Question

Write the stepwise mechanism of nucleophilic addition reactions in the carbonyl compounds.

Answer 1

Generally, the nucleophilic addition reactions of carbonyl compounds take place in three steps:

Step 1: Electrophilic carbonyl compound forms a sigma bond with nucleophilic.

\[\begin{array}{cc}
\phantom{.....................}\ce{Nu}\phantom{.............}\ce{Nu}\\
\phantom{....................}|\phantom{...............}|\\
\ce{R - C = O + \overset{\bullet\bullet}{Nu} -> R - C - \overset{\bullet\bullet}{O} ->[H+] R - C - OH}\\
\phantom{....}|\phantom{.....................}|\phantom{...............}|\phantom{......}\\
\phantom{..}\ce{R/H}\phantom{..................}\ce{R/H}\phantom{...........}\ce{R/H}\phantom{.}\\
\end{array}\]

Step 2: The carbon-oxygen pi bond is broken to form negatively charged alkoxide.

Step 3: Protonation on alkoxide farming a derivative of alcohol.