A LevelChemistryCambridge (CIE)Exam Questions21 .Organic SynthesisOrganic Synthesis

Organic Synthesis (Cambridge (CIE) A Level Chemistry): Exam Questions

Exam code: 9701

2 hours30 questions

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Organic Synthesis

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1
1 mark

Lactic acid occurs naturally, for example in sour milk.

Displayed formula of lactic acid (CH₃CH(OH)COOH) showing the hydroxyl group on the central carbon and the carboxylic acid group

Which property does lactic acid have?

  • It decolourises aqueous bromine rapidly.

  • It is insoluble in water.

  • It reacts with sodium carbonate.

  • It reduces Fehling's reagent.

Choose your answer

2
1 mark

Which reagent can be used to convert CH3CH2CO2CH3 into CH3CH2CO2CH2Cl?

  • Chlorine in bright sunlight at 100 °C

  • Concentrated hydrochloric acid at 100 °C

  • Phosphorus pentachloride at room temperature

  • Sulphur dichloride oxide (thionyl chloride, SOCl2) at 50 °C

Choose your answer

3
1 mark

Which reaction produces a coloured organic compound?

  • CH2=CH2 + cold dilute acidified KMnO4

  • CH3CH2OH + acidified K2Cr2O7

  • CH3CHO + 2,4-dinitrophenylhydrazine reagent

  • CH3COCH3 + Fehling's solution

Choose your answer

4
1 mark

A compound X has the following properties:

  • liquid at room temperature

  • soluble in water

  • reacts with cold aqueous sodium hydroxide

Which of the following could be compound X?

  • Propanoic acid

  • Propanol

  • Propene

  • Propyl propanoate

Choose your answer

5
1 mark

Tartaric acid (HO2CCH(OH)CH(OH)CO2H) can occur naturally, for example in wine, and may be synthesised in the laboratory.

The laboratory synthesis occurs in 2 steps:

    OHCCHO  rightwards arrow with step space 1 on top  intermediate  rightwards arrow with step space 2 on top  HO2CCH(OH)CH(OH)CO2H

Which reagents could be used for this synthesis?

Step 1

Step 2

A

HCl (aq)

HCN (g)

B

H2SO4 (aq)

K2Cr2O7 / H2SO4 (aq)

C

KCN (aq/alcoholic)

K2Cr2O7 / H2SO4 (aq)

D

HCN, NaCN (aq/alcoholic)

H2SO4 (aq)

    Choose your answer

    6
    1 mark

    This molecule is responsible for the flavour of spearmint chewing gum.

    Structural formula of carvone (spearmint flavour molecule) with arrow 1 pointing to the C=C alkene double bond in the cyclohexene ring and arrow 2 pointing to the C=O ketone carbonyl group

    Which statement about functional groups 1 and 2 is correct?

    • 1 will undergo electrophilic substitution

    • 1 will undergo nucleophilic addition

    • 2 will undergo electrophilic substitution

    • 2 will undergo nucleophilic addition

    Choose your answer

    1
    1 mark

    Sorbic acid is a natural organic compound which is used as a food preservative because it kills fungi. Sorbic acid reacts with bromine in an organic solvent and hydrogen in the presence of a nickel catalyst.

    Displayed formula of sorbic acid showing H₃C group connected through two conjugated C=C double bonds to a carboxylic acid (COOH) group, with all hydrogen atoms shown

    How many moles of bromine (in an organic solvent) and of hydrogen (in the presence of a Pt / Ni catalyst) will be incorporated into one mole of sorbic acid by these reactions?

    Moles of bromine

    Moles of hydrogen

    A

    2

    2

    B

    2

    3

    C

    \frac{1}{2}

    2

    D

    2\frac{1}{2}

    3

      Choose your answer

      2
      1 mark

      The naturally-occurring molecule civetone was one of the first known ingredients used in perfumery.

      Structural formula of civetone: a 17-membered cyclic ketone containing a C=O group and one C=C double bond (HC=CH), with the remaining ring positions occupied by CH₂ groups

      Which reagent will not react with civetone?

