Question

The product formed in the first step of the reaction

\[\begin{array}{cc}
\ce{Br}\phantom{......}\\
|\phantom{.......}\\
\ce{CH3-CH2-CH-CH2-CH-CH3}\\
\phantom{...............}|\\
\phantom{................}\ce{Br}
\end{array}\]

with excess Mg/Et₂O(Et = C₂H₅) is:

Options

• \[\begin{array}{cc}
  \ce{CH3-CH2-CH-CH2-CH-CH3}\\
  \phantom{.....}|\phantom{...........}|\phantom{.}\\
  \phantom{..}\ce{CH3-CH-CH2-CH-CH2-CH3}
  \end{array}\]

• \[\begin{array}{cc}
  \ce{CH3-CH2-CH-CH2-CH-CH3}\\
  \phantom{.....}|\phantom{...........}|\phantom{.}\\
  \ce{CH3-CH2-CH-CH2-CH-CH3}
  \end{array}\]

• \[\begin{array}{cc}
  \ce{MgBr}\phantom{.....}\\
  |\phantom{.......}\\
  \ce{CH3-CH2-CH-CH2-CH-CH3}\\
  \phantom{...............}|\\
  \phantom{...............}\ce{MgBr}
  \end{array}\]

• 

Answer 1

\[\begin{array}{cc}
\ce{MgBr}\phantom{.....}\\
|\phantom{.......}\\
\ce{CH3-CH2-CH-CH2-CH-CH3}\\
\phantom{...............}|\\
\phantom{...............}\ce{MgBr}
\end{array}\]

Explanation:

\[\begin{array}{cc}
\phantom{.}\ce{Br}\phantom{........................................}\ce{MgBr}\phantom{....}\\
\phantom{}|\phantom{..........................................}|\phantom{.......}\\
\ce{CH3-CH2-CH-CH2-CH-CH3 ->[Excess Mg][Et2O] CH3-CH2-CH-CH2-CH-CH3}\\
\phantom{.....................}|\phantom{..........................................}|\phantom{......}\\
\ce{\underset{(Grignard's reagent)}{\phantom{...................}Br\phantom{........................................}MgBr\phantom{}}}
\end{array}\]