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Carbon–carbon bond formation

Past-paper questions pack

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Class
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Questions are numbered; the mark schemes (the answer key) follow on separate pages so the question pages can be handed out alone. www.chemistryaleveltutor.com

OCR AS and A-level Chemistry past-paper questions since 2016 · 27 parts · mark schemes follow the questions · www.chemistryaleveltutor.com · Questions and mark schemes © OCR

1. June 2025 · Paper 2 · Q19(a)(i) · 3 marks ·
19 This question is about reactions of haloalkanes. (a) Haloalkanes can react with potassium cyanide to form new carbon–carbon bonds. (i) Outline the mechanism for the reaction of 2-bromopropane with cyanide ions. Show curly arrows, relevant dipoles and products. Br [3]
2. June 2025 · Paper 2 · Q19(a)(ii) · 1 marks ·
(ii) Name this type of mechanism. ..................................................................................................................................................... [1]
3. June 2025 · Paper 2 · Q20(c)(i) · 1 marks ·
(c) Compound G is an organic compound used in the production of pesticides. Compound G can be synthesised from benzene in the two-stage process shown. Synthesis 1 CH3 CH3 NO2 Stage 1 Stage 2 Benzene Methylbenzene Compound G (i) Suggest a reagent and halogen carrier that could be used in Stage 1 of Synthesis 1. ..................................................................................................................................................... [1]
4. June 2024 · Paper 2 · Q18(b) · 9 marks ·
(b) Complete the flowchart by filling in each box. amine reagent(s) ............................................. reagent(s) H ............................................. H3C C Br H bromoethane alcohol reagent(s) .......................................................... H H3C C C N H nitrile reagent(s) reagent(s) .......................................................... ............................................. carboxylic acid amine [9]
5. June 2024 · Paper 2 · Q21(a)(ii) · 5 marks ·
(ii) Outline the mechanism for this reaction, including the role of Al Cl 3 as a halogen carrier. [5]
6. June 2023 · Paper 2 · Q14 · 1 marks · AO1
14 Which compound(s) is/are hydrolysed by HCl (aq) to produce butanoic acid? 1 CH3CH2CH2COOCH3 2 CH3CH2CH2CH2CN 3 CH3CH2CH2CH2Cl A 1, 2 and 3 B Only 1 and 2 C Only 2 and 3 D Only 1 Your answer [1]
7. June 2023 · Paper 2 · Q19 · 6 marks · AO3
19* A student intends to synthesise compound Z, as shown in the flowchart below. H H C Br C C H H H Stage 1 Intermediate 1 Stage 2 Intermediate 2 Stage 3 Br H H H H C C C C NH2 H H H H Compound Z Plan this synthesis showing reagents, the structures of intermediate 1 and intermediate 2, and equations. [6] .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... Additional answer space if required. .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... ..........................................................................................................................................................
8. June 2023 · Paper 2 · Q22(a)(i) · 4 marks · AO1, 2
22 This question is about reactions of acrolein, H2C=CHCHO. (a) Acrolein reacts with sodium cyanide in acidic conditions, NaCN(aq) / H+(aq). (i) Outline the reaction mechanism for this reaction, showing the intermediate and the organic product. The structure of acrolein has been provided. Include curly arrows and relevant dipoles. H H C C H C O H [4]
9. June 2023 · Paper 3 · Q3 · 6 marks · AO3
3* A chemist is investigating compound A, shown below, as a potential organic intermediate. O OH CN Compound A Describe the type of stereoisomerism shown by compound A and suggest three reactions of compound A, one for each of the three functional groups using reagents of your choice. In your answer, show stereoisomers of compound A, your chosen reactants and conditions, and the structures for the organic products produced. Mechanisms and equations are not required. 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10. June 2022 · Paper 2 · Q9 · 1 marks · AO2
9 The compound below reacts with hydrogen gas to form a saturated compound. CN What is the volume of hydrogen, measured at room temperature and pressure, that reacts with 0.0500 mol of the compound? A 2.40 dm3 B 3.60 dm3 C 4.80 dm3 D 6.00 dm3 Your answer [1]
11. June 2022 · Paper 2 · Q19(b) · 4 marks · AO2
(b) The structure of 2-hydroxybutanoic acid is shown below. H CH3CH2 C COOH OH 2-hydroxybutanoic acid Fill in the flowchart for reactions involving 2-hydroxybutanoic acid. C6H5COOH / H2SO4 (CH3)2CHOH / H2SO4 reflux reflux H H ............................... CH3CH2 C CN CH3CH2 C COOH OH OH 2-hydroxybutanoic acid NaBH4 [4]
12. June 2022 · Paper 2 · Q21 · 6 marks · AO1, 2
21* Carbon-carbon bond formation is used in synthesis to increase the length of a carbon chain. Describe the formation of carbon–carbon bonds in aliphatic compounds by two different mechanisms. Your answer should include mechanisms for each aliphatic compound. [6] .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... Additional answer space if required. .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... ..........................................................................................................................................................
13. November 2021 · Paper 2 · Q9 · 1 marks ·
