A-LevelChemistryHydroxy compounds9701/43 · Oct/Nov 2024 · Q87 Marks

An aqueous solution of phenol, C6H5OH, is acidic at 298 K. Phenol can be produced from phenylamine in a two-step synthesis. [reaction scheme: phenylamine -> intermediate compound -> phenol]

(a)Explain why phenol is more acidic than water.[2]
(b)(i)Name the two products formed when phenol reacts with an excess of Br2(aq).[1]
(b)(ii)Draw the structures of the two isomeric organic products, with Mr = 139, that are formed when phenol reacts with HNO3(aq) at room temperature.[1]
(b)(iii)Write the equation for the reaction between phenol, C6H5OH, and sodium metal.[1]
(c)Describe the reagents and conditions needed in each step.[2]

Mark scheme

Marking points from the official mark scheme (Oct/Nov 2024). The mark or mark type is shown in brackets.

[1] (a) M1: p orbital / lone pair on the oxygen / O AND is delocalised into the ring / overlaps with delocalised ring [1] M2: O-H weakened (in phenol) OR anion / phenoxide ion / conjugate base is stabilised/more stable [1]
[1] (b)(i) 2,4,6-tribromophenol (name) AND hydrogen bromide / HBr [1]
[1] (b)(ii) [Structures of 2-nitrophenol and 4-nitrophenol] AND NO2 [1]
[1] (b)(iii) 2C6H5OH + 2Na → 2C6H5ONa + H2
[1] (c) step one: HNO2 (+ HCl) OR NaNO2 + HCl AND T≤10 °C [1] step two: H2O AND warm / T> 10 °C any two [1] all four [2]

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