Chemistry 9701 · AS & A Level · Organic synthesis

Organic synthesis — practice question

Compound $\text{B}$ is a fruity-smelling liquid. The reaction scheme shows how $\text{B}$ can be prepared from ethanol, $\text{C}_2\text{H}_5\text{OH$.
(a(i))[2]

Reaction 1 is an oxidation reaction. Give the reagent(s) and conditions needed for reaction 1.

(a(ii))[1]

Construct an equation to show reaction 1. Use $[\text{O}]$ to represent an oxygen atom from the oxidising agent in this reaction.

(a(iii))[1]

Suggest the type of reaction taking place in reaction 2.

(a(iv))[1]

$\text{H}_2\text{SO}_4$ is acting as a homogeneous catalyst in reaction 3. Explain why $\text{H}_2\text{SO}_4$ is called homogeneous.

(b)[3]

Reaction 2 must be carried out without water present so that compound $\text{C}$ is not formed. If $\text{C}$ is in the reaction mixture of reaction 3, a different compound, compound $\text{D}$, will also be produced. Compound $\text{D}$ has two identical functional groups. The infrared spectrum of $\text{D}$ shows strong absorptions at $1100\,\text{cm}^{-1}$ and $1720\,\text{cm}^{-1}$, but there is no absorption due to O-H bonds. Use the Data Booklet to identify the functional group present in $\text{D}$. Explain your answer as fully as you can.

(c(i))[1]

Draw the structure of E.

(c(ii))[1]

Suggest why $\text{NaBH}_4$ is not an appropriate reagent for making F, $(\text{CH}_2\text{OH})_2$, from C. Explain your answer.

(c(iii))[1]

Construct an equation for the reaction between $(\text{CH}_2\text{OH})_2$ and $\text{SOCl}_2$ to make G, $(\text{CH}_2\text{Cl})_2$.

(d)[1]

Explain why C dissolves very readily in water.

Worked solution & mark scheme

This 12-mark question has a full step-by-step worked solution and mark scheme. One marking point: Oxidising reagent potassium/sodium dichromate(VI): $K_2Cr_2O_7$ or $Na_2Cr_2O_7$

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