question_answer

In the following reaction, \[\underset{\underset{\text{Major}\,\text{product}}{\mathop{\text{A}}}\,\text{+}\underset{\text{Minor}\,\text{product}}{\mathop{\text{B}}}\,}{\mathop{{{\text{H}}_{\text{3}}}\text{C}-\underset{\begin{smallmatrix}  \text{ }\!\!|\!\!\text{ } \\  \text{C}{{\text{H}}_{\text{3}}} \end{smallmatrix}}{\overset{\begin{smallmatrix}  \text{C}{{\text{H}}_{\text{3}}} \\  \text{ }\!\!|\!\!\text{ } \end{smallmatrix}}{\mathop{\text{C}}}}\,-\text{CH}\,\text{=}\,\text{C}{{\text{H}}_{\text{2}}}\xrightarrow[{}]{{{\text{H}}_{\text{2}}}\text{O/}{{\text{H}}^{\text{{ }\!\!\mathrm{\AA}\!\!\text{ }}}}}}}\,\]

A) \[{{\text{H}}_{\text{3}}}\text{C}-\underset{\begin{smallmatrix}  | \\  \text{OH} \end{smallmatrix}}{\overset{\begin{smallmatrix}  \text{C}{{\text{H}}_{\text{3}}} \\  | \end{smallmatrix}}{\mathop{\text{C}-}}}\,\underset{\begin{smallmatrix}  \text{ }\!\!|\!\!\text{ } \\  \text{C}{{\text{H}}_{\text{3}}} \end{smallmatrix}}{\mathop{\text{CH}}}\,-\text{C}{{\text{H}}_{\text{3}}}\]

B) \[\underset{\begin{smallmatrix}  | \\  \text{OH} \end{smallmatrix}}{\mathop{\text{C}{{\text{H}}_{\text{2}}}}}\,-\text{C}-\underset{\begin{smallmatrix}  | \\  \text{C}{{\text{H}}_{\text{3}}} \end{smallmatrix}}{\overset{\begin{smallmatrix}  \text{C}{{\text{H}}_{\text{3}}} \\  | \end{smallmatrix}}{\mathop{\text{C}-}}}\,\text{C}{{\text{H}}_{\text{2}}}-\text{C}{{\text{H}}_{\text{3}}}\]

C) \[{{\text{H}}_{\text{3}}}\text{C}-\underset{\begin{smallmatrix}  | \\  \text{C}{{\text{H}}_{\text{3}}} \end{smallmatrix}}{\overset{\begin{smallmatrix}  \text{C}{{\text{H}}_{\text{3}}} \\  | \end{smallmatrix}}{\mathop{\text{C}-}}}\,\underset{\begin{smallmatrix}  \text{ }\!\!|\!\!\text{ } \\  \text{OH} \end{smallmatrix}}{\mathop{\text{CH}}}\,-\text{C}{{\text{H}}_{\text{3}}}\]

D) \[{{\text{H}}_{\text{3}}}\text{C}-\underset{\begin{smallmatrix}  | \\  \text{C}{{\text{H}}_{\text{3}}} \end{smallmatrix}}{\overset{\begin{smallmatrix}  \text{C}{{\text{H}}_{\text{3}}} \\  | \end{smallmatrix}}{\mathop{\text{C}-}}}\,\text{C}{{\text{H}}_{2}}-\underset{\begin{smallmatrix}  \text{ }\!\!|\!\!\text{ } \\  \text{OH} \end{smallmatrix}}{\mathop{\text{C}{{\text{H}}_{\text{2}}}}}\,\]

Correct Answer: A

Solution :

\[{{\text{H}}_{\text{3}}}\text{C}-\underset{\begin{smallmatrix}  \text{ }\!\!|\!\!\text{ } \\  \text{C}{{\text{H}}_{\text{3}}} \end{smallmatrix}}{\overset{\begin{smallmatrix}  \text{C}{{\text{H}}_{\text{3}}} \\  | \end{smallmatrix}}{\mathop{\text{C}}}}\,-\text{CH}\,\text{=}\,\text{C}{{\text{H}}_{\text{2}}}\xrightarrow[{}]{\text{H+}}\underset{{{2}^{o}}carbocation}{\mathop{{{\text{H}}_{\text{3}}}-\underset{\begin{smallmatrix}  \text{ }\!\!|\!\!\text{ } \\  \text{C}{{\text{H}}_{\text{3}}} \end{smallmatrix}}{\overset{\begin{smallmatrix}  \text{C}{{\text{H}}_{\text{3}}} \\  | \end{smallmatrix}}{\mathop{\text{C}}}}\,-}}\,\overset{\text{+}}{\mathop{\text{C}}}\,\text{H}-\text{C}{{\text{H}}_{\text{3}}}\]         \[{{\text{H}}_{\text{3}}}\text{C}-\underset{\begin{smallmatrix}  {{\text{3}}^{\text{o}}}\,\text{carbocation} \\  \text{(more}\,\text{stable)} \end{smallmatrix}}{\mathop{\underset{+}{\overset{\begin{smallmatrix}  \text{C}{{\text{H}}_{\text{3}}} \\  | \end{smallmatrix}}{\mathop{\text{C}}}}\,-\underset{\begin{smallmatrix}  | \\  \text{H} \end{smallmatrix}}{\overset{\begin{smallmatrix}  \text{C}{{\text{H}}_{\text{3}}} \\  | \end{smallmatrix}}{\mathop{\text{C}}}}\,-\text{C}{{\text{H}}_{\text{3}}}}}\,\xrightarrow[{}]{{{\text{H}}_{\text{2}}}\text{\ddot{O}:}}\]