      • 2,4-dinitrophenylhydrazine reagent

      • Fehling's reagent

      • Hydrogen bromide

      • Sodium tetrahydridoborate (III), NaBH4

      Choose your answer

      3
      1 mark

      An alkene is reacted with acidified manganate (VII) ions, MnO4- . The organic product has a relative molecular mass greater than that of the alkene by 34.

      Which of the following are the correct conditions for this reaction?

      • Cold, concentrated MnO4-

      • Cold, dilute MnO4-

      • Hot, concentrated MnO4-

      • Hot, dilute MnO4-

      Choose your answer

      4
      1 mark

      Pentanoic acid can be produced from 1-bromobutane using reagents Y and Z as shown below.

      1-bromobutane  rightwards arrow with reagent space straight Y on top  compound X  rightwards arrow with reagent space straight Z on top  pentanoic acid 

      Which of the following could be reagents Y and Z?

      Y

      Z

      A

      KCN in ethanol

      HCl (aq)

      B

      KCN in ethanol

      NaOH (aq)

      C

      NaOH (aq)

      HCl (aq)

      D

      NH3 in ethanol

      H+/Cr2O72- (aq)

        Choose your answer

        5
        1 mark

        In which reaction does a carbocation intermediate form?

        • CH2=CH2 + Br2 → CH2BrCH2Br

        • CH3CH2Br + NaOH → CH3CH2OH + NaBr

        • CH3CH3 + Cl2 → CH3CH2Cl + HCl

        • CH3CHO + HCN rightwards arrow with CN to the power of minus on top CH3CH(OH)CN

        Choose your answer

        6
        1 mark

        Hept-4-enal, shown below, naturally occurs in cow's milk.

        CH3CH2CH=CHCH2CH2CHO

        Which organic product is formed when hept-4-enal is reduced with either hydrogen with a nickel catalyst or sodium borohydride?

        • CH3(CH2)5CH3 when hept-4-enal is reduced by H2 / Ni

        • CH3(CH2)5CHO when hept-4-enal is reduced by NaBH4

        • CH3CH2CH=CHCH2CH2CH2OH when hept-4-enal is reduced by H2 / Ni

        • CH3CH2CH=CHCH2CH2CH2OH when hept-4-enal is reduced by NaBH4

        Choose your answer

        1
        1 mark

        The diagram shows the structure of the naturally-occurring molecule cholesterol.

        Skeletal structure of cholesterol: a steroid with four fused rings, a hydroxyl (-OH) group on ring A, a C=C double bond in ring B, and an isooctyl side chain attached to ring D

        Two separate test tubes of cholesterol are used in an experiment. One test tube of cholesterol is treated with cold, dilute acidified KMnO4, and the other is treated with hot, concentrated acidified KMnO4.

        Which row correctly describes the change in the number of chiral carbon atoms in the molecule during each reaction and the structure of the product in each test tube?

        Cold, dilute acidified KMnO4

        Hot, concentrated acidified KMnO4

        Change in the number of chiral carbons

        Number of hydroxy groups in product

        Change in the number of chiral carbons

        Number of 6-membered rings remaining in product

        A

        +1

        1

        -1

        3

        B

        +1

        1

        0

        2

        C

        +2

        3

        -1

        2

        D

        +2

        3

        0

        3

          Choose your answer

          2
          1 mark

          The cyclic compound G is heated with dilute hydrochloric acid.

          Skeletal formula of compound G (morpholine-2,5-dione): a 6-membered ring containing an NH amide group, an ester linkage (C=O bonded to ring oxygen), and two CH₂ groups

          Which of the following are the products of the reaction?

          • H2NCOCH2OH and HOCH2CHO

          • HO2CCH2NH3+ and HO2CCH2OH

          • HOCH2CO2H and H2NCH2CO2H

          • HOCH2CONH3+ and HOCH2CHO

          Choose your answer

          3
          1 mark

          Santonin is a drug that has been used to treat a worm infection.

          Skeletal formula of santonin: a bicyclic sesquiterpene lactone with a 6-membered ring containing a conjugated C=C–C=O enone system and two CH₃ groups, fused to a 5-membered γ-lactone ring containing a C=O ester group, ring oxygen, and CH₃

          When santonin is first treated with warm dilute H2SO4, product X is formed. If X is treated with cold acidified KMnO4, the final product Y is obtained.

