Benzene reacts with D in the presence of a suitable catalyst to give cumene and non-organic product E. This is an electrophilic substitution reaction. [Figure showing Benzene + D (catalyst) -> Cumene + E]
- (a)(i)Name the reactant D and the non-organic product E.[2]
- (a)(ii)Give the name of the type of aromatic electrophilic substitution reaction taking place.[1]
- (b)(i)Describe the conditions that are used to ensure substitution takes place only in the aromatic ring.[1]
- (b)(ii)Draw the structures of the two major isomeric products of the reaction, formula C9H11Cl, when substitution takes place in the aromatic ring.[1]
- (b)(iii)Describe the conditions that are used to ensure substitution takes place only in the side-chain.[1]
- (b)(iv)Draw the structures of two isomeric products of the reaction, formula C9H11Cl, when substitution takes place in the side-chain.[1]
- (c)Complete the following table to show the structures of the organic products formed when cumene reacts with each reagent. reagent | structure of organic product hot KMnO4(aq) | H₂ + Ni, high pressure |[2]
- (d)Cumene can be nitrated using a mixture of concentrated nitric and sulfuric acids. The mechanism for this reaction is similar to the mechanism for the nitration of benzene. Complete the mechanism for this reaction. Include all relevant charges and curly arrows showing the movement of electron pairs. Draw the structure of the intermediate. You do not need to draw the products. [Figure showing mechanism starting with Cumene and attacking NO2+][4]
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 2018). The mark or mark type is shown in brackets.
- [1] D 2-chloropropane
- [1] E hydrogen chloride
- [1] (Friedel-Crafts) alkylation
- [1] AlCl3 or FeCl3
- [1] (Correct structures for ortho and para chloro-cumene)
- [1] sunlight or UV OR T>100 °C
- [1] (Correct structures for the two isomers where Cl is on the side chain)
- [1] (Structure for reaction with hot KMnO4(aq) - benzoic acid with isopropyl group oxidised to carboxylic acid)
- [1] (Structure for reaction with H2 + Ni, high pressure - saturated cyclohexane ring)
- [1] attacking species is NO2+
- [1] curly arrow starting within hexagon and going to NO2+
- [1] correct intermediate
- [1] 2nd curly arrow from C-H bond into ring
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