A-LevelChemistryOrganic synthesis9701/22 · May/June 2025 · Q413 Marks

(a) Propanoic acid, CH3CH2COOH, reacts with reducing agent Q to produce propan-1-ol, CH3CH2CH2OH. (i) Suggest the formula of reducing agent Q. (ii) Complete the equation to show the reduction of propanoic acid to propan-1-ol. Use [H] to represent one atom of hydrogen from Q. .CH3CH2COOH + ......[H] → (b) Propan-1-ol is converted to compound T in a three-step synthesis. In step 1, SOCl2 is added to propan-1-ol to produce compound E. In step 2, E reacts with a suitable reagent to produce butanenitrile. In step 3, butanenitrile is heated with NaOH(aq). (i) Name the type of reaction that occurs in step 1. (ii) Identify the reagent and conditions required in step 2. (iii) Construct an equation to describe the reaction of butanenitrile with NaOH(aq) in step 3. (iv) Name the type of reaction that occurs in step 3. (c) Compounds A, B and C belong to the alcohol homologous series. Each molecule of A, B and C contains four saturated carbon atoms. (i) Identify the type of hybridisation shown in the saturated carbon atoms of all alcohols. (ii) Identify the gas produced when Na(s) is added to separate samples of each alcohol. (iii) Describe the role of Na(s) when it reacts with alcohols. (d) Table 4.1 shows the results of two tests on separate samples of A, B and C. Table 4.1 compound | heat under reflux with acidified K2Cr2O7 | warm with alkaline I2(aq) A | remains orange | no visible change B | orange to green | no visible change C | orange to green | pale yellow precipitate (i) Deduce the structure of A. (ii) Deduce a possible name for B. (iii) Deduce the identity of C.

(a)(i)Suggest the formula of reducing agent Q.[1]
(a)(ii)Complete the equation to show the reduction of propanoic acid to propan-1-ol. Use [H] to represent one atom of hydrogen from Q. .CH3CH2COOH + ......[H] →[1]
(b)(i)Name the type of reaction that occurs in step 1.[1]
(b)(ii)Identify the reagent and conditions required in step 2.[1]
(b)(iii)Construct an equation to describe the reaction of butanenitrile with NaOH(aq) in step 3.[2]
(b)(iv)Name the type of reaction that occurs in step 3.[1]
(c)(i)Identify the type of hybridisation shown in the saturated carbon atoms of all alcohols.[1]
(c)(ii)Identify the gas produced when Na(s) is added to separate samples of each alcohol.[1]
(c)(iii)Describe the role of Na(s) when it reacts with alcohols.[1]
(d)(i)Deduce the structure of A.[1]
(d)(ii)Deduce a possible name for B.[1]
(d)(iii)Deduce the identity of C.[1]

Mark scheme

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

4(a)(i) LiAlH4
4(a)(ii) CH3CH2CO2H + 4[H] → CH3CH2CH2OH + H2O
4(b)(i) substitution
4(b)(ii) KCN/potassium cyanide in ethanol / C2H5OH AND heat
4(b)(iii) CH3CH2CH2CN + NaOH + H2O → CH3CH2CH2CO2Na + NH3
4(b)(iii) OR CH3CH2CH2CN + NaOH + 2H2O → CH3CH2CH2CO2Na + NH4OH
4(b)(iii) M1 correct organic product (as molecule or anion)
4(b)(iii) M2 rest of equation is correct
4(b)(iv) (alkaline) hydrolysis
4(c)(i) sp³
4(c)(ii) hydrogen / H2
4(c)(iii) (It/Na) reduces A / B / C / the alcohol (group) OR (it / Na behaves as) reducing agent OR (it / Na) donates electrons to A / B / C / the alcohol (group)
4(d)(i) (CH3)3COH
4(d)(ii) butan-1-ol OR (2) methylpropan-1-ol
4(d)(iii) butan-2-ol OR CH3CH2CH(OH)CH3.

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