A-LevelChemistryCarboxylic acids and derivatives9701/43 · Oct/Nov 2025 · Q712 Marks

(a) State the relative acidities of bromoethanoic acid, BrCH2COOH, chloroethanoic acid, CICH2COOH, ethanoic acid, CH3COOH and ethanol, CH3CH2OH. Explain your answer. most acidic least acidic [4] (b) Fig. 7.1 shows the reaction of methylbenzene and ethanedioic acid with KMnO4. Predict the major carbon-containing product for each of these reactions. [Figure 7.1] [2] (c) Polyamide X can be synthesised from ethanedioic acid and benzene-1,4-diamine. [Figure showing structure of benzene-1,4-diamine] (i) Draw the repeat unit of polyamide X in the box. The new functional group formed should be shown displayed. [drawing box] [2] (ii) Benzene-1,4-diamine can be formed by reduction of 1,4-dinitrobenzene. Complete the equation for this reduction. [H] represents one atom of hydrogen from a reducing agent. + [H] H2N NH2 + [1] (d) Fig. 7.2 shows the two-step synthesis of the azo compound W. [Figure 7.2] (i) Suggest structures for compounds V and W and draw them in the boxes in Fig. 7.2. [2] (ii) Give the reagents and conditions for step 1. [1]

(a)State the relative acidities of bromoethanoic acid, BrCH2COOH, chloroethanoic acid, CICH2COOH, ethanoic acid, CH3COOH and ethanol, CH3CH2OH. Explain your answer. most acidic least acidic[4]
(b)Fig. 7.1 shows the reaction of methylbenzene and ethanedioic acid with KMnO4. Predict the major carbon-containing product for each of these reactions. [Figure 7.1][2]
(c)(i)Polyamide X can be synthesised from ethanedioic acid and benzene-1,4-diamine. [Figure showing structure of benzene-1,4-diamine] Draw the repeat unit of polyamide X in the box. The new functional group formed should be shown displayed. [drawing box][2]
(c)(ii)Benzene-1,4-diamine can be formed by reduction of 1,4-dinitrobenzene. Complete the equation for this reduction. [H] represents one atom of hydrogen from a reducing agent. + [H] H2N NH2 +[1]
(d)(i)Suggest structures for compounds V and W and draw them in the boxes in Fig. 7.2.[2]
(d)(ii)Give the reagents and conditions for step 1.[1]

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Mark scheme

Marking points from the official mark scheme (Oct/Nov 2025). The mark or mark type is shown in brackets.

[4] (a) M1: CICH2COOH BrCH2COOH CH3COOH CH3CH2OH most acidic least acidic M2: electron withdrawing groups / electronegative groups / negative inductive effect AND weakens O-H bond / more stable anion OR electron donating groups / positive inductive effect AND strengthens O-H bond / less stable anion M3 M4: • chlorine is more electron-withdrawing / electronegative than bromine (related to XCH2COOH) • electron withdrawing of C=O / negative inductive effect of C=O (related to COOH) • positive inductive effect / electron donating of alkyl / ethyl / R group (related to ROH) any two [1], all three [2]
[2] (b) M1: [drawing of benzoic acid for methylbenzene] M2: CO2
[2] (c)(i) M1: correct displayed amide bond with C=O, (C6H5)–N and (C−)C=O M2: rest of the structure correct with continuation bonds
[1] (c)(ii) O2N-[benzene]-NO2 + 12[H] → H2N-[benzene]-NH2 + 4H2O
[2] (d)(i) M1: [drawing of diazonium salt for V] M2: [drawing of azo dye for W]
[1] (d)(ii) HNO2 (and HCI) AND ≤10 °C OR NaNO2 AND HCI AND <10 °C

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