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NEETChemistryHaloalkanes and Haloarenes

Consider the following reactions of 1-bromo-2-methylcyclopentane: (i) 1-bromo-2-methylcyclopentane aq. KOH, A (major) (ii) 1-bromo-2-methylcyclopentane alc. KOH, B (major) Identify the major products A and B.

Options

  1. AA = 2-methylcyclopentanol, B = 1-methylcyclopentene
  2. BA = 1-methylcyclopentene, B = 2-methylcyclopentanol
  3. CA = 2-methylcyclopentanol, B = 3-methylcyclopentene
  4. DA = 1-methylcyclopentanol, B = 1-methylcyclopentene

Correct answer

A. A = 2-methylcyclopentanol, B = 1-methylcyclopentene

Step-by-step solution

The nature of the solvent plays a crucial role in determining whether an alkyl halide undergoes substitution or elimination with KOH. In reaction (i), aqueous KOH is used. In an aqueous medium, the hydroxide ion ( OH ^- ) acts primarily as a nucleophile, leading to nucleophilic substitution. The bromine atom in 1-bromo-2-methylcyclopentane is replaced by a hydroxyl group, yielding 2-methylcyclopentanol as the major product A. In reaction (ii), alcoholic KOH is used. In an alcoholic medium, the alkoxide ions formed

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