A-LevelChemistryOrganic synthesis9701/41 · Oct/Nov 2023 · Q78 Marks
Sunset Yellow is an additive used for colouring foods. A synthetic route for making Sunset Yellow is shown. Molecules E and G each contain one –SO3¯ group. These groups are unchanged in the formation of Sunset Yellow. [Figure 7.1 with boxes for E, F, G and Sunset Yellow anion structure]
- (a)State the molecular formula of the Sunset Yellow anion.[1]
- (b)Deduce the structures of E, F and G and draw them in the boxes in Fig. 7.1.[3]
- (c)Suggest suitable reagents and conditions for step 1 and 2. step 1 step 2[3]
- (d)Predict the number of peaks in the carbon-13 NMR spectrum of the Sunset Yellow anion.[1]
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Mark scheme
Marking points from the official mark scheme (Oct/Nov 2023). The mark or mark type is shown in brackets.
- [1] C16H10N2O7S22– OR C16H10N2O7S2
- [1] E: -O3SC6H4NH2 (benzene ring with NH2 and SO3-)
- [1] F: -O3SC6H4N2+ (benzene ring with N2+ and SO3-)
- [1] G: HOC10H6SO3- (naphthalene ring with OH and SO3-)
- [1] M1 step 1: HNO2 OR NaNO2 + HCl
- [1] M2 step 1: T < 10 °C
- [1] M3 step 2: NaOH(aq) / alkaline conditions
- [1] 14 / fourteen
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