A-LevelChemistryHydrocarbons9701/42 · May/June 2025 · Q619 Marks

Methylbenzene reacts readily with nitronium ions, NO2+. NO2+ ions are generated by the reaction between concentrated nitric acid and concentrated sulfuric acid. Write an equation for the formation of the NO2+ ion.

(a)(i)Methylbenzene reacts readily with nitronium ions, NO2+. NO2+ ions are generated by the reaction between concentrated nitric acid and concentrated sulfuric acid. Write an equation for the formation of the NO2+ ion.[1]
(a)(ii)Complete the mechanism in Fig. 6.1 for the nitration of methylbenzene to form 1-methyl-2-nitrobenzene. Include all relevant curly arrows and charges. [Figure 6.1][3]
(b)Phenol can be nitrated with dilute nitric acid. Explain why the nitration of phenol occurs under milder conditions than the nitration of benzene.[2]
(c)A sample of 2-nitrophenol is reacted with sodium. Complete the equation in Fig. 6.2 for the reaction of 2-nitrophenol with sodium. [Figure 6.2][1]
(d)(i)2-nitrophenol can undergo different reactions as shown in Fig. 6.3. [Figure 6.3] Suggest reagents and conditions for reaction 1.[1]
(d)(ii)Name the type of reaction for reaction 1.[1]
(d)(iii)Reaction 2 is carried out at room temperature. Draw the structure of the organic product from reaction 2 in Fig. 6.3.[1]
(d)(iv)Name the mechanism for reaction 2.[1]
(e)The NO2 group in 2-nitrophenol is electron withdrawing. Suggest the relative acidities of ethanol, 2-nitrophenol, phenol and water. Explain your answer. most acidic ............................................ least acidic ............................................[4]
(f)(i)Salbutamol is a pharmaceutical drug that contains a phenol functional group. [Figure 6.4] Name and classify the three other functional groups in salbutamol in Table 6.1. [Table 6.1][2]
(f)(ii)Salbutamol reacts with Br2(aq) to form organic product X. Draw the structure of X.[1]
(f)(iii)Salbutamol reacts with an excess of SOCl2 to form organic product Y. The molecular formula of Y is C13H19C12NO. Draw the structure of Y.[1]

This question uses a diagram from the original paper, which isn't shown here. Open the full paper from the past papers archive to see it.

Mark scheme

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

[1] HNO3 + H2SO4 → NO2+ + HSO4 + H2O OR HNO3 + 2H2SO4 → NO2+ + 2HSO4 + H3O+
[1] M1: curly arrow 1 from inside the hexagon to nitrogen of NO2+
[1] M2: intermediate, usual rules for horseshoe and + charge
[1] M3: curly arrow 2 from C-H bond into hexagon AND H+
[1] M1: p-orbital/lone pair from O / oxygen AND is delocalised / overlaps AND into the ring / π system
[1] M2: so electron density of the ring is increased OR polarises electrophiles / NO2+ better
[1] (diagram showing ONa instead of OH)
[1] (hot) tin / Sn AND concentrated AND HCl
[1] reduction
[1] (diagram showing OCOCH3 instead of OH)
[1] (nucleophilic) addition – elimination
[1] M1: 2-nitrophenol > phenol > water > ethanol
[1] M2: weakens O-H bond / anion stabilised
[1] AND proton/H+ (more easily) lost / proton / H+ (more easily) donated
[1] M3: (for 2-nitrophenol / phenol), a p-orbital / lone pair from O / oxygen AND is delocalised / overlaps AND into the ring / π system (and increases electron density in the ring)
[1] M4: (for ethanol), positive inductive effect / electron donating of alkyl group
[1] alcohol / hydroxyl primary
[1] alcohol / hydroxyl secondary
[1] amine secondary
Any three correct [1] all six correct [2]
[1] (diagram showing Br at 3,5 positions)
[1] (diagram showing OHs and NH replaced with Cl)