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An unknown alkyl bromide X ( C₉H₁₁Br ) is subjected to the following sequence of reactions: (i) t -BuOK / heat (ii) B₂H₆ followed by H₂O₂ / OH^- (iii) Jones reagent If the final isolated product is 2-phenylpropanoic acid, the structure of the starting material X is :

Options

  1. A1-Bromo-1-phenylpropane
  2. B2-Bromo-2-phenylpropane
  3. C1-Bromo-3-phenylpropane
  4. D2-Bromo-1-phenylpropane

Correct answer

B. 2-Bromo-2-phenylpropane

Step-by-step solution

The problem can be solved by retrosynthetic analysis: 1. The final product is 2-phenylpropanoic acid, which is formed by the oxidation of a primary alcohol using Jones reagent. The precursor must be 2-phenyl-1-propanol. 2. 2-phenyl-1-propanol is formed by the anti-Markovnikov hydration of an alkene using B₂H₆ / H₂O₂, OH^- . The required alkene is 2-phenylpropene. 3. 2-phenylpropene is formed by the dehydrohalogenation (E2 elimination) of the alkyl bromide X ( C₉H₁₁Br ) using a strong bulky base ( t -BuOK). Among th

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