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JEE MainChemistryHaloalkanes and Haloarenes

An unknown aromatic alkyl halide X undergoes the following sequence of reactions: (i) NaCN (ii) NaOEt, cyclopentanone (iii) LiAlH ₄ If the major final product is 1-(2-amino-1-phenylethyl)cyclopentan-1-ol, the structure of X is

Options

  1. A(2-Bromoethyl)benzene
  2. B1-Bromo-1-phenylethane
  3. C2-Bromotoluene
  4. DBenzyl bromide

Correct answer

D. Benzyl bromide

Step-by-step solution

Working backwards from the final product: The final product, 1-(2-amino-1-phenylethyl)cyclopentan-1-ol, contains a primary amine group ( - CH ₂ NH ₂ ) which is formed by the reduction of a nitrile ( - CN) group using LiAlH ₄ in step (iii). The precursor before reduction is 1-(cyanophenylmethyl)cyclopentan-1-ol. This -hydroxynitrile is formed in step (ii) via the nucleophilic addition of a carbanion to cyclopentanone. The carbanion is generated by the deprotonation of the acidic -hydrogen of a nitrile. The required

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