          How many atoms of hydrogen in each molecule of product Y could be displaced in a reaction with sodium metal?

          • 2

          • 4

          • 5

          • 6

          Choose your answer

          4
          1 mark

          Compound M is used in leather processing.

          Skeletal formula of compound M (glycolide/1,4-dioxane-2,5-dione): a 6-membered cyclic diester ring containing two C=O groups and two ring oxygen atoms, with two CH₂ groups completing the ring

          Compound M is synthesised in the presence of concentrated sulfuric acid and heat.

          Which other starting materials are required to synthesise compound M?

          • CH3COOCH2COOH only

          • CH3COOH mixed with HOCH2COOH

          • CH3COOH only

          • HOCH2COOH only

          Choose your answer

          5
          1 mark

          Mixture F is produced upon refluxing compound G with aqueous sodium hydroxide.

          Upon distillation of mixture F with acidified potassium dichromate (VI), propanone is produced. Mixing compound G with aqueous silver nitrate and dilute nitric acid gives a cream precipitate.

          Which of the following could be compound G?

          • CH3CH2CH2Br

          • CH3CH2CH2I

          • CH3CHBrCH3

          • CH3CHICH3

          Choose your answer

          6
          1 mark

          Antipyrine is a drug used to reduce fever. The initial step of its synthesis is the reaction of phenylhydrazine with compound X.

          Reaction equation showing phenylhydrazine (C₆H₅-NHNH₂) reacting with compound X (ethyl acetoacetate: CH₃COCH₂CO₂CH₂CH₃, containing both a ketone and an ester group) to give product Y

          Which of the following is product Y?

          • Acetoacetanilide: CH₃COCH₂CONH-C₆H₅, where the ester group of compound X has been replaced by an amide linkage with the amine of phenylhydrazine; the ketone group is retained
          • Aniline derivative: C₆H₅-NHCH₂CO₂CH₂CH₃, where both the ketone group and the N–N bond of phenylhydrazine appear to have been lost, leaving only a simple NH linkage and the ester group
          • Para-substituted compound: CH₃COCH₂CO attached directly to the para position of the phenyl ring with an unreacted NHNH₂ group; no condensation has occurred at the ketone
          • Phenylhydrazone of ethyl acetoacetate: C₆H₅-NH-N=C(CH₃)CH₂CO₂CH₂CH₃, the correct condensation product where the ketone C=O has reacted with the NHNH₂ to form a C=N linkage with loss of water; the ester group is preserved

          Choose your answer

          7
          1 mark

          Ibuprofen is an anti-inflammatory drug, the structure of which is shown below.

          Skeletal formula of ibuprofen: a para-substituted benzene ring with an isobutyl group at one position and a methylcarboxylic acid group (-CH(CH₃)CO₂H) at the para position

          Which reaction leads to the formation of ibuprofen?

          • Aldehyde precursor: (CH₃)₂CHCH₂-C₆H₄-CH(CH₃)CHO reacting with warm acidified K₂Cr₂O₇; oxidation of the aldehyde (-CHO) to a carboxylic acid (-CO₂H) gives ibuprofen
          • Alkene precursor: (CH₃)₂CHCH₂-C₆H₄-C(CH₃)=CH₂ reacting with hot concentrated KMnO₄; oxidative cleavage of the C=C gives a methyl ketone and CO₂, not ibuprofen
          • Methyl ketone precursor: (CH₃)₂CHCH₂-C₆H₄-CH(CH₃)COCH₃ reacting with warm sulfuric acid (aq); warm sulfuric acid cannot oxidise a ketone to a carboxylic acid, so ibuprofen is not formed
          • Two alkene precursor: CH₂=C(CH₃)CH₂-C₆H₄-C(=CH₂)COCH₃ reacting with H₂/Pt catalyst; hydrogenation reduces C=C bonds to C-C bonds but does not introduce a carboxylic acid group, so ibuprofen is not formed

          Choose your answer