A-LevelChemistryHydroxy compounds9701/42 · May/June 2023 · Q78 Marks

Fig. 7.1 shows some reactions of phenol. [Figure 7.1]

(a)Explain why phenol is brominated much more easily than benzene is brominated.[3]
(b)Iodine monobromide, I–Br, reacts with benzene in the presence of an AlBr3 catalyst. Predict whether the organic product will be bromobenzene or iodobenzene. Explain your answer.[1]
(c)(i)Give an equation for the reaction of phenol with Na(s).[1]
(c)(ii)Draw the structure of the organic product, R, formed when phenol reacts with an excess of Br2(aq).[1]
(c)(iii)State the reagents and conditions for reaction 1 and reaction 2 in Fig. 7.1. reaction 1 reaction 2[2]

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Mark scheme

Marking points from the official mark scheme (May/June 2023). The mark or mark type is shown in brackets.

[1] M1 p-orbital/lone pair from O atom is overlaps / delocalised into the ring
[1] M2 greater π electron density around the ring OR makes the ring more electron rich / positions 2,4,6 more electron rich
[1] M3 polarises electrophiles more easily
[1] iodobenzene AND as Br is more electronegative (than I / I+/I+ in the electrophile)
[1] C6H5OH + Na → C6H5O-Na+ + ½H2
[1] Structure of 2,4,6-tribromophenol
[1] M1 reaction 1: aqueous HNO3 / dilute HNO3
[1] M2 reaction 2: alkaline/ NaOH AND C6H5N2+ (Cl-) OR alkaline / NaOH AND benzene / phenyl diazonium ion / salt

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