Chemistry 9701 · AS & A Level · States of matter

States of matter — practice question

Capsaicin occurs in chilli peppers. Assume that the $\text{CH}_3\text{O}$ group does not react in the reactions used in this question.
(a)[1]

Name every functional group present in capsaicin apart from the $\text{CH}_3\text{O}$ group.

(b)[3]

Complete the equation for the reaction of capsaicin with excess $\text{Br}_2(\text{aq})$ in the dark. Draw the structure of the organic product in the labelled box.

(c)[2]

Capsaicin is heated with excess hydrogen gas in the presence of platinum metal. Under these conditions, the six-membered ring reacts in the same way as benzene. Draw the structure of the organic product formed.

(d(i))[1]

When capsaicin is treated with reagent J under suitable conditions, one of the products is methylpropanoic acid, $\text{CH}_3\text{CH}(\text{CH}_3)\text{COOH}$. Identify reagent J and any necessary conditions.

(d(ii))[3]

There are three distinct peaks in the proton ($^1\text{H}$) NMR spectrum of $\text{CH}_3\text{CH}(\text{CH}_3)\text{COOH}$ in $\text{CDCl}_3$. Use Table 8.1 to complete Table 8.2 and state: the usual proton ($^1\text{H}$) chemical shift values ($\delta$) for the protons; the splitting pattern (singlet, doublet, triplet, quartet or multiplet) shown by each peak; the explanation for the splitting patterns of the $\text{CH}_3$ protons and the $\text{CH}$ proton.

(e(i))[2]

Capsaicin is heated with excess hot aqueous $\text{NaOH}$. Draw the structures of the two organic products H and K.

(e(ii))[1]

Name the two reaction types in (e)(i).

(f)[1]

Draw the structure of the organic product L formed when capsaicin is treated with $\text{LiAlH}_4$ in dry ether.

Worked solution & mark scheme

This 14-mark question has a full step-by-step worked solution and mark scheme. One marking point: Phenol, amide and alkene all identified

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