Chemistry 9701 · AS & A Level · Halogen compounds

Halogen compounds — practice question

$\text{CH}_3(\text{CH}_2)_5\text{CHBrCH}_3$ occurs as a pair of stereoisomers.
(a)[2]

Draw the three-dimensional representations of the two stereoisomers of $\text{CH}_3(\text{CH}_2)_5\text{CHBrCH}_3$. $R$ may be used for $\text{CH}_3(\text{CH}_2)_5$.

(b)[3]

A sample of $\text{CH}_3(\text{CH}_2)_5\text{CHBrCH}_3$ reacts with NaOH to produce $\text{CH}_3(\text{CH}_2)_5\text{CH(OH)CH}_3$ by an $\mathrm{S_N1}$ mechanism. Complete Fig. 4.1 to show the mechanism for the reaction of $\text{CH}_3(\text{CH}_2)_5\text{CHBrCH}_3$ with NaOH. Add charges, dipoles, lone pairs of electrons and curly arrows where appropriate.

(c)[3]

Separate portions of $\text{CH}_3(\text{CH}_2)_5\text{CHBrCH}_3$, $\text{CH}_3(\text{CH}_2)_5\text{CH(OH)CH}_3$ and $\text{CH}_3(\text{CH}_2)_5\text{CHCH}_2$ are each tested with different reagents. Complete Table 4.1. If there is no reaction, enter $\times$ in the appropriate box.

(d(i))[1]

Name the type of reaction involved.

(d(ii))[1]

Identify D and state the conditions used.

(e(i))[2]

A molecule of E contains both $\sigma$ and $\pi$ bonds because the carbon atoms have different hybridisations. Complete Table 4.2 to show the number of carbon atoms with each hybridisation type in a molecule of E.

(e(ii))[3]

Describe the essential feature of an unbranched hydrocarbon that makes its molecules capable of stereoisomerism. Explain how this feature leads to stereoisomerism.

Worked solution & mark scheme

This 15-mark question has a full step-by-step worked solution and mark scheme. One marking point: Accurate 3D drawing of one enantiomer of $\mathrm{CH_3(CH_2)_5CHBrCH_3}$

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