CAIE A-Level Chemistry 34.2.2 Phenylamine Reactions Question Bank

Practise phenylamine reactions with bromine water and nitrous acid, including diazonium salts, phenol formation and observations.

Exam points

use Br2(aq) to distinguish phenylamine by a white precipitate and draw the brominated product
form benzenediazonium salts from phenylamine with HNO2 below 10 °C
predict phenol from warming a diazonium salt with water or aqueous acid

[Maximum number: 2]

Potassium iodide, KI, is used as a reagent in both inorganic and organic chemistry.

$\quad \mathrm{KI}$ is used as a source of $\mathrm{I}^{-}$ ions in organic synthesis.

One example of this is shown in the synthetic route in Fig. 1.1.

Fig. 1.1

Step 3 occurs in two stages.
stage I $\mathrm{NaNO}_{2}$ and HCl undergo an acid-base reaction to produce $\mathrm{HNO}_{2}$ .
stage II $\mathrm{HNO}_{2}$ reacts with $\mathbf{C}, \mathrm{C}_{6} \mathrm{H}_{5} \mathrm{NH}_{2}$ , to produce $\mathbf{D}, \mathrm{C}_{6} \mathrm{H}_{5} \mathrm{~N}_{2}{ }^{+}$ .
Complete the equations for stage I and for stage II.

$stage I $\mathrm{NaNO}_{2}+\mathrm{HCl} \rightarrow$$

stage II

step $1 \quad \mathrm{NaNO}_{2}+\mathrm{HCl} \rightarrow \mathrm{HNO}_{2}+\mathrm{NaCl}$

step $2 \quad \mathrm{C}_{6} \mathrm{H}_{5} \mathrm{NH}_{2}+\mathrm{HNO}_{2}+\mathrm{H}^{+} \rightarrow \mathrm{C}_{6} \mathrm{H}_{5} \mathrm{~N}_{2}+2 \mathrm{H}_{2} \mathrm{O}$

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34.2.2—Describe question 1