of lone pair on N to receive H+ • phenylamine – LP, delocalised / overlaps into ring [1] • diethylamine – ethyl are electron donating [1] Two bullet points for one mark, three bullet points for two marks. 9(c) 2 Q or [1] N or N=N circled AND dye / colouring[1] 2 © UCLES 2023 Page 13 of 14 9(d)(i) box one box two box three 11 HCl box one: 4 1 dipole on C=O 2 LP on N of amine [1] 3 CA from N of amine to C of acyl chloride 4 CA from = to O of acyl chloride [1] box two: 5 + on what was N of amine and nowhere else 6 – on what was O of acyl chloride and nowhere else 7 LP on what was O of acyl chloride [1] 8 CA from N-H bond to what was N of amine 9 CA from C-Cl bond to what was Cl of acyl chloride 10 CA from (LP on) O to reform C=O [1] box three: 11 HCl 9(d)(ii) Addition-elimination 1 © UCLES 2023 Page 14 of 14

7(a) C H N O S 2– OR C H N O S [1] 1 16 10 2 7 2 16 10 2 7 2 © UCLES 2023 Page 12 of 18 7(b) 3 [1] [1] ECF from E [1] 7(c) M1 step 1: HNO OR NaNO + HCl [1] 3 2 2 M2 step 1: T ⩽ 10 °C [1] M3 step 2: NaOH(aq) / alkaline conditions [1] 7(d) 14 / fourteen [1] 1 © UCLES 2023 Page 13 of 18

6(a)(i) pH at which a molecule has 1 no overall charge / is neutral/ is a Zwitterion / charges cancel out 6(a)(ii) 1 6(b)(i) ethanol AND heat in a sealed tube 1 OR ethanol AND high pressure 6(b)(ii) C 6 H 5 COCl / benzoyl chloride / benzoyl anhydride 1 6(b)(iii) 2 • carboxylic acid to primary alcohol COOH to CH OH 2 • amide to amine CONH to CH NH 2 • rest of the molecule is correct (carbons and benzene ring) mark as  ✓ ✓ © Cambridge University Press & Assessment 2024 Page 12 of 13 6(b)(iv) 2 6(c)(i) M1 nitrogen lone pair in amides is delocalised with C=O 1 M2 lone pair less available for donation / to accept H+ 1 OR less electron density on N / NH so less able to accept H+ 2 6(c)(ii) chloroethanoic acid is a stronger acid (than ethanoic acid) 1 because electron-withdrawing (–I / inductive) effect of Cl substituent 1 AND weakens O—H / carboxylate anion stabilised 6(d)(i) 4 proton a b c d e  9.0–13.0 6.0–9.0 2.3–3.0 3.2–4.0 1.0–5.0 splitting singlet multiplet triplet triplet singlet any three [1] any five [2] any seven [3] all nine [4] 6(d)(ii) 1 proton a b c d e present in D 2 O ✓ ✓ ✓ © Cambridge University Press & Assessment 2024 Page 13 of 13

8(a)(i) two 1 8(a)(ii) amide 2 amine ester carboxylic acid / carboxyl any two [1] all four [2] 8(b)(i) M1 hydrolysis 2 M2 acid–base 8(b)(ii) 3 one mark for each structure © Cambridge University Press & Assessment 2024 Page 16 of 18

8(a) M1 benzylamine > ammonia > phenylamine 3 M1 M2 Any two for one mark, all three for two marks:  (basicity linked to) p orbital of N / lone pair on N AND being able to bond / accept / donate to / coordinate to a proton / H+  (benzylamine) R / alkyl / CH group AND is electron donating / positive inductive effect / has + I effect 2  (phenylamine) p orbital of N / lone pair on N is overlaps / incorporated / delocalised in the ring / -bond system © Cambridge University Press & Assessment 2024 Page 11 of 15 8(b)(i) M1 white ppt. 2 M2 structure 8(b)(ii) M1 lone pair / p-orbital / electrons on the nitrogen / NH AND overlap / delocalised / incorporated AND with the (–electrons) 2 2 ring /  system M2 increasing its electron density (of the ring) OR it can polarise the electrophile / Br better 2 8(c) lone pair / p-orbital on N is delocalised AND into C=O group / across the two electronegative O and N 1 © Cambridge University Press & Assessment 2024 Page 12 of 15 8(d) 4 M1 / M2 any two for one mark, all four for two marks:  lone pair on N  correct arrow from lone pair N to C (of C=O)  correct dipole on C=O  correct arrow from the C=O bond to O atom M3 correct intermediate M4 arrow from O(–) to C–O bond AND arrow from C–Cl bond to Cl ALLOW arrow from anywhere on O– to C–O bond 8(e)(i) pH at which a molecule has no overall charge / is neutral / exist as a zwitterion 1 8(e)(ii) C H CH CH(NH )COO– 1 6 5 2 2 8(f) 2 OR M1 correct peptide bond displayed (there must be a saturated carbon attached to either side of the peptide group) M2 rest of the dipeptide correct © Cambridge University Press & Assessment 2024 Page 13 of 15

