NEETChemistryHaloalkanes and Haloarenes
Identify the major product formed when 1-chloro-2-methylpropane is subjected to the following sequence of reactions: 1-chloro-2-methylpropane [ (ii) H ₃ O ^+, ] (i) KCN A [ (iv) H ₂ O ] (iii) Br ₂/ Red P Major Product
Options
- A3-bromo-3-methylbutanoic acid
- B2-bromo-3-methylbutanoic acid
- C3-methylbutanoic acid
- D2-bromo-2-methylpropanoic acid
Correct answer
B. 2-bromo-3-methylbutanoic acid
Step-by-step solution
1-chloro-2-methylpropane reacts with KCN to undergo nucleophilic substitution, forming 3-methylbutanenitrile (an additional carbon is introduced to the main chain). Acidic hydrolysis of the nitrile group yields 3-methylbutanoic acid. Finally, treatment with Br ₂ and red phosphorus followed by hydrolysis is the Hell-Volhard-Zelinsky (HVZ) reaction. This reaction selectively halogenates the -carbon (the carbon adjacent to the carboxyl group). The -carbon in 3-methylbutanoic acid is a -CH ₂ - group. Replacing one hydr