Question

What type of hybridisation is present in carbocation formed during the alkaline hydrolysis of 1- bromo-1- phenyl ethane?

Options

• sp²

• sp

• d²sp²

• sp³

Answer 1

sp² 

Explanation:

Alkaline hydrolysis of 1-bromo-1-phenylethane produce 1-phenylethan-1-ol. The reaction proceeds via S_N 1 reaction. A carbocation Is formed in the slow step of an S_N 1 reaction. The positively charged carbon of the carbocation intermediate is sp² - hybridised and the three bonds connected to an sp² - hybridised are in the same plane. Reaction involved is as follows:

\[\begin{array}{cc}
\phantom{........}\ce{Br}\phantom{..................................}\ce{OH}\\
\phantom{......}|\phantom{....................................}|\\
\ce{CH3 - CH <=> CH3 - CH ->[OH^⊖][S_N1reaction] CH3 - CH}\\
\phantom{.....}|\phantom{...............}|\phantom{....................}|\\
\phantom{....}\ce{\underset{\text{-1 -phenyl ethane}}{\underset{\text{1-bromo}}{Ph}}}\phantom{..}\ce{\underset{\text{(hybridised)}}{\underset{\ce{sp^2}}{Ph}}}\phantom{............}\ce{Ph}\phantom{...}
\end{array}\]