Chemistry 9701 · AS & A Level · Halogen compounds

Halogen compounds — practice question

Several reactions involving 1-bromobutane, $\text{CH}_3(\text{CH}_2)_3\text{Br}$, are illustrated.
(a)[6]

For each reaction, state the reagent(s), any required conditions, and the reaction type. Select the reaction type from the list: elimination, hydrolysis, substitution, oxidation, addition, condensation. Any type may be used once, more than once or not at all. A reaction may be described by more than one type.

(b)[2]

Complete the diagram so that it shows the $\mathrm{S_N2}$ mechanism for reaction 1. $R$ stands for the $\text{CH}_3(\text{CH}_2)_2$ group. Show every required charge, dipole, lone pair and curly arrow.

(c(i))[4]

Define the term structural isomer and name the three different types of structural isomerism.

(c(ii))[3]

2-bromo-2-methylpropane is reacted with the same reagents as in reaction 1. Methylpropan-2-ol is formed. Identify the mechanism for this reaction. Explain why this reaction takes place by a different mechanism from reaction 1.

(d(i))[2]

Explain what is meant by the term stereoisomers.

(d(ii))[2]

Give two reasons why but-1-ene does not exhibit stereoisomerism.

(d(iii))[2]

Name $X$ and $Y$.

(d(iv))[1]

Name the type of stereoisomerism shown by $X$.

(d(v))[2]

Use the standard convention to draw the two stereoisomers of $X$.

Worked solution & mark scheme

This 24-mark question has a full step-by-step worked solution and mark scheme. One marking point: Reaction 1: substitution / hydrolysis using aqueous / dilute $\mathrm{NaOH}$ or $\mathrm{KOH}$ or water

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