8(a)(i) two 1 8(a)(ii) amide 2 amine ester carboxylic acid / carboxyl any two [1] all four [2] 8(b)(i) M1 hydrolysis 2 M2 acid–base 8(b)(ii) 3 one mark for each structure © Cambridge University Press & Assessment 2024 Page 16 of 18

4(a) propanamide < ammonia < propylamine 4 (basicity linked to) p orbital of N / lone pair on N AND being accept / donate to / coordinate to a proton/H+ (propanamide) lone pair / p-orbital on N is delocalised AND into C=O group / over N-C-O group / across the two electronegative O & N (propylamine) R / alkyl / propyl group AND is electron donating / positive inductive effect 4(b) K = CH 3 CH 2 COCl / propanoyl chloride 3 L = CH CH CN / propanenitrile 3 2 M = LiAlH 4 OR H 2 / Ni / correct names © Cambridge University Press & Assessment 2025 Page 9 of 14 4(c) 4 M1: (un)protonated benzylamine M2: (un)protonated amine as above M3: ethanoic acid M4: all amine groups protonated (—NH +) AND all acid groups as —COOH 3 4(d)(i) C H NO + 6[H] → C H NH + 2H O 1 7 7 2 7 7 2 2 4(d)(ii) 6 step reagents and conditions type of reaction 1 • Sn & conc. HCl (+ heat) reduction 2 • CH 3 Br / CH 3 Cl / CH 3 I • (nucleophilic) (in ethanol) substitution 3 • hot MnO –/KMnO • oxidation 4 4 4 condensation • (+ conc. H SO ) 2 4 [1] x 6 Question Answer Marks

9(a)(i) • nitrobenzene / C H NO 2 6 5 2 • Sn and HCl • concentrated HCl and heat / boil / reflux Two correct point [1] all three correct points [2] 9(a)(ii) M1: propylamide / propenamide / C H CONH OR propanenitrile / C H CN 2 2 5 2 2 5 M2: LiAlH 4 9(a)(iii) M1: bromine (aq) AND phenylamine / C H NH 2 6 5 2 M2: correct structure 9(b) M1: phenylamine ammonia propylamine 4 M2: a base has a lone pair that can accept a proton / H+ M3: the lone pair on the nitrogen atom of phenylamine is delocalised into the benzene ring / -system M4: propylamine has an electron donating alkyl group © Cambridge University Press & Assessment 2025 Page 15 of 16

7(a) rotate the plane of polarised light equally in the opposite direction 1 7(b)(i) M1: nitrogen / N can accept / bond to a proton / H+ ion 2 OR donation of lone pair/electrons on the nitrogen / N to a proton / H+ ion M2: CH CH(NH )CH CH + H O → CH CH(NH +)CH CH + OH– 3 2 2 3 2 3 3 2 3 7(b)(ii) M1: more electron donating alkyl / ethyl group on N / NH (in diethylamine) 2 OR two electron donating alkyl / R / alkane / ethyl group on N / NH (in diethylamine) M2: increase electron density on N OR make lone pair on N more available (to accept H+) 7(b)(iii) (CH CH ) NH + CH COOH → (CH CH ) NH + CH COO– 1 3 2 2 3 3 2 2 2 3 © Cambridge University Press & Assessment 2025 Page 14 of 17 7(b)(iii) (CH CH ) NH + CH COOH → (CH CH ) NH + CH COO– 1 3 2 2 3 3 2 2 2 3 7(b)(iv) (CH CH ) NH + CH COCl → CH CON(CH CH ) + HCl 1 3 2 2 3 3 2 3 2 7(c)(i) 1 monomer type of polymerisation addition condensation CH CH(NH )COOH condensation 3 2 7(c)(ii) 2 M1: correct displayed amide linkage with an adjacent C=O (to CO) and C(H ) to NH 2 M2: rest of the structure correct (only one repeat unit) with continuation bonds 7(c)(iii) they are chemically inert / difficult to hydrolyse / C-C bonds are non-polar 1 Question Answer Marks

