Chemistry 9701 · AS & A Level · Nitrogen compounds

Nitrogen compounds — practice question

(a)[3]

State the order of basicity, in aqueous solution, for phenylamine, C$_6$H$_5$NH$_2$, benzylamine, C$_6$H$_5$CH$_2$NH$_2$, and ammonia, NH$_3$. Explain your answer.

(b(i))[2]

State the observations you would expect when C$_6$H$_5$NH$_2$ reacts with Br$_2$(aq), and draw the structure of product M.

(b(ii))[2]

Suggest why Br$_2$(aq) reacts with C$_6$H$_5$NH$_2$ yet shows no reaction with C$_6$H$_6$.

(c)[1]

Explain why benzamide, C$_6$H$_5$CONH$_2$, is far less basic than ammonia, NH$_3$.

(d)[4]

$\text{C}_6\text{H}_5\text{CONH}_2$ is produced when benzoyl chloride, $\text{C}_6\text{H}_5\text{COCl}$, reacts with $\text{NH}_3$. Complete the mechanism in Fig. 8.1 for the reaction of $\text{C}_6\text{H}_5\text{COCl}$ with $\text{NH}_3$. Include all relevant lone pairs of electrons, curly arrows, charges and dipoles. Draw the structure of the organic intermediate.

(e(i))[1]

Phenylalanine, $\text{C}_6\text{H}_5\text{CH}_2\text{CH(NH}_2\text{)COOH}$, is an amino acid with an isoelectric point of $5.5$. State what is meant by isoelectric point.

(e(ii))[1]

Draw the structure of $\text{C}_6\text{H}_5\text{CH}_2\text{CH(NH}_2\text{)COOH}$ at $\text{pH }10$.

(f)[2]

$\text{C}_6\text{H}_5\text{CH}_2\text{CH(NH}_2\text{)COOH}$ and alanine, $\text{CH}_3\text{CH(NH}_2\text{)COOH}$, react to form a dipeptide containing both amino acid residues. Draw the structure of this dipeptide. The peptide functional group formed should be shown.

Worked solution & mark scheme

This 16-mark question has a full step-by-step worked solution and mark scheme. One marking point: benzylamine > ammonia > phenylamine, in descending order

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