Which of the following are secondary bromides?
Which of the following compounds can be classified as aryl halides?
Alkyl halides are prepared from alcohols by treating with
Alkyl fluorides are synthesised by alkyl chloride/bromide in presence of ............. or .......... .
Aryl chlorides and bromides can be easily prepared by electrophilic substitution of arenes with chlorine and bromine respectively in the presence of Lewis acid catalysts. But why does preparation of aryl iodides requires presence of an oxidising agent?
Iodination reactions are reversible in nature.
$$\mathrm{C}_6 \mathrm{H}_6+\mathrm{I}_2 \rightleftharpoons \mathrm{C}_6 \mathrm{H}_5 \mathrm{I}+\mathrm{HI}$$
In this above reaction, hydrogen iodide is formed apart from the required product. It has to be removed from the reaction mixture in order to prevent the backward reaction. To carry out the reaction in the forward direction, HI formed during the reaction is removed by oxidation using oxidising agent. Such as $\mathrm{HIO}_3$ or $\mathrm{HNO}_3$. The reaction is as follow
$$\begin{gathered} 5 \mathrm{HI}+\mathrm{HIO}_3 \longrightarrow 3 \mathrm{I}_2+3 \mathrm{H}_2 \mathrm{O} \\ 2 \mathrm{HI}+2 \mathrm{HNO}_3 \longrightarrow \mathrm{I}_2+2 \mathrm{NO}_2+2 \mathrm{H}_2 \mathrm{O} \end{gathered}$$
By using a suitable oxidising agent HI is oxidised to give $\mathrm{I}_2$.