9(a) 2 M1: correct displayed peptide bond with an adjacent C(H) (to CO) and C(H) to NH M2: rest of the dipeptide correct 9(b)(i) pH at which a molecule has no overall charge / no net charge 1 © Cambridge University Press & Assessment 2025 Page 16 of 17 9(b)(ii) 3 M1: correct relative positions of the spots drawn M2: ser not moved AND as it is a zwitterion / neutral OR ser-lys / lys AND move towards negative (pole) as they are positively charged M3: lys moves the furthest / fastest AND as it has the lower M / smaller size (than ser-lys) r 9(c)(i) 1 9(c)(ii) M1: step 1 aqueous AND HCl / H SO AND heat / reflux[1] 2 2 4 M2: step 2 conc. H SO catalyst AND high temp / heat 2 4 © Cambridge University Press & Assessment 2025 Page 17 of 17

9(a)(i) • nitrobenzene / C H NO 2 6 5 2 • Sn and HCl • concentrated HCl and heat / boil / reflux Two correct point [1] all three correct points [2] 9(a)(ii) M1: propylamide / propenamide / C H CONH OR propanenitrile / C H CN 2 2 5 2 2 5 M2: LiAlH 4 9(a)(iii) M1: bromine (aq) AND phenylamine / C H NH 2 6 5 2 M2: correct structure 9(b) M1: phenylamine ammonia propylamine 4 M2: a base has a lone pair that can accept a proton / H+ M3: the lone pair on the nitrogen atom of phenylamine is delocalised into the benzene ring / -system M4: propylamine has an electron donating alkyl group © Cambridge University Press & Assessment 2025 Page 15 of 16

9(a) M1: (basicity linked to) ability of lone pair / p-orbital to 2 AND accept / coordinate with a proton / H+ M2: (lone pair of) electrons on N is delocalised into C=O group (and make amides neutral) © Cambridge University Press & Assessment 2025 Page 17 of 19 9(b)(i) M1: M 2 M2: N 9(b)(ii) LiAlH 4 1 9(c) ketone / carbonyl AND secondary / 2o 1 9(d)(i) 2 curly arrow 1: from O lone pair to C atom (in C=C) curly arrow 2: from C=C bond to the right-hand O atom in O=O curly arrow 3: from O=O bond to O+ © Cambridge University Press & Assessment 2025 Page 18 of 19 9(d)(ii) 1 © Cambridge University Press & Assessment 2025 Page 19 of 19

8(a) the pH at which an amino acid exists as a zwitterion 1 8(b) M1: [HOOCCH(NH )CH CONH ]+ 2 3 2 2 M2: [HOOCCH(NH )CH COOH]+ 3 2 © Cambridge University Press & Assessment 2025 Page 12 of 15 8(c) M1: HOCH CH(NH )CH CH NH 2 2 2 2 2 2 M2: HOCH CH(NH )CH CH OH 2 2 2 2 8(d)(i) HOOCCH 2 COOH + 2SOCl2 → ClOCCH 2 COCl + 2SO 2 + 2HCl [1] 1 8(d)(ii) HOOCCH(CH CONH )NHCOCH CONHCH(CH CONH )COOH 2 2 2 2 2 2 M1: three molecules joined, with four correct amide groups only M2: whole structure correct as above, displayed formula accepted, skeletal formula as below accepted 8(e) M1: hydrolysis of amide to carboxylate ion 2 M2: hydrolysis of –COOH to carboxylate ion and rest of molecule –OOCCH(NH )CH COO– 2 2 © Cambridge University Press & Assessment 2025 Page 13 of 15 8(f) • three monomer residues 3 • all linkages correct • correct trailing bonds • repeat unit marked contains correct atoms Any two [1], any three [2], all four [3] CH CONH CH CONH 2 2 2 2 | | –COCHNH–[–COCHNH–]–COCHNH– | CH CONH 2 2 8(g)(i) • rotate the plane of the plane polarised light 2 • by the same angle • in opposite directions Any two [1], all three [2] 8(g)(ii) racemic mixture 1 Question Answer Marks

