Identify the intermediate compound 'P' in the given chemical...

The reaction of toluene with $\text{Cl}_2$ in the presence of sunlight ($h\nu$) proceeds via a free radical substitution mechanism at the side chain (benzylic position).

Since the final product upon hydrolysis is benzaldehyde ($\text{C}_6\text{H}_5\text{CHO}$), the intermediate compound P must be a geminal dihalide. Hydrolysis of a gem-dihalide yields an unstable gem-diol, which readily loses a water molecule to form an aldehyde.

Therefore, toluene reacts with two equivalents of $\text{Cl}_2$ to form benzal chloride ($\text{C}_6\text{H}_5\text{CHCl}_2$) as the intermediate P.

The reaction sequence is:
$\text{C}_6\text{H}_5\text{CH}_3 \xrightarrow{2\text{Cl}_2, h\nu} \text{C}_6\text{H}_5\text{CHCl}_2 \text{ (P)}$

$\text{C}_6\text{H}_5\text{CHCl}_2 \xrightarrow{\text{H}_2\text{O}, 373\text{ K}} [\text{C}_6\text{H}_5\text{CH(OH)}_2] \xrightarrow{-\text{H}_2\text{O}} \text{C}_6\text{H}_5\text{CHO}$

Hence, the intermediate compound P is $\text{C}_6\text{H}_5\text{CHCl}_2$.

Answer: $\text{C}_6\text{H}_5\text{CHCl}_2$