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Explain preparation of alkyl halides by halogen exchange methods. |
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Answer» Solution :(i) Finkelstein Reaction : ALKYL iodides are often prepared by the reaction of alkyl chlorides or alkyl bromides with NaI in dry acetone. `underset("Bromoethane")(CH_(3)-CH_(2)-Br)+NaI overset(" Acetone ")RARR underset("Iodoethane")(CH_(3)CH_(2))-I + NaBr` `underset("Chloroethane")(CH_(3)CH_(2)Cl)+NaI overset(" Acetone ")rarr underset("Iodoethane")(CH_(3)CH_(2)I)+NaCl` NaCl or NaBr thus formed is PRECIPITATED in dry acetone. It facilitates the forward reaction according to Le Chatelier.s Principle. (ii) Swartz Reaction : The synthesis of alkyl fluorides is best accomplished by heating an alkyl chloride or alkyl BROMIDE in the presence of a metallic fluoride such as `AgF, Hg_(2)F_(2), CoF_(2)` or `SbF_(3)`. `H_(3)C-Br+AgF to H_(3)C-F+AgBr`. |
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