9(a) M1: (basicity linked to) ability of lone pair / p-orbital to 2 AND accept / coordinate with a proton / H+ M2: (lone pair of) electrons on N is delocalised into C=O group (and make amides neutral) © Cambridge University Press & Assessment 2025 Page 17 of 19 9(b)(i) M1: M 2 M2: N 9(b)(ii) LiAlH 4 1 9(c) ketone / carbonyl AND secondary / 2o 1 9(d)(i) 2 curly arrow 1: from O lone pair to C atom (in C=C) curly arrow 2: from C=C bond to the right-hand O atom in O=O curly arrow 3: from O=O bond to O+ © Cambridge University Press & Assessment 2025 Page 18 of 19 9(d)(ii) 1 © Cambridge University Press & Assessment 2025 Page 19 of 19

6(a)(i) 2 6(a)(ii) pH at which a molecule is neutral / has no overall charge / charge of zero / no net charge 1 6(a)(iii) 1 © Cambridge University Press & Assessment 2026 Page 17 of 18 6(b) M1: 3 M2: direction in terms of charge of species Z moves towards positive (pole) AND is negatively charged OR X / Y move towards negative (pole) AND is positively charged M3: distance in terms of size X moves farther / faster (than Y) because of lower M / smaller molecular size r 6(c)(i) M1: species with / has two lone pairs / LP (of electrons) 2 M2: that form dative (covalent) / co-ordinate bond(s) to a (central) transition-element / metal AND atom / ion OR donates electron pair(s) to a (central) transition-element / metal AND atom / ion 6(c)(ii) 1 6(c)iii) better / improved biological activity 1 OR reduction of dosage OR the other isomer may have other / different / unwanted biological activity OR the other isomer may have different / unwanted side effects / be toxic / be harmful 6(c)(iv) [Cu(H O) ]2+ + 2Z– → [Cu(Z) (H O) ] + 4H O 1 2 6 2 2 2 2 © Cambridge University Press & Assessment 2026 Page 18 of 18

8(a)(i) CH COOH + SOCl → CH COCl + SO + HCl 1 CON aq. 3 2 3 2 8(a)(ii) PCl or PCl 1 A names, phosphorus(III) chloride, 3 5 phosphorus trichloride, phosphorus(V) chloride, phosphorus pentachloride. CON aq, but not in both 8(a)(i) and 8(a)(ii). 8(a)(iii) 1 Or any unambiguous structural or skeletal formula. or CH CONHCH(CH ) 3 3 2 8(a)(iv) 1 No ecf from 8(a)(iii) – Q specifies L is an amide and gives the structure of M. or CH CHNH CH 3 2 3 or skeletal 8(a)(v) (nucleophilic) addition-elimination 1 No ecf from 8(a)(iii) – Q specifies L is an amide. I ‘condensation’ – correct but not a mechanism. 8(a)(vi) LiAl H 1 No ecf from 8(a)(iii) – Q specifies L is an 4 amide. CON aq. 8(b)(i) • r – triplet 2 ⚫✓⚫✓ two points for one mark, • s – quartet/quadruplet four points for two marks. • t – doublet • u – multiplet A septet, heptet, septuplet. © Cambridge University Press & Assessment 2026 Page 18 of 21 Trace ID: PC-F9EA0E463D Re-uploading, mirroring or re-hosting this file on any other website or domain is unauthorised and traceable. Licensed for hosting on papacambridge.com only. P97a01p/4a1 CMaarkm Scbhermide gJuene 2·0 2p6 a| Spoaurccea: mpapbarciadmgbreid.gceo.comm 9701/41 Mark Scheme June 2026 Downloaded from PapaCambridge - https://papacambridge.com/ 8(b)(ii) M1 one more peak and reference to N-H 2 A ‘NH peak is present’. A ‘NH peak is not present in D O’. 2 Subject of Q is ‘in CDCl ’ so assume this if no solvent specified. A reference to five peaks or five proton 3 See first two ALLOWs in guidance. environments and reference to N-H. A ‘it is exchanged with D’ if NH peak M2 H (of NH) is exchanged with D (in D O) / NH + D → ND + H / already referred to and you are confident 2 H (of NH) is not exchanged with D (in CDCl ) they refer to ‘in D O’. 3 2 A ‘it is not exchanged with D’ if NH peak the bits in brackets for M2 are not essential but if clearly wrong it is CON already referred to and you are confident they refer to ‘in CDCl ’. 3 I ‘D O replaces the H’. 2 © Cambridge University Press & Assessment 2026 Page 19 of 21 Trace ID: PC-F9EA0E463D Re-uploading, mirroring or re-hosting this file on any other website or domain is unauthorised and traceable. Licensed for hosting on papacambridge.com only. P97a01p/4a1 CMaarkm Scbhermide gJuene 2·0 2p6 a| Spoaurccea: mpapbarciadmgbreid.gceo.comm 9701/41 Mark Scheme June 2026 Downloaded from PapaCambridge - https://papacambridge.com/