9 Which reaction is not a reduction? A C6H5NO2 C6H5NH2 B CH3CN CH3CH2NH2 C CH3CH2Cl CH3CH2NH2 D CH3COCH3 CH3CHOHCH3 Your answer [1]
14. November 2021 · Paper 2 · Q16(d)(ii) · 2 marks · AO3
(ii) Two more Diels-Alder reactions of buta-1,3-diene are shown below. In the boxes, draw the organic product of each reaction. O OCH3 + OCH3 O + [2]
15. November 2021 · Paper 2 · Q19(b) · 6 marks · AO2, 3
(b)* A student intends to synthesise compound A using the two-stage route below. O Stage 1 Stage 2 CH2 Cl Intermediate CH2 C OH (chloromethyl)benzene Compound A Plan a two-stage synthesis to prepare 5.44 g of compound A starting from (chloromethyl)benzene, C6H5CH2Cl . Assume that the overall percentage yield of compound A from (chloromethyl)benzene is 25%. In your answer, include the mass of C6H5CH2Cl required, reagents, and equations where appropriate. Purification details are not required. [6] ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... Additional answer space if required. ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ...................................................................................................................................................
16. November 2020 · Paper 2 · Q3 · 1 marks · AO1
3 Which of these reagent(s) will not react with HOCH2CH2CH2COOH? A NaCN in ethanol B C2H5OH in the presence of an acid catalyst C (CH3CO)2O D concentrated H2SO4 Your answer [1]
17. November 2020 · Paper 2 · Q14 · 1 marks · AO2
14 Which of the following reactions produce propan-1-ol? 1 The alkaline hydrolysis of 1-chloropropane. 2 The acid hydrolysis of propyl methanoate. 3 The acid hydrolysis of propanenitrile. A 1, 2 and 3 B Only 1 and 2 C Only 2 and 3 D Only 1 Your answer [1]
18. November 2020 · Paper 2 · Q15 · 1 marks · AO1
15 Which compound(s) could be prepared by reacting benzene with an acyl chloride in the presence of a halogen carrier? CH2COCH3 1 CHO 2 COCH3 3 A 1, 2 and 3 B Only 1 and 2 C Only 2 and 3 D Only 1 Your answer [1]
19. June 2019 · Paper 2 · Q19(b)(iii) · 5 marks · AO1, 2, 3
(iii) In the synthesis of compounds D and E, benzene is first reacted with ethanoyl chloride, CH3COCl, to form phenylethanone, shown below. H3C O C phenylethanone The reaction takes place in the presence of aluminium chloride, Al Cl 3, which acts as a catalyst. In the mechanism for this reaction, • ethanoyl chloride first reacts with aluminium chloride to form the CH3–C+=O cation • the CH3–C+=O cation then behaves as an electrophile. Complete the mechanism for the reaction. Include equations to show the role of the Al Cl 3 catalyst, relevant curly arrows and the structure of the intermediate. Formation of electrophile ................................................................................................... + H3C C O Intermediate H3C O C + H+ Regeneration of catalyst ................................................................................................... [5]
20. June 2019 · Paper 2 · Q19(b)(iv) · 7 marks · AO2
(iv) Complete the flowchart for the synthesis of compounds D and E from phenylethanone. H3C O C NaBH4 phenylethanone NaCN(aq) / H+(aq) .................................................. H H C H C .................................................. CH3 compound D Br C CN .................................................. CH3 H2N C COOH .................................... compound E [7]
21. June 2018 · Paper 2 · Q10 · 1 marks ·
10 Benzene reacts with an organic reagent in the presence of a halogen carrier to form phenylethanone. O C CH3 phenylethanone Which organic reagent is required? A CH3CH2OH B CH3CHO C CH3COCl D CH3COOH Your answer [1]
22. June 2018 · Paper 2 · Q15 · 1 marks ·
15 Which of the following could react with the compound below to form a carbon–carbon bond? H O C C Br OH 1 CH3Cl and Al Cl 3 2 KCN in ethanol 3 CH3OH and H2SO4 A 1, 2 and 3 B Only 1 and 2 C Only 2 and 3 D Only 1 Your answer [1]
23. June 2018 · Paper 2 · Q20(c) · 5 marks ·
(c) The flowchart below shows some reactions starting with cinnamaldehyde. Draw the structures of the missing organic compounds in the boxes and add the missing reagent(s) on the dotted line. excess H2/Ni OH CHO reagent(s): .......................... CN cinnamaldehyde NaBH4 H+(aq) [5]
24. June 2018 · Paper 3 · Q6(a)(ii) · 1 marks ·
(ii) What type of reaction has taken place? ...................................................................................................................................... [1]
25. June 2018 · Paper 3 · Q6(a)(iv) · 1 marks ·
(iv) A similar reaction takes place when propanone, (CH3)2CO, is mixed with OH–(aq) ions. Draw the structure of the organic product of this reaction. [1]
26. June 2017 · Paper 2 · Q18(a)(i) · 3 marks ·
18 This question is about organic compounds containing nitrogen. (a) Sodium cyanide, NaCN, can be reacted with many organic compounds to increase the length of a carbon chain. (i) 1-Chloropropane, CH3CH2CH2Cl, reacts with ethanolic sodium cyanide by nucleophilic substitution. Outline the mechanism for this reaction. Include curly arrows, relevant dipoles and the structure of the organic product. [3]
27. June 2017 · Paper 2 · Q18(a)(ii) · 3 marks ·
(ii) Compound G is used to synthesise compounds H and I as shown in the flowchart below. Complete the flowchart showing the structure of compound G and the formulae of the reagents for Reaction 2 and Reaction 3. OH O H C C OH H compound I Reaction 3 reagents: .......................................... OH Reaction 1 H C CN NaCN/H+ H compound G Reaction 2 reagents: .......................................... OH H H C C NH2 H H compound H [3]

