Methods Of Preparation Of Haloalkanes

The conversion of ethyl bromide to ethyl iodide using sodium iodide and dry acetone, this reaction is known as Finkelstein reaction.

In dry acetone, sodium bromide gets precipitated.

Concept: Alcoholic KOH promotes elimination reactions (E2 mechanism) in alkyl halides, leading to the formation of alkenes. According to Saytzeff's rule, the more substituted alkene is the major product.

Step 1: Identify the reaction type. 2-bromopentane reacts with alcoholic KOH via β-elimination, removing a hydrogen atom from the β-carbon and bromine from the α-carbon.

Step 2: Apply Saytzeff's rule. The elimination favors formation of the more substituted alkene. Therefore, pent-2-ene is formed as the major product rather than pent-1-ene. Thus,