9(a) M1 One pair of diagrams of P with correct use of 3D showing mirror images of 3 two optical isomers Q may be given above, and P may be given below. Mirror plane not essential. M2 One pair of diagrams showing correct E and Z of Q M3 conditional on optical linked to an attempt on P and geometrical / cistrans M3 Optical or enantiomerism in the right place and / EZ linked to an attempt on Q in M1 and Geometric(al) or E / Z or A cis/trans in the right place M2. 9(b)(i) the pH at which (the amino acid is) 1 A clear and correct description of a zwitterion / no net charge / no overall charge / no total charge zwitterion for second component. electrically neutral / charge is neutral © Cambridge University Press & Assessment 2026 Page 20 of 21 Trace ID: PC-F9EA0E463D Re-uploading, mirroring or re-hosting this file on any other website or domain is unauthorised and traceable. Licensed for hosting on papacambridge.com only. P97a01p/4a1 CMaarkm Scbhermide gJuene 2·0 2p6 a| Spoaurccea: mpapbarciadmgbreid.gceo.comm 9701/41 Mark Scheme June 2026 Downloaded from PapaCambridge - https://papacambridge.com/ 9(b)(ii) 3 pH 4.0 pH 5.5 pH 8.0 ⚫✓⚫✓ ⚫✓ T two structures for one mark, four structures for two marks, six structures for three mark. Phe at 5.5 can be U Table left is repeated larger after 9(c)(iii). 9(c)(i) 2 Fully correct [2]. M1 – amide links correct M2 – remainder is fully correct, e.g. terminal groups not trailing bonds neutral, zwitterion, 1+ or 1– side/R groups CH – H – CH 3 3 all H atoms on -carbons 9(c)(ii) hydrolysis 1 I acid / alkaline / enzymatic / NS. 9(c)(iii) condensation 1 I addition-elimination. © Cambridge University Press & Assessment 2026 Page 21 of 21 Trace ID: PC-F9EA0E463D Re-uploading, mirroring or re-hosting this file on any other website or domain is unauthorised and traceable. Licensed for hosting on papacambridge.com only. P97a01p/4a1 CMaarkm Scbhermide gJuene 2·0 2p6 a| Spoaurccea: mpapbarciadmgbreid.gceo.comm 9701/41 Mark Scheme June 2026 Downloaded from PapaCambridge - https://papacambridge.com/

