Chemistry 9701 · AS & A Level · 6.1

6.1 — practice question

Compound X is obtained from benzene by the sequence illustrated in Fig. 9.1. In Fig. 9.1, benzene is changed in step 1 into methylbenzene, in step 2 into nitromethylbenzene, in step 3 into compound W (a nitrobenzoic acid), and in step 4 into compound X (an aminobenzoic acid).
(a)[3]

Describe the bonding in benzene, $\mathrm{C_6H_6}$. Your answer should cover: the hybridisation of the six carbon atoms; the kinds of bond present between the carbon atoms; the orbitals that overlap to make the bonds between the carbon atoms; the bond type between the carbon atoms and the hydrogen atoms; and the orbitals that overlap to make the bonds between the carbon atoms and the hydrogen atoms.

(b)[1]

Describe the reagents and conditions needed for step 1 in Fig. 9.1.

(c)[3]

In step 1 of Fig. 9.1, benzene reacts with $\mathrm{CH_3^+}$. Complete Fig. 9.2 to show the mechanism for this reaction, including: the movement of electron pairs with curly arrows; and the structure of the intermediate formed.

(d)[2]

Describe the reagents and conditions needed for step 2 of Fig. 9.1.

(e)[1]

Identify the reagents needed for step 3 of Fig. 9.1. Compound W is the product from this step.

(f)[1]

Name the compound represented by W.

(g)[1]

The reagents often used for step 4 will not reduce the $\mathrm{-COOH}$ group. Identify the reagents and conditions needed for step 4 of Fig. 9.1.

(h)[2]

Benzene can also be used as the starting material for compound Y. Describe how the route shown in Fig. 9.1 (repeated below) can be altered to produce compound Y rather than compound X. Explain your answer.

Worked solution & mark scheme

This 14-mark question has a full step-by-step worked solution and mark scheme. One marking point: all C atoms are sp2 hybridised

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