question_answer

The hydrolysis of 2-bromo-3-methyl butane by \[{{S}_{N}}1\] mechanism gives mainly

A)  3-methl-2-butanol

B)  2-methyl-2-butanol

C)  2, 2-dimethyl-l-propanol

D)  2 methyl-1-butanol

Correct Answer: B

Solution :

\[C{{H}_{3}}-\underset{\begin{smallmatrix}  | \\  Br \end{smallmatrix}}{\mathop{C}}\,H-\underset{\begin{smallmatrix}  | \\  C{{H}_{3}} \end{smallmatrix}}{\mathop{C}}\,H-C{{H}_{3}}\xrightarrow[-HBr]{{{H}^{+}}}\] \[\xrightarrow{{{H}^{-}}\text{Rearrangement}}\underset{3{}^\circ carbocation(more\,\,stable)}{\mathop{C{{H}_{3}}-C{{H}_{2}}-\underset{\begin{smallmatrix}  | \\  C{{H}_{3}} \end{smallmatrix}}{\overset{+}{\mathop{C}}}\,-C{{H}_{3}}}}\,\] \[\xrightarrow{O{{H}^{-}}}\underset{\text{2-methyl-2butanol}}{\mathop{C{{H}_{3}}-C{{H}_{2}}-\underset{\begin{smallmatrix}  | \\  OH \end{smallmatrix}}{\overset{\begin{smallmatrix}  C{{H}_{3}} \\  | \end{smallmatrix}}{\mathop{C}}}\,-C{{H}_{3}}}}\,\]