7(a)(i) (a substance able to) rotate plane polarised light 1 A (a substance able to) rotate plane of (plane) polarised light. I rotating an amino acid instead of plane of polarised light. 7(a)(ii) (a mixture containing) equal amounts / proportions / concentrations 1 and of optical isomers / enantiomers / stereoisomers 7(b)(i) pH at (which a molecule / amino acid) has 1 and I ‘pH when the molecule has no charge’ alone. no overall charge / is neutral / is a zwitterion [1] 7(b)(ii) CH CH(NH )COO– 1 3 2 7(c) 2 A ecf for 1 mark here for M2 – repeat error. Also ecf M2 if H omitted on both N – repeat M1 two peptide linkage shown error. (C=O needs to be displayed but allow NH not displayed) CON M1 -CO-HN -. M2 rest of the structure correct DEP on M1 (except for specific ecfs in guidance) A M1 if more than 2 amide links but M2 not A carboxylate ion / zwitterion / NH + ion 3 available. © Cambridge University Press & Assessment 2026 Page 21 of 25 Trace ID: PC-9D76E91B48 Re-uploading, mirroring or re-hosting this file on any other website or domain is unauthorised and traceable. Licensed for hosting on papacambridge.com only. P97a01p/4a2 CMaarkm Scbhermide gJuene 2·0 2p6 a| Spoaurccea: mpapbarciadmgbreid.gceo.comm 9701/42 Mark Scheme June 2026 Downloaded from PapaCambridge - https://papacambridge.com/ 7(d)(i) 2 M1M2 7(d)(ii) M1 step 1 CH COCl CON (aq) 3 ecf penalise (aq) once only in step 1,2 and 3. 3 CON additional reagent e.g. AlCl , cH SO 3 2 4 A M1 CH COOCOCH for ‘CH COCl’. 3 3 3 M2 step 2 PCl + heat or SOCl or PCl CON (aq) 3 2 5 All u / c marking points. M3 step 3 C H and Al Cl CON (aq) 6 6 3 A any viable halogen carrier for acylation (e.g. FeBr ). 3 © Cambridge University Press & Assessment 2026 Page 22 of 25 Trace ID: PC-9D76E91B48 Re-uploading, mirroring or re-hosting this file on any other website or domain is unauthorised and traceable. Licensed for hosting on papacambridge.com only. P97a01p/4a2 CMaarkm Scbhermide gJuene 2·0 2p6 a| Spoaurccea: mpapbarciadmgbreid.gceo.comm 9701/42 Mark Scheme June 2026 Downloaded from PapaCambridge - https://papacambridge.com/

9(a) M1 Q ammonia P 4 most basic least basic explanation M2 (basicity linked to) ability of lone pair / p-orbital to I ‘attract’ for accept. accept / donate to / coordinate with a proton / H+ A explanations in terms of hyperconjugation of Explanation M3 M4 alkyl group. “alkyl group can donate electron density into • lone pair / p-orbital from N (in P) empty (p) orbital on positively-charged carbon”. and delocalised / overlaps with (-)ring / benzene I incorporated / donated. • electron donating / +I and R / alkyl / CH grp (in Q) LP with N can be qualified anywhere in their 2 answer. • increases electron density on N or N is more electron rich I ‘charge density’ for electron density. or N LP is more available (in Q) ora ● ✓✓ 9(b)(i) M1 step 1 HNO and H SO and conc. / concentrated 2 CON omission of conc. once. 3 2 4 M2 step 2 Sn and conc. HCl I temp. but CON 10 °C or lower –CON once. CON (aq) in step 1 only. CON Sn catalyst in step 2. I NaOH with step 2. 9(b)(ii) 1 CON 6 [H+] © Cambridge University Press & Assessment 2026 Page 24 of 25 Trace ID: PC-9D76E91B48 Re-uploading, mirroring or re-hosting this file on any other website or domain is unauthorised and traceable. Licensed for hosting on papacambridge.com only. P97a01p/4a2 CMaarkm Scbhermide gJuene 2·0 2p6 a| Spoaurccea: mpapbarciadmgbreid.gceo.comm 9701/42 Mark Scheme June 2026 Downloaded from PapaCambridge - https://papacambridge.com/ 9(c)(i) or 1 A –N Cl or –N + form. 2 2 A –N≡NCl or –N+≡N form. A –N=NCl or –N=N+ form. if a Cl present - must be electrically neutral. Position of + charge must be correct if seen. CON covalent N–Cl bond seen. 9(c)(ii) M1 step 1 NaNO with HCl or HNO 2 CON heat at 10 oC. 2 2 and ⩽10 °C [1] I NaNO . 3 A ‘HNO / H SO ’ for HCl 3 2 4 M2 step 2 alkaline / NaOH A M2 respective phenoxide ion and for both reagents in step 2. I ‘base’ alone. A sulfonic acid phenol as an alternative with NaOH. A structures with SO – (no Na+). 3 I temp for M2. © Cambridge University Press & Assessment 2026 Page 25 of 25 Trace ID: PC-9D76E91B48 Re-uploading, mirroring or re-hosting this file on any other website or domain is unauthorised and traceable. Licensed for hosting on papacambridge.com only. P97a01p/4a2 CMaarkm Scbhermide gJuene 2·0 2p6 a| Spoaurccea: mpapbarciadmgbreid.gceo.comm 9701/42 Mark Scheme June 2026 Downloaded from PapaCambridge - https://papacambridge.com/

