Skip to content
Try on iPad

Organic mechanisms: OCR A‑Level Chemistry B questions

Every OCR A-Level Chemistry B exam question on DF Organic mechanisms (specification points DF(q)), 2016–2025, with its mark scheme and examiner’s report.

Find questions2,049
Calculations

2,049 questions

  1. Q31(b)(ii)

    June 2025 · Paper 1

    3 marksDF Organic mechanisms
    The whole paper ↗
    June 2025 Paper 1, question 31(b)(ii): The presence of the double bond in oleic acid can be shown by its reaction with bromine. Draw the mechanism of the reaction of ethene with bromine. Show curly a

  2. Q2(d)

    June 2025 · AS Paper 2

    4 marksDF Organic mechanisms
    The whole paper ↗
    June 2025 AS Paper 2, question 2(d): Cyclopentene can be made into cyclopentanol using sulfuric acid. Complete the first part of step 1 of the mechanism for the addition of sulfuric acid to form a

  3. Q2(f)

    June 2022 · Paper 2

    3 marksDF Organic mechanisms
    The whole paper ↗
    June 2022 Paper 2, question 2(f): But-2-ene, CH3CH=CHCH3, reacts with hydrogen bromide. Draw the mechanism for this reaction. Show curly arrows, full charges and the product. [3]

  4. Q21(b)

    June 2022 · AS Paper 1

    2 marksDF Organic mechanisms
    The whole paper ↗
    June 2022 AS Paper 1, question 21(b): Vinyl chloride reacts with HBr in an electrophilic addition reaction. Possible products are CH2BrCH2Cl and CH3CHBrCl. There is not an equal mix of products. The

  5. Q1(c)

    November 2021 · AS Paper 2

    1 markDF Organic mechanisms
    The whole paper ↗
    November 2021 AS Paper 2, question 1(c): When propene is bubbled into a solution containing chlorine and sodium iodide, a mixture of products is obtained, including CH3CHICH2Cl. Draw the structure of t

  6. Q33(b)

    November 2020 · Paper 1

    3 marksDF Organic mechanisms
    The whole paper ↗
    November 2020 Paper 1, question 33(b): The HCl produced in step 2 can be used to make more CH2=CHCl by direct reaction with ethyne, HC≡CH. Suggest the mechanism for the reaction of HCl with ethyne. S

  7. Q1(d)(i)

    November 2020 · AS Paper 2

    1 markDF Organic mechanisms
    The whole paper ↗
    November 2020 AS Paper 2, question 1(d)(i): Name the mechanism of this reaction. [1]

  8. Q1(d)(ii)

    November 2020 · AS Paper 2

    3 marksDF Organic mechanisms
    The whole paper ↗
    November 2020 AS Paper 2, question 1(d)(ii): Draw the mechanism for this reaction. Show curly arrows and full and partial charges. [3]

  9. Q35(g)(i)

    June 2019 · Paper 1

    2 marksDF Organic mechanisms
    The whole paper ↗
    June 2019 Paper 1, question 35(g)(i): Show the mechanism of the reaction of compound A with hydrogen bromide. Use curly arrows and partial and full charges where appropriate. [2]

  10. Q35(g)(ii)

    June 2019 · Paper 1

    3 marksDF Organic mechanisms
    The whole paper ↗
    June 2019 Paper 1, question 35(g)(ii): Compound A is reacted with aqueous hydrogen bromide containing dissolved sodium chloride. A student suggests that the products shown below are formed in additio

  11. Q1(e)

    June 2019 · AS Paper 2

    3 marksDF Organic mechanisms
    The whole paper ↗
    June 2019 AS Paper 2, question 1(e): When but-1-ene, CH3CH2CH=CH2, reacts with ICl the main product is 1-iodo-2-chlorobutane, CH3CH2CHCl CH2I. Suggest a mechanism for this reaction. Show full and p

  12. Q23(a)(iii)

    June 2018 · AS Paper 1

    3 marksDF Organic mechanisms
    The whole paper ↗
    June 2018 AS Paper 1, question 23(a)(iii): Draw the mechanism for the reaction of ethene with Br2. Show curly arrows, full charges and the product. [3]