Mark schemes

1. June 2025 · Paper 2 · Q19(a)(i)
Mark scheme June 2025 Paper 2 Q19(a)(i)
2. June 2025 · Paper 2 · Q19(a)(ii)
Mark scheme June 2025 Paper 2 Q19(a)(ii)
3. June 2025 · Paper 2 · Q20(c)(i)
Mark scheme June 2025 Paper 2 Q20(c)(i)
4. June 2024 · Paper 2 · Q18(b)
Mark scheme June 2024 Paper 2 Q18(b)
5. June 2024 · Paper 2 · Q21(a)(ii)
Mark scheme June 2024 Paper 2 Q21(a)(ii)
6. June 2023 · Paper 2 · Q14
Mark scheme June 2023 Paper 2 Q14
7. June 2023 · Paper 2 · Q19
Mark scheme June 2023 Paper 2 Q19
8. June 2023 · Paper 2 · Q22(a)(i)
Mark scheme June 2023 Paper 2 Q22(a)(i)
9. June 2023 · Paper 3 · Q3
Mark scheme June 2023 Paper 3 Q3
10. June 2022 · Paper 2 · Q9
Mark scheme June 2022 Paper 2 Q9
11. June 2022 · Paper 2 · Q19(b)
Mark scheme June 2022 Paper 2 Q19(b)
12. June 2022 · Paper 2 · Q21
Mark scheme June 2022 Paper 2 Q21
13. November 2021 · Paper 2 · Q9
Mark scheme November 2021 Paper 2 Q9
14. November 2021 · Paper 2 · Q16(d)(ii)
Mark scheme November 2021 Paper 2 Q16(d)(ii)
15. November 2021 · Paper 2 · Q19(b)
Mark scheme November 2021 Paper 2 Q19(b)
16. November 2020 · Paper 2 · Q3
Mark scheme November 2020 Paper 2 Q3
17. November 2020 · Paper 2 · Q14
Mark scheme November 2020 Paper 2 Q14
18. November 2020 · Paper 2 · Q15
Mark scheme November 2020 Paper 2 Q15
19. June 2019 · Paper 2 · Q19(b)(iii)
Mark scheme June 2019 Paper 2 Q19(b)(iii)
20. June 2019 · Paper 2 · Q19(b)(iv)
Mark scheme June 2019 Paper 2 Q19(b)(iv)
21. June 2018 · Paper 2 · Q10
Mark scheme June 2018 Paper 2 Q10
22. June 2018 · Paper 2 · Q15
Mark scheme June 2018 Paper 2 Q15
23. June 2018 · Paper 2 · Q20(c)
Mark scheme June 2018 Paper 2 Q20(c)
24. June 2018 · Paper 3 · Q6(a)(ii)
Mark scheme June 2018 Paper 3 Q6(a)(ii)
25. June 2018 · Paper 3 · Q6(a)(iv)
Mark scheme June 2018 Paper 3 Q6(a)(iv)
26. June 2017 · Paper 2 · Q18(a)(i)
Mark scheme June 2017 Paper 2 Q18(a)(i)
27. June 2017 · Paper 2 · Q18(a)(ii)
Mark scheme June 2017 Paper 2 Q18(a)(ii)