Chemistry 9701 · AS & A Level · 8.1

8.1 — practice question

In electrophilic substitution of arenes, different substituents may direct substitution to different positions on the ring. Carbon-carbon bond formation is an important reaction in organic synthesis. Fig. 8.1 illustrates the synthesis of compound Q from benzene in two reaction steps.
(a(i))[1]

Describe the directing effect of the $-\text{NO}_2$ group. Explain your answer.

(a(ii))[1]

The nitration of arenes uses a mixture of concentrated $\text{HNO}_3$ and concentrated $\text{H}_2\text{SO}_4$ to produce the $\text{NO}_2^+$ electrophile. Write an equation for the formation of the $\text{NO}_2^+$ electrophile.

(b(i))[1]

Draw the structure of compound P in the box in Fig. 8.1.

(b(ii))[2]

Suggest reagents and conditions for reactions 1 and 2 in Fig. 8.1.

(c)[3]

Separate samples of $\mathrm{C_6H_5Br}$ and $\mathrm{C_6H_5CH_2Br}$ are placed in warm $\mathrm{AgNO_3(aq)}$. State the expected observations, if any. Explain your answer.

(d(i))[1]

The mechanism of this reaction is similar to that of the reaction of $\mathrm{H_2O}$ with acyl chlorides, $\mathrm{RCOCl}$. Name the mechanism of this reaction.

(d(ii))[4]

Complete the mechanism in Fig. 8.2 for the reaction of $\mathrm{RCOBr}$ with $\mathrm{H_2O}$. Include all relevant lone pairs of electrons, curly arrows, charges and dipoles. Draw the structure of the intermediate.

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