Cumene is an aromatic hydrocarbon used in the synthesis of other useful chemicals.

1. (a)Complete Table 5.1 to show the number of sp² and sp³ hybridised carbon atoms that are present in a molecule of cumene. [Figure 5.1] Table 5.1 type of hybridisation sp2 sp3 number of carbon atoms[1]
2. (b)(i)Cumene can be synthesised via a Friedel-Crafts alkylation reaction, as shown in Fig. 5.2. [Figure 5.2] Name the mechanism involved in the Friedel-Crafts alkylation shown in Fig. 5.2.[1]
3. (b)(ii)The first step of the reaction forms the (CH3)2CH+ cation. Identify a suitable reagent for the formation of this cation from 2-bromopropane, (CH3)2CHBr.[1]
4. (b)(iii)Complete Fig. 5.3 to show the mechanism for the reaction of benzene with the (CH3)2CH+ cation. Include all relevant curly arrows and charges. [Figure 5.3] (CH3)2CH+ intermediate +[3]
5. (b)(iv)The Friedel–Crafts alkylation of benzene by 1-bromopropane, CH3CH2CH2Br, also produces cumene as the major product. The CH3CH2CH2+ cation formed in the first step quickly rearranges to form the (CH3)2CH+ cation. Suggest why this is the case. Explain your answer.[1]
6. (c)(i)Cumene oxidises in air to form phenol, C6H5OH, and propanone, CH3COCH3. reaction 1 C6H5CH(CH3)2 + O2 → C6H5OH + CH3COCH3 ΔH° = −371 kJ mol-1 Table 5.2 gives some relevant standard entropies for reaction 1. Table 5.2 compound C6H5CH(CH3)2 O2 C6H5OH CH3COCH3 standard entropy, S°/JK-1 mol-1 278 205 146 200 Calculate the standard entropy change, ΔS°, of reaction 1. ΔS° = ...................................... JK-1 mol-1[1]
7. (c)(ii)Show that reaction 1 is feasible at 25°C.[2]
8. (d)(i)Fig. 5.4 shows two reactions of phenol. [Figure 5.4] State the conditions for the bromination of phenol in reaction 2. Explain why these conditions are different from those for the bromination of benzene. conditions ........................................................................................................................................................... explanation ...........................................................................................................................................................[4]
9. (d)(ii)Draw the structure of organic compound Q in Fig. 5.4.[1]
10. (d)(iii)Identify organic reagent R.[1]
11. (d)(iv)Name the functional group that is formed in reaction 3.[1]
12. (d)(v)The reaction of phenol with HNO3 produces a mixture of isomers with molecular formula C6H5NO3. Identify the two isomers that are produced in the largest quantities. Explain your answer. isomer 1 ........................................................................................................................................................... isomer 2 ........................................................................................................................................................... explanation .......................................................................................................................................................................[2]

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