Question
In the following reactions,
\[\left( \text{i} \right)C{{H}_{3}}\overset{\begin{smallmatrix}
\,\,C{{H}_{3}} \\
|\,\,\,\,
\end{smallmatrix}}{\mathop{-CH-}}\,\underset{\begin{smallmatrix}
|\,\,\,\,\,\,\,\,\,\,\, \\
OH\,\,\,\,\,\,\,\,
\end{smallmatrix}}{\mathop{CH-}}\,C{{H}_{3}}\] \[\xrightarrow{\frac{{{H}^{+}}}{\text{heat}}}\underset{\left[ \begin{smallmatrix}
\text{Major} \\
\text{product}
\end{smallmatrix} \right]}{\mathop{A}}\,+\underset{\left[ \begin{smallmatrix}
\text{Minor} \\
\text{product}
\end{smallmatrix} \right]}{\mathop{B}}\,\]
\[\left( \text{ii} \right)A\xrightarrow[\text{in absence of peroxide }]{HBr,\,\text{dark}}\] \[\underset{\left[ \begin{smallmatrix}
\text{Major} \\
\text{product}
\end{smallmatrix} \right]}{\mathop{C}}\,+\underset{\left[ \begin{smallmatrix}
\text{Minor} \\
\text{product}
\end{smallmatrix} \right]}{\mathop{D}}\,\]
The major products $$A$$ and $$C$$ are respectively
A.
\[C{{H}_{2}}=\overset{\begin{smallmatrix}
\,\,C{{H}_{3}} \\
|\,\,\,
\end{smallmatrix}}{\mathop{C-}}\,C{{H}_{2}}-C{{H}_{3}}\,\,\text{and}\] \[\underset{\begin{smallmatrix}
|\,\,\,\,\,\,\,\,\,\,\,\,\, \\
Br\,\,\,\,\,\,\,\,\,\,\,\,
\end{smallmatrix}}{\mathop{C{{H}_{2}}-}}\,\overset{\begin{smallmatrix}
C{{H}_{3}}\,\, \\
|\,\,\,\,\,\,\,\,
\end{smallmatrix}}{\mathop{CH-}}\,C{{H}_{2}}-C{{H}_{3}}\]
B.
\[C{{H}_{3}}\overset{\begin{smallmatrix}
\,\,\,\,\,C{{H}_{3}} \\
|
\end{smallmatrix}}{\mathop{-C=}}\,CH-C{{H}_{3}}\,\,\text{and}\] \[C{{H}_{3}}\underset{\begin{smallmatrix}
| \\
Br
\end{smallmatrix}}{\overset{\begin{smallmatrix}
\,\,\,\,\,\,C{{H}_{3}} \\
\,|
\end{smallmatrix}}{\mathop{-C-}}}\,C{{H}_{2}}-C{{H}_{3}}\]
C.
\[C{{H}_{3}}\overset{\begin{smallmatrix}
\,\,\,\,\,C{{H}_{3}} \\
|
\end{smallmatrix}}{\mathop{-C=}}\,CH-C{{H}_{3}}\,\,\text{and}\] \[C{{H}_{3}}\overset{\begin{smallmatrix}
\,\,\,C{{H}_{3}} \\
|\,\,\,
\end{smallmatrix}}{\mathop{-CH-}}\,\underset{\begin{smallmatrix}
|\,\,\,\,\,\,\,\,\,\,\,\, \\
Br\,\,\,\,\,\,\,\,\,\,\,
\end{smallmatrix}}{\mathop{CH-}}\,C{{H}_{3}}\]
D.