8(a)(i) CH COOH + SOCl → CH COCl + SO + HCl 1 CON aq. 3 2 3 2 8(a)(ii) PCl or PCl 1 A names, phosphorus(III) chloride, 3 5 phosphorus trichloride, phosphorus(V) chloride, phosphorus pentachloride. CON aq, but not in both 8(a)(i) and 8(a)(ii). 8(a)(iii) 1 Or any unambiguous structural or skeletal formula. or CH CONHCH(CH ) 3 3 2 8(a)(iv) 1 No ecf from 8(a)(iii) – Q specifies L is an amide and gives the structure of M. or CH CHNH CH 3 2 3 or skeletal 8(a)(v) (nucleophilic) addition-elimination 1 No ecf from 8(a)(iii) – Q specifies L is an amide. I ‘condensation’ – correct but not a mechanism. 8(a)(vi) LiAl H 1 No ecf from 8(a)(iii) – Q specifies L is an 4 amide. CON aq. 8(b)(i) • r – triplet 2 ⚫✓⚫✓ two points for one mark, • s – quartet/quadruplet four points for two marks. • t – doublet • u – multiplet A septet, heptet, septuplet. © Cambridge University Press & Assessment 2026 Page 18 of 21 Trace ID: PC-F2CDA313A1 Re-uploading, mirroring or re-hosting this file on any other website or domain is unauthorised and traceable. Licensed for hosting on papacambridge.com only. P97a01p/4a3 CMaarkm Scbhermide gJuene 2·0 2p6 a| Spoaurccea: mpapbarciadmgbreid.gceo.comm 9701/43 Mark Scheme June 2026 Downloaded from PapaCambridge - https://papacambridge.com/ 8(b)(ii) M1 one more peak and reference to N-H 2 A ‘NH peak is present’. A ‘NH peak is not present in D O’. 2 Subject of Q is ‘in CDCl ’ so assume this if no solvent specified. A reference to five peaks or five proton 3 See first two ALLOWs in guidance. environments and reference to N-H. A ‘it is exchanged with D’ if NH peak M2 H (of NH) is exchanged with D (in D O) / NH + D → ND + H / already referred to and you are confident 2 H (of NH) is not exchanged with D (in CDCl ) they refer to ‘in D O’. 3 2 A ‘it is not exchanged with D’ if NH peak the bits in brackets for M2 are not essential but if clearly wrong it is CON already referred to and you are confident they refer to ‘in CDCl ’. 3 I ‘D O replaces the H’. 2 © Cambridge University Press & Assessment 2026 Page 19 of 21 Trace ID: PC-F2CDA313A1 Re-uploading, mirroring or re-hosting this file on any other website or domain is unauthorised and traceable. Licensed for hosting on papacambridge.com only. P97a01p/4a3 CMaarkm Scbhermide gJuene 2·0 2p6 a| Spoaurccea: mpapbarciadmgbreid.gceo.comm 9701/43 Mark Scheme June 2026 Downloaded from PapaCambridge - https://papacambridge.com/

