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Hydrocarbons — Chemistry STD 11 Science — Question

Gujarat BoardEnglish MediumSTD 11 ScienceChemistryHydrocarbons1 Mark
MCQ
A direct iodination of benzene is not possible because :
  • A
    Iodine is an oxidising agent.
  • ✓
    Resulting $\mathrm{C}_6 \mathrm{H}_5 \mathrm{I}$ is reduced to $\mathrm{C}_6 \mathrm{H}_6$ by $\text{HI}.$
  • C
    $\text{HI}$ is unstable.
  • D
    The ring gets deactivated.
✓

Answer

Correct option: B.
Resulting $\mathrm{C}_6 \mathrm{H}_5 \mathrm{I}$ is reduced to $\mathrm{C}_6 \mathrm{H}_6$ by $\text{HI}.$
The direct iodination reaction of benzene is, $\mathrm{C}_6 \mathrm{H}_6+\mathrm{I}_2 \rightleftharpoons \mathrm{C}_6 \mathrm{H}_5 \mathrm{I}+\mathrm{HI}$
This reaction is a reversible reaction. The product $\ce{HI}$ reacts with iodobenzene to get back benzene.
Hence, direct iodination of benzene is not possible because the product $\ce{C_6​H_5 I}$ is reduced by $\ce{HI}.$

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