\[C{{H}_{2}}\overset{\begin{smallmatrix}
\,\,\,\,\,\,\,\,C{{H}_{3}} \\
\,\,\,|
\end{smallmatrix}}{\mathop{=C-}}\,C{{H}_{2}}-C{{H}_{3}}\,\,\text{and}\] \[C{{H}_{3}}\underset{\begin{smallmatrix}
| \\
Br
\end{smallmatrix}}{\overset{\begin{smallmatrix}
\,\,\,\,\,\,C{{H}_{3}} \\
\,|
\end{smallmatrix}}{\mathop{-C-}}}\,C{{H}_{2}}-C{{H}_{3}}\]
Answer :
\[C{{H}_{3}}\overset{\begin{smallmatrix}
\,\,\,\,\,C{{H}_{3}} \\
|
\end{smallmatrix}}{\mathop{-C=}}\,CH-C{{H}_{3}}\,\,\text{and}\] \[C{{H}_{3}}\underset{\begin{smallmatrix}
| \\
Br
\end{smallmatrix}}{\overset{\begin{smallmatrix}
\,\,\,\,\,\,C{{H}_{3}} \\
\,|
\end{smallmatrix}}{\mathop{-C-}}}\,C{{H}_{2}}-C{{H}_{3}}\]
Solution :
\[\overset{\begin{smallmatrix}
\,\,\,\,\,\,\,\,C{{H}_{3}} \\
\,\,\,|
\end{smallmatrix}}{\mathop{C{{H}_{3}}CH-}}\,\underset{\begin{smallmatrix}
|\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, \\
OH\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,
\end{smallmatrix}}{\mathop{CHC{{H}_{3}}}}\,\xrightarrow[\text{heat}]{{{H}^{+}}}\] \[\underset{\,\,\,\,\downarrow 1\text{, 2-hydride shift}}{\mathop{C{{H}_{3}}\overset{\begin{smallmatrix}
\,\,\,C{{H}_{3}} \\
|\,\,\,
\end{smallmatrix}}{\mathop{-CH-}}\,\underset{+\,\,\,\,}{\mathop{CH}}\,-C{{H}_{3}}}}\,\]
\[\underset{\begin{smallmatrix}
\left( A \right) \\
\text{Major}
\\
\text{+}
\end{smallmatrix}}{\mathop{C{{H}_{3}}\overset{\begin{smallmatrix}
\,\,\,\,\,C{{H}_{3}} \\
|
\end{smallmatrix}}{\mathop{-C=}}\,CH-C{{H}_{3}}}}\,\xleftarrow{-{{H}^{+}}}\] \[C{{H}_{3}}\underset{+}{\overset{\begin{smallmatrix}
\,\,\,\,\,C{{H}_{3}} \\
|
\end{smallmatrix}}{\mathop{-C-}}}\,C{{H}_{2}}-C{{H}_{3}}\]
\[\,\,\,\,\,\,\,\underset{\begin{smallmatrix}
\left( B \right) \\
\text{Minor}
\end{smallmatrix}}{\mathop{C{{H}_{3}}\overset{\begin{smallmatrix}
\,\,C{{H}_{3}} \\
|\,\,\,
\end{smallmatrix}}{\mathop{-CH-}}\,CH=C{{H}_{2}}}}\,\]
\[\underset{\begin{smallmatrix}
\left( A \right) \\
\text{Major}
\end{smallmatrix}}{\mathop{C{{H}_{3}}\overset{\begin{smallmatrix}
\,\,\,\,\,C{{H}_{3}} \\
|
\end{smallmatrix}}{\mathop{-C=}}\,CH-C{{H}_{3}}}}\,\] \[\xrightarrow[\text{in absence of peroxide}]{HBr,\,\text{dark}}\]
\[\underset{\left( C \right)\,\text{Major}}{\mathop{C{{H}_{3}}\underset{\begin{smallmatrix}
| \\
Br
\end{smallmatrix}}{\overset{\begin{smallmatrix}
\,\,\,\,\,\,C{{H}_{3}} \\
\,|
\end{smallmatrix}}{\mathop{-C-}}}\,C{{H}_{2}}-C{{H}_{3}}}}\,+\] \[\underset{\left( D \right)\text{ Minor}}{\mathop{C{{H}_{3}}\overset{\begin{smallmatrix}
\,\,\,C{{H}_{3}} \\
|\,\,\,
\end{smallmatrix}}{\mathop{-CH-}}\,\underset{\begin{smallmatrix}
|\,\,\,\,\,\,\,\,\,\,\,\, \\
Br\,\,\,\,\,\,\,\,\,\,\,
\end{smallmatrix}}{\mathop{CH-}}\,C{{H}_{3}}}}\,\]