9(a) M1 One pair of diagrams of P with correct use of 3D showing mirror images of 3 two optical isomers Q may be given above, and P may be given below. Mirror plane not essential. M2 One pair of diagrams showing correct E and Z of Q M3 conditional on optical linked to an attempt on P and geometrical / cistrans M3 Optical or enantiomerism in the right place and / EZ linked to an attempt on Q in M1 and Geometric(al) or E / Z or A cis/trans in the right place M2. 9(b)(i) the pH at which (the amino acid is) 1 A clear and correct description of a zwitterion / no net charge / no overall charge / no total charge zwitterion for second component. electrically neutral / charge is neutral © Cambridge University Press & Assessment 2026 Page 20 of 21 Trace ID: PC-F2CDA313A1 Re-uploading, mirroring or re-hosting this file on any other website or domain is unauthorised and traceable. Licensed for hosting on papacambridge.com only. P97a01p/4a3 CMaarkm Scbhermide gJuene 2·0 2p6 a| Spoaurccea: mpapbarciadmgbreid.gceo.comm 9701/43 Mark Scheme June 2026 Downloaded from PapaCambridge - https://papacambridge.com/ 9(b)(ii) 3 pH 4.0 pH 5.5 pH 8.0 ⚫✓⚫✓ ⚫✓ T two structures for one mark, four structures for two marks, six structures for three mark. Phe at 5.5 can be U Table left is repeated larger after 9(c)(iii). 9(c)(i) 2 Fully correct [2]. M1 – amide links correct M2 – remainder is fully correct, e.g. terminal groups not trailing bonds neutral, zwitterion, 1+ or 1– side/R groups CH – H – CH 3 3 all H atoms on -carbons 9(c)(ii) hydrolysis 1 I acid / alkaline / enzymatic / NS. 9(c)(iii) condensation 1 I addition-elimination. © Cambridge University Press & Assessment 2026 Page 21 of 21 Trace ID: PC-F2CDA313A1 Re-uploading, mirroring or re-hosting this file on any other website or domain is unauthorised and traceable. Licensed for hosting on papacambridge.com only. P97a01p/4a3 CMaarkm Scbhermide gJuene 2·0 2p6 a| Spoaurccea: mpapbarciadmgbreid.gceo.comm 9701/43 Mark Scheme June 2026 Downloaded from PapaCambridge - https://papacambridge.com/

9(a) • asparagine is negative / contains COO– 3 A ecf for bullets 2 and 6 if charges and • asparagine moves left / towards the positive/anode directions are reversed. • histidine is a zwitterion / neutral / uncharged A bullets 2, 4 and 6 from diagram only if • histidine does not move directions not mentioned. • lysine is positive / contains NH + 3 • lysine moves right / towards the negative/cathode ✓ ✓ ✓ ⚫ ⚫ ⚫ © Cambridge University Press & Assessment 2026 Page 19 of 21 Trace ID: PC-0F078E40FE Re-uploading, mirroring or re-hosting this file on any other website or domain is unauthorised and traceable. Licensed for hosting on papacambridge.com only. P97a01p/4a4 CMaarkm Scbhermide gJuene 2·0 2p6 a| Spoaurccea: mpapbarciadmgbreid.gceo.comm 9701/44 Mark Scheme June 2026 Downloaded from PapaCambridge - https://papacambridge.com/ 9(b)(i) 1 Correct 3D. Correct formulae. Diagrams are different isomers. No connectivity penalty for any group may see RH structure same orientation as LH structure with any 2 groups switched. 9(b)(ii) racemic / racemate 1 A near misses, e.g. racemix. 9(b)(iii) M1 effect on/rotation of plane polarised light 2 I angle of rotation, optical activity. M2 biological activity / interaction with enzyme A biological reactivity / biochemistry. / biological effects / bioactivity. A interaction with chiral reagents. I comments on structure. I chemical biology, biological active, etc. 9(b)(iv) H NCH(CH OH)COOH + 2PCl → 2POCl + 2HCl + H NCH(CH Cl)COCl 2 A [1] if molecular formula used, 2 2 5 3 2 2 C H NOCl as only mistake. 3 5 2 M1 Correct organic product A any unambiguous structure. A [1] if only one OH substituted and M2 all correct otherwise all correct. A ammonium salt but beware balancing with HCl, e.g. H NCH(CH OH)COOH + 2PCl → 2POCl + HCl + ClH NCH(CH Cl)COCl 2 2 5 3 3 2 © Cambridge University Press & Assessment 2026 Page 20 of 21 Trace ID: PC-0F078E40FE Re-uploading, mirroring or re-hosting this file on any other website or domain is unauthorised and traceable. Licensed for hosting on papacambridge.com only. P97a01p/4a4 CMaarkm Scbhermide gJuene 2·0 2p6 a| Spoaurccea: mpapbarciadmgbreid.gceo.comm 9701/44 Mark Scheme June 2026 Downloaded from PapaCambridge - https://papacambridge.com/