  13. Q2(c)(ii)

    June 2017 · AS Paper 2

    1 markDF Organic mechanisms
    The whole paper ↗
    June 2017 AS Paper 2, question 2(c)(ii): The first step in the mechanism for the reaction of phenylethene with bromine is shown below. Br – Br + CH = CH2 CHBr CH2 + Br– intermediate 1 What name is give

  14. Q2(c)(iii)

    June 2017 · AS Paper 2

    1 markDF Organic mechanisms
    Mark scheme (PDF)
    The whole paper ↗
    June 2017 AS Paper 2, question 2(c)(iii): If an aqueous mixture of bromine and potassium chloride is added to phenylethene, some of compound B is produced, as well as compound A. CHBrCH2Br CHBrCH2Cl com
All 14 questions on Organic mechanisms, as a list
  1. June 2025, Paper 1, Q31(b)(ii) (3 marks): The presence of the double bond in oleic acid can be shown by its reaction with bromine. Draw the mechanism of the reaction of ethene with bromine. Show curly a
  2. June 2025, AS Paper 2, Q2(d) (4 marks): Cyclopentene can be made into cyclopentanol using sulfuric acid. Complete the first part of step 1 of the mechanism for the addition of sulfuric acid to form a
  3. June 2022, Paper 2, Q2(f) (3 marks): But-2-ene, CH3CH=CHCH3, reacts with hydrogen bromide. Draw the mechanism for this reaction. Show curly arrows, full charges and the product. [3]
  4. June 2022, AS Paper 1, Q21(b) (2 marks): Vinyl chloride reacts with HBr in an electrophilic addition reaction. Possible products are CH2BrCH2Cl and CH3CHBrCl. There is not an equal mix of products. The
  5. November 2021, AS Paper 2, Q1(c) (1 mark): When propene is bubbled into a solution containing chlorine and sodium iodide, a mixture of products is obtained, including CH3CHICH2Cl. Draw the structure of t
  6. November 2020, Paper 1, Q33(b) (3 marks): The HCl produced in step 2 can be used to make more CH2=CHCl by direct reaction with ethyne, HC≡CH. Suggest the mechanism for the reaction of HCl with ethyne. S
  7. November 2020, AS Paper 2, Q1(d)(i) (1 mark): Name the mechanism of this reaction. [1]
  8. November 2020, AS Paper 2, Q1(d)(ii) (3 marks): Draw the mechanism for this reaction. Show curly arrows and full and partial charges. [3]
  9. June 2019, Paper 1, Q35(g)(i) (2 marks): Show the mechanism of the reaction of compound A with hydrogen bromide. Use curly arrows and partial and full charges where appropriate. [2]
  10. June 2019, Paper 1, Q35(g)(ii) (3 marks): Compound A is reacted with aqueous hydrogen bromide containing dissolved sodium chloride. A student suggests that the products shown below are formed in additio
  11. June 2019, AS Paper 2, Q1(e) (3 marks): When but-1-ene, CH3CH2CH=CH2, reacts with ICl the main product is 1-iodo-2-chlorobutane, CH3CH2CHCl CH2I. Suggest a mechanism for this reaction. Show full and p
  12. June 2018, AS Paper 1, Q23(a)(iii) (3 marks): Draw the mechanism for the reaction of ethene with Br2. Show curly arrows, full charges and the product. [3]
  13. June 2017, AS Paper 2, Q2(c)(ii) (1 mark): The first step in the mechanism for the reaction of phenylethene with bromine is shown below. Br – Br + CH = CH2 CHBr CH2 + Br– intermediate 1 What name is give
  14. June 2017, AS Paper 2, Q2(c)(iii) (1 mark): If an aqueous mixture of bromine and potassium chloride is added to phenylethene, some of compound B is produced, as well as compound A. CHBrCH2Br CHBrCH2Cl com

Questions, mark schemes and examiner’s reports are © OCR, from their published past papers. Plumi isn’t affiliated with any exam board. Want whole papers? Every OCR A-Level Chemistry B paper.

Rather write your answers by hand on iPad? Plumi marks them against the same mark schemes.