Chemistry 9701 · AS & A Level · 4.1

4.1 — practice question

P and Q are structural isomers.
(a(i))[2]

Define structural isomerism in terms of molecular formula and structure.

(a(ii))[2]

P shows geometrical isomerism. Draw the geometrical isomer of P. Explain why the two isomers are not identical in terms of rotation about the $C=C$ bond.

(a(iii))[1]

Both P and Q react with aqueous bromine. Name the mechanism for this reaction.

(a(iv))[2]

Q undergoes oxidation with hot concentrated acidified $\text{KMnO}_4(aq)$, giving two different organic products. Construct an equation for this reaction. Use $[\text{O}]$ to represent an atom of oxygen from the oxidising agent. $(\text{CH}_3)_2\text{C}=\text{CHCH}_3 \; \ldots$

(a(v))[2]

Q reacts with $\mathrm{HBr(g)}$ to form two structural isomers, R and S, as shown in Fig. 4.2. State and explain why isomer S is the major product in this reaction.

(a(vi))[2]

The mass spectrum of R has peaks at $m/e = 150$ and $m/e = 152$. Suggest structures for the ions responsible for these peaks.

(b(i))[1]

Fig. 4.3 shows a synthesis starting from T, another isomer of R and S. Identify the reagent and conditions for reaction 1.

(b(ii))[1]

Reaction 2 involves hydrolysis. Construct an equation for reaction 2. $(\mathrm{C_2H_5})_2\mathrm{CHCN}\ \ldots$

(b(iii))[3]

V reacts with propan-2-ol in the presence of a catalytic amount of $\mathrm{H_2SO_4}$ to form organic compound W. Complete Table 4.1 to give details of this reaction: type of reaction; functional group formed; molecular formula of organic product W.

Worked solution & mark scheme

This 16-mark question has a full step-by-step worked solution and mark scheme. One marking point: (molecules with the) same molecular formula / same count of atoms of each element

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