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Give preparation of aryl halides from aromatic hydrocarbons. |
Answer» Solution :Haloarenes are obtained by the electrophilic substitution reactions of arenes. Aryl chlorides and Aryl bromides are prepared by chlorination and bromination respectively in presence of Lewis acid catalysts like iron or iron (III) chloride. The o - and p - isomers can be easily separated due to large difference in their melting points. Reactions with iodine are REVERSIBLE in nature and required the presence of an oxidiing agent such as `HNO_(3)` or `HIO_(4)` to oxidise the HI formed during iodination. `5HI+HIO_(3)to 3I_(2)+3H_(2)O`  Fluoroarenes are not prepared by this METHOD because of HIGH REACTIVITY of fluorine is difficult to control. |
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